Science.gov

Sample records for 2-10 kev band

  1. Decline of the 2-10 keV Emission from Eta Carinae

    NASA Technical Reports Server (NTRS)

    Liburd, Jamar; Corcoran, Michael F.; Hamaguchi, Kenji; Gull, Theodore R.; Madura, Thomas; Teodoro, Mairan; Moffat, Anthony; Richardson, Noel; Russell, Chris; Pollock, Andrew; Owocki, Stan

    2014-01-01

    Analysis of Eta Car's X-ray spectrum in the 2-10 keV band using processed data from the X-ray Telescope on Swift reveals a peak flux on July 16, 2014 of 0.046 photons s(exp -1) cm(exp -2) (3.37+/-0.15×10(exp -10) ergs s(exp -1) cm(exp -2). This flux is similar to the previous maximum flux seen by the XRT, 3.53+/-0.13×10(exp -10) ergs s(exp -1) cm(exp -2) (0.049 photons s(exp -1) cm(exp -2), ATEL #6298). Since this peak on July 16, the most recent Swift XRT quicklook data show a drop in flux. On July 20, 2014 the XRT flux as seen in the quicklook data was 0.011 photons s(exp -1) cm(exp -2) (8.3+/-0.5×10(exp -11) ergs s(exp -1) cm(exp -2)). This most likely indicates that the 2-10 keV flux is in its declining phase as Eta Car approaches its deep X-ray minimum stage (Hamaguchi et al., 2014, ApJ, 784, 125) associated with periastron passage of the 2024-day binary orbit. The column density derived from analysis of the July 20 XRT quicklook data is 7.2×10(exp 22) cm(exp -2). This is consistent with the column density seen near the same orbital phase in 2003 (7.7×10(exp 22) cm(exp -2), Hamaguchi et al., 2007, ApJ, 663, 522). Eta Car's deep X-ray minimum phase is expected to begin on July 30, 2014. Weekly Swift/XRT observations of Eta Car in the 2-10 keV band are planned throughout the X-ray minimum.

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

    NASA Astrophysics Data System (ADS)

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

    2000-11-01

    The hard X-ray (>2 keV) emission of the local and distant universe as observed with the HEAO 1 A-2 experiment is reconsidered in the context of large-scale cosmic structure. Using all-sky X-ray samples of active galactic nuclei (AGNs) and galaxy clusters, we remove the dominant local X-ray flux from within a redshift of ~0.02. We evaluate the dipolar and higher order harmonic structure in four X-ray colors. The estimated dipole anisotropy of the unresolved flux appears to be consistent with a combination of the Compton-Getting effect due to the Local Group motion (dipole amplitude Δ=0.0042) and remaining large-scale structure (0.0023<~Δ<~0.0085), in good agreement with the expectations of cold dark matter models. The observed anisotropy does, however, also suggest a nonnegligible Galactic contribution that is more complex than current, simple models of >2 keV Galactic X-ray emission. Comparison of the soft and hard color maps with a harmonic analysis of the 1.5 keV ROSAT all-sky data qualitatively suggests that at least a third of the faint, unresolved ~18° scale structure in the HEAO 1 A-2 data may be Galactic in origin. However, the effect on measured flux dipoles is small (<~3%). We derive an expression for dipole anisotropy and acceleration and demonstrate how the dipole anisotropy of the distant X-ray frame can constrain the amplitude of bulk motions of the universe. From observed bulk motions over a local ~50 h-1 Mpc radius volume, we determine 0.14<~Ω0.60/bX(0)<~0.59, where Ω0 is the universal density parameter and bX(0) is the present-epoch bias parameter, defined as the ratio of fluctuations in the X-ray source density and the mass density.

  3. The 2-10 keV unabsorbed luminosity function of AGN from the LSS, CDFS, and COSMOS surveys

    NASA Astrophysics Data System (ADS)

    Ranalli, P.; Koulouridis, E.; Georgantopoulos, I.; Fotopoulou, S.; Hsu, L.-T.; Salvato, M.; Comastri, A.; Pierre, M.; Cappelluti, N.; Carrera, F. J.; Chiappetti, L.; Clerc, N.; Gilli, R.; Iwasawa, K.; Pacaud, F.; Paltani, S.; Plionis, E.; Vignali, C.

    2016-05-01

    The XMM-Large scale structure (XMM-LSS), XMM-Cosmological evolution survey (XMM-COSMOS), and XMM-Chandra deep field south (XMM-CDFS) surveys are complementary in terms of sky coverage and depth. Together, they form a clean sample with the least possible variance in instrument effective areas and point spread function. Therefore this is one of the best samples available to determine the 2-10 keV luminosity function of active galactic nuclei (AGN) and their evolution. The samples and the relevant corrections for incompleteness are described. A total of 2887 AGN is used to build the LF in the luminosity interval 1042-1046 erg s-1 and in the redshift interval 0.001-4. A new method to correct for absorption by considering the probability distribution for the column density conditioned on the hardness ratio is presented. The binned luminosity function and its evolution is determined with a variant of the Page-Carrera method, which is improved to include corrections for absorption and to account for the full probability distribution of photometric redshifts. Parametric models, namely a double power law with luminosity and density evolution (LADE) or luminosity-dependent density evolution (LDDE), are explored using Bayesian inference. We introduce the Watanabe-Akaike information criterion (WAIC) to compare the models and estimate their predictive power. Our data are best described by the LADE model, as hinted by the WAIC indicator. We also explore the recently proposed 15-parameter extended LDDE model and find that this extension is not supported by our data. The strength of our method is that it provides unabsorbed, non-parametric estimates, credible intervals for luminosity function parameters, and a model choice based on predictive power for future data. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and NASA.Tables with the samples of the posterior probability distributions

  4. Low-temperature volume radiation annealing of cold-worked bands of Al-Li-Cu-Mg alloy by 20-40 keV Ar+ ion

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, V. V.; Gushchina, N. V.; Mozharovsky, S. M.; Kaigorodova, L. I.

    2017-01-01

    The processes of radiation-dynamic nature (in contrast to the thermally-activated processes) in the course of short-term irradiation of 1 mm thick bands of cold-worked aluminum alloy 1441 (of system Al-Li-Cu-Mg) with Ar+ 20-40 keV were studied. An effect of in-the-bulk (throughout the whole of metal bands thickness) low-temperature radiation annealing of the named alloy, multiply accelerated as compared with common thermal annealing processes was registered (with projected ranges of ions of considered energies definitely not exceeding 0.1 μm). The processes of recrystallization and intermetallic structure changes (occurring within a few seconds of Ar+ irradiation) have the common features as well as the differences in comparison with the results of two hour standard thermal annealing.

  5. Sub-arcsec X-Ray Telescope for Imaging The Solar Corona In the 0.25 - 1.2 keV Band

    NASA Technical Reports Server (NTRS)

    Gallagher, Dennis; Cash, Webster; Jelsma, Schuyler; Farmer, Jason

    1996-01-01

    We have developed an X-ray telescope that uses a new technique for focusing X-rays with grazing incidence optics. The telescope was built with spherical optics for all of its components, utilizing the high quality surfaces obtainable when polishing spherical (as opposed to aspherical) optics. We tested the prototype X-ray telescope in the 300 meter vacuum pipe at White Sands Missile Range, NM. The telescope features 2 degee graze angles with tungsten coatings, yielding a bandpass of 0.25-1.5 keV with a peak effective area of 0.8 sq cm at 0.83 keV. Results from X-ray testing at energies of 0.25 keV and 0.93 keV (C-K and Cu-L) verify 0.5 arcsecond performance at 0.93 keV. Results from modeling the X-ray telescope's response to the Sun show that the current design would be capable of recording 10 half arcsecond images of a solar active region during a 300 second NASA sounding rocket flight.

  6. NuSTAR Resolves the First Dual AGN above 10 keV in SWIFT J2028.5+2543

    NASA Astrophysics Data System (ADS)

    Koss, Michael J.; Glidden, Ana; Baloković, Mislav; Stern, Daniel; Lamperti, Isabella; Assef, Roberto; Bauer, Franz; Ballantyne, David; Boggs, Steven E.; Craig, William W.; Farrah, Duncan; Fürst, Felix; Gandhi, Poshak; Gehrels, Neil; Hailey, Charles J.; Harrison, Fiona A.; Markwardt, Craig; Masini, Alberto; Ricci, Claudio; Treister, Ezequiel; Walton, Dominic J.; Zhang, William W.

    2016-06-01

    We have discovered heavy obscuration in the dual active galactic nucleus (AGN) in the Swift/Burst Alert Telescope (BAT) source SWIFT J2028.5+2543 using Nuclear Spectroscopic Telescope Array (NuSTAR). While an early XMM-Newton study suggested the emission was mainly from NGC 6921, the superior spatial resolution of NuSTAR above 10 keV resolves the Swift/BAT emission into two sources associated with the nearby galaxies MCG +04-48-002 and NGC 6921 (z = 0.014) with a projected separation of 25.3 kpc (91″). NuSTAR's sensitivity above 10 keV finds both are heavily obscured to Compton-thick levels (N H ≈ (1-2) × 1024 cm-2) and contribute equally to the BAT detection ({L}10-50 {keV}{{int}} ≈ 6 × 1042 erg s-1). The observed luminosity of both sources is severely diminished in the 2-10 keV band ({L} 2-10 {keV}{{obs}}\\lt 0.1× {L} 2-10 {keV}{{int}}), illustrating the importance of >10 keV surveys like those with NuSTAR and Swift/BAT. Compared to archival X-ray data, MCG +04-48-002 shows significant variability (>3) between observations. Despite being bright X-ray AGNs, they are difficult to detect using optical emission-line diagnostics because MCG +04-48-002 is identified as a starburst/composite because of the high rates of star formation from a luminous infrared galaxy while NGC 6921 is only classified as a LINER using line detection limits. SWIFT J2028.5+2543 is the first dual AGN resolved above 10 keV and is the second most heavily obscured dual AGN discovered to date in the X-rays other than NGC 6240.

  7. Influence of the active medium composition on the gain in the 00/sup 0/2--(10/sup 0/1, 02/sup 0/1)/sub I/ band for a TEA CO/sub 2/ laser with ultraviolet preionization

    SciTech Connect

    Bertel', I.M.; Petukhov, V.O.; Trushin, S.A.; Churakov, V.V.

    1982-07-01

    An experimental and theoretical investigation was made of the small-signal gains of lines in the second sequence band, and of the temperature of the asymmetric ..nu../sub 3/ mode of the CO/sub 2/ molecule in a TEA CO/sub 2/ amplifier as a function of the composition of the CO/sub 2/--N/sub 2/--He mixture. The optimal partial pressures of the component were determined. In a TEA CO/sub 2/ amplifier with ultraviolet preionization provided by auxiliary lateral discharges it was found that the maximum gain of approx.0.01 cm/sup -1/ for the 10P(19) line of the second sequence band was achieved in a CO/sub 2/:N/sub 2/:He = 1:1:3 mixture.

  8. Channel electron multiplier efficiency for protons of 0.2-10 keV.

    NASA Technical Reports Server (NTRS)

    Iglesias, G. E.; Mcgarity, J. O.

    1971-01-01

    The initial results of absolute proton efficiency measurements made in an auroral particle study by sounding rockets are given. The measurements were made at several counting rates from 1000 to 40,000 counts/sec on rocket-borne equipment. The results agree with those of Egidi et al. (1969) in the high energy range and show a disagreement at low energies.

  9. Absolute intensities and foreign gas broadening coefficients of the 11(sub 1,10) from 11(sub 2,10) and 18(sub 0,18) from 18(sub 1,18) lines in the nu(sub 7) band of C2H4

    NASA Technical Reports Server (NTRS)

    Reuter, Dennis C.; Sirota, J. Marcos

    1993-01-01

    Absolute intensities and foreign gas broadening coefficients of the 18(sub 0,18) from 18(sub 1,18) and 11(sub 1,10) from 11(sub 2,10) transitions in the nu(sub 7) band of C2H4 near 948/cm have been measured at a spectral resolution of approximately 5 x 10(exp -4)/cm using tunable diode laser spectrometry. Ar, He, N2, O2 were used as the broadening gases. In order to determine the temperature dependence of the broadening coefficient, data were obtained at temperatures ranging from 150 to 296 K. The absolute intensity of the 5(sub 0,5) from 5(sub 1,5) transition was also found at 296 K. A band strength of 330 +/- 10/sq cm/atm was obtained from weighted averages of the individual line intensities and a rigid asymmetric top calculation.

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  11. BeppoSAX broad-band observations of Gamma Cassiopeiae

    NASA Astrophysics Data System (ADS)

    Owens, A.; Oosterbroek, T.; Parmar, A. N.; Schulz, R.; Stüwe, J. A.; Haberl, F.

    1999-08-01

    We report broad-band X-ray measurements of the Be star gamma Cassiopeiae by the BeppoSAX X-ray astronomy satellite. The observations took place on 1998 July, 18-23. The 0.1-200 keV X-ray spectrum is reasonably well fit by an optically thin thermal plasma model of temperature 12.5+/-0.6 keV with significant residuals around 0.3 keV and 1 keV. The former is interpreted as the variable soft component reported by ROSAT, although there is no evidence for variability at the 5% level. For a blackbody interpretation, the fitted temperature is 100+/- (320) 13 eV, in agreement with the ROSAT value of 200+/- 10 eV. However, a MEKAL interpretation gives a significantly lower temperature of (48+/-11 eV). The fitted abundances are about half solar values, in agreement with previous measurements. At higher energies, the spectrum does not require non-thermal components and the observation of a line at 6.8 keV supports the ASCA interpretation of the source as an accreting white dwarf. Assuming a source distance of 188 pc, the bolometric luminosity in the 2-10 keV band is 6x10(32) ergs s(-1) . Simultaneous optical measurements by the Wendelstein Observatory near Munich, indicate that the source continues to be in a late but rather normal Be phase, with no obvious signs of a transition to the Be-shell phase. The measured magnitudes at B, V and R wavelengths of 2.18+/-0.06, 2.23+/-0.02 and 2.36+/-0.03, respectively, confirm this.

  12. Possible contributions of supernova remnants to the soft X-ray diffuse background (0.1 - 1keV)

    NASA Technical Reports Server (NTRS)

    Sanders, W. T.; Burrows, D. N.; Mccammon, D.; Kraushaar, W. L.

    1982-01-01

    Almost all of the B band (0.10-0.19 keV) and C band (0.15-0.28 keV) X-rays probably originate in a hot region surrounding the Sun, which Cox and Anderson modeled as a supernova remnant. This same region may account for a significant fraction of the M band (0.5-1 keV) X-rays if the nonequilibrium models of Cox and Anderson are applicable. A population of distant SNR similar to the local region, with center-to-center spacing of about 300 pc, could provide enough galactic M band emission to fill in the dip in the count rate in the galactic plane that would otherwise be present due to absorption of both the extra galactic power law flux and any large-scale-height stellar (or galactic halo) emission.

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

    DOEpatents

    Wang, Ching L.

    1983-01-01

    An apparatus utilizing filter-fluorescer combinations is provided to measure short bursts of high fluence x-rays above 120 keV energy, where there are no practical absorption edges available for conventional filter-fluorescer techniques. The absorption edge of the prefilter is chosen to be less than that of the fluorescer, i.e., E.sub.PRF E.sub.F. In this way, the response function is virtually zero between E.sub.PRF and E.sub.F and well defined and enhanced in an energy band of less than 1000 keV above the 120 keV energy.

  14. GENIE Production Release 2.10.0

    SciTech Connect

    Alam, M.; Andreopoulos, C.; Athar, M.; Bodek, A.; Christy, E.; Coopersmith, B.; Dennis, S.; Dytman, S.; Gallagher, H.; Geary, N.; Golan, T.; Hatcher, R.; Hoshina, K.; Liu, J.; Mahn, K.; Marshall, C.; Morrison, J.; Nirkko, M.; Nowak, J.; Perdue, G. N.; Yarba, J.

    2015-12-25

    GENIE is a neutrino Monte Carlo event generator that simulates the primary interaction of a neutrino with a nuclear target, along with the subsequent propagation of the reaction products through the nuclear medium. It additionally contains libraries for fully-featured detector geometries and for managing various types of neutrino flux. This note details recent updates to GENIE, in particular, changes introduced into the newest production release, version 2.10.0.

  15. Grazing incidence diffraction of keV helium atoms on a Ag(110) surface.

    PubMed

    Bundaleski, N; Khemliche, H; Soulisse, P; Roncin, P

    2008-10-24

    Diffraction of fast atoms at grazing incidence has been recently demonstrated on the surface of alkali halides and wide band gap semiconductors, opening applications for the online monitoring of surface processes such as growth of ultrathin layers. This Letter reports energy resolved diffraction of helium on Ag(110) metal surface showing that a band gap is not mandatory to restrict the decoherence due to electron-hole pair excitations by the keV projectile. Measurement of the energy loss, which is in the eV range, sheds light on the scattering process.

  16. The 2-79 keV X-ray spectrum of the Circinus galaxy with NuSTAR, XMM-Newton, and Chandra: a fully Compton-thick active galactic nucleus

    SciTech Connect

    Arévalo, P.; Bauer, F. E.; Puccetti, S.; Walton, D. J.; Fuerst, F.; Grefenstette, B. W.; Harrison, F. A.; Madsen, K. K.; Koss, M.; Boggs, S. E.; Craig, W. W.; Brandt, W. N.; Luo, B.; Brightman, M.; Christensen, F. E.; Comastri, A.; Gandhi, P.; Hailey, C. J.; Madejski, G.; and others

    2014-08-20

    The Circinus galaxy is one of the closest obscured active galactic nuclei (AGNs), making it an ideal target for detailed study. Combining archival Chandra and XMM-Newton data with new NuSTAR observations, we model the 2-79 keV spectrum to constrain the primary AGN continuum and to derive physical parameters for the obscuring material. Chandra's high angular resolution allows a separation of nuclear and off-nuclear galactic emission. In the off-nuclear diffuse emission, we find signatures of strong cold reflection, including high equivalent-width neutral Fe lines. This Compton-scattered off-nuclear emission amounts to 18% of the nuclear flux in the Fe line region, but becomes comparable to the nuclear emission above 30 keV. The new analysis no longer supports a prominent transmitted AGN component in the observed band. We find that the nuclear spectrum is consistent with Compton scattering by an optically thick torus, where the intrinsic spectrum is a power law of photon index Γ = 2.2-2.4, the torus has an equatorial column density of N {sub H} = (6-10) × 10{sup 24} cm{sup –2}, and the intrinsic AGN 2-10 keV luminosity is (2.3-5.1) × 10{sup 42} erg s{sup –1}. These values place Circinus along the same relations as unobscured AGNs in accretion rate versus Γ and L{sub X} versus L {sub IR} phase space. NuSTAR's high sensitivity and low background allow us to study the short timescale variability of Circinus at X-ray energies above 10 keV for the first time. The lack of detected variability favors a Compton-thick absorber, in line with the spectral fitting results.

  17. The 2-79 keV X-Ray Spectrum of the Circinus Galaxy with NuSTAR, XMM-Newton, and Chandra: A Fully Compton-thick Active Galactic Nucleus

    NASA Astrophysics Data System (ADS)

    Arévalo, P.; Bauer, F. E.; Puccetti, S.; Walton, D. J.; Koss, M.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Comastri, A.; Craig, W. W.; Fuerst, F.; Gandhi, P.; Grefenstette, B. W.; Hailey, C. J.; Harrison, F. A.; Luo, B.; Madejski, G.; Madsen, K. K.; Marinucci, A.; Matt, G.; Saez, C.; Stern, D.; Stuhlinger, M.; Treister, E.; Urry, C. M.; Zhang, W. W.

    2014-08-01

    The Circinus galaxy is one of the closest obscured active galactic nuclei (AGNs), making it an ideal target for detailed study. Combining archival Chandra and XMM-Newton data with new NuSTAR observations, we model the 2-79 keV spectrum to constrain the primary AGN continuum and to derive physical parameters for the obscuring material. Chandra's high angular resolution allows a separation of nuclear and off-nuclear galactic emission. In the off-nuclear diffuse emission, we find signatures of strong cold reflection, including high equivalent-width neutral Fe lines. This Compton-scattered off-nuclear emission amounts to 18% of the nuclear flux in the Fe line region, but becomes comparable to the nuclear emission above 30 keV. The new analysis no longer supports a prominent transmitted AGN component in the observed band. We find that the nuclear spectrum is consistent with Compton scattering by an optically thick torus, where the intrinsic spectrum is a power law of photon index Γ = 2.2-2.4, the torus has an equatorial column density of N H = (6-10) × 1024 cm-2, and the intrinsic AGN 2-10 keV luminosity is (2.3-5.1) × 1042 erg s-1. These values place Circinus along the same relations as unobscured AGNs in accretion rate versus Γ and LX versus L IR phase space. NuSTAR's high sensitivity and low background allow us to study the short timescale variability of Circinus at X-ray energies above 10 keV for the first time. The lack of detected variability favors a Compton-thick absorber, in line with the spectral fitting results.

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

    NASA Technical Reports Server (NTRS)

    Phillips, K. J. H.

    2004-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Böke, Aysun

    2014-09-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  1. Rotational bands in99Sr

    NASA Astrophysics Data System (ADS)

    Pfeiffer, B.; Monnand, E.; Pinston, J. A.; Münzel, J.; Möller, P.; Krumlinde, J.; Ziegert, W.; Kratz, K.-L.

    1984-02-01

    The β-decay of 59 ms99Rb has been studied at OSTIS. As is confirmed by RPA calculations with Nilsson model wave functions, the lowest energy levels in99Sr are consistent with rotational bands built on the [411 3/2], [413 5/2] and [422 3/2] Nilsson neutron configurations at 0, 423 and 1071 keV, respectively. All three bands have similar values of the inertial parameter ħ2/2θ indicating a nearly rigid rotor.

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

    SciTech Connect

    Maire, D.; Lebreton, L.; Richer, J.P.; Bosson, G.; Bourrion, O.; Guillaudin, O.; Riffard, Q.; Santos, D.

    2015-07-01

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

  3. Implications of the 17 keV neutrino

    SciTech Connect

    Hall, L.J.

    1991-06-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  5. Study about the coloration of quartz glass induced by proton radiation with 80 keV

    NASA Astrophysics Data System (ADS)

    Wei, Q.; Liu, H.; He, S. Y.

    2004-03-01

    Under the environment of vacuum and heat sink, the change in optical transmittance of JGS3 optical quartz glass induced by radiation of protons with 80 keV was studied. When the radiation fluence exceeded 5 x 10(14) cm(-2) , two absorption bands appeared in the wavelength range of 209 and 220-240 nm and their peaks increased monotonously with the growing radiation fluence. With higher radiation fluence, weaker absorption bands were formed in the near-ultraviolet and visible regions. Color center E' was responsible for the 209 nm absorption peak, while it was disturbed by hydrogen for the 220-240 nm absorption peak. During the radiation, not only breaking of Si-O bonds and the formation of para-magnetism E' but also transition from the [=Si] and [=SiO] radicals into the [=SiH] and [=SiOH] should occur. Thus, a varied color center E' is formed.

  6. Band structure in 113Sn

    NASA Astrophysics Data System (ADS)

    Banerjee, P.; Ganguly, S.; Pradhan, M. K.; Sharma, H. P.; Muralithar, S.; Singh, R. P.; Bhowmik, R. K.

    2016-07-01

    The structure of collective bands in 113Sn, populated in the reaction 100Mo(19F,p 5 n ) at a beam energy of 105 MeV, has been studied. A new positive-parity sequence of eight states extending up to 7764.9 keV and spin (39 /2+) has been observed. The band is explained as arising from the coupling of the odd valence neutron in the g7 /2 or the d5 /2 orbital to the deformed 2p-2h proton configuration of the neighboring even-A Sn isotope. Lifetimes of six states up to an excitation energy of 9934.9 keV and spin 47 /2-belonging to a Δ I =2 intruder band have been measured for the first time, including an upper limit for the last state, from Doppler-shift-attenuation data. A moderate average quadrupole deformation β2=0.22 ±0.02 is deduced from these results for the five states up to spin 43 /2- . The transition quadrupole moments decrease with increase in rotational frequency, indicating a reduction of collectivity with spin, a feature common for terminating bands. The behavior of the kinematic and dynamic moments of inertia as a function of rotational frequency has been studied and total Routhian surface calculations have been performed in an attempt to obtain an insight into the nature of the states near termination.

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

    NASA Astrophysics Data System (ADS)

    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

    The Astronomical Röntgen Telescope (ART) is a medium-energy x-ray telescope system proposed for the Russian-led mission Spectrum Röntgen-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 > 3×1023 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.

  8. Small-scale fluctuations and angular correlations of the X-ray background in the HEAO 1 A-2 energy band - Constraints on clustering of X-ray sources

    NASA Technical Reports Server (NTRS)

    Martin-Mirones, J. M.; De Zotti, G.; Franceschini, A.; Boldt, E. A.; Marshall, F. E.; Danese, L.; Persic, M.

    1991-01-01

    HEAO 1 A-2 all-sky survey data have been used to determine the amplitude of intensity fluctuations of the extragalactic 2-10 keV X-ray background (XRB) over an effective solid angle of 1.84 sq deg and their angular correlation function on angular scales of less than 3 deg. A good empirical fit to the data is obtained assuming that the integral counts in the A-2 band have a slope of 1.65 + 0.06 or - 0.07. Alternatively, the data may imply a significant clustering of extragalactic X-ray sources.

  9. Seeded quantum FEL at 478 keV

    SciTech Connect

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

    2012-07-09

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

  10. Compact, maintainable 80-KeV neutral beam module

    DOEpatents

    Fink, Joel H.; Molvik, Arthur W.

    1980-01-01

    A compact, maintainable 80-keV arc chamber, extractor module for a neutral beam system immersed in a vacuum of <10.sup.-2 Torr, incorporating a nested 60-keV gradient shield located midway between the high voltage ion source and surrounding grounded frame. The shield reduces breakdown or arcing path length without increasing the voltage gradient, tends to keep electric fields normal to conducting surfaces rather than skewed and reduces the peak electric field around irregularities on the 80-keV electrodes. The arc chamber or ion source is mounted separately from the extractor or ion accelerator to reduce misalignment of the accelerator and to permit separate maintenance to be performed on these systems. The separate mounting of the ion source provides for maintaining same without removing the ion accelerator.

  11. Band heterotopia.

    PubMed

    Alam, M S; Naila, N

    2010-01-01

    Band heterotopias are one of the rarest groups of congenital disorder that result in variable degree of structural abnormality of brain parenchyma. Band of heterotopic neurons result from a congenital or acquired deficiency of the neuronal migration. MRI is the examination of choice for demonstrating these abnormalities because of the superb gray vs. white matter differentiation, detail of cortical anatomy and ease of multiplanar imaging. We report a case of band heterotopia that showed a bilateral band of gray matter in deep white matter best demonstrated on T2 Wt. and FLAIR images.

  12. The Soft Gamma-Ray Spectrum of A0535+26: Detection of an Absorption Feature at 110 keV by OSSE

    DTIC Science & Technology

    1995-01-01

    At the maximum, the pulsed emission reached 8 Crab ( nebula + pulsar) ux units in the 20{40 keV band (Finger, Wilson, & Hagedon 1994; Wilson et al...observation, the source and background elds were placed to ensure that the Crab Nebula , a potentially contaminating source, did not cause a signi cant

  13. 46 CFR 2.10-101 - Annual vessel inspection fee.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... listed in table 2.10-101 for its vessel category. (2) A vessel certificated for more than one service must pay only the higher of the two applicable fees in table 2.10-101 of this section. (b) The vessel... Inspection, reinspections (annual and periodic inspections), hull (drydock) inspections,...

  14. 46 CFR 2.10-101 - Annual vessel inspection fee.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... listed in table 2.10-101 for its vessel category. (2) A vessel certificated for more than one service must pay only the higher of the two applicable fees in table 2.10-101 of this section. (b) The vessel... Inspection, reinspections (annual and periodic inspections), hull (drydock) inspections,...

  15. 21 CFR 2.10 - Examination and investigation samples.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Examination and investigation samples. 2.10 Section 2.10 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL... samples. (a)(1) When any officer or employee of the Department collects a sample of a food, drug,...

  16. 21 CFR 2.10 - Examination and investigation samples.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Examination and investigation samples. 2.10 Section 2.10 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL... samples. (a)(1) When any officer or employee of the Department collects a sample of a food, drug,...

  17. 21 CFR 2.10 - Examination and investigation samples.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Examination and investigation samples. 2.10 Section 2.10 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL... samples. (a)(1) When any officer or employee of the Department collects a sample of a food, drug,...

  18. 21 CFR 2.10 - Examination and investigation samples.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Examination and investigation samples. 2.10 Section 2.10 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL... samples. (a)(1) When any officer or employee of the Department collects a sample of a food, drug,...

  19. 21 CFR 2.10 - Examination and investigation samples.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Examination and investigation samples. 2.10 Section 2.10 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL... samples. (a)(1) When any officer or employee of the Department collects a sample of a food, drug,...

  20. 28 CFR 2.10 - Date service of sentence commences.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 28 Judicial Administration 1 2012-07-01 2012-07-01 false Date service of sentence commences. 2.10 Section 2.10 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT... absconded from parole supervision; or (4) Comes within the provisions of paragraph (b) of this section....

  1. 28 CFR 2.10 - Date service of sentence commences.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 28 Judicial Administration 1 2011-07-01 2011-07-01 false Date service of sentence commences. 2.10 Section 2.10 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT... absconded from parole supervision; or (4) Comes within the provisions of paragraph (b) of this section....

  2. 28 CFR 2.10 - Date service of sentence commences.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 28 Judicial Administration 1 2014-07-01 2014-07-01 false Date service of sentence commences. 2.10 Section 2.10 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT... absconded from parole supervision; or (4) Comes within the provisions of paragraph (b) of this section....

  3. 10 CFR 960.5-2-10 - Hydrology.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 4 2013-01-01 2013-01-01 false Hydrology. 960.5-2-10 Section 960.5-2-10 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Preclosure Guidelines Ease and Cost of Siting, Construction, Operation, and Closure §...

  4. 10 CFR 960.5-2-10 - Hydrology.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 4 2012-01-01 2012-01-01 false Hydrology. 960.5-2-10 Section 960.5-2-10 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Preclosure Guidelines Ease and Cost of Siting, Construction, Operation, and Closure §...

  5. 10 CFR 960.5-2-10 - Hydrology.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 4 2014-01-01 2014-01-01 false Hydrology. 960.5-2-10 Section 960.5-2-10 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Preclosure Guidelines Ease and Cost of Siting, Construction, Operation, and Closure §...

  6. 10 CFR 960.5-2-10 - Hydrology.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 4 2011-01-01 2011-01-01 false Hydrology. 960.5-2-10 Section 960.5-2-10 Energy DEPARTMENT OF ENERGY GENERAL GUIDELINES FOR THE PRELIMINARY SCREENING OF POTENTIAL SITES FOR A NUCLEAR WASTE REPOSITORY Preclosure Guidelines Ease and Cost of Siting, Construction, Operation, and Closure §...

  7. 28 CFR 2.10 - Date service of sentence commences.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Date service of sentence commences. 2.10 Section 2.10 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT OF PRISONERS, YOUTH OFFENDERS, AND JUVENILE DELINQUENTS United States Code Prisoners and Parolees §...

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  9. KevJumba and the Adolescence of YouTube

    ERIC Educational Resources Information Center

    Saul, Roger

    2010-01-01

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

  10. OSSE observations of galactic 511 keV annihilation radiation

    NASA Technical Reports Server (NTRS)

    Purcell, W. R.; Grabelsky, D. A.; Johnson, W. N.; Jung, G. V.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Ulmer, M. P.

    1992-01-01

    The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma-Ray Observatory has performed several observations of the galactic plane and galactic center region to measure the distribution of galactic 511 keV positron annihilation radiation. Preliminary analysis of data collected during the observation of the galactic center region over the period 13-24 Jun. 1991, indicates the presence of a 511 keV line and positronium continuum superimposed on a power-law continuum. The line of flux was found to be (2.7 +/- 0.5) x 10(exp -4) gamma/sq cm sec, with a positronium fraction of (0.9 +/- 0.2). The 3(sigma) upper limit to daily variations in the 511 keV line flux from the mean during the observation interval is 3 x 10(exp -4) gamma/sq cm sec. If all of the observed annihilation radiation is assumed to originate from the x-ray source 1E 1740.7-2942, the corresponding 511 keV line flux would be (3.0 +/- 0.6) x 10(exp -4) gamma/sq cm sec. The 3(sigma) upper limit for 511 keV line emission from the x-ray binary GX1+4 is 6 x 10(exp -4) gamma/sq cm sec. Results from the galactic plane observations at galactic longitudes of 25 degrees (16-21 Aug. 1991) and 339 degrees (6-11 Sep. 1991) suggest that the emission is concentrated near the galactic center. The observations and the preliminary results are described.

  11. A photoluminescence study of CuInSe2 single crystals ion implanted with 5 keV hydrogen

    NASA Astrophysics Data System (ADS)

    Yakushev, M. V.; Krustok, J.; Grossberg, M.; Volkov, V. A.; Mudryi, A. V.; Martin, R. W.

    2016-03-01

    CuInSe2 single crystals ion implanted with 5 keV hydrogen at doses from 3  ×  1014 to 1016 cm-2 are studied by photoluminescence (PL). The PL spectra before and after implantation reveal two bands, a main dominant band centred at 0.96 eV and a lower intensity band centred at 0.93 eV. Detailed analysis of the shape of these bands, their temperature and excitation intensity dependencies allow the recombination mechanisms to be identified as band-to-tail (BT) and band-to-impurity (BI), respectively. The implantation causes gradual red shifts of the bands increasing linearly with the dose. The average depth of potential fluctuations is also estimated to increase with the dose and saturates for doses above 1015 cm-2. A model is proposed which associates the potential fluctuations with the antisite defects copper on indium site and indium on copper site. The saturation is explained by full randomization of copper and indium atoms on the cation sub-lattice.

  12. Spectroscopy from 2 to 200 keV

    NASA Technical Reports Server (NTRS)

    Helfand, D. J.; Chanan, G. A.; Novick, R.; Maccallum, C. J.; Leventhal, M.

    1981-01-01

    The astrophysical processes responsible for line and continuum emission in the spectra range 2 keV to 200 keV are examined from the viewpoint of designing a spectrometer which would operate in this regime. Phenomena considered include fluorescent line radiation in X-ray binaries, magnetically shifted iron lines and cyclotron emission from neutron star surfaces, line emission from cosmically abundant elements in thermal plasmas, and nuclear deexcitation lines in fresh nucleosynthetically produced matter. An instrument consisting of a approximately 10 sq cm array of planar germanium detectors surrounded by a large sodium-iodide anticoincidence shield is described and projected background rates and sensitivities are considered. A sample observing program for a two-day shuttle-based mission is included as an example of the wide range of scientific questions which could be addressed by such an instrument.

  13. Excitation of Banded Whistler Waves in the Magnetosphere

    SciTech Connect

    Gary, S. Peter; Liu, Kaijun; Winske, Dan

    2012-07-13

    Banded whistler waves can be generated by the whistler anisotropy instability driven by two bi-Maxwellian electron components with T{sub {perpendicular}}/T{sub {parallel}} > 1 at different T{sub {parallel}} For typical magnetospheric condition of 1 < {omega}{sub e}/{Omega}{sub e} < 5 in regions associated with strong chorus, upper-band waves can be excited by anisotropic electrons below {approx} 1 keV, while lower-band waves are excited by anisotropic electrons above {approx} 10 keV. Lower-band waves are generally field-aligned and substantially electromagnetic, while upper-band waves propagate obliquely and have quasi-electrostatic fluctuating electric fields. The quasi-electrostatic feature of upper-band waves suggests that they may be more easily identified in electric field observations than in magnetic field observations. Upper-band waves are liable to Landau damping and the saturation level of upperband waves is lower than lower-band waves, consistent with observations that lower-band waves are stronger than upper-band waves on average. The oblique propagation, the lower saturation level, and the more severe Landau damping together would make upper-band waves more tightly confined to the geomagnetic equator (|{lambda}{sub m}| < {approx}10{sup o}) than lower-band waves.

  14. Anisotropy measurements of nearly 50 KeV solar protons

    NASA Technical Reports Server (NTRS)

    Gold, R. E.; Bostrom, C. O.; Roelof, E. C.; Williams, D. J.

    1975-01-01

    The Energetic Particles Experiment on IMP-7 measures the angular distribution of 50-200 keV solar protons in 16 sectors. The velocity of 50 keV protons may be less than 5 times that of the solar wind. A generalized nonlinear Compton-Getting point transformation into the co-moving frame that contains no assumptions as to the angular distribution of either the spectrum or intensity is presented. Nearly 50 keV proton data in the spacecraft frame exhibit an anisotropy ratio that is large (not less than 5) and radial throughout the October 29, 1972 event lasting more than 9 days at this energy. This anisotropy argues against impulsive injection and diffusive decay in the inner solar system. Application of the transformation to the data reveals a long lasting residual anisotropy in the co-moving frame with protons streaming from the sun. Differences between the co-moving frame and solar wind frame velocities suggest residual electric fields upstream from the bow shock.

  15. Evaluation of the 232Th Neutron Cross Sections between 4 keV and 140 keV

    SciTech Connect

    Volev, K.; Koyumdjieva, N.; Brusegan, A.; Borella, A.; Siegler, P.; Schillebeeckx, P.; Janeva, N.; Lukyanov, A.; Leal, L.

    2005-05-24

    An evaluation of the 232Th neutron total and capture cross sections has been performed in the energy region between 4 keV and 140 keV. The evaluation results from a simultaneous analysis of capture, transmission, and self-indication measurement data, including the most recent capture cross-section data obtained at the GELINA facility of the Institute for Reference Materials and Measurements at Geel (B) and at the n-TOF facility at CERN (CH). The experimental data have been analysed in terms of average resonance parameters exploiting two independent theoretical approaches -- the Characteristic Function model and the Hauser-Feshbach-Moldauer theory. The resulting parameters are consistent with the resolved resonance parameters deduced from the transmission measurements of Olsen et al. at the ORELA facility.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  17. 28 CFR 2.10 - Date service of sentence commences.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Section 2.10 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT... imposed. (b) The imposition of a sentence of imprisonment for civil contempt shall interrupt the running of any sentence of imprisonment being served at the time the sentence of civil contempt is...

  18. 36 CFR 2.10 - Camping and food storage.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Camping and food storage. 2... RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.10 Camping and food storage. (a) The superintendent may... revocation of the permit. (d) Food storage. The superintendent may designate all or a portion of a park...

  19. 36 CFR 2.10 - Camping and food storage.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 36 Parks, Forests, and Public Property 1 2011-07-01 2011-07-01 false Camping and food storage. 2... RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.10 Camping and food storage. (a) The superintendent may... revocation of the permit. (d) Food storage. The superintendent may designate all or a portion of a park...

  20. 36 CFR 2.10 - Camping and food storage.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 36 Parks, Forests, and Public Property 1 2013-07-01 2013-07-01 false Camping and food storage. 2... RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.10 Camping and food storage. (a) The superintendent may... revocation of the permit. (d) Food storage. The superintendent may designate all or a portion of a park...

  1. 36 CFR 2.10 - Camping and food storage.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 36 Parks, Forests, and Public Property 1 2014-07-01 2014-07-01 false Camping and food storage. 2... RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.10 Camping and food storage. (a) The superintendent may... revocation of the permit. (d) Food storage. The superintendent may designate all or a portion of a park...

  2. 36 CFR 2.10 - Camping and food storage.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 36 Parks, Forests, and Public Property 1 2012-07-01 2012-07-01 false Camping and food storage. 2... RESOURCE PROTECTION, PUBLIC USE AND RECREATION § 2.10 Camping and food storage. (a) The superintendent may... revocation of the permit. (d) Food storage. The superintendent may designate all or a portion of a park...

  3. Astrophysics and cosmology confront the 17 keV neutrino

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.; Turner, Michael S.

    1991-01-01

    A host of astrophysical and cosmological arguments severely constrain the properties of a 17 keV Dirac neutrino. Such a neutrino must have interactions beyond those of the standard electroweak theory to reduce its cosmic abundance (through decay or annihilation) by a factor of two hundred. A predicament arises because the additional helicity states of the neutrino necessary to construct a Dirac mass must have interactions strong enough to evade the astrophysical bound from SN 1987A, but weak enough to avoid violating the bound from primordial nucleosynthesis.

  4. Proposed FNAL 750 KeV Linac Injector Upgrade

    SciTech Connect

    Tan, C.Y.; Bollinger, D.S.; Schmidt, C.W.; /Fermilab

    2009-04-01

    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.

  5. Astrophysics and cosmology confront the 17-keV neutrino

    NASA Technical Reports Server (NTRS)

    Kolb, Edward W.; Turner, Michael S.

    1991-01-01

    A host of astrophysical and cosmological arguments severely constrain the properties of a 17 keV Dirac neutrino. Such a neutrino must have interactions beyond those of the standard electroweak theory to reduce its cosmic abundance (through decay or annihilation) by a factor of two hundred. A predicament arises because the additional helicity states of the neutrino necessary to construct a Dirac mass must have interactions strong enough to evade the astrophysical bound from SN 1987A, but weak enough to avoid violating the bound from primordial nucleosynthesis.

  6. GALAXY CLUSTERS IN THE SWIFT/BAT ERA. II. 10 MORE CLUSTERS DETECTED ABOVE 15 keV

    SciTech Connect

    Ajello, M.; Reimer, O.; Rebusco, P.; Cappelluti, N.; Boehringer, H.; La Parola, V.; Cusumano, G.

    2010-12-20

    We report on the discovery of 10 additional galaxy clusters detected in the ongoing Swift/Burst Alert Telescope (BAT) all-sky survey. Among the newly BAT-discovered clusters there are Bullet, A85, Norma, and PKS 0745-19. Norma is the only cluster, among those presented here, which is resolved by BAT. For all the clusters, we perform a detailed spectral analysis using XMM-Newton and Swift/BAT data to investigate the presence of a hard (non-thermal) X-ray excess. We find that in most cases the clusters' emission in the 0.3-200 keV band can be explained by a multi-temperature thermal model confirming our previous results. For two clusters (Bullet and A3667), we find evidence for the presence of a hard X-ray excess. In the case of the Bullet cluster, our analysis confirms the presence of a non-thermal, power-law-like, component with a 20-100 keV flux of 3.4 x 10{sup -12} erg cm{sup -2} s{sup -1} as detected in previous studies. For A3667, the excess emission can be successfully modeled as a hot component (kT {approx} 13 keV). We thus conclude that the hard X-ray emission from galaxy clusters (except the Bullet) has most likely a thermal origin.

  7. Galaxy Clusters in the Swift/BAT era II: 10 more Clusters detected above 15 keV

    SciTech Connect

    Ajello, M.; Rebusco, P.; Cappelluti, N.; Reimer, O.; Boehringer, H.; La Parola, V.; Cusumano, G.; /Palermo Observ.

    2010-10-27

    We report on the discovery of 10 additional galaxy clusters detected in the ongoing Swift/BAT all-sky survey. Among the newly BAT-discovered clusters there are: Bullet, Abell 85, Norma, and PKS 0745-19. Norma is the only cluster, among those presented here, which is resolved by BAT. For all the clusters we perform a detailed spectral analysis using XMM-Newton and Swift/BAT data to investigate the presence of a hard (non-thermal) X-ray excess. We find that in most cases the clusters emission in the 0.3-200 keV band can be explained by a multi-temperature thermal model confirming our previous results. For two clusters (Bullet and Abell 3667) we find evidence for the presence of a hard X-ray excess. In the case of the Bullet cluster, our analysis confirms the presence of a non-thermal, power-law like, component with a 20-100 keV flux of 3.4 x 10{sup -12} erg cm{sup -2} s{sup -1} as detected in previous studies. For Abell 3667 the excess emission can be successfully modeled as a hot component (kT = {approx}13 keV). We thus conclude that the hard X-ray emission from galaxy clusters (except the Bullet) has most likely thermal origin.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  9. Observations of the Galactic center 511 keV line

    NASA Technical Reports Server (NTRS)

    Gehrels, Neil

    1991-01-01

    A review of observations of the positron annihilation 511 keV line from the Galactic center and plane is presented. Emphasis is given to the new data from balloon observations in 1988 and 1989. The positron annihilation source in the direction of the center was found to be turned on again in 1988 October after being observed in a quiescent state since the early 1980s. There is evidence for variability between May and October in 1988. The new observations give the first data in which the line is spectrally resolved and in which the Galactic center and plane components of the annihilation radiation are independently measured. These data support the two-component model of the emission with a variable point source near the center and a steady-state source distributed along the galactic plane. Comparing measurements of narrow and wide field instruments in the 1980s gives a flux of about 8 x 10 exp -4 photons/sq cm/s for the point source in its high state and a flux of about 1.2 x 10 exp-3 photons/sq cm/s/rad for the galactic plane component with a relatively flat distribution over the central radian. The line width for the point source component is about 3 keV FWHM.

  10. Laparoscopic gastric banding

    MedlinePlus

    ... adjustable gastric banding; Bariatric surgery - laparoscopic gastric banding; Obesity - gastric banding; Weight loss - gastric banding ... gastric banding is not a "quick fix" for obesity. It will greatly change your lifestyle. You must ...

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

    SciTech Connect

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

    2008-02-25

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

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

    SciTech Connect

    Kumar, Rajiv Goyal, Meetika Sharma, Ambika; Aggarwal, Sanjeev; Sharma, Annu; Kanjilal, D.

    2015-05-15

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

  13. Magnetospheric plasma modeling (0-100 keV)

    NASA Technical Reports Server (NTRS)

    Garrett, H. B.; Spitale, G. C.

    1985-01-01

    Spacecraft surface charging, which is primarily a current balance phenomenon, is in general a function of the dominant currents to and from the vehicle's surface. Within the near-earth magnetosphere the dominant currents to the surface are the ambient space plasma fluxes between approximately 0 and 100 keV. A major effort to understand the near-earth environment was initiated when spacecraft charging became a major issue. The present paper has the objective to summarize the basic features of the models which have resulted from this effort. A description is given of four categories of models, based primarily on the degree of empirical and theoretical input. Types of quantitative models are discussed, taking into account definitions, statistical models, analytic models, static models, and time-dependent models. Engineering models are also considered, giving attention to baseline models and 'worst-case' models.

  14. Broad-Band Spectroscopy of Hercules X-1 with Suzaku

    NASA Technical Reports Server (NTRS)

    Asami, Fumi; Enoto, Teruaki; Iwakiri, Wataru; Yamada, Shin'ya; Tamagawa, Toru; Mihara, Tatehiro; Nagase, Fumiaki

    2014-01-01

    Hercules X-1 was observed with Suzaku in the main-on state from 2005 to 2010. The 0.4- 100 keV wide-band spectra obtained in four observations showed a broad hump around 4-9 keV in addition to narrow Fe lines at 6.4 and 6.7 keV. The hump was seen in all the four observations regardless of the selection of the continuum models. Thus it is considered a stable and intrinsic spectral feature in Her X-1. The broad hump lacked a sharp structure like an absorption edge. Thus it was represented by two different spectral models: an ionized partial covering or an additional broad line at 6.5 keV. The former required a persistently existing ionized absorber, whose origin was unclear. In the latter case, the Gaussian fitting of the 6.5-keV line needs a large width of sigma = 1.0-1.5 keV and a large equivalent width of 400-900 eV. If the broad line originates from Fe fluorescence of accreting matter, its large width may be explained by the Doppler broadening in the accretion flow. However, the large equivalent width may be inconsistent with a simple accretion geometry.

  15. Identification of the Hard X-Ray Source Dominating the E > 25 keV Emission of the Nearby Galaxy M31

    NASA Astrophysics Data System (ADS)

    Yukita, M.; Ptak, A.; Hornschemeier, A. E.; Wik, D.; Maccarone, T. J.; Pottschmidt, K.; Zezas, A.; Antoniou, V.; Ballhausen, R.; Lehmer, B. D.; Lien, A.; Williams, B.; Baganoff, F.; Boyd, P. T.; Enoto, T.; Kennea, J.; Page, K. L.; Choi, Y.

    2017-03-01

    We report the identification of a bright hard X-ray source dominating the M31 bulge above 25 keV from a simultaneous NuSTAR–Swift observation. We find that this source is the counterpart to Swift J0042.6+4112, which was previously detected in the Swift BAT All-sky Hard X-ray Survey. This Swift BAT source had been suggested to be the combined emission from a number of point sources; our new observations have identified a single X-ray source from 0.5 to 50 keV as the counterpart for the first time. In the 0.5–10 keV band, the source had been classified as an X-ray Binary candidate in various Chandra and XMM-Newton studies; however, since it was not clearly associated with Swift J0042.6+4112, the previous E < 10 keV observations did not generate much attention. This source has a spectrum with a soft X-ray excess (kT ∼ 0.2 keV) plus a hard spectrum with a power law of {{Γ }}∼ 1 and a cutoff around 15–20 keV, typical of the spectral characteristics of accreting pulsars. Unfortunately, any potential pulsation was undetected in the NuSTAR data, possibly due to insufficient photon statistics. The existing deep HST images exclude high-mass (>3 {M}ȯ ) donors at the location of this source. The best interpretation for the nature of this source is an X-ray pulsar with an intermediate-mass (<3 {M}ȯ ) companion or a symbiotic X-ray binary. We discuss other possibilities in more detail.

  16. CPLOAS_2 V2.10 verification report.

    SciTech Connect

    Groth, Katrina M.

    2014-07-01

    A series of test cases designed to verify the correct implementation of several features of the CPLOAS_2 program are documented. CPLOAS_2 is used to calculate the probability of loss of assured safety (PLOAS) for a weak link (WL)/strong link (SL) system. CPLOAS_2 takes physical properties (e.g., temperature, pressure, etc.) of a WL/SL system and uses these properties and definitions of link failure properties in probabilistic calculations to determine PLOAS. The features being tested include (i) six aleatory distribution forms, (ii) five numerical procedures for the determination of PLOAS (i.e., one quadrature procedure, two simple random sampling procedures, and two importance sampling procedures), and (iii) time and environmental margin calculations. All tests were performed with CPLOAS_2 version 2.10.

  17. An X-ray Raman spectrometer for EXAFS studies on minerals: bent Laue spectrometer with 20 keV X-rays.

    PubMed

    Hiraoka, N; Fukui, H; Tanida, H; Toyokawa, H; Cai, Y Q; Tsuei, K D

    2013-03-01

    An X-ray Raman spectrometer for studies of local structures in minerals is discussed. Contrary to widely adopted back-scattering spectrometers using ≤10 keV X-rays, a spectrometer utilizing ~20 keV X-rays and a bent Laue analyzer is proposed. The 20 keV photons penetrate mineral samples much more deeply than 10 keV photons, so that high intensity is obtained owing to an enhancement of the scattering volume. Furthermore, a bent Laue analyzer provides a wide band-pass and a high reflectivity, leading to a much enhanced integrated intensity. A prototype spectrometer has been constructed and performance tests carried out. The oxygen K-edge in SiO(2) glass and crystal (α-quartz) has been measured with energy resolutions of 4 eV (EXAFS mode) and 1.3 eV (XANES mode). Unlike methods previously adopted, it is proposed to determine the pre-edge curve based on a theoretical Compton profile and a Monte Carlo multiple-scattering simulation before extracting EXAFS features. It is shown that the obtained EXAFS features are reproduced fairly well by a cluster model with a minimal set of fitting parameters. The spectrometer and the data processing proposed here are readily applicable to high-pressure studies.

  18. Triaxial Superdeformed Bands in ^163Tm

    NASA Astrophysics Data System (ADS)

    Pattabiraman, N. S.; Ghugre, S. S.; Garg, Umesh; Li, T.; Nayak, B. K.; Zhu, S.; Chakrawarthy, R. S.; Macchiavelli, A. O.; Janssens, R. V. F.

    2002-10-01

    Following the recent discovery of triaxial superdeformation bands in the Z = 71, 72 nuclei [1,2], we have investigated the Z = 69 nucleus ^163 Tm using the reaction ^130 Te( ^37 Cl, 4n) ^163 Tm with a beam energy of 170 MeV. Gamma-ray spectroscopy was performed using the Gammasphere array at LBNL. The data were sorted into a hypercube. The preliminary results have indicated two bands with δ E _γ 60 keV above the previously known 5286 keV, 49/2^- state. These bands appear to talk to one another. It may be recalled that evidence for wobbling motion has recently been reported in the isobaric nucleus ^163 Lu The detailed experimental results and comparisons with the neighboring nuclei will be presented. [1] H. Amro et al, Phys. Lett. B 506, 39(2001). [2] G. Schonwasser eet al., Eur. Phys. J. A13, 291(2002). [3] D. R. Jensen et al, Nucl. Phys. A 703, 3 (2002).

  19. Extended structure and fate of the nucleus in Henize 2-10

    SciTech Connect

    Nguyen, Dieu D.; Seth, Anil C.; Den Brok, Mark; Reines, Amy E.; Sand, David; McLeod, Brian E-mail: aseth@astro.utah.edu E-mail: areines@nrao.edu E-mail: bmcleod@cfa.harvard.edu

    2014-10-10

    We investigate the structure and nuclear region of the black hole (BH) hosting galaxy Henize 2-10. Surface brightness profiles are analyzed using Magellan/Megacam g- and r-band images. Excluding the central starburst, we find a best-fit two-component Sérsic profile with n {sub in} ∼ 0.6, r {sub eff,} {sub in} ∼ 260 pc and n {sub out} ∼ 1.8, r ∼ 1 kpc. Integrating out to our outermost data point (100'' ∼ 4.3 kpc), we calculate M{sub g} = –19.2 and M{sub r} = –19.8. The corresponding enclosed stellar mass is M {sub *} ∼ (10 ± 3) × 10{sup 9} M {sub ☉}, ∼3 × larger than previous estimates. Apart from the central ≲500 pc, with blue colors and an irregular morphology, the galaxy appears to be an early-type system. The outer color is quite red, (g – r){sub 0} = 0.75, suggesting a dominant old population. We study the nuclear region of the galaxy using archival Gemini/NIFS K-band adaptive optics spectroscopy and Hubble Space Telescope imaging. We place an upper limit on the BH mass of ∼10{sup 7} M {sub ☉} from the NIFS data, consistent with that from the M {sub BH}-radio-X-ray fundamental plane. No coronal lines are seen, but a Brγ source is located at the position of the BH with a luminosity consistent with the X-ray emission. The starburst at the center of Henize 2-10 has led to the formation of several super star clusters, which are within ∼100 pc of the BH. We examine the fate of the nucleus by estimating the dynamical masses and dynamical friction timescales of the clusters. The most massive clusters (∼10{sup 6} M {sub ☉}) have τ{sub dyn} ≲ 200 Myr, and thus Henize 2-10 may represent a rare snapshot of nuclear star cluster formation around a preexisting massive BH.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

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

    SciTech Connect

    Maté, B.; Tanarro, I.; Escribano, R.; Moreno, M. A.; Herrero, V. J.

    2015-06-20

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

  2. Stability of Extraterrestrial Glycine under Energetic Particle Radiation Estimated from 2 keV Electron Bombardment Experiments

    NASA Astrophysics Data System (ADS)

    Maté, B.; Tanarro, I.; Escribano, R.; Moreno, M. A.; Herrero, V. J.

    2015-06-01

    The destruction of solid glycine under irradiation with 2 keV electrons has been investigated by means of IR spectroscopy. Destruction cross sections, radiolysis yields, and half-life doses were determined for samples at 20, 40, 90, and 300 K. The thickness of the irradiated samples was kept below the estimated penetration depth of the electrons. No significant differences were obtained in the experiments below 90 K, but the destruction cross section at 300 K was larger by a factor of 2. The radiolysis yields and half-life doses are in good accordance with recent MeV proton experiments, which confirms that electrons in the keV range can be used to simulate the effects of cosmic rays if the whole sample is effectively irradiated. In the low temperature experiments, electron irradiation leads to the formation of residues. IR absorptions of these residues are assigned to the presence CO2, CO, OCN-, and CN- and possibly to amide bands I to III. The protection of glycine by water ice is also studied. A water ice film of ˜150 nm is found to provide efficient shielding against the bombardment of 2 keV electrons. The results of this study show also that current Monte Carlo predictions provide a good global description of electron penetration depths. The lifetimes estimated in this work for various environments ranging from the diffuse interstellar medium to the inner solar system, show that the survival of hypothetical primeval glycine from the solar nebula in present solar system bodies is not very likely.

  3. Measurement of the x-ray mass energy-absorption coefficient of air using 3 keV to 10 keV synchrotron radiation.

    PubMed

    Büermann, L; Grosswendt, B; Kramer, H-M; Selbach, H-J; Gerlach, M; Hoffmann, M; Krumrey, M

    2006-10-21

    For the first time absolute photon mass energy-absorption coefficients of air in the energy range 3 keV to 10 keV have been measured with relative standard uncertainties less than 1%, significantly smaller than those of up to 5% assumed hitherto for calculated data. Monochromatized synchrotron radiation was used to measure both the total radiant energy by means of silicon photodiodes calibrated against a cryogenic radiometer and the fraction of radiant energy that is deposited in dry air by means of a free air ionization chamber. The measured ionization charge was converted into energy absorbed in air by calculated effective W values of photons as a function of their energy based on new measurements of the W values in dry air for electron kinetic energies between 1 keV and 7 keV, also presented in this work. The measured absorption coefficients were compared with state-of-the art calculations and found to agree within 0.7% with data calculated earlier by Hubbell at energies above 4 keV but were found to differ by values up to 2.1% at 10 keV from more recent calculations of Seltzer.

  4. An Einstein survey of the 1 keV soft X-ray background in the Galactic plane

    NASA Technical Reports Server (NTRS)

    Stanford, John M.; Caillault, Jean-Pierre

    1994-01-01

    We have analyzed 56 Einstein Observatory Imaging Proportional Counter (IPC) observations within +/- 3 deg of the Galactic plane in order to determine the low-latitude soft X-ray background flux in the 0.56-1.73 keV band. Any detected X-ray point source which fell within our regions of study was removed from the image, enabling us to present maps of the background flux as a function of Galactic latitude along 18 meridians. These maps reveal considerable structure to the background in the Galactic plane on an angular scale of approximately 1 deg. Our results are compared with those of an earlier study of the 1 keV X-ray background along l = 25 deg by Kahn & Caillault. The double-peaked structure they found is not discernible in our results, possibly because of the presence of solar backscattered flux in their data. A model which takes into account contributions to the background by extragalactic and stellar sources, the distribution of both atomic and molecular absorbing material with the Galaxy, the energy dependence of the cross section for absorption of X-rays, and the energy dependence of the detector has been constructed and fitted to these new data to derive constraints on the scale height, temperature, and volume emissivity of the unaccounted-for X-ray-emitting material. The results of this model along l = 25 deg are roughly similar to those of the model of Kahn & Caillault along the same meridian.

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

    NASA Technical Reports Server (NTRS)

    Bai, Taeil

    1986-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1994-06-01

    We have searched for evidence of the emission of a 17 keV neutrino in the internal bremsstrahlung (IB) spectrum accompanying the electron capture decay of 125I. The IB spectrum, recorded in a planar Ge detector, has 1.2×106 counts per keV at 17 keV below the 2p end point. We set an upper limit of 0.4% for the admixture of a 17 keV neutrino, at the 90% confidence level, and exclude a 0.8% admixture at the 99.6% confidence level. The QEC value is found to be 185.77+/-0.06 keV. We also find that the recent calculations of Surić et al., which employ relativistic self-consistent-field atomic wave functions, reproduce the shape and relative intensity of IB partial spectra within a few percent.

  7. On the source of the 5-55 keV Heliosphere ENAs measured with Cassini/INCA

    NASA Astrophysics Data System (ADS)

    Dialynas, Konstantinos; Roelof, Edmond; Mitchell, Donald; Krimigis, Stamatios; Decker, Robert

    2016-07-01

    The Low Energy Charged Particle (LECP) in situ measurements from V1 and V2 have revealed a reservoir of ions and electrons that constitute the heliosheath (HS) after crossing the termination shock (TS) 35deg north and 32deg south of the ecliptic plane at 94 and 84 astronomical units (1 AU= 1.5 x10 ^{8} km), respectively. The outer Heliosphere boundary, the Heliopause (HP), has now been determined in the direction of V1 to be at ˜122 AU. The in situ measurements by each Voyager were placed in a global context by remote sensing images using ENA obtained with the Ion and Neutral Camera (INCA) onboard Cassini orbiting Saturn. The ENA images have revealed a 5.2-55 keV hydrogen (H) ENA region (Belt) that loops through the celestial sphere and contributes to balancing the pressure of the interstellar magnetic field (ISMF). Here we address one of the remaining and most important questions: Where do the 5-55 keV ENAs that INCA measures come from? We analyzed INCA all-sky maps from 2003 to 2015 and compare the solar cycle (SC) variation of the ENAs in both the nose (upstream) and anti-nose (downstream) directions with the intensities of > 30 keV ions (source of ENA through charge exchange-CE with H) measured in-situ by V1 and V2, in overlapping energy bands ˜30-55 keV. ENA intensities decrease during the declining phase of SC23 by ˜x3 from 2003 to 2011 but recover through 2014 (SC24); similarly, V1 and V2 ion intensities also decrease and then recover through 2014. The similarity of time profiles of remotely sensed ENA and locally measured ions are consistent with (a) ENA originating in the HS, and (b) the global HS responding promptly (within ˜1-1.5 years) to outward-propagating solar wind changes throughout the SC. Further, recovery of the Belt during SC24 precedes asymmetrically from south to north in the general direction of the nose. This may be related to the non-symmetric evolution of solar coronal holes during SC recovery.

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

    SciTech Connect

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

    2010-07-07

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

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

    NASA Technical Reports Server (NTRS)

    Sonbas, Eda; Rossi, A.; Schulze, S.; Klose, S.; Kann, D. A.; Ferrero, P.; NicuesaGuelbenzu, A.; Rau, A.; Kruehler, T.; Greiner, J.; Schady, P.; Afonso, P. M. J.; Clemens, C.; Filgas, R.; KuepcuYoldas, A.; McBreen, S.; Olivares, F.; Szokoly, G.; Yoldas, A.; Krimm, H. A.; Johannesson, G.; Panaitescu, A.; Yuan, F.; Pandey, S. B.; Akerlof, C. W.

    2010-01-01

    We present the results of a comprehensive study of the Gamma-Ray Burst 080928 and of its afterglow. GRB 08092 was a long burst detected by Swift/BAT and Fermi/GBM, It is one of the exceptional cases where optical emission was already detected when the GRB itself was still radiating in the gamma-ray band. for nearly 100 seconds simultaneous optical X-ray and gamma-ray data provide a coverage of the spectral energy distribution of the transient source from about 1 eV to 150 keV. Here we analyze the prompt emission, constrain its spectral propertIes. and set lower limits on the initial Lorentz factor of the relativistic outflow, In particular. we show that the SED during the main prompt emission phase is in agreement with synchrotron radiation. We construct the optical/near-infrared light curve and the spectral energy distribution based on Swift/UVOT. ROTSE-Illa (Australia) and GROND (La Silla) data and compare it to the X-ray light curve retrieved from the Swift/XRT repository. We show that its bumpy shape can be modeled by multiple energy injections into the forward shock. Furthermore, we provide evidence that the temporal and spectral evolution of the first strong flare seen in the early X-ray light curve can be explained by large-angle emission. Finally, we report on the results of our search for the GRB host galaxy, for which only a deep upper limit can be provided.

  10. Extension of the yrast band in 74Se

    NASA Astrophysics Data System (ADS)

    Gross, C. J.; Cottle, P. D.; Headly, D. M.; Hüttmeier, U. J.; Moore, E. F.; Tabor, S. L.

    1987-11-01

    New states in the yrast band of 74Se have been seen with the reaction 52Cr(28Si,α2p)74Se at 98 MeV. The new states extend the known level scheme up to Jπ=(22+). For the states Jπ>=6+ the spectrum shows a relatively constant moment of inertia parameter ħ2/2θ=27.8+/-0.5 keV.

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

    NASA Astrophysics Data System (ADS)

    Gjorgieva, Slavica; Barandovski, Lambe

    2016-03-01

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

  12. Come Join the Band

    ERIC Educational Resources Information Center

    Olson, Cathy Applefeld

    2011-01-01

    A growing number of students in Blue Springs, Missouri, are joining the band, drawn by a band director who emphasizes caring and inclusiveness. In the four years since Melissia Goff arrived at Blue Springs High School, the school's extensive band program has swelled. The marching band alone has gone from 100 to 185 participants. Also under Goff's…

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

    PubMed

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

    2010-03-01

    Electronic brachytherapy systems are being developed that can deliver X rays of varying energy depending on the material of a secondary target. A copper target produces characteristic 8 keV X rays. Our aim was to determine whether 8 keV X rays might deliver greater biological effectiveness than megavoltage photons. Cells of the U251 human glioma cell line were used to compare the biological effects of 8 keV X rays and (60)Co gamma rays in terms of relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and DNA damage. The RBE at 50% and 10% survival was 2.6 and 1.9, respectively. At 50% survival, the OER for cells treated with 8 keV X rays was 1.6 compared with 3.0 for (60)Co gamma rays. The numbers of H2AX foci per Gy after treatment with 8 keV X rays and (60)Co gamma rays were similar; however, the size of the foci generated at 8 keV was significantly larger, possibly indicating more complex DNA damage. The mean area of H2AX foci generated by 8 keV X rays was 0.785 microm(2) (95% CI: 0.756-0.814) compared with 0.491 microm(2) (95% CI: 0.462-0.520) for (60)Co gamma rays (P < 0.0001). Characteristic 8 keV X rays produce two to three times the biological effectiveness of megavoltage photons, with a radiobiological profile similar to higher-LET radiations.

  14. 75 FR 66734 - Proposed Voluntary Product Standard PS 2-10, Structural Plywood

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-29

    ... National Institute of Standards and Technology Proposed Voluntary Product Standard PS 2-10, Structural... Structural-Use Panels. This revised standard, PS 2-10, was prepared by the Standing Committee for PS 2 and... Acrobat File) of the proposed standard, PS 2-10, can be obtained at the following Web site:...

  15. Adjustable gastric banding (image)

    MedlinePlus

    ... normal digestive process. In this procedure, a hollow band made of special material is placed around the ... pouch and causes a feeling of fullness. The band can be tightened or loosened over time to ...

  16. Low Power Band to Band Tunnel Transistors

    DTIC Science & Technology

    2010-12-15

    the E-field and tunneling at the source- pocket junction you form a parasitic NPN + transistor and the injection mechanism of carriers into the...hypothesis that the 1000 ° C, 5s anneal split lead to a very wide pocket and the accidental formation of a NPN + transistor , while the 1000 ° C, 1s anneal...Low Power Band to Band Tunnel Transistors Anupama Bowonder Electrical Engineering and Computer Sciences University of California at Berkeley

  17. Solar Cycle dependence of 5-55 keV Cassini/INCA energetic neutral atom (ENA) images of the Heliosheath and in situ Voyager/LECP ion measurements

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

    The heliosheath has been identified as the most probable source of ENAs that INCA detects but its variability due to solar activity throughout the solar cycle (SC) has not been resolved to date. We show all-sky, 5-55 keV ENA H maps from the year 2003 to 2014 and compare the solar cycle variation of the ENAs in both the heliospheric nose (upstream) and anti-nose (downstream) directions with the > 30 keV ions measured within the heliosheath by the Low Energy Charged Particle (LECP) detector on Voyagers 1, 2 (V1, V2) where we measure protons in overlapping energy bands ~30-55 keV. We find that a) Toward the anti-nose direction the ENA-H intensities decline during SC23, i.e. after 2003 ENA intensities decreased by ~ x2 at all energies by the end of year 2011, ~1 year after the observed minimum in solar activity; b) This ENA decrease (5.2-55 keV) during 2009-2011 is consistent with the concurrent intensity decrease of the > 30 keV ions (by a factor of 2-3) observed in situ by V1 and V2 in the heliosheath; c) Toward the nose direction, minimum intensities in both INCA ENAs and the V2 ions at E > 28 keV occur during the year 2013, with a subsequent recovery from 2014 to date (by a factor of ~2 in the > 35 keV ENA data). These quantitative correlations between the decreases of INCA ENAs (in both the heliospheric nose and anti-nose directions) and the in situ V1 and V2 ion measurements (separated by > 130 AU) during the declining phase of SC23, along with their concurrent jointly shared recoveries at the onset of SC24, imply that: 1) the 5-55 keV ENAs are produced in the heliosheath (because their transit times over 100 AU are less than a few months at energies > 40 keV), thus proving that our ENA observations can provide the ground truth for constructing comprehensive global heliosphere models; 2) the global heliosheath responds promptly (within ~1-1.5 yrs) to outward-propagating solar wind changes throughout the solar cycle.

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

    SciTech Connect

    Siekhaus, W. J.; Teslich, N. E.; Weber, P. K.

    2014-10-23

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

  19. The Search for 17-KEV Neutrino Emission in the Beta-Decay Spectrum of SULFUR-35.

    NASA Astrophysics Data System (ADS)

    Berman, Gregg Evan

    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 1985, evidence supporting a 1% 17-keV neutrino branch in the decay spectra of ^3 H, ^{35}S, ^{63}Ni, ^{55 }Fe, ^{14}C and ^{71}Ge has since been reported. However, other groups observing these nuclei have not seen any evidence of 17-keV neutrino emission, and very stringent limits ruling out a 1% branch have been published. Therefore, an important goal of this work is to reduce and/or understand experimental systematic errors that can mask or mimic the effects of a 17-keV neutrino. This ^{35}S spectrum measurement was performed using Princeton's extensively renovated, iron-free, intermediate-image, magnetic spectrometer. To ensure radio-chemical purity, the ^{35 }S source was prepared by ion-implantation using an isotope separator. To accurately determine the overall response of the spectrometer, electron data was accumulated over the very wide energy range of 40-167 keV. In addition, a detailed study of the spectrometer response using various ^{111}In calibration sources was undertaken, and the effects of source positioning and background magnetic fields have been explored. Furthermore, new computer codes for electron orbit raytracing and Monte-Carlo simulations have been developed to help further study the response of the spectrometer as well as to predict the effects of electron backscattering in both the source and detector substrates. To analyze the experimental data for the presence of a 17-keV neutrino branch, the measured ^ {35}S spectrum was convolved with the overall response of the spectrometer, and then fit by least -squares reduction to a theoretical beta -decay shape that allows heavy-neutrino mixing. The results show that the

  20. 330-keV electron line in e sup + +Th interactions

    SciTech Connect

    Sakai, M.; Fujita, Y.; Imamura, M.; Omata, K.; Ohya, S.; Muto, S.; Miura, T.; Gono, Y.; Chojnacki, S. Niigata University, Niigata National Laboratory for High Energy Physics, Tsukuba Institute for Physical and Chemical Research, Wako-shi, Saitama-ken Accelerator Laboratory, Warsaw University, Warsaw )

    1991-09-01

    The previously reported 330.8{plus minus}1.0-keV electron line in {ital e}{sup +}+Th interactions has been reinvestigated to confirm its existence. We have made a definite observation of the relevant peak with an energy of 330.1{plus minus}0.3 keV, a fullwidth at half maximum of less than 1.7{plus minus}0.7 keV and a cross section of 160(1{plus minus}0.19{plus minus}0.25) mb. We have assigned the generation site of the electrons to the Th target by comparing the energy shift and the shape change of the line with those of the neighboring conversion lines in the spectra taken under different scattering conditions.

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

    NASA Astrophysics Data System (ADS)

    Huang, Xiao-Long; Jiang, Li-Yang; Chen, Xiong-Jun; Chen, Guo-Chang

    2014-04-01

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

  2. keV sterile neutrino dark matter and low scale leptogenesis

    NASA Astrophysics Data System (ADS)

    Kang, Sin Kyu; Patra, Ayon

    2016-10-01

    We consider a simple extension of the Standard Model to consistently explain the observation of a peak in the galactic X-ray spectrum at 3.55 keV, the light neutrino masses, and the baryon asymmetry of the universe. The baryon asymmetry is generated through leptogenesis, the lepton asymmetry being generated by the decay of a heavy neutrino with a TeV mass scale. The extra singlet fermion introduced in the model can be identified as a dark matter candidate with a mass of 7.1 keV. It decays with a lifetime much larger than the age of the universe, producing a final state photon. The Yukawa interactions between the extra singlet neutrino and a heavier right-handed neutrino play a crucial role in simultaneously achieving low-scale leptogenesis and the relic density of the keV dark matter candidate.

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

    NASA Astrophysics Data System (ADS)

    Lawson, Kyle; Zhitnitsky, Ariel

    2017-02-01

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

  4. The energy spectrum of 662 keV photons in a water equivalent phantom

    NASA Astrophysics Data System (ADS)

    Akar Tarim, U.; Gurler, O.; Ozmutlu, E. N.; Yalcin, S.; Gundogdu, O.; Sharaf, J. M.; Bradley, D. A.

    2012-07-01

    Investigation is made on the energy spectrum of photons originating from interactions of 662 keV primary gamma-ray photons emitted by a point source positioned at the centre of a water equivalent solid phantom of dimensions 19 cm×19 cm×24 cm. Peaks resulting from total energy loss (photopeak) and multiple and back scattering have been observed using a 51 mm×51 mm NaI(Tl) detector; good agreement being found between the measured and simulated response functions. The energy spectrum of the gamma photons obtained through the Monte Carlo simulation reveals local maxima at about 100 keV and 210 keV, being also observed in the experimental response function. Such spectra can be used as a method of testing the water equivalence of solid phantom media before their use for dosimetry measurements.

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

    NASA Technical Reports Server (NTRS)

    Elsner, R.; Branduardi-Raymont, G.; Galand, M.; Grodent, D.; Waite, J. H.; Cravens, T.; Ford, P.

    2007-01-01

    The discovery in XMM-Newton X-ray data of X-ray emission above 2 keV from Jupiter's aurorae has led us to reexamine the Chandra ACIS-S observations taken in Feb 2003. Chandra's superior spatial resolution has revealed that the auroral X-rays with E > 2 keV are emitted from the periphery of the region emitting those with E < 1 keV. We are presently exploring the relationship of this morphology to that of the FUV emission from the main auroral oval and the polar cap. The low energy emission has previously been established as due to charge exchange between energetic precipitating ions of oxygen and either sulfur or carbon. It seems likely to us that the higher energy emission is due to precipitation of energetic electrons, possibly the same population of electrons responsible for the FUV emission. We discuss our analysis and interpretation.

  6. Appearance of chromosomal aberrations in females heterozygous for deletion MS2-10: Maternal effect

    SciTech Connect

    Artemova, E.V.; Chadov, B.F.

    1995-01-01

    The mutagenic effect of the paracentromeric heterochromatin deletion MS2-10 was studied in direct and reciprocal crosses of laboratory and wild-type lines of Drosophila melanogaster. The effect of deletion MS2-10 depended on the opposite chromosome. This was shown for the combination of autosome MS2-10 with autosome 2 from the Berlin wild line, but when MS2-10 was combined with an autosome 2 from lines Canton S and pr pk cn, the effect was absent. When deletion MS2-10 was inherited from the female parent and the opposite chromosome from the male parent, the effect of the deletion was present, but it was absent in males heterozygous for MS2-10, obtained in reciprocal crosses. In maternal effect, this case of mutagenesis is similar to hybrid dysgenesis. However, the pattern of P-M dysgenesis was shown to differ from the type of mutagenesis described in the present work.

  7. 3.55 keV line in minimal decaying dark matter scenarios

    SciTech Connect

    Arcadi, Giorgio; Covi, Laura; Dradi, Federico

    2015-07-20

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

  8. Relative biological effectiveness of 280 keV neutrons for apoptosis in human lymphocytes.

    PubMed

    Ryan, L A; Wilkins, R C; McFarlane, N M; Sung, M M; McNamee, J P; Boreham, D R

    2006-07-01

    The relative biological effectiveness (RBE) of neutrons varies from unity to greater than ten depending upon neutron energy and the biological endpoint measured. In our study, we examined apoptosis in human lymphocytes to assess the RBE of low energy 280 keV neutrons compared to Cs gamma radiation and found the RBE to be approximately one. Similar results have been observed for high energy neutrons using the same endpoint. As apoptosis is a major process that influences the consequences of radiation exposure, our results indicate that biological effect and the corresponding weighting factors for 280 keV neutrons may be lower in some cell types and tissues.

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

    NASA Astrophysics Data System (ADS)

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

    2008-11-01

    Polyethyleneterephthalate (PET) has been modified by 100 keV Ni + and N + ions using metal ion from volatile compound (MIVOC) ion source to fluence ranging from 1 × 10 14 to 1 × 10 16 ions/cm 2. The increasing application of polymeric material in technological and scientific field has motivated the use of surface treatment to modify the physical and chemical properties of polymer surfaces. When a material is exposed to ionization radiation, it suffers damage leading to surface activation depending on the type. The surface morphology was observed by atomic force microscopy (AFM). That show the roughness increases with fluence in both the cases. The Ni particles as precipitation in PET were observed by cross-section transmission electron microscopy (XTEM). The optical band gap ( Eg) deduced from absorption spectra; was calculated by Tau'c relation. Raman spectroscopy shows quantitatively the chemical nature at the damage caused by the Ni + and N + bombardment. The ration of 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.

  10. Wide Band to ''Double Band'' upgrade

    SciTech Connect

    Kasper, P.; Currier, R.; Garbincius, P.; Butler, J.

    1988-06-01

    The Wide Band beam currently uses electrons obtained from secondary photon conversions to produce the photon beam incident on the experimental targets. By transporting the positrons produced in these conversions as well as the electrons it is possible to almost double the number of photons delivered to the experiments per primary beam proton. 11 figs.

  11. Broad-band X-ray observations of CIR X-1

    NASA Astrophysics Data System (ADS)

    Maisack, M.; Staubert, R.; Balucinska-Church, M.; Skinner, G.; Doebereiner, S.; Englhauser, J.; Aref'ev, V. A.; Efremov, V. V.; Sunyaev, R. A.

    1995-08-01

    We present broad-band (2-88 keV) X-ray observations of the X-ray binary Cir X-1 with the TTM and HEXE instruments on board of the Mir space station. The observations were made in January/February 1989. The spectrum is best described by a model with 3 components: a blackbody at low energies, an iron line and a Comptonized hard continuum. The spectrum is variable during our observations; when the Comptonized component becomes harder, the spectrum becomes softer below 15 keV. The high-energy spectrum resembles that of X-ray binary pulsars.

  12. Solar wind ions accelerated to 40 keV by shock wave disturbances

    NASA Astrophysics Data System (ADS)

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

    1980-02-01

    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 100 eV up to at least 40 keV in a broad region, typically 10 million kilometers wide, following interplanetary shocks. Peak differential fluxes up to 5000/sq cm s sr keV at 28 keV are observed either at the shock or within the first 1.5 hours following shock passage. In the solar wind frame the distribution function of these ions is roughly isotropic, peaks near zero velocity, and above 5 keV can adequately be characterized as power law in energy with a spectral index of 2.7. The effective 'temperature' of these ions generally exceeds 100 million K. These suprathermal interplanetary ions are almost certainly solar wind ions which have been accelerated by some mechanism associated with the shock wave disturbance. Present evidence leads the authors to favor stochastic particle acceleration involving electrostatic and/or electromagnetic turbulence in the postshock flow.

  13. A gas scintillation proportional detector to search for 17 keV neutrinos

    SciTech Connect

    Okx, W.J.C.; Bom, V.R.; Eijk, C.W.E. van; Hollander, R.W. )

    1993-08-01

    Evidence for the existence of a 17 keV neutrino was first reported in 1985. Since then many experiments have been performed with contradicting results. In this paper the authors describe an experiment with a new approach to the problem by the introduction of a Gas Scintillation Proportional Detector.

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

    SciTech Connect

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

    2012-06-05

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    Since 2008 December, the Interstellar Boundary Explorer (IBEX) has been making detailed observations of neutrals from the boundaries of the heliosphere using two neutral atom cameras with overlapping energy ranges. The unexpected, yet defining feature discovered by IBEX is a Ribbon that extends over the energy range from about 0.2 to 6 keV. This Ribbon is superposed on a more uniform, globally distributed heliospheric neutral population. With some important exceptions, the focus of early IBEX studies has been on neutral atoms with energies greater than approx. 0.5 keV. With nearly three years of science observations, enough low-energy neutral atom measurements have been accumulated to extend IBEX observations to energies less than approx. 0.5 keV. Using the energy overlap of the sensors to identify and remove backgrounds, energy spectra over the entire IBEX energy range are produced. However, contributions by interstellar neutrals to the energy spectrum below 0.2 keV may not be completely removed. Compared with spectra at higher energies, neutral atom spectra at lower energies do not vary much from location to location in the sky, including in the direction of the IBEX Ribbon. Neutral fluxes are used to show that low energy ions contribute approximately the same thermal pressure as higher energy ions in the heliosheath. However, contributions to the dynamic pressure are very high unless there is, for example, turbulence in the heliosheath with fluctuations of the order of 50-100 km/s.

  16. 41 CFR 60-2.10 - General purpose and contents of affirmative action programs.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 1 2010-07-01 2010-07-01 true General purpose and contents of affirmative action programs. 60-2.10 Section 60-2.10 Public Contracts and Property Management... EMPLOYMENT OPPORTUNITY, DEPARTMENT OF LABOR 2-AFFIRMATIVE ACTION PROGRAMS Purpose and Contents of...

  17. 41 CFR 60-2.10 - General purpose and contents of affirmative action programs.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 41 Public Contracts and Property Management 1 2012-07-01 2009-07-01 true General purpose and contents of affirmative action programs. 60-2.10 Section 60-2.10 Public Contracts and Property Management... EMPLOYMENT OPPORTUNITY, DEPARTMENT OF LABOR 2-AFFIRMATIVE ACTION PROGRAMS Purpose and Contents of...

  18. 41 CFR 60-2.10 - General purpose and contents of affirmative action programs.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 41 Public Contracts and Property Management 1 2014-07-01 2014-07-01 false General purpose and contents of affirmative action programs. 60-2.10 Section 60-2.10 Public Contracts and Property Management... EMPLOYMENT OPPORTUNITY, DEPARTMENT OF LABOR 2-AFFIRMATIVE ACTION PROGRAMS Purpose and Contents of...

  19. 9 CFR 2.10 - Licensees whose licenses have been suspended or revoked.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Licensees whose licenses have been suspended or revoked. 2.10 Section 2.10 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION... have been suspended or revoked. (a) Any person whose license has been suspended for any reason...

  20. 41 CFR 102-2.10 - What is the FMR's purpose?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 41 Public Contracts and Property Management 3 2010-07-01 2010-07-01 false What is the FMR's purpose? 102-2.10 Section 102-2.10 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION GENERAL 2-FEDERAL MANAGEMENT REGULATION...

  1. 41 CFR 102-2.10 - What is the FMR's purpose?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 41 Public Contracts and Property Management 3 2011-01-01 2011-01-01 false What is the FMR's purpose? 102-2.10 Section 102-2.10 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION GENERAL 2-FEDERAL MANAGEMENT REGULATION...

  2. 41 CFR 102-2.10 - What is the FMR's purpose?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 41 Public Contracts and Property Management 3 2012-01-01 2012-01-01 false What is the FMR's purpose? 102-2.10 Section 102-2.10 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION GENERAL 2-FEDERAL MANAGEMENT REGULATION...

  3. 41 CFR 102-2.10 - What is the FMR's purpose?

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 41 Public Contracts and Property Management 3 2013-07-01 2013-07-01 false What is the FMR's purpose? 102-2.10 Section 102-2.10 Public Contracts and Property Management Federal Property Management Regulations System (Continued) FEDERAL MANAGEMENT REGULATION GENERAL 2-FEDERAL MANAGEMENT REGULATION...

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

    SciTech Connect

    Derrien, H.

    2000-05-22

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

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

    SciTech Connect

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

    2000-05-01

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

  6. Singing with the Band

    ERIC Educational Resources Information Center

    Altman, Timothy Meyer; Wright, Gary K.

    2012-01-01

    Usually band, orchestra, and choir directors work independently. However, the authors--one a choral director, the other a band director--have learned that making music together makes friends. Not only can ensemble directors get along, but joint concerts may be just the way to help students see how music can reach the heart. Combined instrumental…

  7. Rubber Band Science

    ERIC Educational Resources Information Center

    Cowens, John

    2005-01-01

    Not only are rubber bands great for binding objects together, but they can be used in a simple science experiment that involves predicting, problem solving, measuring, graphing, and experimenting. In this article, the author describes how rubber bands can be used to teach the force of mass.

  8. Stretch Band Exercise Program

    ERIC Educational Resources Information Center

    Skirka, Nicholas; Hume, Donald

    2007-01-01

    This article discusses how to use stretch bands for improving total body fitness and quality of life. A stretch band exercise program offers a versatile and inexpensive option to motivate participants to exercise. The authors suggest practical exercises that can be used in physical education to improve or maintain muscular strength and endurance,…

  9. High-spin states and a new band based on the isomeric state in 152Nd

    NASA Astrophysics Data System (ADS)

    Yeoh, E. Y.; Zhu, S. J.; Hamilton, J. H.; Ramayya, A. V.; Yang, Y. C.; Sun, Y.; Hwang, J. K.; Liu, S. H.; Wang, J. G.; Luo, Y. X.; Rasmussen, J. O.; Lee, I. Y.; Ding, H. B.; Li, K.; Gu, L.; Xu, Q.; Xiao, Z. G.; Ma, W. C.

    2010-08-01

    High-spin states of the neutron-rich 152Nd nucleus have been reinvestigated by measuring the prompt γ -rays in the spontaneous fission of 252Cf . The ground-state band and a side negative-parity band have been updated. A new band based on the 2243.7keV isomeric state has been identified. The half-life for the isomeric state has been measured to be 63(7)ns. The projected shell model is employed to study the band structure of this nucleus. The results show that the calculated levels of the bands are in good agreement with the experimental ones, and the isomeric state and the negative-parity band are based on the proton π5/2-[532] ⊗ π9/2+[404] and neutron ν3/2-[521] ⊗ ν5/2+[642] two-quasiparticles configurations, respectively.

  10. Progressive Band Selection

    NASA Technical Reports Server (NTRS)

    Fisher, Kevin; Chang, Chein-I

    2009-01-01

    Progressive band selection (PBS) reduces spectral redundancy without significant loss of information, thereby reducing hyperspectral image data volume and processing time. Used onboard a spacecraft, it can also reduce image downlink time. PBS prioritizes an image's spectral bands according to priority scores that measure their significance to a specific application. Then it uses one of three methods to select an appropriate number of the most useful bands. Key challenges for PBS include selecting an appropriate criterion to generate band priority scores, and determining how many bands should be retained in the reduced image. The image's Virtual Dimensionality (VD), once computed, is a reasonable estimate of the latter. We describe the major design details of PBS and test PBS in a land classification experiment.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    This study aims to investigate the effect of Ar8+ ions pre-damage on the following He2+ irradiation behavior of polycrystalline tungsten. We compared the irradiation resistance performance against 60 keV He2+ ions of undamaged tungsten samples with that of pre-damaged samples which were preliminarily exposed to 800 keV Ar8+ ions at a fluence of 4 × 1019 ions m-2. The experimental results indicate that the helium blistering of tungsten could be effectively relieved by the Ar8+ ions pre-damage, while the retention of helium around low energy desorption sites in the pre-damaged tungsten was larger than that of the undamaged samples. A strong orientation dependence of blistering had been observed, with the blister occurred preferentially on the surface of grains with normal direction close to <111>. The Ar8+ ions irradiation-induced damage altered the morphology of helium bubbles in tungsten exposed to the following He2+ irradiation significantly. The intensity of helium release peaks at relatively low temperatures (<600 K) was enhanced due to Ar8+ ions pre-damage.

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

    NASA Astrophysics Data System (ADS)

    Earnhart, Jonathan Raby Dewitt

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

  13. Cerebrospinal fluid oligoclonal bands in childhood opsoclonus-myoclonus.

    PubMed

    Pranzatelli, Michael R; Slev, Patricia R; Tate, Elizabeth D; Travelstead, Anna L; Colliver, Jerry A; Joseph, Suja Anne

    2011-07-01

    Oligoclonal bands in cerebrospinal fluid reflect local B-cell responses associated with various neuroinflammatory disorders. In opsoclonus-myoclonus syndrome, cerebrospinal fluid B-cell expansion was demonstrated, but no studies of oligoclonal bands are available. In a prospective case-control study of 132 children (103 with opsoclonus-myoclonus, 29 neurologic control subjects), cerebrospinal fluid oligoclonal bands, measured by isoelectric focusing with immunofixation, were observed in 35% with opsoclonus-myoclonus and none of the control subjects, with the highest frequency in severe cases (56%). In oligoclonal band-positive patients, the mean band number was 5 ± 3 S.D. (range, 2-10) and the total severity score was significantly higher than in band-negative patients, whereas the frequency of CD19(+) B cells, opsoclonus-myoclonus duration, neuroblastoma detection, and relapse history did not differ. The cerebrospinal fluid immunoglobulin G synthesis rate, immunoglobulin index, and Q albumin were normal. In 17 untreated children receiving adrenocorticotropic hormone, intravenous immunoglobulins, and rituximab, the number of oligoclonal band-positive decreased by 75%, and the mean band count fell by 80%. Oligoclonal band detection adds useful information to neuroimmunologic "staging" in opsoclonus-myoclonus. However, flow cytometry provides a more sensitive measure of B-cell infiltration. Cerebrospinal fluid oligoclonal bands warrant monitoring in long-term follow-up studies of disease-modifying drugs for opsoclonus-myoclonus.

  14. Iliotibial band friction syndrome

    PubMed Central

    2010-01-01

    Published articles on iliotibial band friction syndrome have been reviewed. These articles cover the epidemiology, etiology, anatomy, pathology, prevention, and treatment of the condition. This article describes (1) the various etiological models that have been proposed to explain iliotibial band friction syndrome; (2) some of the imaging methods, research studies, and clinical experiences that support or call into question these various models; (3) commonly proposed treatment methods for iliotibial band friction syndrome; and (4) the rationale behind these methods and the clinical outcome studies that support their efficacy. PMID:21063495

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

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  16. Colliding the hydrocarbon building blocks of astrochemical polycyclic aromatic hydrocarbons with 8 keV He+* and H2+* ions: Luminescence from methane, acetylene, benzene and naphthalene

    NASA Astrophysics Data System (ADS)

    Rashid, Shaan; Sit, Alicia; West, Brandi; Mayer, Paul M.

    2017-01-01

    Emission spectra from collisions of 8 keV He+ and H2+rad with neutral naphthalene, benzene, acetylene and methane were acquired over 190-1020 nm on a modified double-focusing mass spectrometer. The bands, emission intensities and the minimum excitation energy to produce the observed transitions (Emin) were compared for the two projectile ions. Emin values were the same for both projectiles but the emission intensity is greater in the case of He+ . This is consistent with calculations at the CISD/6-311+G(2df) level on the excited states of the respective collision complexes which exhibited two distinct state-crossing points for He+ collisions but none for H2+rad collisions.

  17. 9 CFR 2.10 - Licensees whose licenses have been suspended or revoked.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL WELFARE REGULATIONS Licensing § 2.10 Licensees whose licenses... of suspension is in effect. No partnership, firm, corporation, or other legal entity in which...

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

    SciTech Connect

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

    2008-04-30

    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.

  19. CSF oligoclonal banding

    MedlinePlus

    ... system. Oligoclonal bands may be a sign of multiple sclerosis. How the Test is Performed A sample of ... Performed This test helps support the diagnosis of multiple sclerosis (MS). However, it does not confirm the diagnosis. ...

  20. Decay of superdeformed bands

    SciTech Connect

    Carpenter, M.P.; Khoo, T.L.; Lauritsen, T.

    1995-12-31

    One of the major challenges in the study of superdeformation is to directly connect the large number of superdeformed bands now known to the yrast states. In this way, excitation energies, spins and parities can be assigned to the levels in the second well which is essential to establish the collective and single-particle components of these bands. This paper will review some of the progress which has been made to understand the decay of superdeformed bands using the new arrays including the measurement of the total decay spectrum and the establishment of direct one-step decays from the superdeformed band to the yrast line in {sup 194}Hg. 42 refs., 5 figs.

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

    SciTech Connect

    Leo, K. W.; Chulan, R. M. Hashim, S. A.; Baijan, A. H.; Sabri, R. M.; Mohtar, M.; Glam, H.; Lojius, L.; Zahidee, M.; Azman, A.; Zaid, M.

    2016-01-22

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

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

    SciTech Connect

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

    2005-05-24

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

  3. Microbeam of 100 keV x ray with a sputtered-sliced Fresnel zone plate

    NASA Astrophysics Data System (ADS)

    Kamijo, Nagao; Suzuki, Yoshio; Takano, Hidekazu; Tamura, Shigeharu; Yasumoto, Masato; Takeuchi, Akihisa; Awaji, Mitsuhiro

    2003-12-01

    Microfocusing of 100 keV x ray with a sputtered-sliced Fresnel zone plate (ss-FZP) has been performed at the 250-m-long beamline (20XU) of SPring-8. The ss-FZP with an outermost zone width 0.16 μm which is composed of 70 layers of alternating Cu and Al layers and having thickness ˜180 μm was fabricated and characterized. The minimum focal spot size attained for the first order focal beam was 0.5 μm with a focal distance 900 mm at a photon energy 100 keV. The total flux of the microprobe was ˜2×106 photons s-1 μm-2.

  4. SMM detection of diffuse Galactic 511 keV annihilation radiation

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

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

    NASA Technical Reports Server (NTRS)

    Elsner, R.; Branduardi-Raymont, G.; Galand, M.; Grodent, D.; Gladstone, G. R.; Waite, J. H.; Cravens, T.; Ford, P.

    2007-01-01

    The discovery in XMM-Newton X-ray data of X-ray emission above 2 keY from Jupiter's aurorae has led us to reexamine the Chandra ACIS-S observations taken in Feb 2003. Chandra's superior spatial resolution has revealed that the auroral X-rays with E > 2 keV are emitted from the periphery of the region emitting those with E < 1 keV. We are presently exploring the relationship of this morphology to that of the FUV emission from the main auroral oval and the polar cap. The low energy emission has previously been established as due to charge exchange between energetic precipitating ions of oxygen and either sulfur or carbon. It seems likely to us that the higher energy emission is due to precipitation of energetic electrons, possibly the same population of electrons responsible for the FUV emission. We discuss our analysis and interpretation.

  7. State-selective electron capture in 30- and 100-keV He++He collisions

    NASA Astrophysics Data System (ADS)

    Guo, D. L.; Ma, X.; Zhang, R. T.; Zhang, S. F.; Zhu, X. L.; Feng, W. T.; Gao, Y.; Hai, B.; Zhang, M.; Wang, H. B.; Huang, Z. K.

    2017-01-01

    A combined experimental and theoretical study on single capture in 30- and 100-keV He+ on He collisions was performed. By using a reaction microscope, we obtained the state selective cross sections and the angular-differential cross sections. It was found that the experimental state-selective cross sections were in good agreement with the dynamic screening classical trajectory Monte Carlo calculation for 100-keV He+ incident. The comparisons with various versions of such calculations reveal the roles played by different electron-electron correlation effects. Moreover, a prominent oscillatory structure was observed in the angular-differential cross sections for both projectile energies. With the single capture probability distribution obtained from the classical trajectory Monte Carlo calculation, the oscillation structures can be well explained by atomic-size Fraunhofer-type diffraction.

  8. Limits on a variable source of 511 keV annihilation radiation near the Galactic center

    NASA Technical Reports Server (NTRS)

    Share, Gerald H.; Leising, Mark D.; Messina, Daniel C.; Purcell, William R.

    1990-01-01

    The Gamma Ray Spectrometer (GRS) on the Solar Maximum Mission satellite (SMM) has observed a strong Galactic source of 511 keV annihilation radiation from its launch in 1980 to its reentry in 1989. These observations are consistent with an extended source having an intensity of about 0.002 gamma/sq cm/s averaged over the central radian of Galactic longitude. These data are searched for evidence of the variable Galactic center source of 511 keV line radiation which was reported to have reappeared in 1988 by Leventhal et al. The SMM data are consistent with, but do not require, a compact source emitting a time-averaged flux of about 0.0004 gamma/sq cm/s during about 3 month transits in 1987 and 1988; they are inconsistent with a compact source flux in excess of 0.0008 gamma/sq cm/s for each year.

  9. Polygonal deformation bands

    NASA Astrophysics Data System (ADS)

    Antonellini, Marco; Mollema, Pauline Nella

    2015-12-01

    We report for the first time the occurrence of polygonal faults in sandstone, which is compelling given that layer-bound polygonal fault systems have been observed so far only in fine-grained sediments such as clay and chalk. The polygonal faults are shear deformation bands that developed under shallow burial conditions via strain hardening in dm-wide zones. The edges of the polygons are 1-5 m long. The shear deformation bands are organized as conjugate faults along each edge of the polygon and form characteristic horst-like structures. The individual deformation bands have slip magnitudes ranging from a few mm to 1.5 cm; the cumulative average slip magnitude in a zone is up to 10 cm. The deformation bands heaves, in aggregate form, accommodate a small isotropic horizontal extension (strain <0.005). The individual shear deformation bands show abutting T-junctions, veering, curving, and merging where they mechanically interact. Crosscutting relationships are rare. The interactions of the deformation bands are similar to those of mode I opening fractures. The documented fault networks have important implications for evaluating the geometry of km-scale polygonal fault systems in the subsurface, top seal integrity, as well as constraining paleo-tectonic stress regimes.

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

    NASA Astrophysics Data System (ADS)

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

    2017-03-01

    High-resolution X-ray spectroscopy with Hitomi was expected to resolve the origin of the faint unidentified E≈ 3.5 {keV} emission line reported in several low-resolution studies of various massive systems, such as galaxies and clusters, including the Perseus cluster. We have analyzed the Hitomi first-light observation of the Perseus cluster. The emission line expected for Perseus based on the XMM-Newton signal from the large cluster sample under the dark matter decay scenario is too faint to be detectable in the Hitomi data. However, the previously reported 3.5 keV flux from Perseus was anomalously high compared to the sample-based prediction. We find no unidentified line at the reported high flux level. Taking into account the XMM measurement uncertainties for this region, the inconsistency with Hitomi is at a 99% significance for a broad dark matter line and at 99.7% for a narrow line from the gas. We do not find anomalously high fluxes of the nearby faint K line or the Ar satellite line that were proposed as explanations for the earlier 3.5 keV detections. We do find a hint of a broad excess near the energies of high-n transitions of S xvi (E≃ 3.44 {keV} rest-frame)—a possible signature of charge exchange in the molecular nebula and another proposed explanation for the unidentified line. While its energy is consistent with XMM pn detections, it is unlikely to explain the MOS signal. A confirmation of this interesting feature has to wait for a more sensitive observation with a future calorimeter experiment.

  11. Compton polarimeter for 10-30 keV x rays

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

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

    SciTech Connect

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

    2011-07-01

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

  13. Compton polarimeter for 10–30 keV x rays

    SciTech Connect

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

    2015-09-15

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

  14. Origin of the Galactic Disk 6.7 kev Line Emission

    NASA Technical Reports Server (NTRS)

    Churchwell, Ed

    1997-01-01

    The goal of this program was to determine if the extended FeXXV 6.7 kev line emission might possibly be produced and confined by the hot wind-shocked bubbles to accompany UC HII regions. The main result of this study are: (1) FeXXV is detected in the W3 complex, but at a level that could only explain a small fraction of the galactic disk emission if all UC HII regions emit at about the same intensity as the W3 complex; (2) Two X-ray sources are detected in W3. W3-X 1 coincides with the radio image of this region, but W3-X2 has no radio, optical, or infrared counterpart; (3) There is no evidence for variability of W3-X1 during the period of observations (approx, 40,000 sec); (4) The X-ray spectrum of W3-X1 has no emission shortward of 1 kev, it peaks at approx. 2 kev and show significant emission out to approx. 6 kev. No individual lines are resolved. There is currently no generally accepted theory for extended hard X-ray emission in HII regions. Perhaps the most significant discovery of this program has been the detection of extended hard X-rays and the realization that some entirely new processes must be invoked to understand this; and (5)A minimum (chi)(sup 2) fit of the spectrum implies a H absorbing column of N(sub H) approx, equals to 2.1 x 10(exp 22)/ cm, a temperature of the emitting plasma of 7 x 10(exp 7) K, and a luminosity of approx. equal to 10(33)erg/s.

  15. The 93Zr(n,γ) reaction up to 8 keV neutron energy

    NASA Astrophysics Data System (ADS)

    Tagliente, G.; Milazzo, P. M.; Fujii, K.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Badurek, G.; Baumann, P.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Calviño, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapiço, 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.; Käppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Kossionides, E.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lukic, S.; Marganiec, J.; Marrone, S.; Martínez, 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

    The (n,γ) 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.

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

    NASA Astrophysics Data System (ADS)

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

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

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

    PubMed

    Szlachetko, J; Dousse, J-Cl; Hoszowska, J; Berset, M; Cao, W; Szlachetko, M; Kavcic, M

    2007-09-01

    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., Kalpha, Kbeta, Lalpha, and Lbeta) 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.

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

    NASA Astrophysics Data System (ADS)

    Gong, Yan; Chen, Xuelei; Feng, Hua

    2017-02-01

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

  19. A study of 2-20 KeV X-rays from the Cygnus region

    NASA Technical Reports Server (NTRS)

    Bleach, R. D.

    1972-01-01

    Two rocket-borne proportional counters, each with 650 sq 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 1970 from discrete sources in Cygnus are presented. The data from Cyg X-1, Cyg X-2, and Cyg X-3 have sufficient statistical significance to indicate mutually exclusive spectral forms for the three. Upper limits are presented for X-ray intensities above 2 keV for Cyg X-4 and Cyg X-5 (Cygnus loop). A search was made on 9 August 1971 for a diffuse component of X-rays 1.5 keV associated with an interarm region of the galaxy at galactic longitudes in the vicinity of 60 degrees. A statistically significant excess associated with a narrow disk component was detected. Several possible emission models are discussed, with the most likely candidate being a population of unresolvable low luminosity discrete sources.

  20. Mutagenic effect of a keV range N + beam on mammalian cells

    NASA Astrophysics Data System (ADS)

    Feng, Huiyun; Wu, Lijun; Yu, Lixiang; Han, Wei; Liu, Xuelan; Yu, Zengliang

    2005-07-01

    The radiobiological effects of a keV (5-20 keV) range nitrogen ion (N +) beam on mammalian cells were studied, particularly with regard to the induction of mutation in the cell genome. The experiment demonstrated that the 20 keV N + beam, which resulted in cell death to a certain extent, induced a 2-3 fold increase in the mutation rates at the CD59 gene locus of the mammalian A L cells as compared to the control. Within certain fluence ranges (0-6 × 10 14 N +/cm 2), the cell survival displayed a down-up-down pattern which is similar to the phenomenon known as 'hyper-radiosensitivity' manifested under low-dose irradiation; the CD59 mutation rate firstly showed a gradual rise up to a 3-fold increment above the background level as the ion fluence went up to 4 × 10 14 N +/cm 2, after this peak point however, a downtrend appeared though the ion fluence increased further. It was also observed that the fraction of CD59 mutation bears no proportional relation to ion energy in further experiments of mutation induction by N + beams with the incident energies of 5, 10, 15 and 20 keV at the same fluence of 3 × 10 14 N +/cm 2. Analyses of the deletion patterns of chromosome 11 in CD59- mutants induced by 5-20 keV N + beams showed that these ions did not result in large-size chromosome deletions in this mammalian cell system. A preliminary discussion, suggesting that the mutagenic effect of such low-energy ion influx on mammalian cells could result from multiple processes involving direct collision of particles with cellular DNA, and cascade atomic and molecular reactions due to plentiful primary and secondary particles, was also presented. The study provided the first glimpse into the roles low-energy ions may play in inducing mutagenesis in mammalian cells, and results will be of much value in helping people to understand the contribution of low-energy ions to radiological effects of various ionising radiations.

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

    NASA Astrophysics Data System (ADS)

    Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Sagheer, Riffat; Naab, Fabian; Toader, Ovidiu; Mahmood, Arshad; Rashid, Rashad; Mahmood, Mazhar

    2015-09-01

    Ion implantation is a useful technique to modify surface properties of polymers without altering their bulk properties. The objective of this work is to explore the 400 keV C+ ion implantation effects on PMMA at different fluences ranging from 5 × 1013 to 5 × 1015 ions/cm2. The surface topographical examination of irradiated samples has been performed using Atomic Force Microscope (AFM). The structural and chemical modifications in implanted PMMA are examined by Raman and Fourier Infrared Spectroscopy (FTIR) respectively. The effects of carbon ion implantation on optical properties of PMMA are investigated by UV-Visible spectroscopy. The modifications in electrical conductivity have been measured using a four point probe technique. AFM images reveal a decrease in surface roughness of PMMA with an increase in ion fluence from 5 × 1014 to 5 × 1015 ions/cm2. The existence of amorphization and sp2-carbon clusterization has been confirmed by Raman and FTIR spectroscopic analysis. The UV-Visible data shows a prominent red shift in absorption edge as a function of ion fluence. This shift displays a continuous reduction in optical band gap (from 3.13 to 0.66 eV) due to formation of carbon clusters. Moreover, size of carbon clusters and photoconductivity are found to increase with increasing ion fluence. The ion-induced carbonaceous clusters are believed to be responsible for an increase in electrical conductivity of PMMA from (2.14 ± 0.06) × 10-10 (Ω-cm)-1 (pristine) to (0.32 ± 0.01) × 10-5 (Ω-cm)-1 (irradiated sample).

  2. Experimental study of {Delta}I=1 bands in {sup 111}In

    SciTech Connect

    Banerjee, P.; Pradhan, M. K.; Ganguly, S.; Sharma, H. P.; Muralithar, S.; Singh, R. P.; Bhowmik, R. K.

    2011-02-15

    The two {Delta}I=1 bands in {sup 111}In, built upon the 3461.0 and 4931.8 keV states, have been studied. The bands were populated in the reaction {sup 100}Mo({sup 19}F, {alpha}4n{gamma}) at a beam energy of 105 MeV. Mean lifetimes of nine states, four in the first and five in the second band, have been determined for the first time from Doppler shift attenuation data. The deduced B(M1) rates and their behavior as a function of level spin support the interpretation of these bands within the framework of the shears mechanism. The geometrical model of Machiavelli et al. has been used to derive the effective gyromagnetic ratios for the two bands.

  3. Anharmonicity of the excited octupole band in actinides using supersymmetric quantum mechanics

    NASA Astrophysics Data System (ADS)

    Jolos, R. V.; von Brentano, P.; Casten, R. F.

    2013-09-01

    Background: Low-lying octupole collective excitations play an important role in the description of the structure of nuclei in the actinide region. Ground state alternating parity rotational bands combining both positive and negative parity states are known in several nuclei. However, only recently it has been discovered in 240Pu an excited positive parity rotational band having an octupole nature and demonstrating strong anharmonicity of the octupole motion in the band head energies.Purpose: To suggest a model describing both ground state and excited alternating parity bands, which includes a description of the anharmonic effects in the bandhead excitation energies and can be used to predict the energies of the excited rotational bands of octupole nature and the E1 transition probabilities.Methods: The mathematical technique of the supersymmetric quantum mechanics with a collective Hamiltonian depending only on the octupole collective variable which keeps axial symmetry is used to describe the ground state and excited alternating parity rotational bands.Results: The excitation energies of the states belonging to the lowest negative parity and the excited positive parity bands are calculated for 232Th, 238U, and 240Pu. The E1 transition matrix elements are also calculated for 240Pu.Conclusions: It is shown that the suggested model describes the excitation energies of the states of the lowest negative parity band with the accuracy around 10 keV. The anharmonicity in the bandhead energy of the excited positive parity band is described also. The bandhead energy of the excited positive parity band is described with the accuracy around 100 keV.

  4. Decay-out of 151Tb Yrast Superdeformed Band and Shape Coexistence

    SciTech Connect

    Duchene, G.; Robin, J.; Odahara, A.; Byrski, Th.; Beck, F.A.; Bednarczyk, P.; Curien, D.; Courtin, S.; Dorvaux, O.; Gall, B.; Joshi, P.; Nourreddine, A.; Pachoud, E.; Piqueras, I.; Vivien, J.P.; Twin, P.J.; Cullen, D.M.; Ertueck, S.; King, S.L.; Paul, E.S.

    2004-02-27

    Linking transitions between the superdeformed (SD) and the normal deformed (ND) wells have been searched in 151Tb nucleus. Two experiments of 5 and 17 days have been performed with EUROBALL IV. Transitions of 2818 keV and 3748 keV with intensities of about 1 % relative to the yrast SD band have been observed. Their decay-out properties are discussed in the text. In addition the eight known SD bands have been extended towards higher rotational frequencies where orbital crossings are observed. For the first time, weakly populated collective ND structures, likely triaxial, similar to the ones recently identified in 152Dy, 153Ho and 155Er nuclei have been observed in 151Tb. The SD and ND structures are interpreted in the frame of Woods-Saxon theoretical calculations.

  5. Banded transformer cores

    NASA Technical Reports Server (NTRS)

    Mclyman, C. W. T. (Inventor)

    1974-01-01

    A banded transformer core formed by positioning a pair of mated, similar core halves on a supporting pedestal. The core halves are encircled with a strap, selectively applying tension whereby a compressive force is applied to the core edge for reducing the innate air gap. A dc magnetic field is employed in supporting the core halves during initial phases of the banding operation, while an ac magnetic field subsequently is employed for detecting dimension changes occurring in the air gaps as tension is applied to the strap.

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

    NASA Astrophysics Data System (ADS)

    Hu, Chia-Yu; Lin, Chun-Hung

    2017-03-01

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

  7. Observation of the single step links of the yrast superdeformed band in {sup 194}Pb

    SciTech Connect

    Hannachi, F.; Lopez-Martens, A.; Schueck, C.

    1996-12-01

    The EUROGAM array has been used to investigate the decay out of the yrast superdeformed (SD) band in {sup 194}Pb. Eigth single step decays from the lowest observed SD states to low-lying states at normal deformation (ND) have been identified. From this observation, the excitation energy (4877 {plus_minus} 1.5 keV) and the spin (6+) of the lowest observed SD state in {sup 194}Pb are established.

  8. Efficiency of Scintillator Materials in the Energy Range 8.0-32.0 keV

    SciTech Connect

    Kinney, J H; Haupt, D L

    2002-07-01

    X-ray microtomography requires the measurement of x-ray attenuation along ray paths through a specimen, and on the inversion of these data to obtain a spatially resolved mapping of the microstructure of the specimen. To do this efficiently, two-dimensional array detectors are often used to measure the transmitted x-rays by capturing and recording each x-ray incident on the detector. The highest resolution CT instruments perform this by converting the incident x-rays to visible light, and then focusing this light onto a charge-coupled-device (CCD) detector. The light output of the scintillator (photons per incident x-ray), the numerical aperture of the optical lens system, and the quantum efficiency of the CCD govern the efficiency of the detection process. Several years earlier, our group performed an investigation aimed at determining the best scintillator material for high-resolution synchrotron CT. The selection criteria included light output in the 8-32 keV energy range, the spatial resolution of the scintillator, the wavelength of the scintillation radiation, and the stability and ease of polishing of the scintillator. A list of the scintillators that we considered, with the exceptions of the more recently developed glass scintillators, is provided in Table 1. Among these scintillators, we concluded that single crystal cadmium tungstate was optimum; we have used this material in all subsequent synchrotron CT systems. Since this original study, several doped-glass scintillators have become available. The LSO (Lu orthosilicates) scintillators, developed for PET scanning, show considerable light output at high energy (energies above 500 keV). Theoretically, the light output of these scintillators should be twice that of the cadmium tungstate. The purpose of this study was to determine the efficiency of two such scintillators (LSO:Yt and IQI-401 high density terbium activated glass) in the energy range from 8-32 keV.

  9. NEW OBSERVATIONS OF THE SOLAR 0.5–5 KEV SOFT X-RAY SPECTRUM

    SciTech Connect

    Caspi, Amir; Woods, Thomas N.; Warren, Harry P.

    2015-03-20

    The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the high-temperature corona, and is also an important driver of ionospheric dynamics at Earth. There is a crucial observational gap between ∼0.2 and ∼4 keV, outside the ranges of existing spectrometers. We present observations from a new SXR spectrometer, the Amptek X123-SDD, which measured the spatially integrated solar spectral irradiance from ∼0.5 to ∼5 keV, with ∼0.15 keV FWHM resolution, during sounding rocket flights on 2012 June 23 and 2013 October 21. These measurements show that the highly variable SXR emission is orders of magnitude greater than that during the deep minimum of 2009, even with only weak activity. The observed spectra show significant high-temperature (5–10 MK) emission and are well fit by simple power-law temperature distributions with indices of ∼6, close to the predictions of nanoflare models of coronal heating. Observations during the more active 2013 flight indicate an enrichment of low first-ionization potential elements of only ∼1.6, below the usually observed value of ∼4, suggesting that abundance variations may be related to coronal heating processes. The XUV Photometer System Level 4 data product, a spectral irradiance model derived from integrated broadband measurements, significantly overestimates the spectra from both flights, suggesting a need for revision of its non-flare reference spectra, with important implications for studies of Earth ionospheric dynamics driven by solar SXRs.

  10. Multi-Band-SWIFT

    NASA Astrophysics Data System (ADS)

    Idiyatullin, Djaudat; Corum, Curtis A.; Garwood, Michael

    2015-02-01

    A useful extension to SWIFT (SWeep Imaging with Fourier Transformation) utilizing sidebands of the excitation pulse is introduced. This MRI method, called Multi-Band-SWIFT, achieves much higher bandwidth than standard SWIFT by using multiple segmented excitations (bands) of the field of view. A description of the general idea and variants of the pulse sequence are presented. From simulations and semi-phenomenological theory, estimations of power deposition and signal-to-noise ratio are made. MB-SWIFT and ZTE (zero-TE) sequences are compared based on images of a phantom and human mandible. Multi-Band-SWIFT provides a bridge between SWIFT and ZTE sequences and allows greatly increased excitation and acquisition bandwidths relative to standard SWIFT for the same hardware switching parameters and requires less peak amplitude of the radiofrequency field (or greater flip angle at same peak amplitude) as compared to ZTE. Multi-Band-SWIFT appears to be an attractive extension of SWIFT for certain musculoskeletal and other medical imaging applications, as well as for imaging materials.

  11. Multi-Band-SWIFT.

    PubMed

    Idiyatullin, Djaudat; Corum, Curtis A; Garwood, Michael

    2015-02-01

    A useful extension to SWIFT (SWeep Imaging with Fourier Transformation) utilizing sidebands of the excitation pulse is introduced. This MRI method, called Multi-Band-SWIFT, achieves much higher bandwidth than standard SWIFT by using multiple segmented excitations (bands) of the field of view. A description of the general idea and variants of the pulse sequence are presented. From simulations and semi-phenomenological theory, estimations of power deposition and signal-to-noise ratio are made. MB-SWIFT and ZTE (zero-TE) sequences are compared based on images of a phantom and human mandible. Multi-Band-SWIFT provides a bridge between SWIFT and ZTE sequences and allows greatly increased excitation and acquisition bandwidths relative to standard SWIFT for the same hardware switching parameters and requires less peak amplitude of the radiofrequency field (or greater flip angle at same peak amplitude) as compared to ZTE. Multi-Band-SWIFT appears to be an attractive extension of SWIFT for certain musculoskeletal and other medical imaging applications, as well as for imaging materials.

  12. Banded Sunflower Moth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The banded sunflower moth, Cochylis hospes Walsingham, is an important insect pest of cultivated sunflower. Eggs are deposited on the bracts of sunflower heads. Larvae develop through five instars within the heads and are present in fields from mid-July to mid-September. Larvae feed initially on the...

  13. Microchannel plate pinhole camera for 20 to 100 keV x-ray imaging

    SciTech Connect

    Wang, C.L.; Leipelt, G.R.; Nilson, D.G.

    1984-10-03

    We present the design and construction of a sensitive pinhole camera for imaging suprathermal x-rays. Our device is a pinhole camera consisting of four filtered pinholes and microchannel plate electron multiplier for x-ray detection and signal amplification. We report successful imaging of 20, 45, 70, and 100 keV x-ray emissions from the fusion targets at our Novette laser facility. Such imaging reveals features of the transport of hot electrons and provides views deep inside the target.

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

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

    In chromatin, DNA is tightly packed into one complex together with histone and non-histone proteins. These proteins are known to protect the DNA against indirect and to some extent even direct radiation damage. Radiation action upon amino acids is thus one of the primary steps in biological radiation action. In this paper we investigate the ionization and fragmentation of the gas-phase amino acids glycine, alanine and valine upon interaction with keV α-particles. High resolution coincidence time-of-flight mass spectrometry is used to determine the dominant fragmentation channels as well as fragment kinetic energies.

  15. Inelastic scattering of 45-keV neutrons by {sup 187}Os

    SciTech Connect

    Litvinskii, L.L.; Zhigalov, Ya.A.; Libman, V.A.; Murzin, A.V.; Shkarupa, A.M.

    1995-02-01

    The cross sections of elastic and inelastic scattering of 45-keV neutrons by {sup 187}Os are measured by the technique of filtered neutron beams at the Kiev VVR-M reactor and are found to be {sigma}{sub e1} = 11.90 {+-} 0.50 b and {sigma}{sub inel} = 1.51 {+-} 0.45 b, respectively. These results confirm the existence of a nonstatistical enhancement of the inelastic-scattering channel due to a noticeable contribution of a preequilibrium state involving two particles and a hole. 8 refs., 1 fig.

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

    NASA Astrophysics Data System (ADS)

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

    1992-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1993-01-01

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

  18. Simultaneous ejection of two molecular ions from keV gold atomic and polyatomic projectile impacts.

    PubMed

    Rickman, R D; Verkhoturov, S V; Parilis, E S; Schweikert, E A

    2004-01-30

    We present the first experimental data on the simultaneous ejection of two molecular ions from the impact of Au(+)(n) (1< or =n< or =4) with energies ranging between 17 and 56 keV. The yields from single phenylalanine (Ph) emission, coemission of two Ph ions, and emission of the Ph dimer were measured. Large increases (1 to 2 orders of magnitude) in coemitted ion yields were observed with increasing projectile energy and complexity. Correlation coefficients were calculated for the coemission of two Ph ions; their behavior suggests differences in emission pathways for bombardment by atomic and polyatomic projectiles.

  19. Asymmetric 511 keV Positron Annihilation Line Emission from the Inner Galactic Disk

    NASA Technical Reports Server (NTRS)

    Skinner, Gerry; Weidenspointner, Georg; Jean, Pierre; Knodlseder, Jurgen; Ballmoos, Perer von; Bignami, Giovanni; Diehl, Roland; Strong, Andrew; Cordier, Bertrand; Schanne, Stephane; Winkler, Christoph

    2008-01-01

    A recently reported asymmetry in the 511 keV gamma-ray line emission from the inner galactic disk is unexpected and mimics an equally unexpected one in the distribution of LMXBs seen at hard X-ray energies. A possible conclusion is that LMXBs are an important source of the positrons whose annihilation gives rise to the line. We will discuss these results, their statistical significance and that of any link between the two. The implication of any association between LMXBs and positrons for the strong annihilation radiation from the galactic bulge will be reviewed.

  20. The effect of 1 to 5 keV electrons on the reproductive integrity of microorganisms

    NASA Technical Reports Server (NTRS)

    Barengoltz, J. B.; Brady, J.

    1977-01-01

    Microorganisms were exposed to simulated space environment in order to assess the effect of electrons in the energy range 1 to 5 keV on their colony-forming ability. The test system consisted of an electron gun and power supply, a dosimetry subsystem, and a vacuum subsystem. The system was capable of current densities ranging from 0.1 nA/sq cm to 5 micro A/sq cm on a 25 sq on target and an ultimate vacuum of 0.0006 N/sq m (0.000004 torr). The results of the experimental program show a significant reduction in microbial reproductive integrity.

  1. On the vectorial photoelectric effect at 2.69 keV

    NASA Technical Reports Server (NTRS)

    Shaw, P. S.; Hanany, S.; Liu, Y.; Church, E. D.; Fleischman, J.; Kaaret, P.; Novick, R.; Santangelo, A.

    1991-01-01

    Recent experiments conducted to study the vectorial photoelectric effect with CsI, Al2O3 and Si photocathodes at 2.69 keV indicate null results. Detailed analysis shows that previously measured modulation can be well explained by geometrical misalignment and a combination of the asymmetric shape of the incident X-ray beam and a small detection area of the photoelectron detector. After the elimination of the sources of spurious modulation, we observed a modulation factor of less than 3 percent for a grazing incidence angle as small as 5 deg. There is no observable difference in the pulse height distribution between s and p states.

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

    SciTech Connect

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

    2007-01-19

    High pressure x-ray absorption has been performed down to 3.6 keV, thanks to the new LUCIA beamline (SLS, PSI) and to the use of perforated diamonds or Be gasket. Various experimental geometries are proposed, depending on the energy of the edge and on the concentration of the studied element. A few examples will be presented: BaTiO3 at the titanium K edge, Zn0.95 Mn0.05O at the manganese K edge, KCl at the potassium K edge.

  3. 3.55 keV line in minimal decaying dark matter scenarios

    SciTech Connect

    Arcadi, Giorgio; Covi, Laura; Dradi, Federico E-mail: Laura.Covi@theorie.physik.uni-goettingen.de

    2015-07-01

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

  4. Calibration of the 67 keV mössbauer resonance of73Ge

    NASA Astrophysics Data System (ADS)

    Svane, A.; Antoncik, E.

    1986-06-01

    Using the first-principles scalar-relativistic LMTO method, we have calculated the electronic structure of crystalline Ge and rutile-structured GeO2. By comparing the calculated electron contact densities with experimental isomer shifts of the 67 keV transition of73Ge in these materials, we obtain a value for the relative change in the nuclear radius of Δ R/R=(7.4±0.7)×10-4. The results of the present work are compared with previous attempts to calibrate this isomeric transition.

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

    SciTech Connect

    Cafarelli, Pierre; Champeaux, Jean-Philippe; Le Padellec, Arnaud; Moretto-Capelle, Patrick; Rabier, Julien; Sence, Martine; Carcabal, Pierre

    2008-12-08

    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.

  6. SEARCH FOR TWO-PHONON OCTUPOLE VIBRATIONAL BANDS IN 88, 89, 92, 93, 94, 96Sr AND 95, 96, 97, 98Zr

    NASA Astrophysics Data System (ADS)

    Hwang, J. K.; Hamilton, J. H.; Ramayya, A. V.; Brewer, N. T.; Wang, E. H.; Luo, Y. X.; Zhu, S. J.

    2012-09-01

    Several new gamma transitions were identified in 94Sr, 93Sr, 92Sr, 96Zr and 97Zr from the spontaneous fission of 252Cf. Excited states in 88, 89, 92, 94, 96Sr and 95, 96, 97, 98Zr were reanalyzed and reorganized to propose the new two-phonon octupole vibrational states and bands. The spin and parity of 6+ are assigned to a 4034.5 keV state in 94Sr and 3576.4 keV state in 98Zr. These states are proposed as the two-phonon octupole vibrational states along with the 6+ states at 3483.4 keV in 96Zr, at 3786.0 keV in 92Sr and 3604.2 keV in 96Sr. The positive parity bands in 88, 94, 96Sr and 96, 98Zr are the first two-phonon octupole vibrational bands based on a 6+ state assigned in spherical nuclei. It is thought that in 94, 96Sr and 96, 98Zr a 3- octupole vibrational phonon is weakly coupled to an one-phonon octupole vibrational band to make the two-phonon octupole vibrational band. Also, the high spin states of odd-A95Zr and 97Zr are interpreted to be generated by the neutron 2d5/2 hole and neutron 1g7/2 particle, respectively, weakly coupled to one- and two-phonon octupole vibrational bands of 96Zr. The high spin states of odd-A87Sr are interpreted to be caused by the neutron 1g9/2 hole weakly coupled to 3- and 5- states of 88Sr. New one- and two-POV bands in 95, 97Zr and 87, 89Sr are proposed, for the first time, in the present work.

  7. IET. Inside the coupling station during Snaptran tests. Snaptran 2/10A1 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    IET. Inside the coupling station during Snaptran tests. Snaptran 2/10A-1 plug and flexible hoses make connections with experiment on other side. Photographer: Page Comiskey. Date: August 11, 1965. INEEL negative no. 65-4060 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  8. Experimental study of the 2p-2h band in {sup 111}Sn

    SciTech Connect

    Ganguly, S.; Banerjee, P.; Ray, I.; Kshetri, R.; Raut, R.; Bhattacharya, S.; Saha-Sarkar, M.; Goswami, A.; Basu, S. K.

    2008-09-15

    The {delta}I=2 intruder band in {sup 111}Sn, built upon the 4074.3 keV state, was studied. The states were populated in the {sup 100}Mo({sup 20}Ne, {alpha}5n) reaction at a beam energy of 136 MeV. Mean lifetimes of five states up to 8737.2 keV (spin 43/2{sup -}) have been measured for the first time using the Doppler shift attenuation method. In addition, an upper limit of mean lifetime has been estimated for the 9860.0 keV (spin 47/2{sup -}) state. The B(E2) values, derived from the present lifetime results, indicate a quadrupole deformation of {beta}{sub 2}=0.28{+-}0.02 for the 31/2{sup -} state and decrease progressively with spin, suggesting a reduction in collectivity. The dynamic moment of inertia for the band also decreases continuously up to the highest observed frequencies. These results, along with the predictions of a total Routhian surface calculation, suggest that the {delta}I=2 band in {sup 111}Sn undergoes a change of shape from collective prolate to triaxial with increase in spin and possibly terminates in a noncollective oblate state at a high spin.

  9. Band reject filtration of the excitation spectrum at energy dispersive X-ray spectroscopy of weak signals

    NASA Astrophysics Data System (ADS)

    Tur'yanskii, A. G.; Gizha, S. S.; Senkov, V. M.; Pirshin, I. V.; Stanishevskii, Ya. M.

    2016-09-01

    The possibility of the efficient band reject filtration of the continuous X-ray excitation spectrum in the energy range E ≥ 8 keV is demonstrated. This makes it possible to strongly increase the sensitivity of energy dispersive X-ray spectroscopy at detecting of weak fluorescence lines. Spectral rejection is implemented by transmitting a primary beam through highly oriented pyrolytic graphite with given structural parameters. Diffraction extinction in pyrolytic graphite ensures the possibility of reducing the intensity by more than 20 dB and rejecting the spectral band with a width of 1 keV. The reduction of statistical fluctuations of the background of elastically scattered radiation is achieved when the bottom of the formed spectral valley is adjusted to the analyzed fluorescence line. The proposed scheme of band reject filtration also allows the suppression of intense characteristic lines in the primary and scattered radiation spectra.

  10. R-Matrix Analysis of 238U High Resolution Neutron Transmissions and Capture Cross Sections in the Energy Range 0 keV to 20 keV

    SciTech Connect

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

    2009-01-01

    The neutron resonance parameters of 238U 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 to 200 pcm.

  11. Model study of the mid-latitude atmospheric interaction with energetic O/sup +/ and He/sup +/ (< 20 keV) precipitation during a storm

    SciTech Connect

    Ishimoto, M.

    1986-01-01

    The purpose of this study is to use a model computation to investigate the mid-latitude atmospheric interaction with energetic O/sup +/ and He/sup +/ (<20 keV) precipitation during a storm. The steady-state continuity equations for the fluxes are formulated as a system of first-order ordinary differential equations. The model, consisting of three components, O, N/sub 2/ and He, computes the upward and downward fluxes resulting from energetic ion precipitation by solving sets of this system of equations. The model computes the heating, the ion production, the N/sub 2//sup +/ first negative (O-O) band and N/sub 2/ second-positive (O-O) band emission intensities in the atmosphere, and the escape fluxes to the magnetosphere. Energetic O/sup +/ deposit 80% of their energy for heating and a few percent for ionization below 200 km, and bring 20% of their incident energy back to the magnetosphere together with 30 O and 5 N/sub 2/ particles from the ionospheres for each incident O/sup +/. Energetic He/sup +/ dissipate by ionization (50%) instead of atmospheric heating (10%). He/sup +/ are reflected at an altitude of about 200 km back to the magnetosphere without losing much energy. He/sup +/ precipitation does not bring the ionospheric neutrals back to the magnetosphere.

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

    SciTech Connect

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

    2004-10-01

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

  13. Symmetry properties of the K =0 sup + bands in reflection asymmetric sup 224 Ac

    SciTech Connect

    Sheline, R.K.; Kvasil, J. ); Liang, C.F.; Paris, P. )

    1991-11-01

    Parity doublet bands with {ital K}=0{sup {plus minus}} implying reflection asymmetry (with an average spacing between the levels of the same spin and opposite parity of 12.6 keV) are observed in {sup 224}Ac. In the strong coupling limit all {ital K}=0{sup {plus minus}} parity doublet bands are shown to be constrained to Newby splittings with the same absolute magnitude, but with opposite sign. Experimentally, the Newby splittings in {sup 224}Ac approach this theoretical expectation.

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

    PubMed

    Tereshchenko, Evgeny E; Moiseev, Nikolay

    2012-09-01

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

  15. Dose dependence of surface damage profiles for Ge(111) irradiated with 3 keV Ar +

    NASA Astrophysics Data System (ADS)

    Kido, Yoshiaki; Nakano, Hirohiko

    1990-12-01

    The damage profiles of 3 keV Ar + -irradiated Ge(111) were measured by medium energy ion scattering (MEIS) with 220 keV H + beams. A depth resolution of 0.5 nm has been achieved using an electrostatic toroidal analyzer. With doses over 1 × 10 14Ar+/ cm2 at room temperature, an amorphous layer is formed and the amorphous layer thickness is saturated by a dose of 1 × 10 15Ar+/ cm2. The saturated amorphous layer thickness of 12-13 nm obtained is in good agreement with that observed by a cross section transmission electron microscope. The dose dependence of the induced defects derived from MEIS is consistent with that determined by electron channeling pattern analysis. The amorphized damage profiles determined directly by MEIS agree well with those obtained by solving the rate equation using the unsaturated initial defect profile for a dose of 2 × 10 13Ar+/ cm2 and assuming a sputtering rate of 2.4-3.0.

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

    SciTech Connect

    Derrien, H.

    2002-09-30

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

  17. Full characterization of a laser-produced keV x-ray betatron source

    NASA Astrophysics Data System (ADS)

    Albert, F.; Phuoc, K. Ta; Shah, R.; Corde, S.; Fitour, R.; Tafzi, A.; Burgy, F.; Douillet, D.; Lefrou, T.; Rousse, A.

    2008-12-01

    This paper presents the complete characterization of a kilo-electron-volt laser-based x-ray source. The main parameters of the electron motion (amplitude of oscillations and initial energy) in the laser wakefield have been investigated using three independent methods relying on spectral and spatial properties of this betatron x-ray source. First we will show studies on the spectral correlation between electrons and x-rays that is analyzed using a numerical code to calculate the expected photon spectra from the experimentally measured electron spectra. High-resolution x-ray spectrometers have been used to characterize the x-ray spectra within 0.8-3 keV and to show that the betatron oscillations lie within 1 µm. Then we observed Fresnel edge diffraction of the x-ray beam. The observed diffraction at the center energy of 4 keV agrees with the Gaussian incoherent source profile of full width half maximum <5 µm, meaning that the amplitude of the betatron oscillations is less than 2.5 µm. Finally, by measuring the far field spatial profile of the radiation, we have been able to characterize the electron's trajectories inside the plasma accelerator structure with a resolution better than 0.5 µm.

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

    PubMed

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

    2005-01-01

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

  19. Improving accuracy and reliability of 186-keV measurements for unattended enrichment monitoring

    SciTech Connect

    Ianakiev, Kiril D; Boyer, Brian D; Swinhoe, Martyn T; Moss, Calvin E; Goda, Joetta M; Favalli, Andrea; Lombardi, Marcie; Paffett, Mark T; Hill, Thomas R; MacArthur, Duncan W; Smith, Morag K

    2010-04-13

    Improving the quality of safeguards measurements at Gas Centrifuge Enrichment Plants (GCEPs), whilst reducing the inspection effort, is an important objective given the number of existing and new plants that need to be safeguarded. A useful tool in many safeguards approaches is the on-line monitoring of enrichment in process pipes. One aspect of this measurement is a simple, reliable and precise passive measurement of the 186-keV line from {sup 235}U. (The other information required is the amount of gas in the pipe. This can be obtained by transmission measurements or pressure measurements). In this paper we describe our research efforts towards such a passive measurement system. The system includes redundant measurements of the 186-keV line from the gas and separately from the wall deposits. The design also includes measures to reduce the effect of the potentially important background. Such an approach would practically eliminate false alarms and can maintain the operation of the system even with a hardware malfunction in one of the channels. The work involves Monte Carlo modeling and the construction of a proof-of-principle prototype. We will carry out experimental tests with UF{sub 6} gas in pipes with and without deposits in order to demonstrate the deposit correction.

  20. 3.55 keV line from exciting dark matter without a hidden sector

    NASA Astrophysics Data System (ADS)

    Berlin, Asher; DiFranzo, Anthony; Hooper, Dan

    2015-04-01

    Models in which dark matter particles can scatter into a slightly heavier state which promptly decays to the lighter state and a photon (known as eXciting Dark Matter, or XDM) have been shown to be capable of generating the 3.55 keV line observed from galaxy clusters, while suppressing the flux of such a line from smaller halos, including dwarf galaxies. In most of the XDM models discussed in the literature, this up-scattering is mediated by a new light particle, and dark matter annihilations proceed into pairs of this same light state. In these models, the dark matter and the mediator effectively reside within a hidden sector, without sizable couplings to the Standard Model. In this paper, we explore a model of XDM that does not include a hidden sector. Instead, the dark matter both up-scatters and annihilates through the near resonant exchange of an O (1 02) GeV pseudoscalar with large Yukawa couplings to the dark matter and smaller, but non-neglibile, couplings to Standard Model fermions. The dark matter and the mediator are each mixtures of Standard Model singlets and S U (2 )W doublets. We identify parameter space in which this model can simultaneously generate the 3.55 keV line and the gamma-ray excess observed from the Galactic center, without conflicting with constraints from colliders, direct detection experiments, or observations of dwarf galaxies.

  1. Feasibility study for DEXA using synchrotron CT at 20-35 keV

    NASA Astrophysics Data System (ADS)

    Midgley, S. M.

    2013-02-01

    A nonlinear model for the x-ray linear attenuation coefficient μ is employed for dual energy x-ray analysis (DEXA). Nonlinear simultaneous equations formed by μ and energy dependent model parameters are solved for the electron density Ne and fourth compositional ratio R4 which has the same ‘units’ as the atomic number. Computed tomography data was acquired at 20-35 keV using bending magnet synchrotron radiation, a double crystal monochromator, a rotation stage and an area detector. Test objects contained liquid samples as mixtures of ethanol, water and salt solutions with known density and composition. Various noise sources are identified and give μ uncertainties of 1-2%. A fan beam geometry allowed the detection of forward scattered radiation with measured μ being 6% lower than expectations for a narrow beam. Energy dependent model parameters were obtained by solving linear simultaneous equations formed by μ and material parameters based upon Ne and R4. DEXA accuracy was studied as a function of photon energy and sample composition. Propagation of errors analysis identifies the importance of the fractional compositional cross-products whose difference at the two beam energies should exceed 0.1, requiring 10 keV or more separation. For a reasonable approximation for the adjustable model parameters, the mean difference between the DEXA solution and true values (ΔNe, ΔR4) are (1.0%, 0.5%) for soft tissue and (1.5%, 0.8%) for bone like samples.

  2. The 16 August 1997 Novaya Zemlya seismic event as viewed from GSN stations KEV and KBS

    SciTech Connect

    Hartse, H.E.

    1997-11-01

    Using current and historic seismic records from Global Seismic Network stations KEV and KBS, the authors find that S minus P arrival time comparisons between nuclear explosions and the 16 August 1997 seismic event (m{sub b} {approx} 3.6) from near Novaya Zemlya clearly indicate that (relative to KEV) the 16 August event occurred at least 80 km east of the Russian test site. Including S minus P arrival times from KBS constrains the location to beneath the Kara Sea and in good agreement with previously reported locations, over 100 km southeast of the test site. From an analysis of P{sub n}/S{sub n} waveform ratios at frequencies above 4 Hz, they find that the 16 August event falls within the population of regional earthquakes and is distinctly separated from Novaya Zemlya and other northern Eurasian nuclear explosion populations. Thus, given its location and waveform characteristics, they conclude the 16 August event was an earthquake. The 16 August event was not detected at teleseismic distances, and thus, this event provides a good example of the regional detection, location, and identification efforts that will be required to monitor the Comprehensive Test Ban Treaty below m{sub b} {approx} 4.

  3. Application of keV and MeV ion microbeams through tapered glass capillaries

    NASA Astrophysics Data System (ADS)

    Ikeda, T.; Kojima, T. M.; Kobayashi, T.; Meissl, W.; Mäckel, V.; Kanai, Y.; Yamazaki, Y.

    2012-11-01

    We have developed a method to produce micrometer-sized beams of keV energy highly charged ions (HCIs) and MeV energy protons/helium ions with tapered glass capillary optics for the applications of micrometer sized surface modifications and a biological tool, respectively. The transmission experiments of keV HCIs through the glass capillaries show a density enhancement of about 10, beam guiding up to 5°, and the extracted beam keeping the initial charge-state. The combination of MeV ion beams and the capillary with a thin end window at its outlet was used for the irradiation of a part of nucleus of a HeLa cell in culture solution. Escherichia coli cells are irradiated by MeV proton microbeam to determine the minimum dose to stop the single flagellar motor. Scanning irradiation of polymer surface by the beam extracted from the capillary in solution containing acrylic acid was found to provide a deposition layer with large affinity with water.

  4. Observation of 'Band' Structures in Spacecraft Observations of Inner Magnetosphere Plasma Electrons

    NASA Astrophysics Data System (ADS)

    Mohan Narasimhan, Kirthika; Fazakerley, Andrew; Milhaljcic, Branislav; Grimald, Sandrine; Dandouras, Iannis; Owen, Chris

    2013-04-01

    In previous studies, several authors have reported inner magnetosphere observations of proton distributions confined to narrow energy bands in the range of 1-25 keV. These structures have been known as "nose structures", with reference to their appearance in energy-time spectrograms and are known as "bands" if they are observed for extended periods of time. These proton structures have been studied quite extensively with multiple mechanisms proposed for their formation, not all of which apply for electrons. We examine Double-Star TC1 PEACE electron data recorded in the inner magnetosphere (L<15) near the equatorial plane to see if these features are also observed in the electron energy spectra. These "bands" also appear in electron spectrograms, spanning an energy range of 0.2-30 keV, and are shown to occur predominantly towards the dayside and dusk sectors. We also see multiple bands in some instances. We investigate the properties of these multi-banded structures and carry out a statistical survey analysing them as a function of geomagnetic activity, looking at both the Kp and Auroral Indices, in an attempt to explain their presence.

  5. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1996-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  6. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1994-04-05

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figures.

  7. Banded electromagnetic stator core

    DOEpatents

    Fanning, Alan W.; Gonzales, Aaron A.; Patel, Mahadeo R.; Olich, Eugene E.

    1994-01-01

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups.

  8. Banded electromagnetic stator core

    DOEpatents

    Fanning, A.W.; Gonzales, A.A.; Patel, M.R.; Olich, E.E.

    1996-06-11

    A stator core for an electromagnetic pump includes a plurality of circumferentially adjoining groups of flat laminations disposed about a common centerline axis and collectively defining a central bore and a discontinuous outer perimeter, with adjacent groups diverging radially outwardly to form V-shaped gaps. An annular band surrounds the groups and is predeterminedly tensioned to clamp together the laminations, and has a predetermined flexibility in a radial direction to form substantially straight bridge sections between the adjacent groups. 5 figs.

  9. Wideband S Band Transmitter

    DTIC Science & Technology

    1989-10-01

    the phase variations across a +/-I nanosecond compressed pulse . During experimentation in the RADC Module Evaluation Lab the paired echos could be...22 4-11. Pulsing Interlock ....................................... 23 4-12. Pulse Fault Detector and Fault Summary...band transmitter was built by RCA Corporation under contract F30602-78-C-0122, titled "Wideband Amplifier, P/O Digitally Coded Radar’. After use by

  10. Micromechanics of shear banding

    SciTech Connect

    Gilman, J.J.

    1992-08-01

    Shear-banding is one of many instabilities observed during the plastic flow of solids. It is a consequence of the dislocation mechanism which makes plastic flow fundamentally inhomogeneous, and is exacerbated by local adiabatic heating. Dislocation lines tend to be clustered on sets of neighboring glide planes because they are heterogeneously generated; especially through the Koehler multiple-cross-glide mechanism. Factors that influence their mobilities also play a role. Strain-hardening decreases the mobilities within shear bands thereby tending to spread (delocalize) them. Strain-softening has the inverse effect. This paper reviews the micro-mechanisms of these phenomena. It will be shown that heat production is also a consequence of the heterogeneous nature of the microscopic flow, and that dislocation dipoles play an important role. They are often not directly observable, but their presence may be inferred from changes in thermal conductivity. It is argued that after deformation at low temperatures dipoles are distributed a la Pareto so there are many more small than large ones. Instability at upper yield point, the shapes of shear-band fronts, and mechanism of heat generation are also considered. It is shown that strain-rate acceleration plays a more important role than strain-rate itself in adiabatic instability.

  11. A multitude of rotational bands in {sup 163}Er and their mutual interaction

    SciTech Connect

    Bosetti, P.; Leoni, S.; Bracco, A.

    1996-12-31

    Using the {sup 150}Nd({sup 18}O, 5n){sup 163}Er reaction a multitude of rotational bands have been established with firm spin and parity assignments in {sup 163}Er. In 16 out of {approximately} 23 band crossings E2 cross-band transitions have been observed. The interaction strength varies between {approximately} 1 and {approximately} 50 keV. These interactions sample a variety of the lowest (multi)-quasiparticle configurations. Some of the band configurations, in particular those with high K-values, can be rather well established. Quite complicated changes in the wavefunctions must occur at these crossings, and, to explain the observed interaction strengths, one may have to invoke coupling to various vibrational degrees of freedom, in addition to possible residual neutron-proton interactions.

  12. Identification of a quasiparticle band in very neutron-rich {sup 104}Zr

    SciTech Connect

    Yeoh, E. Y.; Wang, J. G.; Ding, H. B.; Gu, L.; Xu, Q.; Xiao, Z. G.; Zhu, S. J.; Hamilton, J. H.; Ramayya, A. V.; Hwang, J. K.; Liu, S. H.; Liu, Y. X.; Sun, Y.; Luo, Y. X.; Rasmussen, J. O.; Lee, I. Y.

    2010-08-15

    The high spin levels of a very neutron-rich {sup 104}Zr nucleus have been reinvestigated by measuring the prompt {gamma} rays in the spontaneous fission of {sup 252}Cf. The ground-state band has been confirmed. A new sideband has been identified with a band-head energy at 1928.7 keV. The projected shell model is employed to investigate the band structure of {sup 104}Zr. The results of calculated levels are in good agreement with the experimental data, and suggest that the new band in {sup 104}Zr may be based on the neutron {nu}5/2{sup -}[532] x {nu}3/2{sup +}[411] configuration.

  13. An actively accreting massive black hole in the dwarf starburst galaxy Henize 2-10.

    PubMed

    Reines, Amy E; Sivakoff, Gregory R; Johnson, Kelsey E; Brogan, Crystal L

    2011-02-03

    Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first 'seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. Here we report that the nearby dwarf starburst galaxy Henize 2-10 (refs 5 and 6) contains a compact radio source at the dynamical centre of the galaxy that is spatially coincident with a hard X-ray source. From these observations, we conclude that Henize 2-10 harbours an actively accreting central black hole with a mass of approximately one million solar masses. This nearby dwarf galaxy, simultaneously hosting a massive black hole and an extreme burst of star formation, is analogous in many ways to galaxies in the infant Universe during the early stages of black-hole growth and galaxy mass assembly. Our results confirm that nearby star-forming dwarf galaxies can indeed form massive black holes, and that by implication so can their primordial counterparts. Moreover, the lack of a substantial spheroidal component in Henize 2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids.

  14. An actively accreting massive black hole in the dwarf starburst galaxy Henize2-10

    NASA Astrophysics Data System (ADS)

    Reines, Amy E.; Sivakoff, Gregory R.; Johnson, Kelsey E.; Brogan, Crystal L.

    2011-02-01

    Supermassive black holes are now thought to lie at the heart of every giant galaxy with a spheroidal component, including our own Milky Way. The birth and growth of the first `seed' black holes in the earlier Universe, however, is observationally unconstrained and we are only beginning to piece together a scenario for their subsequent evolution. Here we report that the nearby dwarf starburst galaxy Henize2-10 (refs 5 and 6) contains a compact radio source at the dynamical centre of the galaxy that is spatially coincident with a hard X-ray source. From these observations, we conclude that Henize2-10 harbours an actively accreting central black hole with a mass of approximately one million solar masses. This nearby dwarf galaxy, simultaneously hosting a massive black hole and an extreme burst of star formation, is analogous in many ways to galaxies in the infant Universe during the early stages of black-hole growth and galaxy mass assembly. Our results confirm that nearby star-forming dwarf galaxies can indeed form massive black holes, and that by implication so can their primordial counterparts. Moreover, the lack of a substantial spheroidal component in Henize2-10 indicates that supermassive black-hole growth may precede the build-up of galaxy spheroids.

  15. Band crossing in a shears band of {sup 108}Cd

    SciTech Connect

    Roy, Santosh; Datta, Pradip; Pal, S.; Chattopadhyay, S.; Bhattacharya, S.; Goswami, A.; Jain, H. C.; Joshi, P. K.; Bhowmik, R. K.; Kumar, R.; Muralithar, S.; Singh, R. P.; Madhavan, N.; Rao, P. V. Madhusudhana

    2010-05-15

    The level lifetimes have been measured for a shears band of {sup 108}Cd that exhibits band crossing. The observed level energies and B(M1) rates have been successfully described by a semiclassical geometric model based on shear mechanism. In this geometric model, the band crossing in the shears band has been described as the reopening of the angle between the blades of a shear.

  16. Investigations into the origin of the spurious 17 keV neutrino signal observed in35S beta decay

    NASA Astrophysics Data System (ADS)

    Bowler, M. G.; Jelley, N. A.

    1995-09-01

    An exhaustive study has been made of the β spectrum of35S, recorded with a Si(Li) detector. The object was to identify the origin of a distortion in the35S β spectrum some 17 keV below the end point, reported over three years ago and interpreted then as evidence for a 17 keV neutrino. Measurements with different source-detector spacings and with varied collimation have shown that there is a long range curvature in the Kurie plot which is a sensitive function of configuration, but the principal origin of the distortion is energy loss in the35S sources. The35S sources, prepared by chemical adsorption of Ba35SO4 on a gold substrate, are clumped and locally thick. Electrons near the end point lose ˜0.3 keV in the source material and if this is taken into account the spectra are well fitted without any admixture of 17 keV neutrino. The source thickness has been investigated with a proton microprobe and determined from both source tilting and the yield of barium K X-rays; these studies are discussed in detail. The uncertainties in and justification for the form of the electron response function employed are also thoroughly discussed. If there is no systematic error common to the majority of 14 independent sets of35S data, the admixture of 17 keV neutrino is <10-3 (95% CL). A simple search for a kink at 150 keV in the combined data from all 14 runs yielded a limit of 1.8×10-3 (95% CL). The end point of the35S β spectrum is found to be 167.60±0.05 keV.

  17. Noise exposure in marching bands

    NASA Astrophysics Data System (ADS)

    Keefe, Joseph

    2005-09-01

    Previous studies involving orchestras have shown that music ensembles can produce hazardous noise levels. There are no similar data for marching bands and pep bands. In order to evaluate the noise levels produced by marching and pep bands, 1/3-octave-band sound-pressure levels were measured while these groups rehearsed and performed. Data were collected while marching with the bands to ensure a realistic environment. Comparing these data to OSHA and NIOSH criteria, marching and pep band exposures often exceed safe values. For typical exposures, OSHA doses range from 11% to 295%, while NIOSH doses range from 35% to 3055%. Exposures that would be considered hazardous in the workplace are common in marching and pep bands; students and band directors should take steps to recognize the risk posed by various instruments and various locations, and should implement hearing conservation efforts.

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

    NASA Astrophysics Data System (ADS)

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

    2017-04-01

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

  19. Neutral beam injector for 475 keV MARS sloshing ions

    SciTech Connect

    Goebel, D.M.; Hamilton, G.W.

    1983-12-13

    A neutral beam injector system which produces 5 MW of 475 keV D/sup 0/ neutrals continuously on target has been designed. The beamline is intended to produce the sloshing ion distribution required in the end plug region of the conceptual MARS tandem mirror commercial reactor. The injector design utilizes the LBL self-extraction negative ion source and Transverse Field Focusing (TFF) accelerator to generate a long, ribbon ion beam. A laser photodetachment neutralizer strips over 90% of the negative ions. Magnetic and neutron shield designs are included to exclude the fringe fields of the end plug and provide low activation by the neutron flux from the target plasma. The use of a TFF accelerator and photodetachment neutralizer produces a total system electrical efficiency of about 63% for this design.

  20. Preliminary resolved resonance region evaluation of copper-63 from 0 to 300 keV

    SciTech Connect

    Sobes, V.; Forget, B.; Leal, L.; Guber, K.

    2012-07-01

    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)

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

    NASA Astrophysics Data System (ADS)

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

    2007-11-01

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

  2. A microwave beam waveguide undulator for a brilliant above 100 keV photon source.

    SciTech Connect

    Kang, Y. W.

    1999-04-19

    For generation of photons above 100-keV with a magnetic field strength in the range 0.2-0.5 Tesla, an undulator wavelength {lambda}{sub u} shorter than 5 mm may be needed with beam in the Advanced Photon Source (APS) storage ring. A microwave beam waveguide undulator system has been investigated for generation of such light. The waveguide structure consists of two parallel reflector surfaces that can be derived from an elliptically cylindrical waveguide. The structure can support deflecting TE{sub m0} modes with very low microwave loss. A microwave ring resonator circuit employing the beam waveguide is considered to construct an undulator with the above requirement. Microwave properties of the beam waveguide structure have been investigated, and the design criteria for a microwave undulator are discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2008-07-01

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

  4. Irradiation effects on secondary structure of protein induced by keV ions

    NASA Astrophysics Data System (ADS)

    Cui, F. Z.; Lin, Y. B.; Zhang, D. M.; Tian, M. B.

    2001-01-01

    Protein secondary structure changes by low-energy ion irradiation are reported for the first time. The selected system is 30 keV N + irradiation on bovine serum albumin (BSA). After irradiation at increasing fluences from 1.0×10 15 to 2.5×10 16 ion/cm 2, Fourier transform infrared spectra analysis was conducted. It was found that the secondary structures of BSA molecules were very sensitive to ion irradiation. Secondary conformations showed different trends of change during irradiation. With the increase of ion fluence from 0 to 2.5×10 16 ion/cm 2, the fraction of α-helix and β-turns decreased from 17 to 12%, and from 40 to 31%, respectively, while that of random coil and β-sheet structure increased from 18 to 27%, and from 25 to 30%, respectively. Possible explanations for the secondary conformational changes of protein are proposed.

  5. 100 keV 10-B + implantation into poly-(di-n-hexyl silane), (PDHSi)

    NASA Astrophysics Data System (ADS)

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

    2006-07-01

    100 keV10B+ ions were implanted into poly-(di-n-hexyl silane) in different directions at a fluence of 1×1014 cm-2, and their depth distribution was determined by means of the neutron depth profiling technique. In no case were the projectile ions found to come to rest according to their predicted range profiles. Instead, they are always found to undergo considerable long-range migration. During the irradiation process this motion appears to be radiation-enhanced, and during the subsequent annealing steps one appears to deal with regular thermal diffusion. The implant redistribution is always found to be governed strongly by the self-created damage, insofar as both electronic and nuclear defects in the polymer act as trapping centers. Their population ratio is modified by thermal annealing.

  6. Electron Bremsstrahlung Cross Sections at 25 and 50 keV from Xe and Kr

    NASA Astrophysics Data System (ADS)

    Portillo, Salvador; Quarles, C. A.

    2002-05-01

    Absolute doubly differential bremsstrahlung cross sections for radiation at 90 from 25 and 50 keV electron bombardment of Kr and Xe of will be presented. The electrons were accelerated by a Cockcroft - Walton accelerator into an Al chamber through a .06" Al collimator. Thick target bremsstrahlung background was minimized by having Al nipples and fixtures and by the addition of a carbon lined nipple placed at 180 to the SiLi detector. A comparison of the doubly differential cross sections will be made with current bremsstrahlung theories. The ratio of the Kr and Xe cross sections will also be compared with the theoretical cross section ratios. The ratio provides a more sensitive test of the contribution, if any, of polarization bremsstrahlung.

  7. Effects of 70-keV electrons on two polyarylene ether ketones

    NASA Technical Reports Server (NTRS)

    Kingsbury, Kevin B.; Hawkins, Douglas S.; Orwoll, Robert A.; Kiefer, Richard L.; Long, Sheila A. T.

    1989-01-01

    Films prepared from two polyarylene ether ketones with the repeat units -PhC(O)PhC(O)-PhOPhXPhO- where X = C(CH3)2 or CH2 and Ph = C6H4, were bombarded with 70-keV electrons. The effects of irradiation were determined from the fraction of gel formed; the intrinsic viscosities, gel permeation chromatography, and NMR spectroscopy of the soluble portion of the irradiated films; and the changes in the IR spectra of the materials. In a Charlesby-Pinner analysis of the gel fractions of the polyarylene ether ketone with the isopropylidene group, the numbers of scission and cross-linking events per 100 eV (9649 kJ/mol) absorbed were found to be small with G(S) = 0.002 and G(X) = 0.009, respectively.

  8. 350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

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

  9. Ion source development for the proposed FNAL 750keV injector upgrade

    SciTech Connect

    Bollinger, D.S.; /Fermilab

    2010-11-01

    Currently there is a Proposed 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 Quadruple (RFQ). The slit type magnetron being used now will be replaced with a round aperture magnetron similar to the one used at Brookhaven National Lab (BNL). Operational experience from BNL has shown that this type of source is more reliable with a longer lifetime due to better power efficiency. The current source development effort is to produce a reliable source with >60mA of H- beam current, 15Hz rep-rate, 100s pulse width, and a duty factor of 0.15%. The source will be based on the BNL design along with development done at FNAL for the High Intensity Neutrino Source (HINS).

  10. A search for the 478 keV line from the decay of nucleosynthetic Be-7

    NASA Technical Reports Server (NTRS)

    Harris, Michael J.; Leising, Mark D.; Share, Gerald H.

    1991-01-01

    Unstable Be-7 (half-life 53.28 days) is expected to be present in the ejecta of classical novae. If the frequency of novae in the central Galaxy is high enough, a nearly steady state abundance of Be-7 will be present there. Data accumulated during transits of the Galactic center across the aperture of the Solar Maximum Mission Gamma Ray Spectrometer have been searched for evidence of the 478 keV gamma-ray line resulting from Be-7 decay. A 3-sigma upper limit of 0.00016 gamma/sq cm s has been placed on the emission in this line from the central radian of the Galactic plane. Less stringent limits have been set on the production of Be-7 in Nova Aquilae 1982, Nova Vulpeculae 1984 No. 2, and Nova Centauri 1986 from observations with the same instrument.

  11. Laser acceleration and deflection of 963 keV electrons with a silicon dielectric structure

    DOE PAGES

    Leedle, Kenneth J.; Pease, R. Fabian; Byer, Robert L.; ...

    2015-02-12

    Radio frequency particle accelerators are ubiquitous in ultrasmall and ultrafast science, but their size and cost have prompted exploration of compact and scalable alternatives such as the dielectric laser accelerator. We present the first demonstration, to the best of our knowledge, of high gradient laser acceleration and deflection of electrons with a silicon structure. Driven by a 5 nJ, 130 fs mode-locked Ti:sapphire laser at 907 nm wavelength, our devices achieve accelerating gradients in excess of 200 MeV/m and suboptical cycle streaking of 96.30 keV electrons. These results pave the way for high gradient silicon dielectric laser accelerators using commercialmore » lasers and subfemtosecond electron beam experiments.« less

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  14. MOLECULAR DYNAMICS OF CASCADES OVERLAP IN TUNGSTEN WITH 20-KEV PRIMARY KNOCK-ON ATOMS

    SciTech Connect

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

    2015-04-16

    Molecular dynamics simulations are performed to investigate the mutual influence of two subsequent cascades in tungsten. The influence is studied using 20-keV primary knock-on atoms, to induce one cascade after another separated by 15 ps, in a lattice temperature of 1025 K (i.e. 0.25 of the melting temperature of the interatomic potential). The center of mass of the vacancies at the peak damage during the cascade is taken as the location of the cascade. The distance between this location to that of the next cascade is taken as the overlap parameter. Empirical fits describing the number of surviving vacancies and interstitial atoms as a function of overlap are presented.

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

    SciTech Connect

    Fella, C.; Balles, A.; Wiest, W.; Zabler, S.; Hanke, R.

    2016-01-28

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

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

    NASA Astrophysics Data System (ADS)

    Savchenko, D. O.; Iakubovskyi, D. A.

    2015-12-01

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

  17. High Spatial Resolution STXM at 6.2 keV Photon Energy

    SciTech Connect

    Vila-Comamala, Joan; Kewish, Cameron M.; Thibault, Pierre; Guzenko, Vitaliy; Gorelick, Sergey; Menzel, Andreas; Bunk, Oliver; David, Christian; Dierolf, Martin; Pfeiffer, Franz; Pilvi, Tero; Faerm, Elina; Ritala, Mikko

    2010-04-06

    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.

  18. Nonlinear optical properties of Cu nanocluster composite fabricated by 180 keV ion implantation

    NASA Astrophysics Data System (ADS)

    Wang, Y. H.; Wang, Y. M.; Lu, J. D.; Ji, L. L.; Zang, R. G.; Wang, R. W.

    2009-11-01

    Metal nanocluster composite glass prepared by 180 keV Cu ions into silica with dose of 5×10 16 ions/cm 2 has been studied. The microstructural properties of the nanoclusters has been verified by optical absorption spectra and transmission electron microscopy (TEM). Third-order nonlinear optical properties of the nanoclusters were measured at 1064 and 532 nm excitations using Z-scan technique. The nonlinear refraction index, nonlinear absorption coefficient, and the real and imaginary parts of the third-order nonlinear susceptibility were deduced. Results of the investigation of nonlinear refraction by the off-axis Z-scan configuration were presented and the mechanisms responsible for the nonlinear response were discussed. Third-order nonlinear susceptibility χ(3) of this kind of sample was determined to be 8.7×10 -8 esu at 532 nm and 6.0×10 -8 esu at 1064 nm, respectively.

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

    SciTech Connect

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

    2008-07-08

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

  20. Mechanisms of O2 Sputtering from Water Ice by keV Ions

    NASA Technical Reports Server (NTRS)

    Teolis, B. D.; Vidal, R. A.; Shi, J.; Baragiola, R. A.

    2005-01-01

    We have conducted experiments on the sputtering of water ice by 100 keV Ar(+) between 20 and 150 K. Our findings indicate that the temperature dependence of the total sputtering yield is heavily influenced by the thermal and irradiation history of the ice, showing a complex dependence on irradiation fluence that is correlated to the ejection of O2 molecules. The results suggest that O2 produced by the ions inside the ice diffuses to the surface where it is trapped and then ejected via sputtering or thermal desorption. A high concentration of O2 can trap in a subsurface layer during bombardment at 130 K, which we relate to the formation of hydrogen and its escape from that region. A simple model allows us to determine the depth profile of the absolute concentration of O2 trapped in the ice.

  1. Theoretical and experimental investigations of optical, structural and electronic properties of the lower-dimensional hybrid [NH3-(CH2)10-NH3]ZnCl4

    NASA Astrophysics Data System (ADS)

    El Mrabet, R.; Kassou, S.; Tahiri, O.; Belaaraj, A.; Guionneau, P.

    2016-10-01

    In the current study, a combination between theoretical and experimental studies has been made for the hybrid perovskite [NH3-(CH2)10-NH3]ZnCl4. The density functional theory (DFT) was performed to investigate structural and electronic properties of the tilted compound. A local approximation (LDA) and semi-local approach (GGA) were employed. The results are obtained using, respectively, the local exchange correlation functional of Perdew-Wang 92 (PW92) and semi local functional of Perdew-Burke-Ernzerhof (PBE). The optimized cell parameters are in good agreement with the experimental results. Electronic properties have been studied through the calculation of band structures and density of state (DOS), while structural properties are investigated by geometry optimization of the cell. Fritz-Haber-Institute (FHI) pseudopotentials were employed to perform all calculations. The optical diffuse reflectance spectra was mesured and applied to deduce the refractive index ( n), the extinction coefficient ( k), the absorption coefficient (α), the real and imaginary dielectric permittivity parts (ɛr,ɛi)) and the optical band gap energy Eg. The optical band gap energy value shows good consistent with that obtained from DFT calculations and reveals the insulating behavior of the material.

  2. Hard X-ray Polarimetry With Wide Band Laue Lens Telescopes

    NASA Astrophysics Data System (ADS)

    Caroli, E.

    2011-09-01

    Polarimetry is today considered a key observational parameter which can be used to help solve important scientific issues that are still open in the hard X-ray domain (above 10 keV). Therefore the ability to perform high sensitivity polarisation measurements has become a mandatory requirement for the next generation of space telescopes operating in this energy range. In particular the development of new high energy focusing optics, such as wide band Laue lenses operating from ~60 keV up to several hundred keV, with their 50-100 times better sensitivity with respect to current instrumentation, opens a real possibility to make hard X-ray polarimetry an almost standard measurement. Hard X-ray polarimetry can be performed using highly segmented focal plane detectors operated as scattering polarimeters. In this work we summarize results obtained by our group in a series of experiments with CZT/CdTe pixel detector prototypes operating as scattering polarimeters in the range between ~100-700 keV as well as Montecarlo evaluations of the achievable performance in polarisation measurements for Laue lens telescopes using focal planes based on CdTe/CZT pixel detectors.

  3. Broad band waveguide spectrometer

    DOEpatents

    Goldman, Don S.

    1995-01-01

    A spectrometer for analyzing a sample of material utilizing a broad band source of electromagnetic radiation and a detector. The spectrometer employs a waveguide possessing an entry and an exit for the electromagnetic radiation emanating from the source. The waveguide further includes a surface between the entry and exit portions which permits interaction between the electromagnetic radiation passing through the wave guide and a sample material. A tapered portion forms a part of the entry of the wave guide and couples the electromagnetic radiation emanating from the source to the waveguide. The electromagnetic radiation passing from the exit of the waveguide is captured and directed to a detector for analysis.

  4. Dead Band Controls Guide.

    DTIC Science & Technology

    1978-11-01

    n o m i z e r c on t ro l , damper repair may re quire c onsideration. 2. No tubin g costs are included in the above estima tes . Typically 150 to...guidelines include techniques for estimating construction and maintenance cost , and performing economic analysis for each system . N \\ 0~c...43 Cost Estimate 43 Payback Anal ysis 43 PART I V A P P E N D I C E S A EXAMPLE - COST ESTIMATE OF DEAD BAND RETROFIT 52 B E X A M P L E - P A Y B A

  5. K-(alpha) Radiography at 20-100 keV Using Short-Pulse Lasers

    SciTech Connect

    Park, H S; Chambers, D; Clarke, R; Eagleton, R; Giraldez, E; Goldsack, T; Heathcote, R; Izumi, N; Key, M; King, J; Koch, J; Landen, O L; Mackinnon, A; Nikroo, A; Patel, P; Pasley, J; Remington, B; Robey, H; Snavely, R; Steinman, D; Stephenson, R; Stoeckl, C; Storm, M; Tabak, M; Theobald, W; Town, R J

    2005-08-29

    X-ray radiography is an important tool for diagnosing and imaging planar and convergent hydrodynamics phenomena for laser experiments. Until now, hydrodynamics experiments at Omega and NIF utilize E{sub x-ray} < 9 keV backlighter x-rays emitted by thermal plasmas. However, future experiments will need to diagnose larger and denser targets and will require x-ray probes of energies from 20-100 keV and possibly up to 1 MeV. Hard K-{alpha} x-ray photons can be created through high-energy electron interactions in the target material after irradiation by petawatt-class high-intensity-short-pulse lasers with > 10{sup 17} W/cm{sup 2}. We have performed several experiments on the JanUSP, and the Vulcan 100TW, and Vulcan Petawatt lasers to understand K-{alpha} sources and to test radiography concepts. 1-D radiography using an edge-on foil and 2-D radiography using buried wires and cone-fiber targets were tested. We find that 1-D thin edge-on foils can have imaging resolution better than 10 {micro}m. Micro volume targets produce bright sources with measured conversion efficiency from laser energy to x-ray photons of {approx} 1 x 10{sup -5}. This level of conversion may not be enough for 2-D point projection radiography. A comparison of our experimental measurements of small volume sources with the LSP/PIC simulation show similar K-{alpha} creation profiles but discrepancy in absolute yields.

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

    SciTech Connect

    Wang, Linghua; Lin, Robert P.; Salem, Chadi; Pulupa, Marc; Larson, Davin E.; Luhmann, Janet G.; Yoon, Peter H.

    2012-07-01

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

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

    SciTech Connect

    Merle, Alexander; Totzauer, Maximilian E-mail: totzauer@mpp.mpg.de

    2015-06-01

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

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

    SciTech Connect

    Barnett, Irene Li; Lignell, Antti; Gudipati, Murthy S.

    2012-03-01

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

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

    SciTech Connect

    Merle, Alexander; Totzauer, Maximilian

    2015-06-08

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

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

    SciTech Connect

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

    2011-10-15

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

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

    SciTech Connect

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

    2015-09-22

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

  12. The Oxygen a Band

    NASA Astrophysics Data System (ADS)

    Benner, D. Chris; Devi, V. Malathy; Hoo, Jiajun; Hodges, Joseph; Long, David A.; Sung, Keeyoon; Drouin, Brian; Okumura, Mitchio; Bui, Thinh Quoc; Rupasinghe, Priyanka

    2014-06-01

    The oxygen A band is used for numerous atmospheric experiments, but spectral line parameters that sufficiently describe the spectrum to the level required by OCO2 and other high precision/accuracy experiments are lacking. Fourier transform spectra from the Jet Propulsion Laboratory and cavity ring down spectra from the National Institute of Standards and Technology were fitted simultaneously using the William and Mary multispectrum nonlinear least squares fitting technique into a single solution including the entire band. In addition, photoacoustic spectra already available from the California Institute of Technology will be added to the solution. The three types of spectrometers are complementary allowing the strengths of each to fill in the weaknesses of the others. With this technique line positions, intensities, widths, shifts, line mixing, Dicke narrowing, temperature dependences and collision induced absorption have been obtained in a single physically consistent fit. D. Chris Benner, C. P. Rinsland, V. M. Devi, M. A. H. Smith, and D. Atkins, JQSRT 1995;53:705-21. Part of the research described in this paper was performed at The College of William and Mary, the, Jet Propulsion Laboratory, California Institute of Technology, under contracts and cooperative agreements with the National Aeronautics and Space Administration and the Jet Propulsion Laboratory. Support for the National Institute of Standards and Technology was provided by the NIST Greenhouse Gas Measurements and Climate Research Program and a NIST Innovations in Measurement Science (IMS) award.

  13. Study of the beam-foil excitation mechanism using Cl projectiles, 2 10 MeV

    NASA Astrophysics Data System (ADS)

    Jupén, C.; Denne, B.; Ekberg, J. O.; Engström, L.; Litzén, U.; Martinson, I.; Tai-Meng, W.; Trigueiros, A.; Veje, E.

    1982-11-01

    We have studied beam-foil excitation of chlorine projectiles by means of optical spectrometry, in the projectile energy range 2-10 MeV. This is a preliminary report, concentrating on the 3p and 3d level excitations in Cl VII (sodium-like chlorine) and in Cl VIII (neon-like chlorine). A discussion of the results is given, and it is concluded that the 3p and 3d levels in Cl VII and Cl VIII are populated by the same mechanism, namely molecular-orbital electron promotions.

  14. Surface brightness measurements of supernova remanants in the energy band 0.15 - 4 keV and an XUV survey from an altitude controlled rocket

    NASA Technical Reports Server (NTRS)

    Garmire, G. P.; Riegler, G.

    1973-01-01

    Reports are presented concerning the flight of Aerobee 170, 13.063 UG. The papers presented include: soft X-rays for Cygnus X-1 and Cygnus X-2; X-ray spectrum of the entire Cygnus loop; X-ray surface brightness of the Cygnus loop; and observations of He II 304 A and He I 584 a nightglow.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  16. Applications of “Tender” Energy (1-5 keV) X-ray Absorption Spectroscopy in Life Sciences

    SciTech Connect

    Northrup, Paul; Leri, Alessandra; Tappero, Ryan

    2016-02-15

    The “tender” energy range of 1 to 5 keV, between the energy ranges of most “hard” (>5 keV) and “soft” (<1 keV) synchrotron X-ray facilities, offers some unique opportunities for synchrotron-based X-ray absorption fine structure spectroscopy in life sciences. In particular the K absorption edges of Na through Ca offer opportunities to study local structure, speciation, and chemistry of many important biological compounds, structures and processes. This is an area of largely untapped science, in part due to a scarcity of optimized facilities. Such measurements also entail unique experimental challenges. Lastly, this brief review describes the technique, its experimental challenges, recent progress in development of microbeam measurement capabilities, and several highlights illustrating applications in life sciences.

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

    NASA Technical Reports Server (NTRS)

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

    1973-01-01

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

  18. Applications of “Tender” Energy (1-5 keV) X-ray Absorption Spectroscopy in Life Sciences

    DOE PAGES

    Northrup, Paul; Leri, Alessandra; Tappero, Ryan

    2016-02-15

    The “tender” energy range of 1 to 5 keV, between the energy ranges of most “hard” (>5 keV) and “soft” (<1 keV) synchrotron X-ray facilities, offers some unique opportunities for synchrotron-based X-ray absorption fine structure spectroscopy in life sciences. In particular the K absorption edges of Na through Ca offer opportunities to study local structure, speciation, and chemistry of many important biological compounds, structures and processes. This is an area of largely untapped science, in part due to a scarcity of optimized facilities. Such measurements also entail unique experimental challenges. Lastly, this brief review describes the technique, its experimental challenges,more » recent progress in development of microbeam measurement capabilities, and several highlights illustrating applications in life sciences.« less

  19. Multilayer Fresnel zone plates for high energy radiation resolve 21 nm features at 1.2 keV.

    PubMed

    Keskinbora, Kahraman; Robisch, Anna-Lena; Mayer, Marcel; Sanli, Umut T; Grévent, Corinne; Wolter, Christian; Weigand, Markus; Szeghalmi, Adriana; Knez, Mato; Salditt, Tim; Schütz, Gisela

    2014-07-28

    X-ray microscopy is a successful technique with applications in several key fields. Fresnel zone plates (FZPs) have been the optical elements driving its success, especially in the soft X-ray range. However, focusing of hard X-rays via FZPs remains a challenge. It is demonstrated here, that two multilayer type FZPs, delivered from the same multilayer deposit, focus both hard and soft X-rays with high fidelity. The results prove that these lenses can achieve at least 21 nm half-pitch resolution at 1.2 keV demonstrated by direct imaging, and sub-30 nm FWHM (full-pitch) resolution at 7.9 keV, deduced from autocorrelation analysis. Reported FZPs had more than 10% diffraction efficiency near 1.5 keV.

  20. Coulomb excitation of ground band rotational states in /sup 249/Bk

    SciTech Connect

    Bemis, C.E. Jr.; McGowan, F.K.; Ford, J.L.C. Jr.; Milner, W.T.; Robinson, R.L.; Stelson, P.H.

    1982-03-01

    Coulomb-excitation probabilities for the first few members of the 7/2/sup +/(633up-arrow) ground-state rotational band in /sup 249/Bk have been determined with 17.06-MeV /sup 4/He ions. These previously know excited states include the 9/2/sup +/ (41.8-keV), 11/2/sup +/ (93.7-keV), and 13/2/sup +/ (155.8-keV) members of the 7/2/sup +/(633up-arrow) band. Within experimental uncertainties, the Coulomb-excitation probabilities for these rotational states are reproduced by calculated values when only E2 excitations are considered with an intrinsic quadrupole moment, Q/sub 20/, of 12.70 +- 0.24 eb in the rigid rotor limit. The deduced ground-state spectroscopic quadrupole moment is 5.93 +- 0.11 eb. Intraband M1 transition rates have been deduced by combining the Q/sub 20/ result with other experimental data. Within the rotational model, a ground-state magnetic moment of +3.45 +- 0.10 ..mu../sub N/ is indicated.

  1. European Biogenic Volatile Organic Compound emissions estimate using MEGAN v2.10

    NASA Astrophysics Data System (ADS)

    Dawoud, M.; Pozzoli, L.; Unal, A.; Kindap, T.; Poupkou, A.; Katragou, E.; Melas, D.

    2013-12-01

    Biogenic emissions estimations are essential to obtain a comprehensive understanding of both anthropogenic and biogenic contributions of the emissions. In this paper we have calculated the Biogenic Volatile Organic Compound (BVOC) emissions from vegetation over Europe using the newly developed Model of Emissions of Gases and Aerosols from Nature version 2.10 (MEGAN2.10). We performed a simulation of the entire year 2008 for a domain covering all Europe at a resolution of 30 x 30 km. The meteorological fields needed to calculate the BVOC emissions (surface temperature and shortwave radiation) were provided by a WRFv3.3 simulation (driven by NCEP/FNL global reanalysis data at 1° x 1°) and interfaced to MEGAN with MCIPv3.6. We used the global dataset provided with the MEGAN2.10 model containing the Plant Functional Types (PFT, at 0.5° x 0.5°), Leaf Area Indices (LAI, at 30s resolution) and Emission Factors (EF, at 0.01° x 0.01°). The motivation behind this study is to quantify the biogenic emissions as calculated from the new version of MEGAN over Europe for the entire annual cycle, and in second step to quantify the impact of biogenic emissions on air quality, using the Community Multiscale Air Quality model (CMAQ). Isoprene emissions comprise about half of the total global biogenic volatile organic compound (BVOC) estimated using MEGAN2.10, while all Terpenes comprise about 18% of the estimated total global BVOC emissions. Our simulations showed that Isoprene emissions are ranging from 10.7 Gg/month in December to 6572.8 Gg/month over Europe in July, while Terpenes emissions range from 38 Gg/month in January and 1598.23 Gg/month in July. Around 15 Tg/year and 5 Tg/year are estimated as total annual emissions of Isoprene and Terpenes, respectively. In comparison with a previous study using the Natural Emission Model (NEMO), for the same period and the similar domain and resolution, for July we found 70% higher Isoprene emissions and 30% lower Terpenes emissions

  2. Wide Band Artificial Pulsar

    NASA Astrophysics Data System (ADS)

    Parsons, Zackary

    2017-01-01

    The Wide Band Artificial Pulsar (WBAP) is an instrument verification device designed and built by the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virgina. The site currently operates the Green Bank Ultimate Pulsar Processing Instrument (GUPPI) and the Versatile Green Bank Astronomical Spectrometer (VEGAS) digital backends for their radio telescopes. The commissioning and continued support for these sophisticated backends has demonstrated a need for a device capable of producing an accurate artificial pulsar signal. The WBAP is designed to provide a very close approximation to an actual pulsar signal. This presentation is intended to provide an overview of the current hardware and software implementations and to also share the current results from testing using the WBAP.

  3. Anomalous X-ray galactic signal from 7.1 keV spin-3/2 dark matter decay

    SciTech Connect

    Dutta, Sukanta; Goyal, Ashok; Kumar, Sanjeev E-mail: agoyal45@yahoo.com

    2016-02-01

    In order to explain the recently reported peak at 3.55 keV in the galactic X-ray spectrum, we propose a simple model. In this model, the Standard Model is extended by including a neutral spin-3/2 vector-like fermion that transforms like a singlet under SM gauge group. This 7.1 keV spin-3/2 fermion is considered to comprise a portion of the observed dark matter. Its decay into a neutrino and a photon with decay life commensurate with the observed data, fits the relic dark matter density and obeys the astrophysical constraints from the supernova cooling.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  5. Searching for a 3.5-keV line in the spectrum of the deepest Chandra blank fields

    NASA Astrophysics Data System (ADS)

    Urry, C. Megan; Cappelluti, Nico; Bulbul, Esra

    2017-01-01

    We report results of our spectral analysis of ~10 Ms of data in the deep Chandra COSMOS Legacy and CDFS surveys. We discuss a possible emission feature at 3.5 keV, which has been reported in other XMM-Newton, Chandra and NuSTAR X-ray data. If due to dark matter decay, the 3.5-keV feature, together with the result from the DAMA dark matter detection experiment, is to date the only positive dark matter signature surviving experimental tests. We discuss possible instrumental contaminations, proper statistical treatment and interpretation in terms of dark matter decay or S XVII charge exchange.

  6. Measurement of the MACS of 159Tb(n, γ) at kT = 30 keV by Activation

    NASA Astrophysics Data System (ADS)

    Praena, J.; Mastinu, P. F.; Pignatari, M.; Quesada, J. M.; Capote, R.; Morilla, Y.

    2014-06-01

    The measurement of the Maxwellian-Averaged Cross-Section (MACS) of the 159Tb(n, γ) reaction at kT = 30 keV by the activation technique is presented. An innovative method for the generation of Maxwellian neutron spectra at kT = 30 keV is used. An experimental value of 2166 ± 181 mb agrees well with the MACS value derived from the ENDF/B-VII.1 evaluation, but is higher than KADoNiS recommended value of 1580 ± 150 mb. Astrophysical implications are studied.

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

    PubMed

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

    2013-09-01

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

  8. False Color Bands

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The theme for the weeks of 1/17 and 1/24 is the north polar region of Mars as seen in false color THEMIS images. Ice/frost will typically appear as bright blue in color; dust mantled ice will appear in tones of red/orange.

    In a gray scale image, the suble variations seen in this false color image are almost impossible to identify. Note the orange band in the center of the frame, and the bluer bands to either side of it.

    Image information: VIS instrument. Latitude 87, Longitude 65.5 East (294.5 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  9. Hubble Space Telescope Observations of HE 2-10: Outflows and Young Super-Star Clusters

    NASA Astrophysics Data System (ADS)

    Johnson, Kelsey E.; Leitherer, Claus; Vacca, William D.; Conti, Peter S.

    2000-09-01

    We use Hubble Space Telescope (HST) WFPC2 optical images and GHRS ultraviolet spectroscopy to examine the recent star formation history and properties of the Wolf-Rayet galaxy He 2-10. The high spatial resolution afforded by HST has allowed the identification of a number of starburst knots, or ``super-star clusters'' (SSCs). The spatial morphology newly revealed by these HST images exhibits a prominent dust lane between the starburst regions known as A and B and a spur of material to the northwest of the nuclear region. Broadband photometry of the SSCs confirms that these objects have ages as young as a few Myr and masses up to 105 Msolar. Narrowband Hα photometry of the SSCs indicates large equivalent widths for nearly half of them, consistent with ages less than 10 Myr. Since an appreciable fraction of SSCs are this young, the star formation history necessarily must be strongly peaked and not continuous. GHRS UV spectra were obtained for sections of the two starburst regions and were used to determine the parameters of the starburst regions. For a stellar population produced in a single burst with stellar masses between 1 and 100 Msolar, the UV luminosities indicate regions A and B have masses between 1.6-2.6×106 Msolar and 2.6-6.6×104 Msolar, respectively. The total starburst mass was between 1 and 100 Msolar consistent with the UV luminosity ranges between 1.6 and 2.6×106 Msolar and 2.6 and 6.6×104 Msolar for regions A and B, respectively. The observed integrated Hα flux is similar to that predicted by the models, implying that the leakage and/or dust absorption of Lyman continuum photons from the starburst regions is small. The integrated Hα equivalent widths of the two regions are substantially smaller than predicted. We attribute this to contamination by the continuum in the starburst regions (the starburst knots do not uniformly fill the GHRS apertures). The UV spectroscopy of starburst region A indicates a large-scale outflow of the interstellar

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  11. Effects of color bands on Semipalmated Sandpipers banded at hatch

    USGS Publications Warehouse

    Bart, J.; Battaglia, D.; Senner, N.

    2001-01-01

    Effects of color bands on adult birds have been investigated in many studies, but much less is known about the effects of bands on birds banded at hatch. We captured Semipalmated Sandpiper (Calidris pusilla) chicks at hatch on the Alaskan North Slope and attached 0-3 bands to them. The chicks were resighted and reweighed during the subsequent two weeks. The number of chicks banded varied from 18 to 21 among treatments; 6-9 were resighted, and 6-7 were reweighed, per treatment. The proportion resighted varied from 0.33 to 0.45. The estimated resighting probability, given that we encountered a brood, was 82%. We tested for effects of the bands on survival and mass gain by analyzing whether the proportion of chicks resighted, or their mass, varied with the number of bands. We found no evidence that bands affected the chicks and were able to rule out (with 95% confidence) a decline in survivorship of more than 13% and a loss of mass of more than 10%. Although bands had little if any effect on chicks in our study, we believe their effects should be evaluated whenever survivorship or mass gain are estimated using color-marked chicks.

  12. Modelling Neutron-induced Reactions on 232-237U from 10 keV up to 30 MeV

    NASA Astrophysics Data System (ADS)

    Sin, M.; Capote, R.; Herman, M. W.; Trkov, A.

    2017-01-01

    Comprehensive calculations of cross sections for neutron-induced reactions on 232-237U targets are performed in the 10 keV-30 MeV incident energy range with the code EMPIRE-3.2 Malta. The advanced modelling and consistent calculation scheme are aimed at improving our knowledge of the neutron scattering and emission cross sections, and to assess the consistency of available evaluated libraries for light uranium isotopes. The reaction model considers a dispersive optical potential (RIPL 2408) that couples from five (even targets) to nine (odd targets) levels of the ground-state rotational band, and a triple-humped fission barrier with absorption in the wells described within the optical model for fission. A modified Lorentzian model (MLO) of the radiative strength function and Enhanced Generalized Superfluid Model nuclear level densities are used in Hauser-Feschbach calculations of the compound-nuclear decay that include width fluctuation corrections. The starting values for the model parameters are retrieved from RIPL. Excellent agreement with available experimental data for neutron emission and fission is achieved, giving confidence that the quantities for which there is no experimental information are also accurately predicted. Deficiencies in existing evaluated libraries are highlighted.

  13. Measured and Simulated Dark J-V Characteristics of a-Si:H Single Junction p-i-n Solar Cells Irradiated with 40 keV Electrons

    NASA Technical Reports Server (NTRS)

    Lord, Kenneth; Woodyard, James R.

    2002-01-01

    The effect of 40 keV electron irradiation on a-Si:H p-i-n single-junction solar cells was investigated using measured and simulated dark J-V characteristics. EPRI-AMPS and PC-1D simulators were explored for use in the studies. The EPRI-AMPS simulator was employed and simulator parameters selected to produce agreement with measured J-V characteristics. Three current mechanisms were evident in the measured dark J-V characteristics after electron irradiation, namely, injection, shunting and a term of the form CV(sup m). Using a single discrete defect state level at the center of the band gap, good agreement was achieved between measured and simulated J-V characteristics in the forward-bias voltage region where the dark current density was dominated by injection. The current mechanism of the form CV(sup m) was removed by annealing for two hours at 140 C. Subsequent irradiation restored the CV(sup m) current mechanism and it was removed by a second anneal. Some evidence of the CV(sup m) term is present in device simulations with a higher level of discrete density of states located at the center of the bandgap.

  14. Inner Magnetosphere keV Ion Drift Path Boundaries as Observed by the Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Strangeway, R. J.; Zhang, J.; Larsen, B.

    2014-12-01

    The drifts of keV ions in the inner magnetosphere are controlled by both electric field drifts and gradient and curvature (i.e., magnetic field) drifts, and further the magnetic field drifts oppose the corotation electric field drift in the dusk local time sector. Consequently, the ion drift paths can be quite complicated with the medium-energy ions drifting close to the Earth, but still being on open drift paths. In addition, structure in the energy-time spectrograms can be a consequence of either particle injection or particle loss. In order to distinguish between the two we will compare the energy-time spectrograms acquired with the Helium Oxygen Proton Electron (HOPE) mass spectrometer on board the Van Allen Probes with predictions of drift path boundaries. The simplest model assumes a uniform convection electric field and dipole model field, and we will use this a starting point for the comparison. The model can be modified to include shielding of the convection electric field, and rotation in local time of the zero-energy dusk-side stagnation point. As an additional check of the model we will compare the electric field used in the model with the electric field as measured by the Van Allen Probes, as well as the validity of using a dipole magnetic field through comparison with the measured magnetic field.

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

    NASA Astrophysics Data System (ADS)

    Redinger, A.; Standop, S.; Rosandi, Y.; Urbassek, H. M.; Michely, T.

    2011-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Queiroz, Farinaldo S.; Sinha, Kuver

    2014-07-01

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

  17. Frequency analysis of 4- to 6-keV electrons associated with an auroral arc

    NASA Technical Reports Server (NTRS)

    Murphree, J. S.; Anderson, H. R.

    1978-01-01

    The high time resolution (HTR) experiment considered consists of four sections, including electrostatic deflection plates, electron multiplier, preamplifier-integrator, and frequency analyzer. Electrons in the energy range from 4 to 6 keV electrons are selected by the deflection system, after which they are detected, multiplied, and passed to the charge sensitive preamplifier. The charge pulses are amplified and integrated, and the resulting voltage pulse series is fed to the frequency analyzer. The experiment is essentially a flux detector, so that estimates of the input flux can be made from the mean value of the output spectrum. The results obtained with the HTR in a rocket flight on March 14, 1974, are discussed. The lack of modulation noticed in the high-frequency range indicates that there is insufficient wave energy available in the vicinity of the rocket to produce a wave-particle interaction which the HTR is able to observe. This finding is consistent with the stabilization of the plasma by the low flux of energetic electrons.

  18. High-efficiency multilevel zone plates for keV X-rays

    NASA Astrophysics Data System (ADS)

    di Fabrizio, E.; Romanato, F.; Gentili, M.; Cabrini, S.; Kaulich, B.; Susini, J.; Barrett, R.

    1999-10-01

    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.

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

    SciTech Connect

    Agueda, N.; Sanahuja, B.; Vainio, R.

    2012-10-15

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

  20. The production and sputtering of S2 by keV ion bombardment

    NASA Technical Reports Server (NTRS)

    Boring, J. W.; Chrisey, D. B.; Oshaughnessy, D. J.; Phipps, J. A.; Zhao, N.

    1986-01-01

    The ion bombardment of S-containing molecules in comets is simulated experimentally. Mass-analyzed 30-keV beams of Ar(+) and He(+) are directed at solid S, H2S, and CS2 targets at temperatures 15 K, and the neutral molecular species produced are ionized and analyzed using a quadrupole mass spectrometer. The dominant species detected are S1 and S2 for the S target, H2S and S2 for the H2S target, and S, CS, S2, and CS2 for the CS2 target. In the latter case, it is found that after about 10 to the 14th He(+) ions/sq cm have struck the target, further sputtering is prevented by formation of a dark brown deposit which is stable at room temperature; the residue forms more slowly when Ar(+) ions are used. These results, indicating relatively efficient S2 production by ion bombardment, are applied to theoretical models of S2 production and/or ejection by solar-wind, solar-flare, or cosmic-ray ions striking comets. It is found that direct solar-wind production of S2 by sputtering is unlikely at realistic bombardment rates, but that H2S-S2 conversion by energetic ions could be significant, with less stringent ice-temperature and irradiation-flux constraints than in the case of S2 production by photons.

  1. Is keV ion-induced pattern formation on Si(001) caused by metal impurities?

    PubMed

    Macko, Sven; Frost, Frank; Ziberi, Bashkim; Förster, Daniel F; Michely, Thomas

    2010-02-26

    We present ion beam erosion experiments performed in ultrahigh vacuum using a differentially pumped ion source and taking care that the ion beam hits the Si(001) sample only. Under these conditions no ion beam patterns form on Si for angles theta < or = 45 degrees with respect to the global surface normal using 2 keV Kr+ and fluences of approximately 2 x 10(22) ions m(-2). In fact, the ion beam induces a smoothening of preformed patterns. Simultaneous sputter deposition of stainless steel in this angular range creates a variety of patterns, similar to those previously ascribed to clean ion-beam-induced destabilization of the surface profile. Only for grazing incidence with 60 degrees < or = theta < or = 83 degrees do pronounced ion beam patterns form. It appears that the angular-dependent stability of Si(001) against pattern formation under clean ion beam erosion conditions is related to the angular dependence of the sputtering yield, and not primarily to a curvature-dependent yield as invoked frequently in continuum theory models.

  2. Electron capture in Ar++H2 collisions in the keV energy regime

    NASA Astrophysics Data System (ADS)

    Kimura, M.; Chapman, S.; Lane, N. F.

    1986-03-01

    Electron capture in Ar+( 2P)+H2(X 1Σg) collisions in the keV energy regime has been studied theoretically. The molecular-orbital expansion method was used within a semiclassical formalism and an electron translation factor correction was incorporated to the first order in the magnitude of the relative velocity V. The molecular wave function and eigenenergy were obtained using the diatoms-in-molecules (DIM) method. We have examined the effect of the orientation of the target H2 molecule on the electron-capture mechanism within the sudden adiabatic approximation. Since π symmetry arising from the p orbital of the Ar+ ion is involved in this system, a strong influence on the probability of the molecular orientation was found in all energies studied. As the collision energy increases, the Π-symmetry state in the initial channel becomes more important through the rotational coupling to the electron-capture mechanism, while at lower energies the Σ-symmetry state in the initial channel is the dominant source for the electron capture through strong radial coupling. Agreement of the present theory with measurements is good, but marked disagreement is seen with the atomic-orbital calculation.

  3. The galactic 511 keV line from electroweak scale WIMPs

    NASA Astrophysics Data System (ADS)

    Pospelov, Maxim; Ritz, Adam

    2007-07-01

    We consider possible mechanisms via which electroweak scale WIMPs χ could provide the source of the INTEGRAL/SPI 511 keV photon flux from the galactic centre. We consider scenarios where the WIMP spectrum contains near-degeneracies, with MeV-scale splitting, and focus on three possible production mechanisms for galactic positrons: (i) collisional excitation of the WIMP to a nearby charged state, χ+χ→χ+χ, with the subsequent decay producing positrons; (ii) capture of the WIMP by nuclei in the galactic interstellar medium, χ+N→e+(χN); and (iii) the decay of a nearby long-lived state surviving from the big bang, χ20→χ10+e+e. We find that process (i) requires a cross section which is significantly larger than the unitarity bound, process (ii) is allowed by unitarity, but is impractical due to terrestrial bounds on the χN cross section, while process (iii) is viable and we construct a simple model realization with singlet dark matter fields interacting with the Standard Model via the Higgs sector.

  4. Black-hole Binaries: Life Begins at 40 keV

    NASA Astrophysics Data System (ADS)

    Belloni, Tomaso M.; Motta, Sara

    2009-05-01

    In the study of black-hole transients, an important problem that still needs to be answered is how the high-energy part of the spectrum evolves from the low-hard to the high-soft state, given that they have very different properties. Recent results obtained with RXTE and INTEGRAL have given inconsistent results. With RXTE, we have found that the high-energy cutoff in GX 339-4 during the transition first decreases (during the low-hard state), then increases again across the Hard-Intermediate state, to become unmeasurable in the soft states (possibly because of statistical limitations). We show Simbol-X will be able to determine the spectral shape with superb accuracy. As the high-energy part of the spectrum is relatively less known than the one below 20 keV, Simbol-X will provide important results that will help out understanding of the extreme physical conditions in the vicinity of a stellar-mass black hole.

  5. Origins of Anisotropic 40 300 keV Electron Events Observed at Low and High Latitudes

    NASA Astrophysics Data System (ADS)

    Hawkins, S. E., III; Gold, R. E.; Pick, M.; Maia, D.

    2001-05-01

    Using a survey of anisotropic electron events in the energy range of ˜40 300 keV observed by HI-SCALE on Ulysses, we have selected several time intervals during 1999 when Ulysses traveled from about 20° S at 5.2 AU (January 1999) to 42° S at 4.2 AU (January 2000). We compare these events with observations at ˜1 AU using the nearly identical instrument, EPAM on ACE. In order to study the solar origins of these electrons using the imaging Nançay Radioheliograph, we further restricted the list of events to those in which interplanetary magnetic field lines with origins on the visible solar disk, intersected Ulysses. We find that not all the anisotropic electron events are observed by both spacecraft and there exists a strong dependence on the spacecraft's magnetic connection back to the Sun. We have identified the solar origin for five electron events using radio observations, and correlate these with interplanetary type-III radio emissions using the WIND/WAVES experiment.

  6. ON THE SPECTRAL HARDENING AT {approx}>300 keV IN SOLAR FLARES

    SciTech Connect

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

    2013-05-20

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

  7. Monte Carlo calculations of energy deposition distributions of electrons below 20 keV in protein.

    PubMed

    Tan, Zhenyu; Liu, Wei

    2014-05-01

    The distributions of energy depositions of electrons in semi-infinite bulk protein and the radial dose distributions of point-isotropic mono-energetic electron sources [i.e., the so-called dose point kernel (DPK)] in protein have been systematically calculated in the energy range below 20 keV, based on Monte Carlo methods. The ranges of electrons have been evaluated by extrapolating two calculated distributions, respectively, and the evaluated ranges of electrons are compared with the electron mean path length in protein which has been calculated by using electron inelastic cross sections described in this work in the continuous-slowing-down approximation. It has been found that for a given energy, the electron mean path length is smaller than the electron range evaluated from DPK, but it is large compared to the electron range obtained from the energy deposition distributions of electrons in semi-infinite bulk protein. The energy dependences of the extrapolated electron ranges based on the two investigated distributions are given, respectively, in a power-law form. In addition, the DPK in protein has also been compared with that in liquid water. An evident difference between the two DPKs is observed. The calculations presented in this work may be useful in studies of radiation effects on proteins.

  8. The System of Nanosecond 280-KeV He+ Pulsed Beam

    SciTech Connect

    Junphong, P.; Ano, V.; Lekprasert, B.; Suwannakachorn, D.; Thongnopparat, N.; Vilaithong, T.; Wiedemann, H.; /SLAC /SLAC, SSRL

    2006-05-01

    At Fast Neutron Research Facility, the 150 kV-pulses neutron generator is being upgraded to a 280-kV-pulsed-He beam for time-of-flight Rutherford backscattering spectrometry. It involves replacing the existing beam line elements by a multicusp ion source, a 400-kV accelerating tube, 45{sup o}-double focusing dipole magnet and quadrupole lens. The multicusp ion source is a compact filament-driven of 2.6 cm in diameter and 8 cm in length. The current extracted is 20.4 {micro}A with 13 kV of extraction voltage and 8.8 kV of Einzel lens voltage. The beam emittance has found to vary between 6-12 mm mrad. The beam transport system has to be redesigned based on the new elements. The important part of a good pulsed beam depends on the pulsing system. The two main parts are the chopper and buncher. An optimized geometry for the 280 keV pulsed helium ion beam will be presented and discussed. The PARMELA code has been used to optimize the space charge effect, resulting in pulse width of less than 2 ns at a target. The calculated distance from a buncher to the target is 4.6 m. Effects of energy spread and phase angle between chopper and buncher have been included in the optimization of the bunch length.

  9. Sputtering of octatetraene by 15 keV C60 projectiles: Comparison of reactive interatomic potentials

    NASA Astrophysics Data System (ADS)

    Kanski, Michal; Maciazek, Dawid; Golunski, Mikolaj; Postawa, Zbigniew

    2017-02-01

    Molecular dynamics computer simulations have been used to probe the effect of the AIREBO, ReaxFF and COMB3 interatomic potentials on sputtering of an organic sample composed of octatetraene molecules. The system is bombarded by a 15 keV C60 projectile at normal incidence. The effect of the applied force fields on the total time of simulation, the calculated sputtering yield and the angular distribution of sputtered particles is investigated and discussed. It has been found that caution should be taken when simulating particles ejection from nonhomogeneous systems that undergo significant fragmentation described by the ReaxFF. In this case, the charge state of many particles is improper due to an inadequacy of a procedure used for calculating partial charges on atoms in molecules for conditions present during sputtering. A two-step simulation procedure is proposed to minimize the effect of this deficiency. There is also a possible problem with the COMB3 potential, at least at conditions present during cluster impact, as its results are very different from AIREBO or ReaxFF.

  10. Silicon photodiode characterization from 1 eV to 10 keV

    SciTech Connect

    Idzorek, G.C.; Bartlett, R.J.

    1997-10-01

    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.

  11. Pitch angle distributions of 35-1000 keV protons at quasi-perpendicular interplanetary shocks

    NASA Technical Reports Server (NTRS)

    Balogh, A.; Erdoes, G.

    1985-01-01

    The characteristic features of the scatter-free acceleration process near perpendicular shocks are examined in the upstream and downstream pitch angle distributions of 35 to 1000 keV protons. Reasonable quantitative agreement is found between theoretical predictions and observations. The role played by bottle geometries, leading to enhanced acceleration, is highlighted.

  12. Intensity of 253 keV {gamma}-rays ({sup 245}Am) from {alpha}-decay of {sup 249}Bk

    SciTech Connect

    Popov, Yu.S.; Srurov, D.Kh.; Baranov, A.A.; Chistyakov, V.M.; Timofeev, G.A.

    1995-01-01

    The intensity of 253 keV {gamma}-rays ({sup 245}Am) from {alpha}-decay of {sup 249}Bk is 3.09(9)% at the P = 0.95 confidence level. Precision semi-conducting {gamma}-spectrometry and coulometry are used.

  13. Comparative Effects of 10.2 eV Photon and 200 keV Proton Irradiation on Condensed CO

    NASA Astrophysics Data System (ADS)

    Loeffler, M. J.; Baratta, G. A.; Palumbo, M. E.; Strazzulla, G.; Baragiola, R. A.

    2004-03-01

    We present results from experiments that use infrared spectroscopy to compare production rates of carbon dioxide formed by UV photolysis and 200 keV proton irradiation of carbon monoxide ice at 16 K. We find production rates to be similar for both types of irradiation.

  14. 3.55 keV photon lines from axion to photon conversion in the Milky Way and M31

    SciTech Connect

    Conlon, Joseph P.; Day, Francesca V. E-mail: francesca.day@physics.ox.ac.uk

    2014-11-01

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

  15. Radial Profile of the 3.5 keV Line Out to R200 in the Perseus Cluster

    NASA Astrophysics Data System (ADS)

    Franse, Jeroen; Bulbul, Esra; Foster, Adam; Boyarsky, Alexey; Markevitch, Maxim; Bautz, Mark; Iakubovskyi, Dmytro; Loewenstein, Mike; McDonald, Michael; Miller, Eric; Randall, Scott W.; Ruchayskiy, Oleg; Smith, Randall K.

    2016-10-01

    The recent discovery of the unidentified emission line at 3.5 keV in galaxies and clusters has attracted great interest from the community. As the origin of the line remains uncertain, we study the surface brightness distribution of the line in the Perseus cluster since that information can be used to identify its origin. We examine the flux distribution of the 3.5 keV line in the deep Suzaku observations of the Perseus cluster in detail. The 3.5 keV line is observed in three concentric annuli in the central observations, although the observations of the outskirts of the cluster did not reveal such a signal. We establish that these detections and the upper limits from the non-detections are consistent with a dark matter decay origin. However, absence of positive detection in the outskirts is also consistent with some unknown astrophysical origin of the line in the dense gas of the Perseus core, as well as with a dark matter origin with a steeper dependence on mass than the dark matter decay. We also comment on several recently published analyses of the 3.5 keV line.

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

    SciTech Connect

    Alvarez, Pedro D.; Conlon, Joseph P.; Day, Francesca V.; Marsh, M.C. David; Rummel, Markus

    2015-04-09

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

  17. Measuring the 511 keV emission in the direction of 1E1740.7-2942 with BATSE

    NASA Technical Reports Server (NTRS)

    Wallyn, P.; Ling, J. C.; Mahoney, W. A.; Wheaton, W. A.; Durouchoux, P.; Corbel, S.; Astier-Perret, L.; Poirot, L.

    1997-01-01

    Observations of the 511 keV emission in the direction of 1E 1740.7-2942 (1E) using the earth burst and transient source experiment (BATSE) onboard the Compton Gamma Ray Observatory (CGRO), are presented. The CGRO phase 1 average spectrum of 1E is calculated using a method which assumes that a given source spectrum is the sum of the flux coming directly from the object and the contribution from the surrounding diffuse emission. The 1E light curve is calculated in the 40 to 150 keV range. It presents a constant flux excess of 70 mCrab in comparison with observations from the SIGMA gamma ray telescope onboard the GRANAT observatory. By removing this contribution, the 1E spectral transition from the low state to the high standard state observed by SIGMA is confirmed, and it is shown that the 511 keV flux is independent of the 1E long term evolution from low state to high standard state. It is concluded that the 511 keV emission of (4.2 +/- 1.3) x 140(exp -4) photons/sq cm s observed in the direction of 1E is mainly diffuse and spatially extended.

  18. OSSE observations of Galactic 511 keV positron annihilation radiation - Initial phase 1 results. [Oriented Scintillation Spectrometer Experiment

    NASA Technical Reports Server (NTRS)

    Purcell, W. R.; Grabelsky, D. A.; Ulmer, M. P.; Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Jung, G. V.

    1993-01-01

    The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma-Ray Observatory (GRO) has performed numerous observations of the Galactic plane and Galactic center region to measure the distribution of Galactic 511 keV positron annihilation radiation and to search for time variability of the emission. The initial 511 keV line fluxes for the observations performed during the first 18 months of the GRO mission are presented. The 511 keV line flux for a typical Galactic center observation is (2.5 +/- 0.3) x 10 exp -4 gamma/sq cm per sec, where the quoted uncertainty represents the 1 sigma statistical uncertainty. No statistically significant time variability of the line flux has been observed; the 3 sigma upper limit to daily variations from the mean is 3 x 10 exp -4 gamma/sq cm per sec. The distribution of Galactic 511 keV positron annihilation radiation implied by the OSSE observations is discussed and compared with observations by other instruments.

  19. Photonic band structure

    SciTech Connect

    Yablonovitch, E.

    1993-05-01

    We learned how to create 3-dimensionally periodic dielectric structures which are to photon waves, as semiconductor crystals are to electron waves. That is, these photonic crystals have a photonic bandgap, a band of frequencies in which electromagnetic waves are forbidden, irrespective of propagation direction in space. Photonic bandgaps provide for spontaneous emission inhibition and allow for a new class of electromagnetic micro-cavities. If the perfect 3-dimensional periodicity is broken by a local defect, then local electromagnetic modes can occur within the forbidden bandgap. The addition of extra dielectric material locally, inside the photonic crystal, produces {open_quotes}donor{close_quotes} modes. Conversely, the local removal of dielectric material from the photonic crystal produces {open_quotes}acceptor{close_quotes} modes. Therefore, it will now be possible to make high-Q electromagnetic cavities of volume {approx_lt}1 cubic wavelength, for short wavelengths at which metallic cavities are useless. These new dielectric micro-resonators can cover the range all the way from millimeter waves, down to ultraviolet wavelengths.

  20. Band calculation of lonsdaleite Ge

    NASA Astrophysics Data System (ADS)

    Chen, Pin-Shiang; Fan, Sheng-Ting; Lan, Huang-Siang; Liu, Chee Wee

    2017-01-01

    The band structure of Ge in the lonsdaleite phase is calculated using first principles. Lonsdaleite Ge has a direct band gap at the Γ point. For the conduction band, the Γ valley is anisotropic with the low transverse effective mass on the hexagonal plane and the large longitudinal effective mass along the c axis. For the valence band, both heavy-hole and light-hole effective masses are anisotropic at the Γ point. The in-plane electron effective mass also becomes anisotropic under uniaxial tensile strain. The strain response of the heavy-hole mass is opposite to the light hole.

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

    SciTech Connect

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

    1982-11-01

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

  2. A Catalog of Soft X-Ray Shadows, and More Contemplation of the 1/4 KeV Background

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.; Freyberg, M. J.; Kuntz, K. D.; Sanders, W. T.

    1999-01-01

    This paper presents a catalog of shadows in the 1/4 keV soft X-ray diffuse background 4 (SXRB) that were identified by a comparison between ROSAT All-Sky Survey maps and DIRB&corrected IRAS 100 micron maps. These "shadows" are the negative correlations between the surface brightness of the SXRB and the column density of the Galactic interstellar medium (ISIM) over limited angular regions (a few degrees in extent). We have compiled an extensive but not exhaustive set of 378 shadows in the polar regions of the Galaxy (Absolute value (beta) > and approximately equal 20 deg.), and determined their foreground and background X-ray intensities (relative to the absorbing features), and the respective hardness ratios of that emission. The portion of the sky that was examined to find these shadows was restricted in general to regions where the minimum column density is less than and approximately equal to 4 x 10(exp 20) H/square cm, i.e., relatively high Galactic latitudes, and to regions away from distinct extended features in the SXRB such as supernova remnants and superbubbles. The results for the foreground intensities agree well with the recent results of a general analysis of the local 1/4 KeV emission while the background intensities show additional. but not unexpected scatter. The results also confirm the existence of a gradient in the hardness of the local 1/4 keV emission along a Galactic center/ anticenter axis with a temperature that varies from 10(exp 6.13) K to 10(exp 6.02) K, respectively. The average temperature of the foreground component from this analysis is 10(exp 6.08) K, compared to 10(exp 6.06) K in the previous analysis. Likewise, the average temperature for the distant component for the current and previous analyses are 10(exp 6.06) K and 10(exp 6.02) K, respectively. Finally, the results for the 1/4 keV halo emission are compared to the observed fluxes at 3/4 keV, where the lack of correlation suggests that the Galactic halo's 1/4 keV and 3/4 keV

  3. Multiwavelength observations of the energetic GRB 080810: detailed mapping of the broad-band spectral evolution

    NASA Astrophysics Data System (ADS)

    Page, K. L.; Willingale, R.; Bissaldi, E.; Postigo, A. De Ugarte; Holland, S. T.; McBreen, S.; O'Brien, P. T.; Osborne, J. P.; Prochaska, J. X.; Rol, E.; Rykoff, E. S.; Starling, R. L. C.; Tanvir, N. R.; van der Horst, A. J.; Wiersema, K.; Zhang, B.; Aceituno, F. J.; Akerlof, C.; Beardmore, A. P.; Briggs, M. S.; Burrows, D. N.; Castro-Tirado, A. J.; Connaughton, V.; Evans, P. A.; Fynbo, J. P. U.; Gehrels, N.; Guidorzi, C.; Howard, A. W.; Kennea, J. A.; Kouveliotou, C.; Pagani, C.; Preece, R.; Perley, D.; Steele, I. A.; Yuan, F.

    2009-11-01

    GRB 080810 was one of the first bursts to trigger both Swift and the Fermi Gamma-ray Space Telescope. It was subsequently monitored over the X-ray and UV/optical bands by Swift, in the optical by Robotic Optical Transient Search Experiment (ROTSE) and a host of other telescopes, and was detected in the radio by the Very Large Array. The redshift of z = 3.355 +/- 0.005 was determined by Keck/High Resolution Echelle Spectrometer (HIRES) and confirmed by RTT150 and NOT. The prompt gamma/X-ray emission, detected over 0.3-103 keV, systematically softens over time, with Epeak moving from ~600 keV at the start to ~40 keV around 100s after the trigger; alternatively, this spectral evolution could be identified with the blackbody temperature of a quasi-thermal model shifting from ~60 to ~3keV over the same time interval. The first optical detection was made at 38s, but the smooth, featureless profile of the full optical coverage implies that this is originated from the afterglow component, not from the pulsed/flaring prompt emission. Broad-band optical and X-ray coverage of the afterglow at the start of the final X-ray decay (~8ks) reveals a spectral break between the optical and X-ray bands in the range of 1015-2 × 1016Hz. The decay profiles of the X-ray and optical bands show that this break initially migrates blueward to this frequency and then subsequently drifts redward to below the optical band by ~3 × 105s. GRB 080810 was very energetic, with an isotropic energy output for the prompt component of 3 × 1053 and 1.6 × 1052 erg for the afterglow; there is no evidence for a jet break in the afterglow up to 6d following the burst. This paper is dedicated to the memory of Professor Martin Turner, who sadly passed away during its writing. Martin was an influential figure in X-ray Astronomy and an excellent PhD supervisor. He will be greatly missed. E-mail: kpa@star.le.ac.uk ‡ NASA postdoctoral program fellow.

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

    NASA Astrophysics Data System (ADS)

    Krimigis, Stamatios M.

    2016-04-01

    The basic premise of the proposed Interstellar Mapping and Acceleration Probe (IMAP) is detailed scientific understanding of the Heliosheath (HS) and beyond, a region of space explored in situ by Voyager 1 (V1) since 2004, Voyager 2 (V2) since 2007, and remotely via energetic neutral atoms (ENA) by the Cassini/INCA (Ion and Neutral CAmera) since 2003 and IBEX since 2009. The IMAP instrumentation proposed for this purpose combines and extends the IBEX and INCA ENA energy ranges (0.3- 20 keV and 3-200 keV, for low and high energy, respectively). All three missions-Voyagers, Cassini/INCA, and IBEX- have made discovery-class measurements in the HS, the Voyagers providing in situ ion intensities at E > 30 keV, while INCA images ENA in the range 5 < E < 55 keV, and IBEX 0.3 < E < 6 keV. The partial overlap in energy coverage between Voyager ions and INCA ENA allows for the possibility of observing the intensity and time evolution of ions in the HS, thought to give rise to the ENAs via charge-exchange, and the resultant ENA images in the inner heliosphere and their spatial and/or temporal variability. Unfortunately, no such "ground truth" ion measurements are possible at Voyager in the ENA energy range imaged by IBEX. Some of the key findings from the Voyager and Cassini/INCA measurements are as follows: (1) The HS contains a hot plasma population that carries a substantial part (30-50 %) of the total pressure at E > 5 keV, the rest residing below that range, resulting in a beta (particle/magnetic pressure) always > 1, typically >10. (2) The width of the HS in the direction of V1 is ~ 30 AU, but is thought to be larger (40-70 AU) in the southern ecliptic where V2 currently travels.. (3) The ENA intensities at E > 5 keV exhibit a correlation with the solar cycle (SC) over the period 2003 to 2015, with minimum intensities in the anti-nose direction observed ~ 1.5 yrs after solar minimum followed by a recovery thereafter. (4) The in situ ion measurements at V2 within the HS

  5. Garage Band or GarageBand[R]? Remixing Musical Futures

    ERIC Educational Resources Information Center

    Vakeva, Lauri

    2010-01-01

    In this paper, I suggest that it is perhaps time to consider the pedagogy of popular music in more extensive terms than conventional rock band practices have to offer. One direction in which this might lead is the expansion of the informal pedagogy based on a "garage band" model to encompass various modes of digital artistry wherever this artistry…

  6. 43 CFR 3162.2-10 - Will BLM notify me when it determines that drainage is occurring?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 43 Public Lands: Interior 2 2012-10-01 2012-10-01 false Will BLM notify me when it determines that drainage is occurring? 3162.2-10 Section 3162.2-10 Public Lands: Interior Regulations Relating to Public... notify me when it determines that drainage is occurring? We will send you a demand letter by...

  7. 43 CFR 3162.2-10 - Will BLM notify me when it determines that drainage is occurring?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 43 Public Lands: Interior 2 2013-10-01 2013-10-01 false Will BLM notify me when it determines that drainage is occurring? 3162.2-10 Section 3162.2-10 Public Lands: Interior Regulations Relating to Public... notify me when it determines that drainage is occurring? We will send you a demand letter by...

  8. Development of an X-ray Telescope with a Large Effective Area for the Iron K Line Band

    NASA Astrophysics Data System (ADS)

    Matsumoto, Hironori; Tachibana, Sasagu; Yoshikawa, Shun; Tamura, Keisuke; Mori, Hideyuki; Mitsuishi, Ikuyuki; Tawara, Yuzuru; Kunieda, Hideyo; Yamashita, Kojun

    2015-08-01

    X-ray micro-calorimeters such as the Soft X-ray Spectrometer (SXS) on board ASTRO-H will enable precise spectroscopy of iron K lines even for spatially extended objects. To exploit the full power of the high-energy resolution, X-ray telescopes with a large effective area around 6 keV are essentially important. Conventional Wolter-I X-ray telescopes aimed at X-rays below 10 keV have used the principle of total reflection to collect the X-rays. Enlarging the diameter of this type of telescopes is not effective to obtain the large effective area, since the incident angle of X-rays for the outer part of the telescope exceeds the critical angle, and the X-ray reflectivity of the outer part is significantly low. For example, the critical angle of Ir for an X-ray of 6 keV is 0.748 deg. Thus if we assume a focal length of 6 m for a Wolter-I optics using mirrors covered with Ir as a reflector, the mirrors the radial position of which are larger than 34 cm cannot reflect X-rays above 6 keV effectively. If multi-layer mirrors are applied to the outer part of the telescope, however, the X-ray reflectivity can be enhanced significantly by the principle of Bragg reflection. Our objective is to develop a Wolter-I X-ray telescope with an aperture of 110 cm and a focal length of 6 m, and make all mirrors in the telescope can reflect X-rays around 6 keV effectively by utilizing the multi-layer mirrors. The size of the telescope is determined by a boundary condition that can be launched by the epsilon rocket of ISAS/JAXA. The multi-layer is designed to enhance the reflectivity at 6.4 keV, 6.7 keV, or 6.9 keV. Our simulation suggests that the effective area averaged in the 5.7-7.7 keV band could be 2000 cm2, whichis comparable to the effective area of Athena launched in 2028 by ESA. Furthermore, we showed that the Ir/C multi-layers produced by our DC magnetron sputtering machine has a surface roughness of less than 4 angstrom. This value is smaller than the average surface roughness

  9. A 7.2 keV spherical crystal backlighter system for Sandia's Z Pulsed Power Facility

    NASA Astrophysics Data System (ADS)

    Schollmeier, M.; Knapp, P. F.; Ampleford, D. J.; Loisel, G. P.; Robertson, G.; Shores, J. E.; Smith, I. C.; Speas, C. S.; Porter, J. L.; McBride, R. D.

    2016-10-01

    Many experiments on Sandia's Z facility, a 30 MA, 100 ns rise-time, pulsed-power driver, use a monochromatic Quartz crystal imaging backlighter system at 1.865 keV (Si Heα) or 6.151 keV (Mn Heα) x-ray energy to radiograph an imploding liner (cylindrical tube) or wire array. The x-ray source is generated by the Z-Beamlet Laser (ZBL), which provides up to 4.5 kJ at 527 nm during a 6 ns window. Radiographs of an imploding thick-walled Beryllium liner at a convergence ratio of about 20 [CR =Rin . (0) /Rin . (t) ] were too opaque to identify the inner surface of the liner with high confidence, demonstrating the need for a higher-energy x-ray backlighter between 6 and 10 keV. We present the design, test and first application of a Ge (335) spherical crystal x-ray backlighter system using the 7.242 keV Co Heα resonance line. The system operates at an almost identical Bragg angle as the existing 1.865 and 6.151 keV backlighters, enhancing our capabilities such as two-color, two-frame radiography, without changing detector shielding hardware. SAND No: SAND2016-6724 A. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. DoE NNSA under contract DE-AC04-94AL85000.

  10. Band of Rubble

    NASA Technical Reports Server (NTRS)

    2005-01-01

    This artist's animation illustrates a massive asteroid belt in orbit around a star the same age and size as our Sun. Evidence for this possible belt was discovered by NASA's Spitzer Space Telescope when it spotted warm dust around the star, presumably from asteroids smashing together.

    The view starts from outside the belt, where planets like the one shown here might possibly reside, then moves into to the dusty belt itself. A collision between two asteroids is depicted near the end of the movie. Collisions like this replenish the dust in the asteroid belt, making it detectable to Spitzer.

    The alien belt circles a faint, nearby star called HD 69830 located 41 light-years away in the constellation Puppis. Compared to our own solar system's asteroid belt, this one is larger and closer to its star - it is 25 times as massive, and lies just inside an orbit equivalent to that of Venus. Our asteroid belt circles between the orbits of Mars and Jupiter.

    Because Jupiter acts as an outer wall to our asteroid belt, shepherding its debris into a series of bands, it is possible that an unseen planet is likewise marshalling this belt's rubble. Previous observations using the radial velocity technique did not locate any large gas giant planets, indicating that any planets present in this system would have to be the size of Saturn or smaller.

    Asteroids are chunks of rock from 'failed' planets, which never managed to coalesce into full-sized planets. Asteroid belts can be thought of as construction sites that accompany the building of rocky planets.

  11. Report from the banding lab

    USGS Publications Warehouse

    Tautin, J.

    1995-01-01

    Mr. Tautin reported on the seemingly everchanging structure of biological science units within the Interior Department. Current Congressional proposals would either change the name of the Bird Banding Lab's parent agency or make it part of the Geological Survey. The current Congress has not looked favorably on science budgets within the Interior Department, and the Banding Lab's budget is being squeezed ever tighter.

  12. Curriculum Guide for Advanced Band.

    ERIC Educational Resources Information Center

    Bazar, W. Gayre

    The advanced band of the Vermilion Parish School System is a selective organization comprised of school instrumental students who have successfully completed all phases of the beginning and intermediate band programs. It functions largely as a performing group for varied school and community activities. This guide describes the advanced band…

  13. The Moral Ends of Band

    ERIC Educational Resources Information Center

    Allsup, Randall Everett

    2012-01-01

    This article provides a theoretical framework through which to reimagine and revitalize contemporary music education practices, using the large ensemble paradigm called "band" as the primary unit of analysis. Literature suggests that band places too much emphasis on teacher control and external measures of validation. Critics propose replacing…

  14. Excitation energies and spins of a superdeformed band in {sup 194}{ital H}{ital g} from one-step discrete decays to the yrast line

    SciTech Connect

    Khoo, T.L.; Carpenter, M.P.; Lauritsen, T.; Ackermann, D.; Ahmad, I.; Blumenthal, D.J.; Fischer, S.M.; Janssens, R.V.; Nisius, D.; Moore, E.F.; Lopez-Martens, A.; Do Kruecken, R.; Asztalos, S.J.; Becker, J.A.; Bernstein, L.; Clark, R.M.; Deleplanque, M.A.; Diamond, R.M.; Fallon, P.; Farris, L.P.; Hannachi, F.; Henry, E.A.; Korichi, A.; Lee, I.Y.; Macchiavelli, A.O.; Stephens, F.S. ||||||

    1996-03-01

    Discrete {gamma} rays directly connecting states of a superdeformed (SD) band in {sup 194}Hg to the yrast states have been discovered. Thus, the excitation energies and spins of all members of the lowest SD band are established for the first time, together with their likely parity. The SD band decays from its 10{sup +} and 12{sup +} states, which lie 4204.8 and 4407.4 keV above the normal-deformed yrast states of the same spins. {copyright} {ital 1996 The American Physical Society.}

  15. Thermodynamic Properties of He Gas in the Temperature Range 4.2-10 K

    NASA Astrophysics Data System (ADS)

    Mosameh, S. M.; Sandouqa, A. S.; Ghassib, H. B.; Joudeh, B. R.

    2014-05-01

    The thermodynamic properties of He gas are investigated in the temperature-range 4.2-10 K, with special emphasis on the second virial coefficient in both the classical and quantum regimes. The main input in computing the quantum coefficient is the `effective' phase shifts. These are calculated within the framework of the Galitskii-Migdal-Feynman (GMF) formalism, using the HFDHE2 and Sposito potentials. The virial equation of state is constructed. Extensive calculations are carried out for the pressure-volume-temperature (P-V-T) behavior, as well as chemical potential, and nonideality of the system. The following results are obtained. First, the validity of the GMF formalism for the present system is demonstrated beyond any doubt. Second, the boiling point (phase-transition point) of He gas is determined from the P-V behavior using the virial equation of state, its value being closest than all previous results to the experimental value. Third, the chemical potential is evaluated from the quantum second virial coefficient. It is found that increases (becomes less negative) as the temperature decreases or the number density n increases. Further, shows no sensitivity to the differences between the potentials used up to n = 10 m. Finally, the compressibility Z is computed and discussed as a measure of the nonideality of the system.

  16. 1-40-keV fixed-exit monochromator for a wafer mapping TXRF facility

    NASA Astrophysics Data System (ADS)

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

    1998-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  18. Band anticrossing in dilute nitrides

    SciTech Connect

    Shan, W.; Yu, K.M.; Walukiewicz, W.; Wu, J.; Ager III, J.W.; Haller, E.E.

    2003-12-23

    Alloying III-V compounds with small amounts of nitrogen leads to dramatic reduction of the fundamental band-gap energy in the resulting dilute nitride alloys. The effect originates from an anti-crossing interaction between the extended conduction-band states and localized N states. The interaction splits the conduction band into two nonparabolic subbands. The downward shift of the lower conduction subband edge is responsible for the N-induced reduction of the fundamental band-gap energy. The changes in the conduction band structure result in significant increase in electron effective mass and decrease in the electron mobility, and lead to a large enhance of the maximum doping level in GaInNAs doped with group VI donors. In addition, a striking asymmetry in the electrical activation of group IV and group VI donors can be attributed to mutual passivation process through formation of the nearest neighbor group-IV donor nitrogen pairs.

  19. Quantification of Myofascial Taut Bands

    PubMed Central

    Chen, Qingshan; Wang, Hua-jun; Gay, Ralph E.; Thompson, Jeffrey M.; Manduca, Armando; An, Kai-Nan; Ehman, Richard E.; Basford, Jeffrey R.

    2015-01-01

    Objective To assess the correlation of clinician identified myofascial taut bands with their presence and characteristics on Magnetic Resonance Elastography (MRE) imaging. Design Cross-sectional study. Setting An MRI research laboratory. Participants A convenience sample of 65 adults (45 women, 20 men) identified by skilled musculoskeletal physicians as having upper trapezius myofascial pain associated taut bands. Interventions Subjects had their taut bands outlined and were positioned within a 1.5T MRI machine. Shear waves were induced with a pneumatic transducer located over the belly of the involved muscle. Wave propagation was visualized with MRE images across a vibration-cycle. Imaging data was assessed independently by two skilled MRE interpreters. Main Outcome Measures The primary outcome measure was the determination of the intra- and inter-rater reliabilities of MRE taut band identification and their correlation with clinician identification of band presence. Secondary outcomes consisted of the elucidation of the physical characteristics of taut bands and their surrounding muscle tissue. Results MRE intra- and inter-rater reliability was excellent with Kappa's and 95% Confidence intervals (CI) of 0.86, [0.68, 1.00]; and 0.93, [0.79, 1.00], respectively. Stiffness in MRE identified taut bands was elevated at a mean of 11.5 KPa (±2.4 KPa) and fell to a mean of 5.8 KPa (± 0.9 KPa) in surrounding muscle tissue (p<0.001); muscular tone in trapezius muscles without a taut band was relatively uniform at a mean of 6.6 KPa (±2.1 KPa). Agreement between the physicians and the MRE raters, however, was relatively poor (63.1%, 95% CI [50.2%, 74.7%]). Conclusions Our findings suggest that while clinicians may overestimate, and current MRE techniques may underestimate, the presence of taut bands, that these bands exist, can be assessed quantitatively, and do represent localized areas of increased muscle stiffness. PMID:26461163

  20. Reduction of XNkx2-10 expression leads to anterior defects and malformation of the embryonic heart

    PubMed Central

    Allen, Bryan G.; Allen-Brady, Kristina; Weeks, Daniel L.

    2007-01-01

    Normal vertebrate heart development depends upon the expression of homeodomain containing proteins related to the Drosophila gene, tinman. In Xenopus laevis, three such genes have been identified in regions that will eventually give rise to the heart, XNkx2-3, XNkx2-5 and XNkx2-10. Although the expression domains of all three overlap in early development, distinctive differences have been noted. By the time the heart tube forms, there is little XNkx2-10 mRNA detected by in situ analysis in the embryonic heart while both XNkx2-3 and XNkx2-5 are clearly present. In addition, unlike XNkx2-3 and XNkx2-5, injection of XNkx2-10 mRNA does not increase the size of the embryonic heart. We have reexamined the expression and potential role of XNkx2-10 in development via oligonucleotide-mediated reduction of XNkx2-10 protein expression. We find that a decrease in XNkx2-10 leads to a broad spectrum of developmental abnormalities including a reduction in heart size. We conclude that XNkx2-10, like XNkx2-3 and XNkx2-5, is necessary for normal Xenopus heart development. PMID:16949797

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

    NASA Astrophysics Data System (ADS)

    Reyes-Herrera, J.; Miranda, J.

    2016-06-01

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

  2. Coexistence of a weakly-deformed band in a strongly-deformednucleus

    SciTech Connect

    Kulp, W.D.; Wood, J.L.; Krane, K.S.; Loats, J.; Schmelzenbach,P.; Stapels, C.J.; Larimer, R.-M.; Norman, E.B.

    2002-10-27

    A weakly-deformed band J{sup {pi}} (E{sub x} keV) 0+ (1182), 2+ (1418), 4+ (1701) is identified in the strongly-deformed nucleus, {sup 154}Gd. Detailed {gamma}-ray spectroscopy following the beta decays of {sup 154}Eu (J = 3), {sup 154g,m1,m2}Tb (J = 0, 3, 7) are used to establish this structure. The structure is explained in terms of a pairing isomer which results from the {nu}[505] {up_arrow} Nilsson intruder orbital.

  3. Modeling of Band-to-Band Tunneling Mechanisms

    NASA Astrophysics Data System (ADS)

    Wolfgang, Bergner; Roland, Kircher

    1990-12-01

    Measurements and simulations are presented, which allow a better understanding of leakage mechanisms in reverse biased gated diodes. The model for the device simulation describes two mechanisms. In the high field regime the leakage current is identified as direct band-to-band tunneling. In the low field regime it is described as surface-state enhanced tunneling, which combines thermal activation of an electron to a surface-state with tunneling.

  4. Coffee ring deposition in bands

    NASA Astrophysics Data System (ADS)

    Mandre, Shreyas; Wu, Ning; Aizenberg, Joanna; Mahadevan, Lakshminarayanan

    2010-11-01

    Microscopic particles suspended in a liquid are transported and deposited at a contact line, as the contact line recedes due to evaporation. A particle layer of uniform thickness is deposited if the particle concentration is above a threshold; below this threshold the deposit forms periodic bands oriented parallel to the contact line. We present a model for the formation of these bands based on evaporation leading to the breakup of the thin liquid film near the contact line. The threshold results from a competition between evaporation speed and deposition speed. Using this model, we predict the thickness and length of the bands, making the control of patterned deposition possible.

  5. WIDE-BAND SUZAKU ANALYSIS OF THE PERSISTENT EMISSION FROM SGR 0501+4516 DURING THE 2008 OUTBURST

    SciTech Connect

    Enoto, T.; Makishima, K.; Nakazawa, K.; Yamada, S.; Rea, N.; Nakagawa, Y. E.; Sakamoto, T.; Esposito, P.; Mereghetti, S.; Tiengo, A.; Goetz, D.; Israel, G. L.; Stella, L.; Kokubun, M.; Murakami, H.; Turolla, R.; Yamaoka, K.; Yoshida, A.; Zane, S.

    2010-05-20

    We observed the soft gamma repeater SGR 0501+4516 with Suzaku for {approx}51 ks on 2008 August 26-27, about 4 days after its discovery. Following the first paper, which reported on the persistent soft X-ray emission and the wide-band spectrum of an intense short burst, this paper presents an analysis of the persistent broadband (1-70 keV) spectra of this source in outburst, taken with the X-ray Imaging Spectrometer (XIS) and the Hard X-ray Detector (HXD). Pulse-phase folding in the 12-35 keV HXD-PIN data on an ephemeris based on multi-satellite timing measurements at soft X-rays revealed the pulsed signals at {approx_gt}99% confidence in the hard X-ray band. The wide-band spectrum clearly consists of a soft component and a separate hard component, crossing over at {approx}7 keV. When the soft component is modeled by a blackbody plus a Comptonized blackbody, the hard component exhibits a 20-100 keV flux of 4.8{sup +0.8}{sub -0.6}(stat.){sup +0.8}{sub -0.4}(sys.) x 10{sup -11} erg s{sup -1} cm{sup -2} and a photon index of {Gamma} = 0.79{sup +0.20}{sub -0.18}(stat.){sup +0.01}{sub -0.06}(sys.). The hard X-ray data are compared with those obtained by INTEGRAL about 1 day later. Combining the present results with those on other magnetars, we discuss a possible correlation between the spectral hardness of magnetars and their characteristic age and magnetic field strengths.

  6. Band head spin assignment of superdeformed bands in 86Zr

    NASA Astrophysics Data System (ADS)

    Dadwal, Anshul; Mittal, H. M.

    2016-11-01

    Two parameter expressions for rotational spectra viz. variable moment of inertia (VMI), ab formula and three parameter Harris ω 2 expansion are used to assign the band head spins (I 0) of four rotational superdeformed bands in 86Zr. The least-squares fitting method is employed to obtain the band head spins of these four bands in the A ∼ 80 mass region. Model parameters are extracted by fitting of intraband γ-ray energies, so as to obtain a minimum root-mean-square (rms) deviation between the calculated and the observed transition energies. The calculated transition energies are found to depend sensitively on the assigned spins. Whenever an accurate band head spin is assigned, the calculated transition energies are in agreement with the experimental transition energies. The dynamic moment of inertia is also extracted and its variation with rotational frequency is investigated. Since a better agreement of band head spin with experimental results is found using the VMI model, it is a more powerful tool than the ab formula and Harris ω 2 expansion.

  7. Monte Carlo Simulations of Defect Recovery within a 10 keV Collision Cascade in 3C-SiC

    SciTech Connect

    Rong, Zhouwen; Gao, Fei; Weber, William J.

    2007-11-26

    A kinetic lattice Monte Carlo (KLMC) model is developed to investigate the recovery and clustering of defects during annealing of a single 10 keV cascade in cubic silicon carbide. The 10 keV Si cascade is produced by molecular dynamics (MD), and a method of transferring the defects created by MD simulations to the KLMC model is developed. The KLMC model parameters are obtained from molecular dynamics simulations and ab initio calculations of defect migration, recombination and annihilation. The defects are annealed isothermally from 100 K to 1000 K in the KLMC model. Two distinct recovery stages for close Frenkel pairs are observed at about 200 and 550 K, and the growth of complex clusters is observed above 400 K. These simulation results are in good agreement with available experimental results.

  8. A highly stable 30 keV proton accelerator for studies of angular detection efficiency on Si detectors

    NASA Astrophysics Data System (ADS)

    Salas Bacci, Americo; Baessler, Stefan; Carr, Peter; Hefele, Thomas; Pocanic, Dinko; Roane, Nicholas; Ross, Aaron; Slater, R.; Smith, Alexander; Toth, Csaba; Warner, Dane; Zamperini, Shawn; Zotev, Panaiot; Nab experiment Collaboration

    2017-01-01

    The Nab experiment at the SNS measures the electron-neutrino correlation parameter and the Fierz interference term in free neutron beta decay by measuring in coincidence the electron energy and proton momentum in a magnetic spectrometer with two Si detectors. These large area, thick, and 127-hexagonal segmented Si detectors have to be carefully characterized for optimal performance and for control of systematic errors. The angular detection efficiency of 30 keV proton incident on Si is an important part of this studies. We will present the design, simulation, operation, and detection of 30 keV H+ and H2+as well as results to control the beam stability by the correlation of both detected ion signals. At present we have reached beam stability of (1.2 +/-1.3)E-7/sec.

  9. The determination of absolute intensity of 234mPa's 1001 keV gamma emission using Monte Carlo simulation.

    PubMed

    Begy, Robert-Csaba; Cosma, Constantin; Timar, Alida; Fulea, Dan

    2009-05-01

    The 1001 keV gamma line of (234m)Pa became important in gamma spectrometric measurements of samples with (238)U content with the advent of development of HpGe detectors of great dimension and high efficiency. In this study the emission probability of the 1001 keV (Y(gamma)) peak of (234m)Pa, was determined by gamma-ray spectrometric measurements performed on glass with Uranium content using Monte Carlo simulation code for efficiency calibration. This method of calculation was not applied for the values quoted in literature so far, at least to our knowledge. The measurements gave an average of 0.836 +/- 0.022%, a value that is in very good agreement to some of the recent results previously presented.

  10. GRIS detection of Al-26 1809 keV line emission from the Galactic center region as a broad line

    NASA Technical Reports Server (NTRS)

    Naya, Juan E.; Barthelmy, Scott D.; Bartlett, Lyle M.; Gehrels, Neil; Leventhal, Marvin; Parsons, Ann; Teegarden, Bonnard J.; Tueller, Jack

    1997-01-01

    The gamma ray imaging spectrometer (GRIS) was used to observe the 1809 keV emission from the Galactic center region. The observed line is broader than the instrument resolution. The measured intrinsic width is 5.4 +/- 1.4 keV full width half medium, which is more than three times the maximum Doppler broadening expected due to Galactic rotation. The detection of such a wide feature, suggesting a high dispersion velocity has implications for the origin of Galactic Al-26. It suggests a supernova explosion origin or a Wolf-Rayet stellar wind origin of Al-26. The fact that the Al-26 has not come to rest after 10(exp 6) years presents a challenge to the current understanding of the Al-26 production and propagation in the Galaxy.

  11. Diagnostics for the optimization of an 11 keV inverse Compton scattering x-ray source

    NASA Astrophysics Data System (ADS)

    Chauchat, A.-S.; Brasile, J.-P.; Le Flanchec, V.; Nègre, J.-P.; Binet, A.; Ortega, J.-M.

    2013-04-01

    In a scope of a collaboration between Thales Communications & Security and CEA DAM DIF, 11 keV Xrays were produced by inverse Compton scattering on the ELSA facility. In this type of experiment, X-ray observation lies in the use of accurate electron and laser beam interaction diagnostics and on fitted X-ray detectors. The low interaction probability between < 100 μm width, 12 ps [rms] length electron and photon pulses requires careful optimization of pulse spatial and temporal covering. Another issue was to observe 11 keV X-rays in the ambient radioactive noise of the linear accelerator. For that, we use a very sensitive detection scheme based on radio luminescent screens.

  12. The ratios of emission probabilities of Auger electrons for 3d transition elements at 59,5 keV

    NASA Astrophysics Data System (ADS)

    Kündeyi, Kadriye; Aylıkcı, Nuray Küp; Tıraşoǧlu, Engin; Kahoul, Abdelhalim; Aylıkcı, Volkan

    2017-02-01

    The ratios of emission probabilities were determined by using the measured K shell X-ray intensity ratio values for elements from Sc to Zn. For the experimental measurements, the samples were excited by 59.5 keV γ rays from a 241Am annular radioactive source. The emitted K X-rays from the samples were counted by an Ultra-LEGe detector with a resolution of 150 eV at 5.9 keV. The ratios of emission probabilities were denoted as uand v which means p(KLX)/p(KLL) and p(KXY)/p(KLL) respectively. The extracted values from the measured intensity ratios and calculated intensity ratios were compared with the earlier studies. It was found that the ratios of emission probabilities that evaluated from the calculated intensity ratios were agree well with the earlier studies except for Zn.

  13. Experimental investigation of ≈130 keV kinetic energy antiprotons annihilation on nuclei

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    MeV. In 2012, the 100 keV region has been investigated for the first time (Aghai-Khozani et al. Eur. Phys. J. Plus 127, 125-128, 2012). We present here the first preliminary results of this experiment.

  14. keV electron heating in laser-cluster interaction probed by X-ray and electron spectroscopy

    NASA Astrophysics Data System (ADS)

    Yin, H.; Wachter, G.; Deiss, C.; Lemell, C.; Burgdörfer, J.; Lamour, E.; Prigent, C.; Ramond, C.; Rozet, J. P.; Steydli, S.; Trassinelli, M.; Vernhet, D.

    2014-04-01

    The interaction of intense laser pulses with nanoscopic rare-gas clusters provides a testing ground for laser-atom interaction at solid-state densities. We investigate the driven electronic dynamics on the femtosecond time scale both experimentally and theoretically using two complementary observables: the laser intensity dependence of characteristic X-ray emission and of high-energy (keV) electron spectra.

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

    SciTech Connect

    Flint, D B; O’Brien, D J; McFadden, C H; Wolfe, T; Krishnan, S; Sawakuchi, G O; Hallacy, T M

    2015-06-15

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

  16. Banded Structures in Electron Pitch Angle Diffusion Coefficients from Resonant Wave Particle Interactions

    NASA Technical Reports Server (NTRS)

    Tripathi, A. K.; Singhal, R. P.; Khazanov, G. V.; Avanov, L. A.

    2016-01-01

    Electron pitch angle (D (alpha)) and momentum (D(pp)) diffusion coefficients have been calculated due to resonant interactions with electrostatic electron cyclotron harmonic (ECH) and whistler mode chorus waves. Calculations have been performed at two spatial locations L = 4.6 and 6.8 for electron energies 10 keV. Landau (n = 0) resonance and cyclotron harmonic resonances n = +/-1, +/-2,...+/-5 have been included in the calculations. It is found that diffusion coefficient versus pitch angle (alpha) profiles show large dips and oscillations or banded structures. The structures are more pronounced for ECH and lower band chorus (LBC) and particularly at location 4.6. Calculations of diffusion coefficients have also been performed for individual resonances. It is noticed that the main contribution of ECH waves in pitch angle diffusion coefficient is due to resonances n = +1 and n = +2. A major contribution to momentum diffusion coefficients appears from n = +2. However, the banded structures in D alpha and Dpp coefficients appear only in the profile of diffusion coefficients for n = +2. The contribution of other resonances to diffusion coefficients is found to be, in general, quite small or even negligible. For LBC and upper band chorus waves, the banded structures appear only in Landau resonance. The Dpp diffusion coefficient for ECH waves is one to two orders smaller than D alpha coefficients. For chorus waves, Dpp coefficients are about an order of magnitude smaller than D alpha coefficients for the case n does not = 0. In case of Landau resonance, the values of Dpp coefficient are generally larger than the values of D alpha coefficients particularly at lower energies. As an aid to the interpretation of results, we have also determined the resonant frequencies. For ECH waves, resonant frequencies have been estimated for wave normal angle 89 deg and harmonic resonances n = +1, +2, and +3, whereas for whistler mode waves, the frequencies have been calculated for angle

  17. Demonstration of a 13 keV Kr K-shell X-Ray Source at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

    We report 3% conversion efficiency of laser energy into Kr K-shell (~13 keV) radiation, consistent with theoretical predictions. This is ~10 × greater than previous work. The emission was produced from a 4.1 mm diameter, 4 mm tall gas pipe target filled with 1.2 or 1.5 atm of Kr gas. 160 of the NIF laser beams deposited ~700 kJ of 3 ω light into the target in a ~140 TW, 5.0 ns duration square pulse. This laser configuration sufficiently heated the targets to optimize the K-shell x-ray emission. The Dante diagnostics measured ~5 TW into 4 π solid angle of >=12 keV x rays for ~4 ns, which includes both continuum emission and flux in the Kr Heα line at 13 keV. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This work was supported by the Defense Threat Reduction Agency under the intera- gency agreements 10027-1420 and 10027-6167.

  18. Charge transfer and electronic excitation in collisions of protons with water molecules below 10keV

    NASA Astrophysics Data System (ADS)

    Mada, Shogo; Hida, Ken-Nosuke; Kimura, Mineo; Pichl, Lukáš; Liebermann, Heinz-Peter; Li, Yan; Buenker, Robert J.

    2007-02-01

    Charge transfer and electronic excitation processes for H++H2O collisions are investigated theoretically below 10keV . Molecular-orbital close-coupling approach is employed for scattering dynamics, while an ab initio multireference single- and double-configuration interaction method is used for the determination of molecular states. The present results for charge transfer show rather weak energy dependence in the energy range from 10keV down to a few tens of eV with very slowly varying cross-section value of 4-13×10-16cm2 , and are found to be in excellent agreement with experimental measurements by Lindsay [Phys. Rev. A 55, 3945 (1997)] where the energy in the experiment and theory overlaps. The electronic-excitation cross sections are found to be much smaller than those for the charge transfer, but increase rapidly and become comparable to charge transfer at a few keV. Most of the water molecular ions and excited species produced in the collision are unstable and soon undergo dissociation; some insight into the fragmentation process and the fragmented species is given.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

    We perform a detailed study of the stacked Suzaku observations of 47 galaxy clusters, spanning a redshift range of 0.01-0.45, to search for the unidentified 3.5 keV line. This sample provides an independent test for the previously detected line. We detect a 2σ -significant spectral feature at 3.5 keV in the spectrum of the full sample. When the sample is divided into two subsamples (cool-core and non-cool core clusters), the cool-core subsample shows no statistically significant positive residuals at the line energy. A very weak (˜ 2σ confidence) spectral feature at 3.5 keV is permitted by the data from the non-cool-core clusters sample. The upper limit on a neutrino decay mixing angle of {\\sin }2(2θ )=6.1× {10}-11 from the full Suzaku sample is consistent with the previous detections in the stacked XMM-Newton sample of galaxy clusters (which had a higher statistical sensitivity to faint lines), M31, and Galactic center, at a 90% confidence level. However, the constraint from the present sample, which does not include the Perseus cluster, is in tension with previously reported line flux observed in the core of the Perseus cluster with XMM-Newton and Suzaku.

  20. THE X-RAY LINE FEATURE AT 3.5 KeV IN GALAXY CLUSTER SPECTRA

    SciTech Connect

    Phillips, K. J. H.; Sylwester, B.; Sylwester, J. E-mail: bs@cbk.pan.wroc.pl

    2015-08-10

    Recent work by Bulbul et al. and Boyarsky et al. has suggested that a line feature at ∼3.5 keV in the X-ray spectra of galaxy clusters and individual galaxies seen with XMM-Newton is due to the decay of sterile neutrinos, a dark matter candidate. This identification has been criticized by Jeltema and Profumo on the grounds that model spectra suggest that atomic transitions in helium-like potassium (K xviii) and chlorine (Cl xvi) are more likely to be the emitters. Here it is pointed out that the K xviii lines have been observed in numerous solar flare spectra at high spectral resolution with the RESIK crystal spectrometer and also appear in Chandra HETG spectra of the coronally active star σ Gem. In addition, the solar flare spectra at least indicate a mean coronal potassium abundance, which is a factor between 9 and 11 higher than the solar photospheric abundance. This fact, together with the low statistical quality of the XMM-Newton spectra, completely account for the ∼3.5 keV feature and there is therefore no need to invoke a sterile neutrino interpretation of the observed line feature at ∼3.5 keV.

  1. FLUKA and PENELOPE simulations of 10 keV to 10 MeV photons in LYSO and soft tissue

    NASA Astrophysics Data System (ADS)

    Chin, M. P. W.; Böhlen, T. T.; Fassò, A.; Ferrari, A.; Ortega, P. G.; Sala, P. R.

    2014-02-01

    Monte Carlo simulations of electromagnetic particle interactions and transport by FLUKA and PENELOPE were compared. 10 keV to 10 MeV incident photon beams impinged a LYSO crystal and a soft-tissue phantom. Central-axis as well as off-axis depth doses agreed within 1 s.d.; no systematic under- or over-estimate of the pulse height spectra was observed from 100 keV to 10 MeV for both materials, agreement was within 5%. Simulation of photon and electron transport and interactions at this level of precision and reliability is of significant impact, for instance, on treatment monitoring of hadrontherapy where a code like FLUKA is needed to simulate the full suite of particles and interactions (not just electromagnetic). At the interaction-by-interaction level, apart from known differences in condensed history techniques, two-quanta positron annihilation at rest was found to differ between the two codes. PENELOPE produced a 511 keV sharp line, whereas FLUKA produced visible acolinearity, a feature recently implemented to account for the momentum of shell electrons.

  2. Charge transfer and electronic excitation in collisions of protons with water molecules below 10 keV

    SciTech Connect

    Mada, Shogo; Hida, Ken-nosuke; Kimura, Mineo; Pichl, Lukas; Liebermann, Heinz-Peter; Li, Yan; Buenker, Robert J.

    2007-02-15

    Charge transfer and electronic excitation processes for H{sup +}+H{sub 2}O collisions are investigated theoretically below 10 keV. Molecular-orbital close-coupling approach is employed for scattering dynamics, while an ab initio multireference single- and double-configuration interaction method is used for the determination of molecular states. The present results for charge transfer show rather weak energy dependence in the energy range from 10 keV down to a few tens of eV with very slowly varying cross-section value of 4-13x10{sup -16} cm{sup 2}, and are found to be in excellent agreement with experimental measurements by Lindsay et al. [Phys. Rev. A 55, 3945 (1997)] where the energy in the experiment and theory overlaps. The electronic-excitation cross sections are found to be much smaller than those for the charge transfer, but increase rapidly and become comparable to charge transfer at a few keV. Most of the water molecular ions and excited species produced in the collision are unstable and soon undergo dissociation; some insight into the fragmentation process and the fragmented species is given.

  3. Performance of a medical imaging system for photons in the 60-140 keV energy range

    NASA Astrophysics Data System (ADS)

    Amendolia, S. R.; Bisogni, M. G.; Bottigli, U.; Ceccopieri, A.; Delogu, P.; Dipasquale, G.; Fantacci, M. E.; Maestro, P.; Marchi, A.; Marzulli, V. M.; Oliva, P.; Palmiero, R.; Pernigotti, E.; Rosso, V.; Stefanini, A.; Stumbo, S.

    2001-04-01

    We report the status of the art of a prototype based on a GaAs pixel detector bump-bonded to a dedicated VLSI chip to be possibly used for imaging in the nuclear medicine field. This device, with a 200 μm thick pixel matrix (64×64 square pixels, 170 μm side), has already been tested with very good results for digital mammography applications (mean energy 20 keV). For more energetic photons, as in nuclear medicine, a 600 μm thick detector has been chosen. Using radioactive sources ( 241Am, 60 keV and 99 mTc, 140 keV photons) we have measured the performance of our prototype in terms of charge collection and detection efficiency of the detector, discrimination capability of the electronics and imaging properties of the whole system. In particular, we have evaluated the spatial resolution properties measuring the Point Spread Function and the imaging capabilities using a home made thyroid phantom. We present also the comparison between these results and those obtained with a traditional gamma camera and the evaluation, made by both experimental measurements and software simulations, of the geometry related to the use of a collimator.

  4. Decaying vector dark matter as an explanation for the 3.5 keV line from galaxy clusters

    SciTech Connect

    Farzan, Yasaman; Akbarieh, Amin Rezaei E-mail: am_rezaei@physics.sharif.ir

    2014-11-01

    We present a Vector Dark Matter (VDM) model that explains the 3.5 keV line recently observed in the XMM-Newton observatory data from galaxy clusters. In this model, dark matter is composed of two vector bosons, V and V', which couple to the photon through an effective generalized Chern-Simons coupling, g{sub V}. V' is slightly heavier than V with a mass splitting m{sub V'} – m{sub V} ≅ 3.5 keV. The decay of V' to V and a photon gives rise to the 3.5 keV line. The production of V and V' takes place in the early universe within the freeze-in framework through the effective g{sub V} coupling when m{sub V'} < T < Λ, Λ being the cut-off above which the effective g{sub V} coupling is not valid. We introduce a high energy model that gives rise to the g{sub V} coupling at low energies. To do this, V and V' are promoted to gauge bosons of spontaneously broken new U(1){sub V} and U(1){sub V'} gauge symmetries, respectively. The high energy sector includes milli-charged chiral fermions that lead to the g{sub V} coupling at low energy via triangle diagrams.

  5. Intensity formulas for triplet bands

    NASA Technical Reports Server (NTRS)

    Budo, A.

    1982-01-01

    Previous work in this area is surveyed and the mathematics involved in determining the quantitative intensity measurements in triplet bands is presented. Explicit expressions for the intensity distribution in the branches of the 3 Sigma-3 Pi and 1 Sigma-3Pi bands valid for all values of the coupling constant Y of the 3 Pi terms are given. The intensity distribution calculated according to the formulas given is compared with measurements of PH, 3 Pi-3 Sigma. Good quantitative agreement is obtained.

  6. "No One Answer" to Band Problems.

    ERIC Educational Resources Information Center

    Prescott, Michael P.

    1982-01-01

    Describes the results of a survey of problems facing school band programs. Respondents were band and non-band students, their parents, band masters, and retail school music dealers. Among the primary problems were inadequate funding, scheduling conflicts, band members not taking private lessons, and lack of parental encouragement. (AM)

  7. A Broad-band Spectral and Timing Study of the X-Ray Binary System Centaurus X-3

    NASA Technical Reports Server (NTRS)

    Audley, Michael Damian

    1998-01-01

    This dissertation describes a multi-mission investigation of the high mass X-ray binary pulsar Centaurus X-3. Cen X-3 was observed with the Broad Band X-Ray Telescope (BBXRT) in December 1990. This was the first high-resolution solid state X-ray spectrometer to cover the iron K fluorescence region. The Fe K emission feature was resolved into two components for the first time. A broad 6.7 keV feature was found to be a blend of lines from Fe XXI-Fe XXVI with energies ranging from 6.6 to 6.9 keV due to photoionization of the companion's stellar wind. A narrow line at 6.4 keV due to fluorescence of iron in relatively low ionization states was also found. The quasi-periodic oscillations (QPO) at about 40 mHz were used to estimate the surface magnetic field of Cen X-3 as approx. 2.6 x 10(exp 12) G and to predict that there should be a cyclotron scattering resonance absorption feature (CSRF) near 30 keV. In order to further resolve the iron line complex and to investigate the pulse-phase dependence of the iron line intensities, Cen X-3 was observed with the Advanced Satellite for Cosmology and Astrophysics (ASCA). Using ASCA's state-of-the-art non-dispersive X-ray spectrometers the 6.4 keV fluorescent iron line was found to be pulsing while the intensities of the 6.7 and 6.9 keV recombination lines do not vary with pulse phase. This confirms that the 6.4 keV line is due to reflection by relatively neutral matter close to the neutron star while the recombination lines originate in the extended stellar wind. The continuum spectrum was found to be modified by reflection from matter close to the neutron star. Observations with the EXOSAT GSPC were used to search for a CSRF. The EXOSAT spectra were consistent with the presence of a CSRF but an unambiguous detection was not possible because of a lack of sensitivity at energies higher than the cyclotron energy. Cen X-3 was then observed with the Rossi X-Ray Timing Explorer (RXTE) and evidence for a CSRF at 25.1 +/- 0.3 keV was

  8. Dilatational band formation in bone

    PubMed Central

    Poundarik, Atharva A.; Diab, Tamim; Sroga, Grazyna E.; Ural, Ani; Boskey, Adele L.; Gundberg, Caren M.; Vashishth, Deepak

    2012-01-01

    Toughening in hierarchically structured materials like bone arises from the arrangement of constituent material elements and their interactions. Unlike microcracking, which entails micrometer-level separation, there is no known evidence of fracture at the level of bone’s nanostructure. Here, we show that the initiation of fracture occurs in bone at the nanometer scale by dilatational bands. Through fatigue and indentation tests and laser confocal, scanning electron, and atomic force microscopies on human and bovine bone specimens, we established that dilatational bands of the order of 100 nm form as ellipsoidal voids in between fused mineral aggregates and two adjacent proteins, osteocalcin (OC) and osteopontin (OPN). Laser microdissection and ELISA of bone microdamage support our claim that OC and OPN colocalize with dilatational bands. Fracture tests on bones from OC and/or OPN knockout mice (OC−/−, OPN−/−, OC-OPN−/−;−/−) confirm that these two proteins regulate dilatational band formation and bone matrix toughness. On the basis of these observations, we propose molecular deformation and fracture mechanics models, illustrating the role of OC and OPN in dilatational band formation, and predict that the nanometer scale of tissue organization, associated with dilatational bands, affects fracture at higher scales and determines fracture toughness of bone. PMID:23129653

  9. Dependence of Cell Survival on Iododeoxyuridine Concentration in 35-keV Photon-Activated Auger Electron Radiotherapy

    SciTech Connect

    Dugas, Joseph P.; Varnes, Marie E.; Sajo, Erno; Welch, Christopher E.; Ham, Kyungmin; Hogstrom, Kenneth R.

    2011-01-01

    Purpose: To measure and compare Chinese hamster ovary cell survival curves using monochromatic 35-keV photons and 4-MV x-rays as a function of concentration of the radiosensitizer iododeoxyuridine (IUdR). Methods and Materials: IUdR was incorporated into Chinese hamster ovary cell DNA at 16.6 {+-} 1.9%, 12.0 {+-} 1.4%, and 9.2 {+-} 1.3% thymidine replacement. Cells were irradiated from 1 to 8 Gy with 35-keV synchrotron-generated photons and conventional radiotherapy 4-MV x-rays. The effects of the radiation were measured via clonogenic survival assays. Surviving fraction was plotted vs. dose and fit to a linear quadratic model. Sensitization enhancement ratios (SER{sub 10}) were calculated as the ratio of doses required to achieve 10% surviving fraction for cells without and with DNA-incorporated IUdR. Results: At 4 MV, SER{sub 10} values were 2.6 {+-} 0.1, 2.2 {+-} 0.1, and 1.5 {+-} 0.1 for 16.6%, 12.0%, and 9.2% thymidine replacement, respectively. At 35 keV, SER{sub 10} values were 4.1 {+-} 0.2, 3.0 {+-} 0.1, and 2.0 {+-} 0.1, respectively, which yielded SER{sub 10} ratios (35 keV:4 MV) of 1.6 {+-} 0.1, 1.4 {+-} 0.1, and 1.3 {+-} 0.1, respectively. Conclusions: SER{sub 10} increases monotonically with percent thymidine replacement by IUdR for both modalities. As compared to 4-MV x-rays, 35-keV photons produce enhanced SER{sub 10} values whose ratios are linear with percent thymidine replacement and assumed to be due to Auger electrons contributing to enhanced dose to DNA. Although this Auger effectiveness factor is less than the radiosensitization factor of IUdR, both could be important for the clinical efficacy of IUdR radiotherapy.

  10. New Measurements of the Solar Wind Charge Exchange, Local Bubble, and Halo 3/4 keV Emission from XMM-Newton and Suzaku Shadowing Observations

    NASA Astrophysics Data System (ADS)

    Shelton, Robin L.; Henley, David

    2016-06-01

    We report on the analyses of XMM-Newton and/or Suzaku observations of 6 on-cloud and off-cloud shadowing pairs. This study provides the first analysis of two of these pairs and the first uniform analysis of the larger dataset. For every shadowing pair, we determined the foreground and halo components by simultaneously fitting the spectra from both members of the pair with a model that included a foreground component and an absorbed background component. In the past, foreground X-ray emission was thought to come from the Local Bubble of hot gas surrounding the solar neighborhood and so thermal spectral models were used. Now that solar wind charge exchange is recognized as a source of foreground X-ray photons, it is appropriate to consider charge exchange models as well. For this reason, we repeated the analyses using one of 3 possible foreground models: a charge exchange spectral model whose line ratios come from atomic physics calculations and are presented in Cumbee et al. (2014), a charge exchange model based on the AtomDB Charge Exchange code, or a thermal spectrum. The analyses of the larger dataset enabled us to place an upper limit on the Local Bubble's O VII contribution, provide measurements of the local and halo contributions in the 0.4 to 1.0 keV band, comment on the abilities of the various solar wind models to fit the data, and comment on the sensitivity of the fit parameters to the choice of foreground model, metal abundance tables, and X-ray observatory.

  11. Band gap and defect states of MgO thin films investigated using reflection electron energy loss spectroscopy

    SciTech Connect

    Heo, Sung; Cho, Eunseog; Lee, Hyung-Ik; Park, Gyeong Su; Kang, Hee Jae; Nagatomi, T.; Choi, Pyungho; Choi, Byoung-Deog

    2015-07-15

    The band gap and defect states of MgO thin films were investigated by using reflection electron energy loss spectroscopy (REELS) and high-energy resolution REELS (HR-REELS). HR-REELS with a primary electron energy of 0.3 keV revealed that the surface F center (FS) energy was located at approximately 4.2 eV above the valence band maximum (VBM) and the surface band gap width (E{sub g}{sup S}) was approximately 6.3 eV. The bulk F center (F{sub B}) energy was located approximately 4.9 eV above the VBM and the bulk band gap width was about 7.8 eV, when measured by REELS with 3 keV primary electrons. From a first-principles calculation, we confirmed that the 4.2 eV and 4.9 eV peaks were F{sub S} and F{sub B}, induced by oxygen vacancies. We also experimentally demonstrated that the HR-REELS peak height increases with increasing number of oxygen vacancies. Finally, we calculated the secondary electron emission yields (γ) for various noble gases. He and Ne were not influenced by the defect states owing to their higher ionization energies, but Ar, Kr, and Xe exhibited a stronger dependence on the defect states owing to their small ionization energies.

  12. Single-Band and Dual-Band Infrared Detectors

    NASA Technical Reports Server (NTRS)

    Ting, David Z. (Inventor); Gunapala, Sarath D. (Inventor); Soibel, Alexander (Inventor); Nguyen, Jean (Inventor); Khoshakhlagh, Arezou (Inventor)

    2015-01-01

    Bias-switchable dual-band infrared detectors and methods of manufacturing such detectors are provided. The infrared detectors are based on a back-to-back heterojunction diode design, where the detector structure consists of, sequentially, a top contact layer, a unipolar hole barrier layer, an absorber layer, a unipolar electron barrier, a second absorber, a second unipolar hole barrier, and a bottom contact layer. In addition, by substantially reducing the width of one of the absorber layers, a single-band infrared detector can also be formed.

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

    PubMed

    Camargo Moreira, Anderson; Roberto Appoloni, Carlos

    2006-09-01

    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.

  14. William Band at Yenching University

    NASA Astrophysics Data System (ADS)

    Hu, Danian

    2008-04-01

    William Band (1906-1993) has been widely remembered by his American colleagues and students as ``a fine physicist and teacher,'' who taught at Washington State University in Pullman between 1949 and 1971 and authored Introduction to Quantum Statistics (1954) and Introduction to Mathematical Physics (1959). Not many, however, knew much about Band's early career, which was very ``uncommon and eventful.'' Born in England, Band graduated from University of Liverpool in 1927 with an MsSc degree in physics. Instead of pursuing his Ph.D. at Cambridge, he chose to teach physics at Yenching University, a prestigious Christian university in Beijing, China. Arriving in 1929, Band established his career at Yenching, where he taught and researched the theory of relativity and quantum mechanics, pioneered the study on low-temperature superconductivity in China, founded the country's first graduate program in physics, and chaired the Physics Department for 10 years until he fled from Yenching upon hearing of the attack on Pearl Harbor. It took him two years to cross Japanese occupied areas under the escort of the Communist force; he left China in early 1945. This presentation will explore Band's motivation to work in China and his contributions to the Chinese physics research and education.

  15. Ka-band study: 1988

    NASA Technical Reports Server (NTRS)

    Layland, J. W.; Horttor, R. L.; Clauss, R. C.; Wilcher, J. H.; Wallace, R. J.; Mudgway, D. J.

    1989-01-01

    The Ka-band study team was chartered in late 1987 to bring together all the planning elements for establishing 32 GHz (Ka-band) as the primary downlink frequency for deep-space operation, and to provide a stable baseline from which to pursue that development. This article summarizes the results of that study at its conclusion in mid-1988, and corresponds to material presented to NASA's Office of Space Operations on July 14, 1988. For a variety of reasons, Ka-band is the right next major step in deep-space communications. It offers improved radio metric accuracy through reduced plasma sensitivity and increased bandwidth. Because of these improvements, it offers the opportunity to reduce costs in the flight radio system or in the DSN by allocating part of the overall benefits of Ka-band to this cost reduction. A mission scenario is being planned that can drive at least two and possibly all three of the DSN subnets to provide a Ka-band downlink capability by the turn of the century. The implementation scenario devised by the study team is believed to be feasible within reasonable resource expectations, and capable of providing the needed upgrade as a natural follow-on to the technology development which is already underway.

  16. A novel coaxial Ku-band transit radiation oscillator without external guiding magnetic field

    NASA Astrophysics Data System (ADS)

    Ling, Junpu; Zhang, Jiande; He, Juntao; Jiang, Tao

    2014-02-01

    A novel coaxial transit radiation oscillator without external guiding magnetic field is designed to generate high power microwave at Ku-band. By using a coaxial structure, the space-charge potential energy is suppressed significantly, that is good for enhancing efficient beam-wave interaction. In order to improve the transmission stability of the unmagnetized intense relativistic electron beam, a Pierce-like cathode is employed in the novel device. By contrast with conventional relativistic microwave generators, this kind of device has the advantages of high stability, non-guiding magnetic field, and high efficiency. Moreover, with the coaxial design, it is possible to improve the power-handing capacity by increasing the radial dimension of the Ku-band device. With a 550 keV and 7.5 kA electron beam, a 1.25 GW microwave pulse at 12.08 GHz has been obtained in the simulation. The power conversion efficiency is about 30%.

  17. Stopping Narrow-Band X-Ray Pulses in Nuclear Media

    NASA Astrophysics Data System (ADS)

    Kong, Xiangjin; Pálffy, Adriana

    2016-05-01

    A control mechanism for stopping x-ray pulses in resonant nuclear media is investigated theoretically. We show that narrow-band x-ray pulses can be mapped and stored as nuclear coherence in a thin-film planar x-ray cavity with an embedded 57Fe nuclear layer. The pulse is nearly resonant to the 14.4 keV Mössbauer transition in the 57Fe nuclei. The role of the control field is played here by a hyperfine magnetic field which induces interference effects reminiscent of electromagnetically induced transparency. We show that, by switching off the control magnetic field, a narrow-band x-ray pulse can be completely stored in the cavity for approximately 100 ns. Additional manipulation of the external magnetic field can lead to both group velocity and phase control of the pulse in the x-ray cavity sample.

  18. Experimental measurement of Au M-band flux in indirectly-driven double-shell implosions

    SciTech Connect

    Robey, H F; Perry, T S; Park, H S; Amendt, P; Sorce, C M; Compton, S M; Campbell, K M; Knauer, J P

    2004-09-17

    Indirectly-driven double-shell implosions are being investigated as a possible noncryogenic path to ignition on the National Ignition Facility (NIF). In recent double-shell implosions, the inner shell trajectory was shown to exhibit a strong sensitivity to the temporal history of the M-band (2-5 keV) radiation emitted from the Au hohlraum wall. A large time-dependent discrepancy was observed between measurement and simulation of the x-ray flux in this range. In order to better characterize the radiation environment seen in these implosions, an experimental campaign was conducted on the Omega Laser. A number of diagnostics were used to measure both the temporal and spectral nature of the M-band flux. Results were obtained from an absolutely calibrated 12 channel filtered x-ray diode array (Dante) as well as two streaked crystal spectrometers and an absolutely calibrated time-integrated spectrometer (Henway). X-ray backlighting was also used to directly measure the effect of M-band radiation on the trajectory of the inner shell. The data from all diagnostics are shown to be in excellent agreement and provide a consistent picture of the M-band flux. These results are being used to improve the simulation of hohlraum-generated M-band radiation that will be necessary for the design of future double-shell implosions employing higher Z inner shells.

  19. Experimental measurement of Au M-band flux in indirectly-driven double-shell implosions

    SciTech Connect

    Robey, H F; Perry, T S; Park, H S; Amendt, P; Sorce, C M; Compton, S M; Campbell, K M; Knauer, J P

    2005-03-24

    Indirectly-driven double-shell implosions are being investigated as a possible noncryogenic path to ignition on the National Ignition Facility (NIF). In recent double-shell experiments, the inner shell trajectory was shown to exhibit a strong sensitivity to the temporal history of the M-band (2-5 keV) radiation emitted from the Au hohlraum wall. A large time-dependent discrepancy was observed between measurement and simulation of the x-ray flux in this range. In order to better characterize the radiation environment seen in these implosions, an experimental campaign was conducted on the Omega Laser. A number of diagnostics were used to measure both the temporal and spectral nature of the M-band flux. Results were obtained from an absolutely calibrated 12 channel filtered x-ray diode array (Dante) as well as two streaked crystal spectrometers and an absolutely calibrated time-integrated spectrometer (Henway). X-ray backlighting was also used to directly measure the effect of M-band radiation on the trajectory of the inner shell. The data from all diagnostics are shown to be in excellent agreement and provide a consistent picture of the M-band flux. These results are being used to constrain and improve the simulation of hohlraum-generated M-band radiation that will be necessary for the design of future double-shell implosions employing higher-Z inner shells.

  20. Band Structures of Plasmonic Polarons

    NASA Astrophysics Data System (ADS)

    Caruso, Fabio; Lambert, Henry; Giustino, Feliciano

    2015-03-01

    In angle-resolved photoemission spectroscopy (ARPES), the acceleration of a photo-electron upon photon absorption may trigger shake-up excitations in the sample, leading to the emission of phonons, electron-hole pairs, and plasmons, the latter being collective charge-density fluctuations. Using state-of-the-art many-body calculations based on the `GW plus cumulant' approach, we show that electron-plasmon interactions induce plasmonic polaron bands in group IV transition metal dichalcogenide monolayers (MoS2, MoSe2, WS2, WSe2). We find that the energy vs. momentum dispersion relations of these plasmonic structures closely follow the standard valence bands, although they appear broadened and blueshifted by the plasmon energy. Based on our results we identify general criteria for observing plasmonic polaron bands in the angle-resolved photoelectron spectra of solids.

  1. A New Understanding of Near-Threshold Damage for 200 keV Irradiation In Silicon

    SciTech Connect

    Stoddard, Nathan; Duscher, Gerd J M; Windl, Wolfgang; Rozgonyi, G. A.

    2005-01-01

    Recently we reported room temperature point defect creation and subsequent extended defect nucleation in nitrogen-doped silicon during 200 kV electron irradiation, while identical irradiation of nitrogen-free silicon produced no effect. In this paper, first principles calculations are combined with new transmission electron microscope (TEM) observations to support a new model for elastic electron-silicon interactions in the TEM, which encompasses both nitrogen doped and nitrogen free silicon. Specifically, the nudged elastic band method was used to study the energetics along the diffusion path during an electron collision event in the vicinity of a nitrogen pair. It was found that the 0 K estimate for the energy barrier of a knock-on event is lowered from {approx}12 to 6.2 eV. However, this is still inadequate to explain the observations. We therefore propose an increase in the energy barrier for Frenkel pair recombination associated with N{sub 2}-V bonding. Concerning pure silicon, stacking fault formation near irradiation-induced holes demonstrates the participation of bulk processes. In low oxygen float zone material, 2--5 nm voids were formed, while oxygen precipitation in Czochralski Si has been verified by electron energy-loss spectroscopy. Models of irradiation-induced point defect aggregation are presented and it is concluded that these must be bulk and not surface mediated phenomena.

  2. A Broad-Band X-Ray Telescope spectrum of the massive X-ray binary X Persei

    NASA Technical Reports Server (NTRS)

    Schlegel, Eric M.; Serlemitsos, Peter J.; Jahoda, Keith; Marshall, Frank; Petre, Robert; Boldt, Elihu; Mushotzky, Richard; Swank, Jean; Szymkowiak, Andrew; Smale, Alan

    1993-01-01

    The Broad Band X-Ray Telescope, covering the 0.3-12 keV bandpass with moderate spectral resolution, observed the Be/X-ray binary X Per in 1990 December during the Astro-l mission on the Space Shuttle Columbia. The data obtained are the best to date to search for lines and edges. The data are well fitted by a power-law spectrum with a high-energy cutoff. A low value for the high-energy cutoff is found, implying a slightly weaker magnetic field strength for the X-ray pulsar. No iron line is present at about 6.5 keV with an equivalent width greater than 30-40 eV. The BBXRT observation corresponded to the 'off' state of X Per's recent 'phase change'.

  3. Diffuse bands versus extinction parameters

    NASA Technical Reports Server (NTRS)

    Wegner, Walter; Snow, Theodore P.; Sneden, C.; Krelowski, Jacek

    1994-01-01

    All recent available, high quality measurements of the strong diffuse bands 5780 A and 5797 A have been collected. This includes those measurement derived from the authors's recent observations (February, May, and November 1993, taken with a echelle spectrograph) as well as those from a coude spectrograph and from literature. Equivalent widths of the diffuse interstellar bands (DIB's) at 5780 A and 5797 A have been measured on spectrograms. The measured signal-to-noise ratio (S/N) on their own spectrograms ranged from 250 to 500. The Johnson UBV data were used to estimate the color excesses of our targets.

  4. QUIET-TIME SUPRATHERMAL (∼0.1–1.5 keV) ELECTRONS IN THE SOLAR WIND

    SciTech Connect

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

    2016-03-20

    We present a statistical survey of the energy spectrum of solar wind suprathermal (∼0.1–1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ∼0.1–1.5 keV to a Kappa distribution function with an index κ and effective temperature T{sub eff}. We also calculate the number density n and average energy E{sub avg} of strahl and halo electrons by integrating the electron measurements between ∼0.1 and 1.5 keV. We find a strong positive correlation between κ and T{sub eff} for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity)

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

    NASA Astrophysics Data System (ADS)

    Caspi, Amir; Woods, Thomas N.; Warren, Harry P.

    2015-03-01

    The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the high-temperature corona, and is also an important driver of ionospheric dynamics at Earth. There is a crucial observational gap between ˜0.2 and ˜4 keV, outside the ranges of existing spectrometers. We present observations from a new SXR spectrometer, the Amptek X123-SDD, which measured the spatially integrated solar spectral irradiance from ˜0.5 to ˜5 keV, with ˜0.15 keV FWHM resolution, during sounding rocket flights on 2012 June 23 and 2013 October 21. These measurements show that the highly variable SXR emission is orders of magnitude greater than that during the deep minimum of 2009, even with only weak activity. The observed spectra show significant high-temperature (5-10 MK) emission and are well fit by simple power-law temperature distributions with indices of ˜6, close to the predictions of nanoflare models of coronal heating. Observations during the more active 2013 flight indicate an enrichment of low first-ionization potential elements of only ˜1.6, below the usually observed value of ˜4, suggesting that abundance variations may be related to coronal heating processes. The XUV Photometer System Level 4 data product, a spectral irradiance model derived from integrated broadband measurements, significantly overestimates the spectra from both flights, suggesting a need for revision of its non-flare reference spectra, with important implications for studies of Earth ionospheric dynamics driven by solar SXRs.

  6. Motion of 3-6 keV Nonthermal Sources Along the Legs of a Flare Loop

    NASA Technical Reports Server (NTRS)

    Sui, Linhui; Holman, Gordon D.; Dennis, Brian R.

    2007-01-01

    Observations of nonthermal X-ray sources me critical to studying electron acceleration and transport in solar flares. Strong thermal emission radiated from the preheated plasma before the flare impulsive phase often makes it difficult to detect low-energy X-ray sources that are produced by relatively low-energy nonthermal electrons. Knowledge of the distribution of these low-energy nonthermal electrons is particularly important in determining the total nonthermal electron energy in solar flares. We report on an 'early impulsive flare' in which impulsive hard X-ray emission was seen early in the flare before the soft X-ray emission had risen significantly, indicating limited plasma pre-heating. Early in the flare, RHESSI < 25 keV images show coronal sources that moved first downward and then upwards along the legs of a flare loop. In particular, the 3-6 keV source appeared as a single coronal source at the start of the flare, and then it involved into two coronal sources moving down along the two legs of the loop. After nearly reaching the two footpoints at the hard X-ray peak, the two sources moved back up to the looptop again. RHESSI images and light curves all indicate that nonthermal emission dominated at energies as low as 3-6 keV. We suggest that the evolution of both the spectral index and the low-energy cutoff of the injected electron distribution could result in the accelerated electrons reaching a lower altitude along the legs of the dense flare loop and hence result in the observed downward and upward motions of the nonthermal sources.

  7. The Broad-band X-Ray Spectrum of IC 4329A from a Joint NuSTAR/Suzaku Observation

    NASA Astrophysics Data System (ADS)

    Brenneman, L. W.; Madejski, G.; Fuerst, F.; Matt, G.; Elvis, M.; Harrison, F. A.; Ballantyne, D. R.; Boggs, S. E.; Christensen, F. E.; Craig, W. W.; Fabian, A. C.; Grefenstette, B. W.; Hailey, C. J.; Madsen, K. K.; Marinucci, A.; Rivers, E.; Stern, D.; Walton, D. J.; Zhang, W. W.

    2014-06-01

    We have obtained a deep, simultaneous observation of the bright, nearby Seyfert galaxy IC 4329A with Suzaku and NuSTAR. Through a detailed spectral analysis, we are able to robustly separate the continuum, absorption, and distant reflection components in the spectrum. The absorbing column is found to be modest ({\\sim }6 \\times 10^{21} {\\, cm^{-2}\\,}), and does not introduce any significant curvature in the Fe K band. We are able to place a strong constraint on the presence of a broadened Fe Kα line (E_rest=6.46^{+0.08}_{-0.07} \\, keV with \\sigma =0.33^{+0.08}_{-0.07} \\, keV and EW=34^{+8}_{-7} \\, eV), though we are not able to constrain any of the parameters of a relativistic reflection model. These results highlight the range in broad Fe K line strengths observed in nearby, bright, active galactic nuclei (roughly an order of magnitude), and imply a corresponding range in the physical properties of the inner accretion disk in these sources. We have also updated our previously reported measurement of the high-energy cutoff of the hard X-ray emission using both observatories rather than just NuSTAR alone: E cut = 186 ± 14 keV. This high-energy cutoff acts as a proxy for the temperature of the coronal electron plasma, enabling us to further separate this parameter from the plasma's optical depth and to update our results for these parameters as well. We derive kT=50^{+6}_{-3} \\, keV with \\tau =2.34^{+0.16}_{-0.11} using a spherical geometry, kT = 61 ± 1 keV with τ = 0.68 ± 0.02 for a slab geometry, with both having an equivalent goodness-of-fit.

  8. Satellite observations of energy-banded ions during large geomagnetic storms: Event studies, statistics, and comparisons to source models

    NASA Astrophysics Data System (ADS)

    Colpitts, C. A.; Cattell, C. A.; Kozyra, J. U.; Thomsen, M. F.; Lavraud, B.

    2016-07-01

    Energy-banded ions from tens to ten thousands of eV are observed in the low-latitude auroral and subauroral zones during every large (minimum Dst < -150 nT) geomagnetic storm encountered by the FAST satellite. The banded ions persist for many FAST orbits, lasting up to 12 h, in both the northern and southern hemispheres. The energy-banded ions often have more than six distinct bands, and the O+, He+, and H+ bands are often observed at the same energies. The bands are extensive in latitude (~50-75° on the dayside, often extending to 45°) and magnetic local time, covering all magnetic local time over the data set of storms. The distributions are peaked in the perpendicular direction at the altitudes of the FAST satellite (~350-4175 km), although in some cases the precipitating component dominates for the lowest energy bands. At the same time, for some of the events studied in detail, long-lasting intervals of field-aligned energy dispersed ions from ~100 eV to 40 keV are seen in Los Alamos National Laboratory geosynchronous observations, primarily on the dayside and after magnetosheath encounters (i.e., highly compressed magnetosphere). We present both case and statistical studies of the banded ions. These bands are a new phenomenon associated with all large storms, which are distinctly different from other banded populations, and are not readily interpreted using previous models for particle sources, transport, and loss. The energy-banded ions are an energetically important component of the inner magnetosphere during the most intense magnetic storms.

  9. A coincidence study of electron and positron impact ionization of Ar (3p) at 1 keV

    NASA Astrophysics Data System (ADS)

    Campeanu, Radu I.; Walters, James H. R.; Whelan, Colm T.

    2015-10-01

    Distorted-wave calculations of the triple differential cross section (TDCS) are presented for electron and positron impact ionization of Ar(3p) in coplanar asymmetric geometry at an impact energy of 1 keV and are compared with a recent experiment. The experiment indicates that the positron TDCS is generally larger than the equivalent electron TDCS. It is shown that the magnitude of the TDCS is extremely sensitive to the energy of the ejected electron and that only when the cross section is averaged over energy do we get a reasonable agreement with experiment.

  10. A coincidence study of electron and positron impact ionization of Ar (3p) at 1 keV

    NASA Astrophysics Data System (ADS)

    Campeanu, Radu I.; Walters, James H. R.; Whelan, Colm T.

    2015-10-01

    Distorted-wave calculations of the triple differential cross section (TDCS) are presented for electron and positron impact ionization of Ar(3 p) in coplanar asymmetric geometry at an impact energy of 1 keV and are compared with a recent experiment. The experiment indicates that the positron TDCS is generally larger than the equivalent electron TDCS. It is shown that the magnitude of the TDCS is extremely sensitive to the energy of the ejected electron and that only when the cross section is averaged over energy do we get a reasonable agreement with experiment.

  11. Compact, rugged in-chamber transmission spectrometers (7-28 keV) for the Sandia Z facility.

    PubMed

    Sinars, D B; Wenger, D F; Pikuz, S A; Jones, B; Geissel, M; Hansen, S B; Coverdale, C A; Ampleford, D J; Cuneo, M E; McPherson, L A; Rochau, G A

    2011-06-01

    We describe a pair of time-integrated transmission spectrometers that are designed to survey 7-28 keV (1.9 to 0.43 Å) x-ray photons produced by experiments on the Sandia Z pulsed power facility. Each spectrometer uses a quartz 10-11 crystal in a Cauchois geometry with a slit to provide spatial resolution along one dimension. The spectrometers are located in the harsh environment of the Z vacuum chamber, which necessitates that their design be compact and rugged. Example data from calibration tests and Z experiments are shown that illustrate the utility of the instruments.

  12. Neutron scattering measurements in {sup 197}Au from 850 keV to 2.0 MeV

    SciTech Connect

    O`Connor, M.; Chen, J.; Egan, J.J.

    1995-10-01

    Differential elastic and inelastic neutron scattering cross-sections for low lying levels in {sup 197}Au have been measured for incident neutron energies of 1.0 MeV, 1.5 MeV and 2.0 MeV. In addition, the total neutron cross sections in {sup 197}Au was measured from 850 keV to 1.5 MeV. For both experiments the UML 5.5 MV Van-de-Graaff accelerator with a Mobley post acceleration compression system, produced subnanosecond proton pulses which generated neutrons via the {sup 7}Li(p,n) {sup 7}Be reaction.

  13. Calculation of angular distribution of 662 keV gamma rays by Monte Carlo method in copper medium.

    PubMed

    Kahraman, A; Ozmutlu, E N; Gurler, O; Yalcin, S; Kaynak, G; Gundogdu, O

    2009-12-01

    This paper presents results on the angular distribution of Compton scattering of 662 keV gamma photons in both forward and backward hemispheres in copper medium. The number of scattered events graph has been determined for scattered gamma photons in both the forward and backward hemispheres and theoretical saturation thicknesses have been obtained using these results. Furthermore, response function of a 51 x 51 mm NaI(Tl) detector at 60 degrees angle with incoming photons scattered from a 10mm thick copper layer has been determined using Monte Carlo method.

  14. Electron-capture collisions at keV energies of multiply charged ions of carbon and argon with molecular deuterium

    SciTech Connect

    Bliman, S.; Aubert, J.; Geller, R.; Jacquot, B.; Van Houtte, D.

    1981-04-01

    Single- and double-electron-capture cross sections have been measured for C/sup q/+ with initial charges 2 < or = q < or = 6 and for Ar/sup q/+ with initial charges 2 < or = q < or = 12 incident on molecular deuterium gas targets. The cross sections show little dependence on the incident-ion energy for the range studied 2q to 10q keV. The single-electron-capture cross sections do not vary monotonically with the initial charge, but show an oscillation about a mean curve, reflecting the projectile electronic structure.

  15. Measurement of 2-5 keV x-ray emission from laser-target interactions by using fluor-MCP and CsI-XRD detectors

    SciTech Connect

    Lee, P.H.Y.; Tirsell, K.G.; Leipelt, G.R.; Laird, W.B.

    1981-09-29

    For inertial confinement fusion plasma diagnostics, x-ray diode (XRD) detectors using conventional cathodes are not sensitive enough to measure x-rays above approx. 1.5 keV. However, for laser driver fusion targets, x-rays in the range of 2 to 5 keV are important because of their mobility in the target. We have successfully used fluor-microchannel plate (MCP) detectors to obtain absolute x-ray measurements in the 2 to 5 keV range. Recent data obtained from experiments on the Shiva laser system are presented. In addition, designs for a variety of channels in the range using fluor-MCP and CsI-XRD's above 1.5 keV will be discussed.

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

    SciTech Connect

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

    2013-06-13

    We present results of Monte Carlo simulations of microchannel plate (MCP) response to x-rays in the 250 eV to 20 keV energy range as a function of both x-ray energy and impact angle. The model is based on the model presented in Rochau et al. (2006). However, while the Rochau et al. (2006) model was two-dimensional, and their results only went to 5 keV, our results have been expanded to 20 keV, and our model has been incorporated into a three-dimensional Monte Carlo MCP model that we have developed over the past several years (Kruschwitz et al. 2011). X-ray penetration through multiple MCP pore walls is increasingly important above 5 keV. The effect of x-ray penetration through multiple pores on MCP performance was studied and is presented.

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

    SciTech Connect

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

    1994-12-31

    {sup 12}C(d,p){sup 13}T differential cross section data at 200, 220, 250, 280 and 300 keV deuteron energies has been analyzed using finite range DWBA codes PTOLEMY and TWOFNR. It was observed that shape and magnitude of the cross section data at 300, 280 keV energies can be fitted well but the shape of 250, 220 and 200 keV data cannot be fitted. However 250, 220 and 200 keV data shape can be fitted by changing the optical model parameters at each energy. This indicates a very strong energy dependence of the optical model parameters data of the entrance channel over such a small energy range which is not observed in the presently available elastic scattering data of the entrance channel.

  18. Results of total cross section measurements for 197Au in the neutron energy region from 4 to 108 keV at GELINA

    NASA Astrophysics Data System (ADS)

    Sirakov, I.; Becker, B.; Capote, R.; Dupont, E.; Kopecky, S.; Massimi, C.; Schillebeeckx, P.

    2013-11-01

    Transmission measurements have been performed to determine the total cross section for neutron-induced reactions with 197Au in the energy region from 4keV to 108keV. The experiments were carried out at a 50m measurement station of the time-of-flight facility GELINA using a 6Li glass scintillator. The average total cross section as a function of neutron energy was derived after correcting the observed average transmission for cross section fluctuations due to resonance structures. The results have been compared with literature data and with the total cross section resulting from a dispersive coupled-channel optical model potential. The neutron strength function for s -wave neutrons and an orbital-independent scattering radius, together with their covariance matrix, have been derived in the neutron energy region between 4keV and 108keV through a parameterization of the total cross section based on a nuclear reaction theory.

  19. CO2 laser photoacoustic measurements of ethanol absorption coefficients within infrared region of 9.2-10.8 μm

    NASA Astrophysics Data System (ADS)

    Ivascu, I. R.; Matei, C. E.; Patachia, M.; Bratu, A. M.; Dumitras, D. C.

    2016-06-01

    Absorption coefficients of the ethanol vapors at atmospheric pressure and room temperature were measured by photoacoustic technique using a cw, line-tunable, frequency-stabilized CO2 laser as radiation source. The spectrum of the employed CO2 laser includes 54 lines with wavelengths in the infrared region of 9.2-10.8 μm and power levels up to 4.7 W. Measurements revealed a predominant absorption for ethanol within 9.4 μm band of the CO2 laser spectrum, where the highest values of the absorption coefficients were recorded: 3.68 cm- 1 atm- 1 at 9R(20) line and 3.65 cm- 1 atm- 1 at 9R(22) line. The estimated detection range covers six orders of magnitude, from a minimum of 30 ppbV to a maximum of 4% concentration of ethanol in nitrogen, which proves the suitability of the photoacoustic technique for accurate measurements of the ethanol concentration in various applications.

  20. CO2 laser photoacoustic measurements of ethanol absorption coefficients within infrared region of 9.2-10.8 μm.

    PubMed

    Ivascu, I R; Matei, C E; Patachia, M; Bratu, A M; Dumitras, D C

    2016-06-15

    Absorption coefficients of the ethanol vapors at atmospheric pressure and room temperature were measured by photoacoustic technique using a cw, line-tunable, frequency-stabilized CO2 laser as radiation source. The spectrum of the employed CO2 laser includes 54 lines with wavelengths in the infrared region of 9.2-10.8μm and power levels up to 4.7W. Measurements revealed a predominant absorption for ethanol within 9.4μm band of the CO2 laser spectrum, where the highest values of the absorption coefficients were recorded: 3.68cm(-1)atm(-1) at 9R(20) line and 3.65cm(-1)atm(-1) at 9R(22) line. The estimated detection range covers six orders of magnitude, from a minimum of 30ppbV to a maximum of 4% concentration of ethanol in nitrogen, which proves the suitability of the photoacoustic technique for accurate measurements of the ethanol concentration in various applications.

  1. Is there evidence for a 17 keV neutrino in the 35S β spectrum? The case of Ohi et al.

    NASA Astrophysics Data System (ADS)

    Simpson, J. J.

    1986-06-01

    It is shown that there is a threshold 17 keV below the end point of the β spectrum of 35S in the published work of Ohio et al. The distortion of the Kurie plot is consistent with that seen in the 3H β spectrum, strengthening the earlier suggestion that the distortion is due to the emission of a neutrino of mass 17 keV.

  2. Wide band data collection system

    NASA Technical Reports Server (NTRS)

    Turkiewicz, J. M.

    1988-01-01

    The Incorporated Research Institutes for Seismology (IRIS) approached NASA Headquarters in 1986 about the need to collect data daily from seismic stations around the world as part of the Earth Observing System (EOS) mission. A typical IRIS Seismic Station generates 16 Megabytes of data per day when there is seismic activity. The Preliminary Design Parameters of the Wide Band Data Collection System are summarized.

  3. Broad-band beam buncher

    DOEpatents

    Goldberg, David A.; Flood, William S.; Arthur, Allan A.; Voelker, Ferdinand

    1986-01-01

    A broad-band beam buncher is disclosed, comprising an evacuated housing, an electron gun therein for producing an electron beam, a buncher cavity having entrance and exit openings through which the beam is directed, grids across such openings, a source providing a positive DC voltage between the cavity and the electron gun, a drift tube through which the electron beam travels in passing through such cavity, grids across the ends of such drift tube, gaps being provided between the drift tube grids and the entrance and exit grids, a modulator for supplying an ultrahigh frequency modulating signal to the drift tube for producing velocity modulation of the electrons in the beam, a drift space in the housing through which the velocity modulated electron beam travels and in which the beam is bunched, and a discharge opening from such drift tube and having a grid across such opening through which the bunched electron beam is discharged into an accelerator or the like. The buncher cavity and the drift tube may be arranged to constitute an extension of a coaxial transmission line which is employed to deliver the modulating signal from a signal source. The extended transmission line may be terminated in its characteristic impedance to afford a broad-band response and the device as a whole designed to effect broad-band beam coupling, so as to minimize variations of the output across the response band.

  4. ALMA Band 5 Science Verification

    NASA Astrophysics Data System (ADS)

    Humphreys, L.; Biggs, A.; Immer, K.; Laing, R.; Liu, H. B.; Marconi, G.; Mroczkowski, T.; Testi, L.; Yagoubov, P.

    2017-03-01

    ALMA Band 5 (163–211 GHz) was recently commissioned and Science Verification (SV) observations were obtained in the latter half of 2016. A primary scientific focus of this band is the H2O line at 183.3 GHz, which can be observed around 15% of the time when the precipitable water vapour is sufficiently low (< 0.5 mm). Many more lines are covered in Band 5 and can be observed for over 70% of the time on Chajnantor, requiring similar restrictions to those for ALMA Bands 4 and 6. Examples include the H218O line at 203 GHz, some of the bright (3–2) lines of singly and doubly deuterated forms of formaldehyde, the (2–1) lines of HCO+, HCN, HNC, N2H+ and several of their isotopologues. A young star-forming region near the centre of the Milky Way, an evolved star also in our Galaxy, and a nearby ultraluminous infrared galaxy (ULIRG) were observed as part of the SV process and the data are briefly described. The reduced data, along with imaged data products, are now public and demonstrate the power of ALMA for high-resolution studies of H2O and other molecules in a variety of astronomical targets.

  5. Curriculum Guide for Beginners Band.

    ERIC Educational Resources Information Center

    Bazar, W. Gayre

    This curriculum guide for beginners band is the product of a team of teachers, administrators, and supervisory personnel. The prime objectives in the beginning instrument class is the development of correct playing habits, with emphasis on posture, holding position, embouchure, breathing, tonguing, good tone production and intonation. Subjects…

  6. Resistive band for turbomachine blade

    DOEpatents

    Roberts, Herbert Chidsey; Taxacher, Glenn Curtis

    2015-08-25

    A turbomachine system includes a rotor that defines a longitudinal axis of the turbomachine system. A first blade is coupled to the rotor, and the first blade has first and second laminated plies. A first band is coupled to the first blade and is configured to resist separation of the first and second laminated plies.

  7. K-Band Latching Switches

    NASA Technical Reports Server (NTRS)

    Piotrowski, W. S.; Raue, J. E.

    1984-01-01

    Design, development, and tests are described for two single-pole-double-throw latching waveguide ferrite switches: a K-band switch in WR-42 waveguide and a Ka-band switch in WR-28 waveguide. Both switches have structurally simple junctions, mechanically interlocked without the use of bonding materials; they are impervious to the effects of thermal, shock, and vibration stresses. Ferrite material for the Ka-band switch with a proper combination of magnetic and dielectric properties was available and resulted in excellent low loss, wideband performance. The high power handling requirement of the K-band switch limited the choice of ferrite to nickel-zinc compositions with adequate magnetic properties, but with too low relative dielectric constant. The relative dielectric constant determines the junction dimensions for given frequency responses. In this case the too low value unavoidably leads to a larger than optimum junction volume, increasing the insertion loss and restricting the operating bandwidth. Efforts to overcome the materials-related difficulties through the design of a composite junction with increased effective dielectric properties efforts to modify the relative dielectric constant of nickel-zinc ferrite are examined.

  8. K-band latching switches

    NASA Astrophysics Data System (ADS)

    Piotrowski, W. S.; Raue, J. E.

    1984-05-01

    Design, development, and tests are described for two single-pole-double-throw latching waveguide ferrite switches: a K-band switch in WR-42 waveguide and a Ka-band switch in WR-28 waveguide. Both switches have structurally simple junctions, mechanically interlocked without the use of bonding materials; they are impervious to the effects of thermal, shock, and vibration stresses. Ferrite material for the Ka-band switch with a proper combination of magnetic and dielectric properties was available and resulted in excellent low loss, wideband performance. The high power handling requirement of the K-band switch limited the choice of ferrite to nickel-zinc compositions with adequate magnetic properties, but with too low relative dielectric constant. The relative dielectric constant determines the junction dimensions for given frequency responses. In this case the too low value unavoidably leads to a larger than optimum junction volume, increasing the insertion loss and restricting the operating bandwidth. Efforts to overcome the materials-related difficulties through the design of a composite junction with increased effective dielectric properties efforts to modify the relative dielectric constant of nickel-zinc ferrite are examined.

  9. Get Your Band up and Marching

    ERIC Educational Resources Information Center

    Robinson, Matt

    2008-01-01

    The rewards of band membership may be clear, but in tough economic times, with schools, teachers, and students facing new obligations around every corner, it is not always easy to keep a band on track. And so a question arises, one that has relevance both for teachers who want to start a band program from scratch and for veteran band directors…

  10. 47 CFR 90.531 - Band plan.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Band plan. 90.531 Section 90.531...-805 MHz Bands § 90.531 Band plan. This section sets forth the band plan for the 763-775 MHz and 793... and portables subject to Commission-approved regional planning committee regional plans....

  11. 47 CFR 90.531 - Band plan.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Band plan. 90.531 Section 90.531...-805 MHz Bands § 90.531 Band plan. This section sets forth the band plan for the 763-775 MHz and 793... and portables subject to Commission-approved regional planning committee regional plans....

  12. 47 CFR 90.531 - Band plan.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Band plan. 90.531 Section 90.531...-805 MHz Bands § 90.531 Band plan. This section sets forth the band plan for the 758-775 MHz and 788... and portables subject to Commission-approved regional planning committee regional plans....

  13. 47 CFR 90.531 - Band plan.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Band plan. 90.531 Section 90.531...-805 MHz Bands § 90.531 Band plan. This section sets forth the band plan for the 758-775 MHz and 788... and portables subject to Commission-approved regional planning committee regional plans....

  14. 47 CFR 90.531 - Band plan.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Band plan. 90.531 Section 90.531...-805 MHz Bands § 90.531 Band plan. This section sets forth the band plan for the 763-775 MHz and 793... and portables subject to Commission-approved regional planning committee regional plans....

  15. Presence of neutrons in the low-level background environment estimated by the analysis of the 595.8 keV gamma peak

    NASA Astrophysics Data System (ADS)

    Anđelić, Brankica; Knežević, David; Jovančević, Nikola; Krmar, Miodrag; Petrović, Jovana; Toth, Arpad; Medić, Žarko; Hansman, Jan

    2017-04-01

    In order to explore possible improvements of the existing techniques developed to estimate the neutron fluence in low-background Ge-spectroscopy systems, gamma spectra were collected by a HPGe detector in the presence of the 252Cf spontaneous fission neutron source. The spectra were taken with and without a Cd envelope on the detector dipstick, with different thicknesses of plastic used to slow down neutrons. We have analyzed the complex 595.8 keV gamma peak, as well as several more gamma peaks following the neutron interactions in the detector itself and surroundings materials. The investigation shows that some changes of the initial neutron spectra can be monitored by the analysis of the 595.8 keV gamma peak. We have found good agreement in the intensity changes between the long-tail component of the 595.8 keV and the 691 keV gamma peak (72Ge(n,n‧)72Ge reaction), usually used for the estimation of the fast neutron fluence. Results also suggest that the thermal neutrons can have a stronger influence on creation of the Gaussian-like part of 595.8 keV peak, than on the 139 keV one following 74Ge(n,γ)75mGe reaction and used in the standard methods (Škoro et al., 1992) [8] for determination of the thermal neutron flux.

  16. First direct high-precision energy determination for the 8.4 and 20.7 keV nuclear transitions in 169Tm

    NASA Astrophysics Data System (ADS)

    Inoyatov, A. Kh.; Kovalík, A.; Filosofov, D. V.; Ryšavý, M.; Perevoshchikov, L. L.; Gurov, Yu. B.

    2015-06-01

    Energies of 8410.1 ± 0.4, 20743.9 ± 0.3, and 63121.6 ± 1.2 eV were determined for the 8.4 keV M1 + E2, 20.7 keV M1 + E2, and 63.1 keV E1 nuclear transitions in 169Tm (generated in the EC decay of 169Yb, respectively, by means of the internal conversion electron spectroscopy. The 169Yb sources used were prepared by vacuum evaporation deposition on polycrystalline carbon and platinum foils as well as by ion implantation at 30keV into a polycrystalline aluminum foil. The relevant conversion electron spectra were measured by a high-resolution combined electrostatic electron spectrometer at 7 eV instrumental resoluition. Values of 0.0326(14) and 0.0259(17) were derived from our experimental data for the E2 admixture parameter |δ ( E2/ M1)| for the 8.4 and 20.7 keV transitions, respectively. A possible effect of nuclear structure on multipolarity of the 20.7 keV transition was also investigated.

  17. Understanding Bright 13 keV Kr K-shell X-ray Sources at the NIF

    NASA Astrophysics Data System (ADS)

    May, M. J.; Colvin, J. D.; Kemp, G. E.; Fournier, K. B.; Scott, H.; Patel, M.; Barrios, Widmann; Widmann, K.

    2015-11-01

    High x-ray conversion efficiency (CE) K-shell Kr sources are being investigated for High Energy Density experiments. These sources are 4.1 mm in diameter 4.4 mm tall hollow epoxy tubes having a 40 μm thick wall holding either 1.2 or 1.5 atm of Kr gas. The CE of K-shell Kr is dependent upon the peak electron temperature in the radiating plasma. In the NIF experiments, the available energy heats the source to Te = 6-7 keV, well below the temperature of Te ~25 keV needed to optimize the Kr CE. The CE is a steep function of the peak electron temperature. A spatially averaged electron temperature can be estimated from measured He(α) and Ly(α) line ratios. Some disagreement has been observed in the simulated and measured line ratios for some of these K-shell sources. Disagreements have been observed between the simulated and measured line ratios for some of these K-shell sources. To help understand this issue, Kr gas pipes have been shot with 3 ω light at ?750 kJ at ~210, ~140 TW and ~120 TW power levels with 3.7, 5.2 and 6.7 ns pulses, respectively. The power and pulse length scaling of the measured CE and K-shell line ratios and their comparison to simulations will be discussed. This work was performed under the auspic

  18. ENHANCEMENT OF THE 6.4 keV LINE IN THE INNER GALACTIC RIDGE: PROTON-INDUCED FLUORESCENCE?

    SciTech Connect

    Nobukawa, K. K.; Nobukawa, M.; Tsuru, T. G.; Tanaka, T.; Koyama, K.; Uchiyama, H.; Torii, K.; Fukui, Y.; Chernyshov, D. O.; Dogiel, V. A.

    2015-07-01

    A common idea for the origin of the Galactic diffuse X-ray emission, particularly that of the iron lines from neutral and highly ionized atoms, is a superposition of many cataclysmic variables and coronally active binaries. In this scenario, the flux should symmetrically distribute between the east and west on the plane with respect to Sagittarius A* because the stellar mass distribution determined by infrared observations is nearly symmetric. This symmetry is confirmed for the highly ionized iron line as well as the continuum emission. However, a clear excess of the neutral iron line in the near east of the Galactic center compared to the near-west side is found. The flux distribution of the excess emission well correlates with the molecular column density. The X-ray spectrum of the excess emission is described by a power-law continuum plus a 6.4 keV line with a large equivalent width of ∼1.3 keV, which is hardly explained by the low-energy electron bombardment scenario. The longitudinal and latitudinal distribution of the excess emission disfavors the X-ray irradiation, either by Sagittarius A* or by nearby X-ray binaries. Then, the low-energy proton bombardment is the most probable origin, although the high-energy density ∼80 eV cm{sup −3} in 0.1–1000 MeV is required and there is no conventional proton source in the vicinity.

  19. Strength of the Ec.m.=1113 keV resonance in 20Ne(p,γ)21Na

    NASA Astrophysics Data System (ADS)

    Christian, G.; Hutcheon, D.; Akers, C.; Connolly, D.; Fallis, J.; Ruiz, C.

    2013-09-01

    The 20Ne(p,γ)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, ωγ=1.13±0.07 eV, has been misinterpreted as the strength in the center-of-mass frame when it is actually the strength in the laboratory frame. This has motivated a new measurement of the Ec.m.=1113 keV resonance strength in 20Ne(p,γ)21Na using the DRAGON recoil mass spectrometer. The DRAGON result, 0.972±0.11 eV, is in good agreement with the accepted value when both are calculated in the same frame of reference.

  20. The Physical Nature of the Sharp Spectral Feature at 7 keV Detected in 1H0707-495

    NASA Technical Reports Server (NTRS)

    Brandt, Niel

    2005-01-01

    XMM-Newton acquired data on the accepted target, 1H0707-495, on 2002 October 13 during revolution 0521. The observation was successful, with only about 5% data loss due to background flaring. We compared the data from this observation with earlier data taken on this Narrow-Line Seyfert 1 about two years before, performing interpretation studies in the context of the partial-covering model. Our second longer observation once again displays a sharp (< 200 eV) spectral drop above 7 keV. However, in comparison to the first observation, the edge depth and energy have changed significantly. In addition to changes in the edge parameters, the high-energy spectrum appears steeper. The changes in the high-energy spectrum can be adequately explained in terms of a partial-covering absorber out-flowing from the central region. The low-energy spectrum also shows significant long-term spectral variability, including (1) a substantial increase in the disk temperature, (2) detection of an approx. 0.9 keV emission feature, and (3) the presence of ionized absorption that was detected during the ASCA mission. The large increase in disk temperature, and the more modest rise in luminosity, can be understood if we consider a slim-disk model for 1H0707-495. In addition, the higher disk luminosity could be the driving force behind the outflow and the re-appearance of an ionized medium during the second XMM-Newton observation.

  1. Institut d'Astrophysique Spatiale (IAS) 0.1- to 15-keV Synchrotron Radiation Facility beam lines

    NASA Astrophysics Data System (ADS)

    Dhez, Pierre; Jourdain, Erick; Hainaut, Olivier; Hochedez, Jean-Francois E.; Labeque, Alain; Salvetat, Philippe; Song, Xue Yan

    1997-10-01

    Two beam lines have been built at the Institute d'Astrophysique Spatiale (IAS) d'Orsay to perform absolute calibration of the EPIC (European photon imaging camera). EPIC consists of three x-ray charge coupled device (CCD) cameras having imaging and spectroscopic performances set at the Wolter telescope focal planes on board the x-ray multi mirror mission (XMM) planned to be launched by ESA in August 1999. To cover the desired 0.1 - 15 keV range a dedicated beam line has been built on each synchrotron sources of the Laboratoire pour l'Utilisation du Rayonnement Synchrotron (LURE): SACO (0.8 GeV) and DCI (1.5 GeV). Both beam lines are merging in a clean 23 m(superscript 3) vacuum tank containing the camera to calibrate. (1) The SACO windowless beam line is equipped with a grating monochromator. Four plane VLS gratings are used to cover the low energy range (0.1 - 1.2 keV). A triple grazing incidence mirror system set in front of the entrance slit removes the overlapping orders. (2) The high energy beam line on DCI has a 50 micrometer beryllium window and a double flat crystals monochromator equipped with four different crystal pairs. A double grazing incidence mirror system set close to the source absorbs the high energy photon spectra. CCD calibrations will be performed during 1997 second semester and years 1998.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

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

    NASA Astrophysics Data System (ADS)

    Cazaux, J.

    2012-10-01

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

  4. Interactions of neutral and singly charged keV atomic particles with gas-phase adenine molecules

    SciTech Connect

    Alvarado, Fresia; Bari, Sadia; Hoekstra, Ronnie; Schlathoelter, Thomas

    2007-07-21

    KeV atomic particles traversing biological matter are subject to charge exchange and screening effects which dynamically change this particle's effective charge. The understanding of the collision cascade along the track thus requires a detailed knowledge of the interaction dynamics of radiobiologically relevant molecules, such as DNA building blocks or water, not only with ionic but also with neutral species. We have studied collisions of keV H{sup +}, He{sup +}, and C{sup +} ions and H{sup 0}, He{sup 0}, and C{sup 0} atoms with the DNA base adenine by means of high resolution time-of-flight spectrometry. For H{sup 0} and H{sup +} we find qualitatively very similar fragmentation patterns, while for carbon, strong differences are observed when comparing C{sup 0} and C{sup +} impact. For collisions with He{sup 0} and He{sup +} projectiles, a pronounced delayed fragmentation channel is observed, which has not been reported before.

  5. Interaction of 18-keV O{sup -} ions with Al{sub 2}O{sub 3} nanocapillaries

    SciTech Connect

    Sun Guangzhi; Chen Ximeng; Wang Jun; Chen Yifeng; Xu Junkui; Zhou Chunlin; Shao Jianxiong; Cui Ying; Ding Baowei; Yin Yongzhi; Wang Xinan; Lou Fengjun; Lv Xueyang; Qiu Xiyu; Jia Juanjuan; Chen Lin; Xi Fayuan; Chen Zichun; Li Lanting; Liu Zhaoyuan

    2009-05-15

    The transmission of 18-keV O{sup -} ions through Al{sub 2}O{sub 3} nanocapillaries with 50 nm in diameter and 12 {mu}m in length is studied in this work. By measuring angular distribution of transmitted particles when capillaries were tilted with respect to incident ion beam, two peaks were observed. It is distinguished that one of them is composed by direct transmitted ions and another one is composed by scattered ions. A phenomenon referred to as guiding effect, as found for highly charged ions and low-energy electrons, was observed. When negative ions (18-keV O{sup -}) are transmitted through nanocapillaries, most of them were ionized to neutral atoms and even positive ions. The intensity of transmitted particles (O{sup -}, O{sup 0}, and O{sup +}) decreased when the tilt angle increased. In transmitted particles, the fraction of O{sup -} declined but that of O{sup 0} and O{sup +} ions grew when the tilt angle grew. Both elastic collision and electrostatic scattering were found in scattered ions.

  6. Enhancement of the 6.4 keV Line in the Inner Galactic Ridge: Proton-induced Fluorescence?

    NASA Astrophysics Data System (ADS)

    Nobukawa, K. K.; Nobukawa, M.; Uchiyama, H.; Tsuru, T. G.; Torii, K.; Tanaka, T.; Chernyshov, D. O.; Fukui, Y.; Dogiel, V. A.; Koyama, K.

    2015-07-01

    A common idea for the origin of the Galactic diffuse X-ray emission, particularly that of the iron lines from neutral and highly ionized atoms, is a superposition of many cataclysmic variables and coronally active binaries. In this scenario, the flux should symmetrically distribute between the east and west on the plane with respect to Sagittarius A* because the stellar mass distribution determined by infrared observations is nearly symmetric. This symmetry is confirmed for the highly ionized iron line as well as the continuum emission. However, a clear excess of the neutral iron line in the near east of the Galactic center compared to the near-west side is found. The flux distribution of the excess emission well correlates with the molecular column density. The X-ray spectrum of the excess emission is described by a power-law continuum plus a 6.4 keV line with a large equivalent width of ˜1.3 keV, which is hardly explained by the low-energy electron bombardment scenario. The longitudinal and latitudinal distribution of the excess emission disfavors the X-ray irradiation, either by Sagittarius A* or by nearby X-ray binaries. Then, the low-energy proton bombardment is the most probable origin, although the high-energy density ˜80 eV cm-3 in 0.1-1000 MeV is required and there is no conventional proton source in the vicinity.

  7. Ruling out the light weakly interacting massive particle explanation of the Galactic 511 keV line

    NASA Astrophysics Data System (ADS)

    Wilkinson, Ryan J.; Vincent, Aaron C.; BÅ`hm, Céline; McCabe, Christopher

    2016-11-01

    Over the past few decades, an anomalous 511 keV gamma-ray line has been observed from the center of the Milky Way. Dark matter (DM) in the form of light (≲10 MeV ) weakly interacting massive particles (WIMPs) annihilating into electron-positron pairs has been one of the leading hypotheses of the observed emission. Given the small required cross section, ⟨σ v ⟩˜1 0-30 cm3 s-1 , a further coupling to lighter particles is required to produce the correct relic density. Here, we derive constraints from the Planck satellite on light WIMPs that were in equilibrium with either the neutrino or electron sector in the early universe. For the neutrino sector, we obtain a lower bound on the WIMP mass of 4 MeV for a real scalar and 10 MeV for a Dirac fermion DM particle, at 95% C.L. For the electron sector, we find even stronger bounds of 7 and 11 MeV, respectively. Using these results, we show that, in the absence of additional ingredients such as dark radiation, the light thermally produced WIMP explanation of the 511 keV excess is strongly disfavored by the latest cosmological data. This suggests an unknown astrophysical or more exotic DM source of the signal.

  8. High Resolution, 20-100 keV X-ray Backlighters for ICF and HEDS Experiments

    NASA Astrophysics Data System (ADS)

    Park, Hye-Sook; Koch, J. A.; Landen, O. L.; Phillips, T. W.; Schmid, G. J.

    2002-11-01

    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.

  9. Measurement of the Erc .m .=259 keV resonance in the 14N(p ,γ )15O reaction

    NASA Astrophysics Data System (ADS)

    Daigle, S.; Kelly, K. J.; Champagne, A. E.; Buckner, M. Q.; Iliadis, C.; Howard, C.

    2016-08-01

    The 14N(p ,γ )15O reaction regulates the power generated by the CN cycle and thus impacts the structure and evolution of every star at some point in its life. The lowest positive-energy resonance in this reaction is located at Erc .m .=259 keV, too high in energy to strongly influence quiescent stellar burning. However, the strength of this resonance is used as a cross-section normalization for lower-energy measurements of this reaction. We report on new measurements of the energy, strength, and γ -ray branching ratios for the 259-keV resonance, using different detection and data-analysis schemes. We have also reevaluated previous results, where possible. Our new recommended strength of ω γ =12.6 (3 ) meV is in agreement with the previous value of 13.1(6) meV, but is more precise and thus provides a more reliable normalization for low-energy (p ,γ ) measurements.

  10. Electric Fields Associated with Deep Injections of 10s to 100s keV Electrons in the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Califf, S.; Li, X.; Jaynes, A. N.; Zhao, H.; Malaspina, D.

    2015-12-01

    Recent observations by HOPE and MagEIS onboard the Van Allen Probes show frequent penetration of 10s to 100s keV electrons through the slot region and into the inner belt, resulting in an abundant electron population below L=3. The conventional picture is that the source populations of these 10s to 100s keV electrons originate in the plasma sheet and are injected (along with plasma sheet ions) into the inner magnetosphere either through enhancements in the large-scale convection electric field and/or through earthward propagating dipolarization fronts associated with substorms. In such cases the inward radial limit of the injections should coincide with the plasmapause. However, these electron injections often extend inside the plasmasphere, are observed far earthward of the typically accepted "flow-braking" region for dipolarization fronts, and occur at much lower L shells than injections of ions with similar energies. We investigate the electric fields associated with these deep electron injections using data from the Van Allen Probes and THEMIS in order to shed light on the underlying mechanisms that allow them to penetrate so far into the inner magnetosphere.

  11. Making Linked, Wound-Filament Bands

    NASA Technical Reports Server (NTRS)

    Bamford, Robert M.; Stephens, James B.

    1987-01-01

    Chains produced by use of rotating mandrel. Mandrel and locating and driving disks assembled around first band. Mandrel and band then mounted in respective positions on filament-winding machine. Second band linked to first by winding filament around first band on rotating mandrel. Short chains made this way have variety of uses; example, thermal isolators, each consisting of two linked bands of insulating material, used to support two separated insulating sheilds surrounding container of liquid helium.

  12. Fermi Observations of GRB 090510: A Short-Hard Gamma-ray Burst with an Additional, Hard Power-law Component from 10 keV TO GeV Energies

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Asano, K.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bhat, P. N.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Briggs, M. S.; Brigida, M.; Bruel, P.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Connaughton, V.; Conrad, J.; Dermer, C. D.; de Palma, F.; Dingus, B. L.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Finke, J.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Granot, J.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; Kouveliotou, C.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; McGlynn, S.; Meegan, C.; Mészáros, P.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Preece, R.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Ritz, S.; Rodriguez, A. Y.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sander, A.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Stecker, F. W.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Toma, K.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Uehara, T.; Usher, T. L.; van der Horst, A. J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; von Kienlin, A.; Waite, A. P.; Wang, P.; Wilson-Hodge, C.; Winer, B. L.; Wu, X. F.; Yamazaki, R.; Yang, Z.; Ylinen, T.; Ziegler, M.

    2010-06-01

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

  13. Diffuse Interstellar Bands in Emission

    NASA Astrophysics Data System (ADS)

    Williams, T. B.; Sarre, P.; Marshall, C. C. M.; Spekkens, K.; de Naray, R. Kuzio

    Recent Fabry-Pérot observations towards the galaxy NGC 1325 with the Southern African Large Telescope (SALT) led to the serendipitous discovery of an emission feature centered at 661.3 nm arising from material in the interstellar medium (ISM) of our Galaxy; this emission feature lies at the wavelength of one of the sharper and stronger diffuse bands normally seen in absorption. The flux of the feature is 4.2 +/- 0.5 × 10-18 es-1 cm-2 arcsec-2. It appears that this is the first observation of emission from a diffuse band carrier in the ISM, excited in this case by the interstellar radiation field. We present the discovery spectra and describe follow-up measurements proposed for SALT.

  14. High-spin band structure of 192Tl

    NASA Astrophysics Data System (ADS)

    Kreiner, A. J.; Filevich, A.; García Bermúdez, G.; Mariscotti, M. A. J.; Baktash, C.; der Mateosian, E.; Thieberger, P.

    1980-03-01

    High-spin states in 192Tl, excited through the 181Ta(18O,7n) and 181Ta(16O,5n) reactions, were studied using in-beam γ-ray spectroscopic techniques. Excitation functions, activity spectra, γ-ray angular distributions, and multidimensional coincidences were measured. The strongly Coríolis-distorted π~h92×ν~i132 two-quasiparticle band already known in the heavier 194,196,198Tl isotopes has also been found in this case based on an Iπ=8- isomeric state at 250.6 keV above the known long-lived 7+ level. Trends already noted in the other Tl isotopes and also predicted by two-quasiparticle plus-rotor model calculations are confirmed thus reinforcing such a theoretical description. NUCLEAR REACTIONS 181Ta(18O,xnγ), E=105-125 MeV; 181Ta(16O,xnγ), E=95-105 MeV; measured Eγ, Iγ, σ(E, Eγ, θγ), γ-γ coin.; 192Tl levels deduced, J, π, T12. Natural target. Ge(Li) detectors.

  15. Global Kinetic Modeling of Banded Electron Structures in the Plasmasphere

    NASA Technical Reports Server (NTRS)

    Liemohn, M. W.; Khazanov, G. V.

    1997-01-01

    Significant fluxes of 10 eV to 30 keV electrons have been detected in the plasmasphere, appearing as banded structures in energy with broad spatial extents and slowly evolving over several days. It is thought that these populations are decaying plasma sheet electrons injected into the corotating region of near-Earth space. This capture can occur when the convective electric field drops rapidly and the Alfven boundary suddenly outward, trapping the inner edge of the plasma sheet along closed drift paths. Our bounce-averaged kinetic model of superthermal electron transport is able to simulate this capture and the subsequent drift, diffusion, and decay of the plasma cloud. Results of this simulation will be shown and discussed, from the initial injection during the elevated convection to the final loss of the particles. It is thought that not only Coulomb collisions but also wave-particle interactions play a significant role in altering the plasma cloud. Quasilinear diffusion is currently being incorporated into the model and the importance of this mechanism will be examined. Also, the high anisotropy of the trapped population could be unstable and generate plasma waves. These and other processes will be investigated to determine the final fate of the cloud and to quantify where, how, and when the energy of the plasma cloud is deposited. Comparisons with CRRES observations of these events are shown to verify the model and explain the data.

  16. Ka-Band Mobile Experiments

    NASA Technical Reports Server (NTRS)

    Abbe, B. S.; Jedrey, T. C.; Agan, M. J.

    1994-01-01

    The National Aeronautics and Space Administration (NASA) through the Jet Propulsion Laboratory (JPL) has been involved in the development of mobile satcom technologies for more that ten years. The initial work was performed at L-band (1.5-1.6 GHz), and included system studies and analysis, subsystem and full terminal development, and culminated in numerous field experiments and demonstrations under the Mobile Satellite Experiments (MSAT-X) program.

  17. ASTRONOMY: Researchers Get Spectrum Bands.

    PubMed

    Taubes, G

    2000-06-23

    Radio astronomers have been in danger of losing a precious band of the electromagnetic spectrum--the millimeter wavelengths, which promise insight into subjects as diverse as the origins of life and the birth of stars--to the burgeoning telecommunications industry, as millimeter wavelengths also look promising for transmitting high-bandwidth wireless information over relatively short distances. Earlier this month, however, astronomers won an international agreement that guarantees critical wavelengths safe for research.

  18. Observation of 'Band' Structures in Spacecraft Observations of Inner Magnetosphere Plasma Ions

    NASA Astrophysics Data System (ADS)

    Mohan, Kirthika; Fazakerley, Andrew; Grimald, Sandrine; Dandouras, Iannis; Owen, Chris

    2014-05-01

    In previous studies, several authors have reported inner magnetosphere observations of proton distributions confined to narrow energy bands in the range of 1-25 keV (Smith and Hoffman (1974), etc). These structures have been described as "nose structures", with reference to their appearance in energy-time spectrograms and are also known as "bands" if they occur for extended periods of time. Statistical surveys (Buzulukova et al. (2003); Vallat et al. (2007)) of these features in Interball and Cluster data highlight the presence of single nose in nightside sectors and multi-nose strutures in the dayside sectors. We examine Double-Star TC1 HIA data mainly recorded in the equatorial plane of the inner magnetosphere (L<15) to see how observations of "multi-banded structures" compare to the observations from more inclined orbits of Cluster and Interball. We investigate the properties of these multi-banded structures and carry out a statistical survey analysing them as a function of geomagnetic activity. This is a comparison study to a similar study conducted using DoubleStar TC-1 PEACE electron data.

  19. S-Band propagation measurements

    NASA Technical Reports Server (NTRS)

    Briskman, Robert D.

    1994-01-01

    A geosynchronous satellite system capable of providing many channels of digital audio radio service (DARS) to mobile platforms within the contiguous United States using S-band radio frequencies is being implemented. The system is designed uniquely to mitigate both multipath fading and outages from physical blockage in the transmission path by use of satellite spatial diversity in combination with radio frequency and time diversity. The system also employs a satellite orbital geometry wherein all mobile platforms in the contiguous United States have elevation angles greater than 20 deg to both of the diversity satellites. Since implementation of the satellite system will require three years, an emulation has been performed using terrestrial facilities in order to allow evaluation of DARS capabilities in advance of satellite system operations. The major objective of the emulation was to prove the feasibility of broadcasting from satellites 30 channels of CD quality programming using S-band frequencies to an automobile equipped with a small disk antenna and to obtain quantitative performance data on S-band propagation in a satellite spatial diversity system.

  20. Flat bands in topological media

    NASA Astrophysics Data System (ADS)

    Heikkilä, T. T.; Kopnin, N. B.; Volovik, G. E.

    2011-10-01

    Topological media are systems whose properties are protected by topology and thus are robust to deformations of the system. In topological insulators and superconductors the bulk-surface and bulk-vortex correspondence gives rise to the gapless Weyl, Dirac or Majorana fermions on the surface of the system and inside vortex cores. Here we show that in gapless topological media, the bulk-surface and bulk-vortex correspondence is more effective: it produces topologically protected gapless fermions without dispersion—the fiat band. Fermion zero modes forming the flat band are localized on the surface of topological media with protected nodal lines [A. P. Schnyder and S. Ryu, Phys. Rev. B 84, 060504(R) (2011); T. T. Heikkil G. E. Volovik, JETP Lett. 93, 59 (2011)] and in the vortex core in systems with topologically protected Fermi points (Weyl points) [G. E. Volovik, JETP Lett. 93, 66 (2011)]. Flat band has an extremely singular density of states, and we show that this property may give rise in particular to surface superconductivity which could exist even at room temperature.

  1. Variation in the calibrated response of LiF, Al2O3, and silicon dosimeters when used for in-phantom measurements of source photons with energies between 30 KeV AND 300 KeV.

    PubMed

    Poudel, Sashi; Currier, Blake; Medich, David C

    2015-04-01

    The MCNP5 radiation transport code was used to quantify changes in the absorbed dose conversion factor for LiF, Al2O3, and silicon-based electronic dosimeters calibrated in-air using standard techniques and summarily used to measure absorbed dose to water when placed in a water phantom. A mono-energetic photon source was modeled at energies between 30 keV and 300 keV for a point-source placed at the center of a water phantom, a point-source placed at the surface of the phantom, and for a 10-cm radial field geometry. Dosimetric calculations were obtained for water, LiF, Al2O3, and silicon at depths of 0.2 cm and 10 cm from the source. These results were achieved using the MCNP5 *FMESH photon energy-fluence tally, which was coupled with the appropriate DE/DF card for each dosimetric material studied to convert energy-fluence into the absorbed dose. The dosimeter's absorbed dose conversion factor was calculated as a ratio of the absorbed dose to water to that of the dosimeter measured at a specified phantom depth. The dosimeter's calibration value also was obtained. Based on these results, the absorbed dose conversion factor for a LiF dosimeter was found to deviate from its calibration value by up to 9%, an Al2O3 dosimeter by 43%, and a silicon dosimeter by 61%. These data therefore can be used to obtain LiF, Al2O3, and silicon dosimeter correction factors for mono-energetic and poly-energetic sources at measurement depths up to 10 cm under the irradiation geometries investigated herein.

  2. Earth observations during Space Shuttle flight STS-35 - Columbia's Mission to Planet Earth, December 2-10, 1990

    NASA Technical Reports Server (NTRS)

    Lulla, Kamlesh P.; Evans, Cynthia A.; Helfert, Michael R.; Brand, Vance D.; Gardner, Guy S.; Lounge, John M.; Hoffman, Jeffery A.; Parker, Robert A.; Durrance, Samuel T.; Parise, Ronald A.

    1991-01-01

    Some of the most significant earth-viewing imagery obtained during Space Shuttle Columbia's flight STS-35, December 2-10, 1990, is reviewed with emphasis on observations of the Southern Hemisphere. In particular, attention is given to environmental observations in areas of Madagascar, Brazil, and Persian Gulf; observation of land resources (Namibia, offshore Australia); and observations of ocean islands (Phillipines, Indonesia, and Reunion). Some of the photographs are included.

  3. Excitation of Meinel and the first negative band system at the collision of electrons and protons with the nitrogen molecule

    SciTech Connect

    Gochitashvili, Malkhaz R.; Lomsadze, Ramaz A.; Kezerashvili, Roman Ya.

    2010-08-15

    The absolute cross sections for the e-N{sub 2} and p-N{sub 2} collisions for the first negative B{sup 2{Sigma}}{sub u}{sup +}-X{sup 2{Sigma}}{sub g}{sup +} and Meinel A{sup 2{Pi}}{sub u}-X{sup 2{Sigma}}{sub g}{sup +} bands have been measured in the energy region of 400-1500 eV for electrons and 0.4-10 keV for protons, respectively. Measurements are performed in the visible spectral region of 400-800 nm by an optical spectroscopy method. The ratio of the cross sections of the Meinel band system to the cross section of the first negative band system (0,0) does not depend on the incident electron energy. The populations of vibrational levels corresponding to A{sup 2{Pi}}{sub u} states are consistent with the Franck-Condon principle. The ratios of the cross sections of (4,1) to (3,0) bands and (5,2) to (3,0) bands exhibit slight dependence on the proton energy. A theoretical estimation within the quasimolecular approximation provides a reasonable description of the total cross section for the first negative band.

  4. The formation of nanopores in metal materials after irradiation by beams of Ar+ with energy of 30 keV

    NASA Astrophysics Data System (ADS)

    Ivchenko, V. A.

    2017-01-01

    In this paper are the results of direction observations of nanopores in the subsurface volume of metals materials Pt and Pd(CuAg) using field-ion microscopy (FIM). Radiation of tip specimens was carried out with ions having an energy ∼ 25-30 keV in the fluency range of 1016 ‑ 1018 ions/cm2, the current density lying within 150– 340 µA/cm2. Nanopores have been observed immediately after removal of the first atomic layers from the irradiated surface. It was established that, the threshold for ion-implanted platinum corresponds to fluence F = 1017 ions/cm2. For Pd(CuAg) it was revealed that nanopores have been down to 80 nm deep with current density 340 µA/cm2. Their dimensions and volume fractions were determined. The obtained results can be used for prediction of radiation stability of materials based on fcc metals.

  5. Covariance data for{sup 232}Th in the resolved resonance region from 0 to 4 keV

    SciTech Connect

    Leal, L. C.; Derrien, H.; Arbanas, G.; Larson, N. M.; Wiarda, D.

    2006-07-01

    This paper reports on the generation and testing of the covariance matrix associated with the resonance parameter evaluation for {sup 232}Th up to 4 keV. [1] Covariance data are required to correctly assess uncertainties in design parameters in nuclear applications. The error estimation of calculated quantities relies on the nuclear data uncertainty information available in the basic nuclear data libraries, such as the US Evaluated Nuclear Data Library, ENDF/B. Uncertainty files in the ENDF/B library are obtained from analysis of experimental data and are stored as variance and covariance data. In this paper, we address the generation of covariance data in the resonance region via the computer code SAMMY, which is used in the evaluation of experimental data in the resolved and unresolved resonance energy regions. The resolved resonance parameter covariance matrix for {sup 232}Th, obtained using the retroactive approach, is also presented here. (authors)

  6. 20-100 keV K(alpha) X-Ray Source Generation by Short Pulse High Intensity Lasers

    SciTech Connect

    Park, H-S; Koch, J A; Landen, O L; Phillips, T W; Goldsack, T

    2003-08-22

    We are studying the feasibility of utilizing K{alpha} x-ray sources in the range of 20 to 100 keV as a backlighters for imaging various stages of implosions and high areal density planar samples driven by the NIF laser facility. The hard x-ray K{alpha} sources are created by relativistic electron plasma interactions in the target material after a radiation by short pulse high intensity lasers. In order to understand K{alpha} source characteristics such as production efficiency and brightness as a function of laser parameters, we have performed experiments using the 10 J, 100 fs JanUSP laser. We utilized single-photon counting spectroscopy and x-ray imaging diagnostics to characterize the K{alpha} source. We find that the K{alpha} conversion efficiency from the laser energy is {approx} 3 x 10{sup -4}.

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

    NASA Technical Reports Server (NTRS)

    Herrero, Federico A.; Smith, Mark F.

    1992-01-01

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

  8. Observation of the 22.5-keV resonance in (149)Sm by the nuclear lighthouse effect.

    PubMed

    Röhlsberger, R; Quast, K W; Toellner, T S; Lee, P L; Sturhahn, W; Alp, E E; Burkel, E

    2001-07-23

    We have observed coherent nuclear resonant scattering of synchrotron radiation at the 22.5-keV resonance of (149)Sm. 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 (149)Sm to be 22496(4) eV. Because of the angular deflection of the resonant photons, time spectra of coherent nuclear resonant scattering can be recorded as a function of a spatial coordinate. Time resolutions of a few 10 ps can be expected, which are beyond the limits of existing x-ray detection schemes.

  9. Analysis of photon emission from 50--350-keV proton impact on H2O

    NASA Astrophysics Data System (ADS)

    Goldman, Benjamin D.; Timpone, Stephanie A.; Monce, Michael N.; Mitchell, Laurel; Griffin, Brian

    2011-04-01

    We have measured photon emission cross sections from neutral fragments produced by collisions of 50-350 keV protons with H2O molecules. Balmer α-δ emissions from both the target and projectile were recorded. We also analyzed A2Σ+-X2Π (0,0) and (1,0) emission from the excited OH fragment produced during target dissociation. Trends in the cross sections revealed two key properties of the collision process: (1) The Bethe theory accurately describes target emission from both H and OH fragments and (2) the ratio of any two Balmer emission cross sections for both the target and projectile can be approximated by simple functions of the respective optical oscillator strengths. Finally, we provide the Bethe fit parameters necessary to calculate the target emission cross sections at all nonrelativistic impact energies.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  11. The electrical properties of 60 keV zinc ions implanted into semi-insulating gallium arsenide

    NASA Technical Reports Server (NTRS)

    Littlejohn, M. A.; Anikara, R.

    1972-01-01

    The electrical behavior of zinc ions implanted into chromium-doped semiinsulating gallium arsenide was investigated by measurements of the sheet resistivity and Hall effect. Room temperature implantations were performed using fluence values from 10 to the 12th to 10 to the 15th power/sq cm at 60 keV. The samples were annealed for 30 minutes in a nitrogen atmosphere up to 800 C in steps of 200 C and the effect of this annealing on the Hall effect and sheet resistivity was studied at room temperature using the Van der Pauw technique. The temperature dependence of sheet resistivity and mobility was measured from liquid nitrogen temperature to room temperature. Finally, a measurement of the implanted profile was obtained using a layer removal technique combined with the Hall effect and sheet resistivity measurements.

  12. Fully differential cross section for single ionization of helium by 1 KeV electrons in the eikonal approximation

    NASA Astrophysics Data System (ADS)

    Dey, R.; Roy, A. C.

    2009-07-01

    We report new results for fully 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 scattering and perpendicular planes. The present calculation is based on the eikonal approximation due to Glauber. Here we have also incorporated the effect of classical post collision interaction (PCI) in the Glauber approximation (GA). A comparison is made of the present calculation with the results of other theoretical methods and the recent experiment [M. Dürr, C. Dimopoulou, B. Najjari, A. Dorn, K. Bartschat, I. Bray, D.V. Fursa, Z. Chen, D.H. Madison, J. Ullrich, Phys. Rev. A 77 (2008) 032717]. The Glauber results are in good agreement with the experiment in the scattering plane, but strong discrepancies are observed in the plane perpendicular to it. The effect of PCI is not substantial in the present kinematics.

  13. Instrumentation for measurement of in-flight annihilations of 130 keV antiprotons on thin target foils

    NASA Astrophysics Data System (ADS)

    Todoroki, K.; Barna, D.; Hayano, R. S.; Aghai-Khozani, H.; Sótér, A.; Corradini, M.; Leali, M.; Lodi-Rizzini, E.; Mascagna, V.; Venturelli, L.; Prest, V.; Vallazza, L.; De Salvador, D.; Hori, M.

    2016-11-01

    We describe the instrumentation for an experiment to measure the cross sections of antiprotons with kinetic energies of 130±10 keV annihilating on carbon, palladium, and platinum target foils of sub-100 nm thicknesses. A 120 ns long pulsed beam containing 105 -106 antiprotons was allowed to traverse the foils, and the signal annihilations that resulted from this were isolated using a time-of-flight method. Backgrounds arose from Rutherford scattering of the antiprotons off the target foils, their annihilations in the target chamber walls, and π → μ → e decay of the charged pions that emerged from the annihilations. Some antiprotons slowed down and annihilated in the contamination on the target surfaces. This reduced the signal-to-background ratio of the measurement.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  15. Nuclear resonant forward scattering of synchrotron radiation from 121 Sb at 37.13 keV.

    SciTech Connect

    Wille, H. C.; Shvydko, Y. V.; Alp, E. E.; Ruter, H. D.; Leupold, O.; Sergueev, I.; Ruffer, R.; Barla, A.; Sanchez, J. P.; X-Ray Science Division; European Synchrotron Radiation Facility; Univ. of Hamburg; Hamburder Synchrotronstrahlungslabor

    2006-02-22

    We report on the observation of nuclear resonant forward scattering of synchrotron radiation from {sup 121}Sb nuclei. A temperature stabilized {alpha}Al{sub 2}O{sub 3} crystal Bragg backscattering high-resolution monochromator with a relative energy resolution of 2 x 10{sup -7} was introduced. As first spectroscopic applications the hyperfine parameters in Sb{sub 2}O{sub 3}, USb and DySb were determined. The energy of the nuclear transition in {sup 121}Sb was measured to be 37.1298(2)keV, 40 times more precisely than reported before. The results open the field of nuclear resonance spectroscopy on antimony compounds taking advantage of the outstanding features of 3rd-generation synchrotron sources. Nuclear resonance scattering on Sb compounds at these sources allows element-specific dynamical studies on thermoelectric materials as well as studies on magnetism in micro- and nanometer dimensional systems like spintronic devices.

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

    NASA Astrophysics Data System (ADS)

    Igarashi, A.; Gulyás, L.

    2017-02-01

    We have calculated the double and triple differential cross sections for electron ejection with energy of 14.6 eV in single ionization of H2 by 75 keV proton impact. A molecular version of the continuum distorted wave-eikonal initial state approach is applied, where the interaction between the projectile and the residual molecular ion is considered more properly than in previous applications of the method. For triple differential cross sections, the present results are in better agreement with the experimental data than those of other descriptions when large momentum transfer values are considered. For double differential cross sections the experimental data are reproduced quite well for both coherent and incoherent proton beams.

  17. Surface wet-ability modification of thin PECVD silicon nitride layers by 40 keV argon ion treatments

    NASA Astrophysics Data System (ADS)

    Caridi, F.; Picciotto, A.; Vanzetti, L.; Iacob, E.; Scolaro, C.

    2015-10-01

    Measurements of wet-ability of liquid drops have been performed on a 30 nm silicon nitride (Si3N4) film deposited by a PECVD reactor on a silicon wafer and implanted by 40 keV argon ions at different doses. Surface treatments by using Ar ion beams have been employed to modify the wet-ability. The chemical composition of the first Si3N4 monolayer was investigated by means of X-ray Photoelectron Spectroscopy (XPS). The surface morphology was tested by Atomic Force Microscopy (AFM). Results put in evidence the best implantation conditions for silicon nitride to increase or to reduce the wet-ability of the biological liquid. This permits to improve the biocompatibility and functionality of Si3N4. In particular experimental results show that argon ion bombardment increases the contact angle, enhances the oxygen content and increases the surface roughness.

  18. SOLEX: a tunable monochromatic X-ray source in the 1-20 keV energy range for metrology

    NASA Astrophysics Data System (ADS)

    Bonnelle, C.; Jonnard, P.; André, J.-M.; Avila, A.; Laporte, D.; Ringuenet, H.; Lépy, M. C.; Plagnard, J.; Ferreux, L.; Protas, J. C.

    2004-01-01

    A tunable monochromatic X-ray source covering the 1-20 keV energy range is described. The initial X-ray beam is obtained from a dedicated windowless X-ray tube. The energy selection is performed through a cylindrically bent crystal, used either in the reflection (Johann geometry) or in the transmission (Cauchois geometry) mode, by rotating the crystal holder by a 90° angle. Contrary to conventional geometries where the X-ray tube is fixed, here the direction of the exit beam impinging the X-ray detector is fixed. This setup is shown to be useful for various studies: high-resolution spectrometry, characterization of the response function and the efficiency of detectors and optical components, determination of transmission characteristics of different materials. Observations of the Lα line and Kα doublet from a copper anode are presented, that demonstrate the performance of this new setup.

  19. Enhanced room temperature oxidation in silicon and porous silicon under 10 keV x-ray irradiation

    SciTech Connect

    Ryckman, Judson D.; Reed, Robert A.; Weller, Robert A.; Fleetwood, D. M.; Weiss, S. M.

    2010-12-01

    We report the observation of enhanced oxidation on silicon and porous silicon samples exposed in air ambient to high-dose-rate 10 keV x-ray radiation at room temperature. The evolution of the radiation-induced oxide growth is monitored by ellipsometry and interferometric reflectance spectroscopy. Fourier transform infrared (FTIR) spectroscopy shows the emergence of Si-O-Si stretching modes and corresponding suppression of SiH{sub x} and Si-Si modes in the porous silicon samples. The radiation response depends strongly on initial native oxide thickness and Si-H surface species. The enhanced oxidation mechanism is attributed to photoinduced oxidation processes wherein energetic photons are used to dissociate molecular oxygen and promote the formation of more reactive oxygen species.

  20. Experimental observations of Z-dependence of saturation thickness of 662 keV gamma rays in metals and glasses

    NASA Astrophysics Data System (ADS)

    Ravindraswami, K.; Kiran, K. U.; Eshwarappa, K. M.; Somashekarappa, H. M.

    2013-11-01

    In this paper the energy, intensity and angular distributions of multiple scattering of 662 keV gamma photons, emerging from targets of aluminium, copper, iron and glass samples are studied as a function of target thickness. An intense collimated beam obtained from a 137Cs source of 5.8 mCi is allowed to impinge on samples of varying thickness. The scattered photons are detected by a properly shielded 76 mm × 76 mm NaI (Tl) scintillation detector. In Compton scattering experiments, it is observed that the number of multiple backscattered photons increase with an increase in target thickness and become almost constant for particular target thickness called saturation thickness. The saturation thickness decreases with increasing atomic number. The multiple scattering, an interfering background noise in Compton profile, has been successfully used to assign effective atomic number (Z eff ) to composite materials. The experimental results are compared with the Monte Carlo calculations using Monte Carlo nuclear particle code.

  1. CO2 synthesis in solid CO by Lyman-α photons and 200 keV protons

    NASA Astrophysics Data System (ADS)

    Loeffler, M. J.; Baratta, G. A.; Palumbo, M. E.; Strazzulla, G.; Baragiola, R. A.

    2005-05-01

    We have studied the synthesis of carbon dioxide from solid carbon monoxide at 16 K induced by photolysis with Lyman-α photons and by irradiation with 200 keV protons to quantitatively compare the effects of photolysis and ion irradiation on CO ice and to determine the importance of these processes in interstellar ice grains. The CO and CO{2} concentrations during irradiation of an initially pure CO film evolve with fluence to a saturation value, a behaviour that is explained by a two-state model. Our results indicate that the initial CO{2} production rates for both radiation processes are similar when normalized to the absorbed energy and that the solid CO{2} abundance observed in the interstellar ices cannot be explained only by radiolysis and photolysis of pure solid CO.

  2. Long-term stable transmission of 3-keV Ne7+ ions guided through nanocapillaries in polymers

    NASA Astrophysics Data System (ADS)

    Stolterfoht, N.; Herczku, P.; Juhász, Z.; Kovács, S. T. S.; Rácz, R.; Biri, S.; Sulik, B.

    2016-11-01

    We studied blocking effects on 3-keV Ne7+ ion guiding through nanocapillaries in highly insulating polyethylene terephthalate (PET) manufactured at different laboratories. The experiments were motivated in view of previous measurement with PET capillaries prepared at the GSI Helmholtz-Zentrum for which significant blocking effects were observed, whereas in various previous studies with PET capillaries these effects could not be detected. As the blocking effect on the GSI capillaries strongly depends on their areal density, similar dependencies were studied with the FLNR capillaries. Long-term stable transmission was observed for all densities of the FLNR capillaries in contrast to the previous results. These observations are interpreted by differences in the capillary surface conductivities in accordance with charge patch formations within the capillaries. It is pointed out that the observed stable transmission is favorable for applications of ion guiding in capillaries.

  3. Using contour maps to search for red-shifted 511 keV features in BATSE GRB spectra

    NASA Technical Reports Server (NTRS)

    Varmette, Peter G.

    1993-01-01

    Since their discovery twenty years ago, the origin of gamma-ray bursts (GRB's) has remained an intriguing mystery. The quest to understand these objects has given rise to a plethora of competing theories. Several theories suggest that GRB's are galactic in origin while others suggest that GRB's are cosmological. One piece of evidence that might provide scientistis with a key to understanding the origin of GRB's may be whether or not spectral emission and absorption features exist in burst spectra. If the features exist and can be attributed to either cyclotron lines or to red-shifted 511 keV annihilation lines then credence would be given to those theories that support a galactic origin, i.e. near neutron stars. A method of searching for spectral features in burst spectra (BATSE HER data) is outlined.

  4. Characterizations of MCP performance in the hard x-ray range (6–25 keV)

    SciTech Connect

    Wu, Ming Rochau, Greg; Moy, Ken; Kruschwitz, Craig

    2014-11-15

    MCP detector performance at hard x-ray energies from 6 to 25 keV was recently investigated using NSLS beamline X15A at BNL. Measurements were made with an NSTec Gen-II (H-CA-65) framing camera, based on a Photonis MCP with ∼10 μm in diameter pores, ∼12 μm center-center spacing, an L/D ratio of 46, and a bias angle of 8°. The MCP characterizations were focused on (1) energy and angle dependent sensitivity, (2) energy and angle dependent spatial resolution, (3) energy dependent gain performance, and (4) energy dependent dynamic range. These measurement corroborated simulation results using a Monte Carlo model that included hard x-ray interactions and the subsequent electron cascade in the MCP.

  5. Secondary ion yields produced by keV atomic and polyatomic ion impacts on a self-assembled monolayer surface

    PubMed

    Harris; Baker; Van Stipdonk MJ; Crooks; Schweikert

    1999-01-01

    A suite of keV polyatomic or 'cluster' projectiles was used to bombard unoxidized and oxidized self-assembled monolayer surfaces. Negative secondary ion yields, collected at the limit of single ion impacts, were measured and compared for both molecular and fragment ions. In contrast to targets that are orders of magnitude thicker than the penetration range of the primary ions, secondary ion yields from polyatomic projectile impacts on self-assembled monolayers show little to no enhancement when compared with monatomic projectiles at the same velocity. This unusual trend is most likely due to the structural arrangement and bonding characteristics of the monolayer molecules with the Au(111). Copyright 1999 John Wiley & Sons, Ltd.

  6. X-ray filament with a strong 6.7-keV line in the Galactic center region

    NASA Astrophysics Data System (ADS)

    Yamauchi, Shigeo; Shimizu, Miku; Nakashima, Shinya; Nobukawa, Masayoshi; Tsuru, Takeshi Go; Koyama, Katsuji

    2014-12-01

    An elongated X-ray source with a strong K-shell line from He-like iron (Fe XXVI) is found at (RA, Dec)J2000.0 = (17h44m00{s.}0, - 29°13'40{^''.}9) in the Galactic center region. The position coincides with the X-ray thread, G359.55+0.16, which is aligned with the radio non-thermal filament. The X-ray spectrum is well fitted with an absorbed thin thermal plasma (apec) model. The best-fitting temperature, metal abundance, and column density are 4.1^{+2.7}_{-1.8} keV, 0.58^{+0.41}_{-0.32} solar, and 6.1^{+2.5}_{-1.3} × 10^{22} cm-2, respectively. These values are similar to those of the largely extended Galactic center X-ray emission.

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1975-01-01

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

  9. Decrease of keV electron and ion fluxes in the dayside magnetosphere during the early phase of magnetospheric disturbances

    NASA Technical Reports Server (NTRS)

    Hultqvist, B.; Aparicio, B.; Borg, H.; Arnoldy, R.; Moore, T. E.

    1981-01-01

    It is shown that a decrease of the keV particle fluxes in the dayside magnetosphere near the geosynchronous orbit is characteristic of the first several hours of magnetospheric disturbances. After some hours newly injected plasma from the nightside reaches the 'evacuated' regions of the dayside magnetosphere and strong flux increases are observed. The 'evacuation' of the dayside magnetosphere is interpreted in terms of a change in the convection pattern associated with an increase of the large scale electric field at the onset of the disturbance. The model presented is capable of accommodating all characteristics of the observational data, such as the temporal and spatial distributions, energy and pitch angle characteristics, and differences between electrons and protons.

  10. Efficient and fast 511-keV γ detection through Cherenkov radiation: the CaLIPSO optical detector

    NASA Astrophysics Data System (ADS)

    Ramos, E.; Kochebina, O.; Yvon, D.; Verrecchia, P.; Sharyy, V.; Tauzin, G.; Mols, J. P.; Starzinski, P.; Desforges, D.; Flouzat, Ch.; Bulbul, Y.; Jan, S.; Mancardi, X.; Canot, C.; Alokhina, M.

    2016-11-01

    The CaLIPSO project aims to develop a high precision brain-scanning PET device with time-of-flight capability. The proposed device uses an innovative liquid, the TriMethyl Bismuth, as the detection medium. It detects simultaneously the ionization and optical signals from the 511 keV gamma conversion. In this paper we present the design, the Monte Carlo simulation, and the tests results for the CaLIPSO optical prototype. In this prototype we demonstrated the ability to detect efficiently the low number of the optical photons produced by the relativistic electron from the gamma conversion through the Cherenkov effect. The time resolution of the current prototype is limited by the moderate time transition spread of the PMT, but should be improved to the level better than 100 ps (FWHM) by using micro-channel-plate PMT according to the Geant 4 simulation.

  11. Electron impact total cross section calculations for CH3SH (methanethiol) from threshold to 5 keV

    NASA Astrophysics Data System (ADS)

    Limbachiya, Chetan; Vinodkumar, Minaxi; Swadia, Mohit; Barot, Avani

    2014-01-01

    We report calculated total elastic cross sections Qel, total ionisation cross sections, Qion, summed total excitation cross sections ∑Qexc and total cross sections QT for CH3SH upon electron impact for energies from ionisation threshold to 5 keV. We have employed Spherical Complex Optical Potential (SCOP) formalism to calculate total elastic cross section Qel, and total inelastic cross section Qinel and used Complex Scattering Potential - the ionisation contribution (CSP-ic) method to extract the ionisation cross sections, Qion, from the calculated Qinel. The calculated total cross sections are examined as functions of incident electron energy and are compared with available data wherever possible and overall good agreement is observed. In this work Qel, Qion, and ∑Qexc are reported for the first time for CH3SH in this energy range.

  12. AMANDE: a new facility for monoenergetic neutron fields production between 2 keV and 20 MeV.

    PubMed

    Gressier, V; Guerre-Chaley, J F; Lacoste, V; Lebreton, L; Pelcot, G; Pochat, J L; Bolognese-Milstajn, T; Champion, D

    2004-01-01

    The variation of the response of the instruments with the neutron energy has to be determined in well-characterized monoenergetic neutron fields. The AMANDE facility will deliver such neutron fields between 2 keV and 20 MeV in an experimental hall designed with metallic walls for neutron scattering minimisation. The neutrons will be produced by nuclear interaction of accelerated protons or deuterons on thin targets of selected materials. The measuring devices to be characterised will be accurately placed with a fully automated detector transport system. The energy of the neutron field will be validated by time-of-flight experiments and a large set of standard detectors and fluence monitors will be used to determine the neutron fluence references. The scattered neutron fluence and dose equivalent were calculated by the MCNP Monte Carlo code at several measuring points in order to determine their contribution to the neutron field.

  13. INTEGRAL Observations of the Galactic 511 keV Emission and MeV Gamma-ray Astrophysics

    NASA Technical Reports Server (NTRS)

    Watanabe, Ken

    2005-01-01

    Although there are a number of interesting phenomena, such as Nucleosynthesis in stars, in the MeV energy region, the observations have been difficult due to a small signal to noise (background) ratio (less than 1%). While NASA's Compton Gamma-ray Observatory (CGRO) enabled us to explore the Gamma-ray universe, ESA's INTEGRAL mission, launched in 2002, is providing us more detailed information with its superior energy and angular resolution. We will briefly discuss some of the current issues in MeV Gamma-ray Astrophysics. Then, we will focus on the Galactic 511 keV emission with the latest INTEGRAL observations, and talk about challenges we currently have.

  14. Fragmentation of H2O by 1 -- 5 keV He^2+ ions: Experiment and Theory

    NASA Astrophysics Data System (ADS)

    Stolterfoht, N.; Hellhammer, R.; Sobocinski, P.; Cabrera-Trujillo, R.; Ohrn, Y.; Deumens, E.; Sabin, J.

    2006-05-01

    Fragmentation of H2O molecules induced by ^3He^2+ impact was investigated experimentally as a function of the energy in the range from 1-5 keV. Collisions at large impact parameters are found to produce fragment protons with energies centered around peaks at 6 eV and 15 eV. The H^+ fragments were detected in the angular range from 25 to 135 with respect to the incident beam direction. Absolute fragmentation cross sections dσ/dφ, differential in the emission angle are found to be anisotropic, with protons preferentially emitted at angles near 90 . In addition to the experiments, we performed quantum-mechanical calculations to understand the fragmentation mechanisms producing protons at preferred energies and angles. The theoretical results are obtained using the Electron-Nuclear Dynamics formalism (END), which solves the time-dependent Schr"odinger equation.

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

    SciTech Connect

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

    2007-12-10

    The authors measured the absolute response of image plate (Fuji BAS SR2040) for electrons at energies between 100 keV to 4 MeV using an electron spectrometer. The electron source was produced from a short pulse laser irradiated on the solid density targets. This paper presents the calibration results of image plate Photon Stimulated Luminescence PSL per electrons at this energy range. The Monte Carlo radiation transport code MCNPX results are also presented for three representative incident angles onto the image plates and corresponding electron energies depositions at these angles. These provide a complete set of tools that allows extraction of the absolute calibration to other spectrometer setting at this electron energy range.

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

    NASA Astrophysics Data System (ADS)

    Manjunathaguru, V.; Umesh, T. K.

    2006-09-01

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

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

    SciTech Connect

    Ross, James Steven

    2010-01-01

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

  18. Using neutrons to measure keV temperatures in highly compressed plastic at multi-Gbar pressures

    SciTech Connect

    Nilsen, J.; Bachmann, B.; Zimmerman, G. B.; Hatarik, R.; Döppner, T.; Swift, D.; Hawreliak, J.; Collins, G. W.; Falcone, R. W.; Glenzer, S. H.; Kraus, D.; Landen, O. L.; Kritcher, A. L.

    2016-10-27

    In this study, we have designed an experiment for the National Ignition Facility to measure the Hugoniot of materials such as plastic at extreme pressures. The design employs a strong spherically converging shock launched through a solid ball of material using a hohlraum radiation drive. The shock front conditions can be characterized using X-ray radiography until background from shock coalescence overtakes the backlit signal. Shock coalescence at the center is predicted to reach tens of Gbars and can be further characterized by measuring the X-ray self-emission and 2.45 MeV neutrons emitted from the shock flash region. In this simulation design work the standard plastic sphere is replaced with a deuterated polyethylene sphere, CD2, that reaches sufficiently high densities and temperatures in the central hot spot to produce neutrons from Deuterium-Deuterium (DD) fusion reactions that can be measured by a neutron time of flight spectrometer (nTOF) and act as a temperature diagnostic. This paper focuses on the design of these experiments, based on an extensive suite of radiation-hydrodynamics simulations, and the interpretation of the predicted DD neutron signals. The simulations predict mean temperatures of 1 keV in the central hot spot with mean densities of 33 g/cc and mean pressures of 25 Gbar. Lastly, a preliminary comparison with early experimental results looks promising with an average ion temperature of 1.06 ± 0.15 keV in the central hot spot estimated from the nTOF spectral width and measured neutron yield of 7.0 (±0.5) × 109 DD neutrons.

  19. Using neutrons to measure keV temperatures in highly compressed plastic at multi-Gbar pressures

    NASA Astrophysics Data System (ADS)

    Nilsen, J.; Bachmann, B.; Zimmerman, G. B.; Hatarik, R.; Döppner, T.; Swift, D.; Hawreliak, J.; Collins, G. W.; Falcone, R. W.; Glenzer, S. H.; Kraus, D.; Landen, O. L.; Kritcher, A. L.

    2016-12-01

    We have designed an experiment for the National Ignition Facility to measure the Hugoniot of materials such as plastic at extreme pressures. The design employs a strong spherically converging shock launched through a solid ball of material using a hohlraum radiation drive. The shock front conditions can be characterized using X-ray radiography until background from shock coalescence overtakes the backlit signal. Shock coalescence at the center is predicted to reach tens of Gbars and can be further characterized by measuring the X-ray self-emission and 2.45 MeV neutrons emitted from the shock flash region. In this simulation design work the standard plastic sphere is replaced with a deuterated polyethylene sphere, CD2, that reaches sufficiently high densities and temperatures in the central hot spot to produce neutrons from Deuterium-Deuterium (DD) fusion reactions that can be measured by a neutron time of flight spectrometer (nTOF) and act as a temperature diagnostic. This paper focuses on the design of these experiments, based on an extensive suite of radiation-hydrodynamics simulations, and the interpretation of the predicted DD neutron signals. The simulations predict mean temperatures of 1 keV in the central hot spot with mean densities of 33 g/cc and mean pressures of 25 Gbar. A preliminary comparison with early experimental results looks promising with an average ion temperature of 1.06 ± 0.15 keV in the central hot spot estimated from the nTOF spectral width and measured neutron yield of 7.0 (±0.5) × 109 DD neutrons.

  20. Using neutrons to measure keV temperatures in highly compressed plastic at multi-Gbar pressures

    DOE PAGES

    Nilsen, J.; Bachmann, B.; Zimmerman, G. B.; ...

    2016-10-27

    In this study, we have designed an experiment for the National Ignition Facility to measure the Hugoniot of materials such as plastic at extreme pressures. The design employs a strong spherically converging shock launched through a solid ball of material using a hohlraum radiation drive. The shock front conditions can be characterized using X-ray radiography until background from shock coalescence overtakes the backlit signal. Shock coalescence at the center is predicted to reach tens of Gbars and can be further characterized by measuring the X-ray self-emission and 2.45 MeV neutrons emitted from the shock flash region. In this simulation designmore » work the standard plastic sphere is replaced with a deuterated polyethylene sphere, CD2, that reaches sufficiently high densities and temperatures in the central hot spot to produce neutrons from Deuterium-Deuterium (DD) fusion reactions that can be measured by a neutron time of flight spectrometer (nTOF) and act as a temperature diagnostic. This paper focuses on the design of these experiments, based on an extensive suite of radiation-hydrodynamics simulations, and the interpretation of the predicted DD neutron signals. The simulations predict mean temperatures of 1 keV in the central hot spot with mean densities of 33 g/cc and mean pressures of 25 Gbar. Lastly, a preliminary comparison with early experimental results looks promising with an average ion temperature of 1.06 ± 0.15 keV in the central hot spot estimated from the nTOF spectral width and measured neutron yield of 7.0 (±0.5) × 109 DD neutrons.« less

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The pitch angle distribution (PAD) of energetic electrons in the slot region and inner radiation belt received little attention in the past decades due to the lack of quality measurements. Using the state-of-the-art pitch angle-resolved data from the Magnetic Electron Ion Spectrometer instrument onboard the Van Allen Probes, a detailed analysis of hundreds of keV electron PADs below L = 4 is performed, in which the PADs are categorized into three types: normal (flux peaking at 90°), cap (exceedingly peaking narrowly around 90°), and 90° minimum (lower flux at 90°) PADs. By examining the characteristics of the PADs of ˜460 keV electrons for over a year, we find that the 90° minimum PADs are generally present in the inner belt (L<2), while normal PADs dominate at L˜3.5-4. In the region between, 90° minimum PADs dominate during injection times and normal PADs dominate during quiet times. Cap PADs appear mostly at the decay phase of storms in the slot region and are likely caused by the pitch angle scattering of hiss waves. Fitting the normal PADs into sinnα form, the parameter n is much higher below L = 3 than that in the outer belt and relatively constant in the inner belt but changes significantly in the slot region (2 < L < 3) during injection times. As for the 90° minimum PADs, by performing a detailed case study, we find in the slot region this type of PAD is likely caused by chorus wave heating, but this mechanism can hardly explain the formation of 90° minimum PADs at the center of inner belt.

  2. Accretion Properties of a Sample of Hard X-Ray (<60 keV) Selected Seyfert 1 Galaxies

    NASA Astrophysics Data System (ADS)

    Wang, J.; Mao, Y. F.; Wei, J. Y.

    2009-02-01

    We examine the accretion properties in a sample of 42 hard (3-60 keV) X-ray selected nearby broad-line active galactic nuclei (AGNs). The energy range in the sample is harder than that usually used in similar previous studies. These AGNs are mainly complied from the RXTE All Sky Survey, and complemented by the released INTEGRAL AGN catalog. The black hole masses, bolometric luminosities of AGN, and Eddington ratios are derived from their optical spectra in terms of the broad Hβ emission line. The tight correlation between the hard X-ray (3-20 keV) and bolometric/line luminosity is well identified in our sample. Also identified is a strong inverse Baldwin relationship of the Hβ emission line. In addition, all of these hard X-ray AGNs are biased toward luminous objects with a high Eddington ratio (mostly between 0.01 and 0.1) and a low column density (<1022 cm-2), which is most likely due to the selection effect of the surveys. The hard X-ray luminosity is consequently found to be strongly correlated with the black hole mass. We believe the sample completeness will be improved in the next few years by the ongoing Swift and the International Gamma-Ray Astrophysics Laboratory missions, and by the next advanced missions, such as NuSTAR, Simbol-X, and NeXT. Finally, the correlation between RFe (= optical Fe II/Hβ) and disk temperature as assessed by T vprop (L/L Edd)M -1 BH leads us to suggest that the strength of the Fe II emission is mainly determined by the shape of the ionizing spectrum.

  3. Influence of organic ions on DNA damage induced by 1 eV to 60 keV electrons.

    PubMed

    Zheng, Yi; Sanche, Léon

    2010-10-21

    We report the results of a study on the influence of organic salts on the induction of single strand breaks (SSBs) and double strand breaks (DSBs) in DNA by electrons of 1 eV to 60 keV. Plasmid DNA films are prepared with two different concentrations of organic salts, by varying the amount of the TE buffer (Tris-HCl and EDTA) in the films with ratio of 1:1 and 6:1 Tris ions to DNA nucleotide. The films are bombarded with electrons of 1, 10, 100, and 60 000 eV under vacuum. The damage to the 3197 base-pair plasmid is analyzed ex vacuo by agarose gel electrophoresis. The highest yields are reached at 100 eV and the lowest ones at 60 keV. The ratios of SSB to DSB are surprisingly low at 10 eV (∼4.3) at both salt concentrations, and comparable to the ratios measured with 100 eV electrons. At all characteristic electron energies, the yields of SSB and DSB are found to be higher for the DNA having the lowest salt concentration. However, the organic salts are more efficient at protecting DNA against the damage induced by 1 and 10 eV electrons. DNA damage and protection by organic ions are discussed in terms of mechanisms operative at each electron energy. It is suggested that these ions create additional electric fields within the groove of DNA, which modify the resonance parameter of 1 and 10 eV electrons, namely, by reducing the electron capture cross-section of basic DNA units and the lifetime of corresponding transient anions. An interstrand electron transfer mechanism is proposed to explain the low ratios for the yields of SSB to those of DSB produced by 10 eV electrons.

  4. The effectiveness of monoenergetic neutrons at 565 keV in producing dicentric chromosomes in human lymphocytes at low doses.

    PubMed

    Schmid, E; Regulla, D; Guldbakke, S; Schlegel, D; Bauchinger, M

    2000-09-01

    The induction of dicentric chromosomes in human lymphocytes from one individual irradiated in vitro with monoenergetic neutrons at 565 keV was examined to provide additional data for an improved evaluation of neutrons with respect to radiation risk in radioprotection. The resulting linear dose-response relationship obtained (0.813 +/- 0.052 dicentrics per cell per gray) over the dose range of 0.0213-0.167 Gy is consistent with published results obtained for irradiation with neutrons from different sources and with different spectra at energies lower than 1000 keV. Comparing this value to previously published "average" dose-response curves obtained by different laboratories for (60)Co gamma rays and orthovoltage X rays resulted in maximum RBEs (RBE(m)) of about 37 +/- 8 and 16 +/- 4, respectively. However, when our neutron data were matched to low-LET dose responses that were constructed several years earlier for lymphocytes from the same individual, higher values of RBE(m) resulted: 76.0 +/- 29.5 for (60)Co gamma rays and 54.2 +/- 18.4 for (137)Cs gamma rays; differentially filtered 220 kV X rays produced values of RBE(m) between 20.3 +/- 2.0 or 37.0 +/- 7. 1. The results highlight the dependence of RBE(m) on the choice of low-LET reference radiation and raise the possibility that differential individual response to low-LET radiations may need to be examined more fully in this context.

  5. Influence of organic ions on DNA damage induced by 1 eV to 60 keV electrons

    SciTech Connect

    Zheng Yi; Sanche, Leon

    2010-10-21

    We report the results of a study on the influence of organic salts on the induction of single strand breaks (SSBs) and double strand breaks (DSBs) in DNA by electrons of 1 eV to 60 keV. Plasmid DNA films are prepared with two different concentrations of organic salts, by varying the amount of the TE buffer (Tris-HCl and EDTA) in the films with ratio of 1:1 and 6:1 Tris ions to DNA nucleotide. The films are bombarded with electrons of 1, 10, 100, and 60 000 eV under vacuum. The damage to the 3197 base-pair plasmid is analyzed ex vacuo by agarose gel electrophoresis. The highest yields are reached at 100 eV and the lowest ones at 60 keV. The ratios of SSB to DSB are surprisingly low at 10 eV ({approx}4.3) at both salt concentrations, and comparable to the ratios measured with 100 eV electrons. At all characteristic electron energies, the yields of SSB and DSB are found to be higher for the DNA having the lowest salt concentration. However, the organic salts are more efficient at protecting DNA against the damage induced by 1 and 10 eV electrons. DNA damage and protection by organic ions are discussed in terms of mechanisms operative at each electron energy. It is suggested that these ions create additional electric fields within the groove of DNA, which modify the resonance parameter of 1 and 10 eV electrons, namely, by reducing the electron capture cross-section of basic DNA units and the lifetime of corresponding transient anions. An interstrand electron transfer mechanism is proposed to explain the low ratios for the yields of SSB to those of DSB produced by 10 eV electrons.

  6. Influence of organic ions on DNA damage induced by 1 eV to 60 keV electrons

    NASA Astrophysics Data System (ADS)

    Zheng, Yi; Sanche, Léon

    2010-10-01

    We report the results of a study on the influence of organic salts on the induction of single strand breaks (SSBs) and double strand breaks (DSBs) in DNA by electrons of 1 eV to 60 keV. Plasmid DNA films are prepared with two different concentrations of organic salts, by varying the amount of the TE buffer (Tris-HCl and EDTA) in the films with ratio of 1:1 and 6:1 Tris ions to DNA nucleotide. The films are bombarded with electrons of 1, 10, 100, and 60 000 eV under vacuum. The damage to the 3197 base-pair plasmid is analyzed ex vacuo by agarose gel electrophoresis. The highest yields are reached at 100 eV and the lowest ones at 60 keV. The ratios of SSB to DSB are surprisingly low at 10 eV (˜4.3) at both salt concentrations, and comparable to the ratios measured with 100 eV electrons. At all characteristic electron energies, the yields of SSB and DSB are found to be higher for the DNA having the lowest salt concentration. However, the organic salts are more efficient at protecting DNA against the damage induced by 1 and 10 eV electrons. DNA damage and protection by organic ions are discussed in terms of mechanisms operative at each electron energy. It is suggested that these ions create additional electric fields within the groove of DNA, which modify the resonance parameter of 1 and 10 eV electrons, namely, by reducing the electron capture cross-section of basic DNA units and the lifetime of corresponding transient anions. An interstrand electron transfer mechanism is proposed to explain the low ratios for the yields of SSB to those of DSB produced by 10 eV electrons.

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

    SciTech Connect

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

    2015-11-01

    In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low-energy component (up to ∼200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons (kT{sub 0} ∼ 7 keV) is introduced. Above this first component, a clear excess extending up to 400–600 keV leads us to investigate a scenario where an additional (cutoff) power law could correspond to the contribution of the jet synchrotron emission, as proposed in Cyg X-1. A search for an annihilation feature did not provide any firm detection, with an upper limit of 2 × 10{sup −4} ph cm{sup −2} s{sup −1} (2σ) for a narrow line centered at 511 keV, on the averaged obtained spectrum.

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

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

    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.

  9. SMM observations of gamma-ray transients. 2: A search for gamma-ray lines between 400 and 600 keV from the Crab Nebula

    NASA Technical Reports Server (NTRS)

    Harris, Michael J.; Share, Gerald H.; Leising, Mark D.

    1994-01-01

    We have search spectra obtained by the Solar Maximum Mission Gamma-Ray Spectrometer during 1981-1988 for evidence of transient gamma-ray lines from the Crab Nebula which have been reported by previous experiments at energies 400-460 keV and 539 keV. We find no evidence for significant emission in any of these lines on time scales between aproximately 1 day and approximately 1 yr. Our 3 sigma upper limits on the transient flux during 1 d intervals are approximately equal to 2.2 x 10(exp -3) photons/sq cm/s for narrow lines at any energy, and approximately equal to 2.9 x 10(exp -3) photons/sq cm/s for the 539 keV line if it is as broad as 42 keV Full Width at Half Maximum (FWHM). We also searched our data during the approximately 5 hr period on 1981 June 6 during which Owens, Myers, & Thompson (1985) reported a strong line at 405 keV. We detected no line down to a 3 upper sigma limit of 3.3 x 10(exp -3) photons/sq cm/s in disagreement with the flux 7.2 +/- 2.1 x 10(exp -3) photos/sq cm/s measured by Owens et al.

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

    SciTech Connect

    Carlson, Eric; Jeltema, Tesla; Profumo, Stefano E-mail: tesla@ucsc.edu

    2015-02-01

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

  11. The DSS-14 C-band exciter

    NASA Technical Reports Server (NTRS)

    Rowan, D. R.

    1989-01-01

    The development and implementation of a C-band exciter for use with the Block IV Receiver-Exciter Subsystem at Deep Space Station 14 (DSS-14) has been completed. The exciter supplements the standard capabilities of the Block IV system by providing a drive signal for the C-band transmitter while generating coherent translation frequencies for C-band (5-GHz) to S-band (2.2- to 2.3-GHz) Doppler extraction, C-band to L-band (1.6-GHz) zero delay measurements, and a level calibrated L-band test signal. Exciter functions are described, and a general explanation and description of the C-band uplink controller is presented.

  12. Troposcatter at the KU Band

    DTIC Science & Technology

    1994-06-01

    Band by Magnus Wennemyr 1 Introduction Appendix Page no. 1 1.1 Introduction I 1.2 Transhorizonal Microwave Propagation n the Troposphere I 1.3 The...1.7.1 Diurnal and Seasonal variations 4 1.7.2 Modes of Propagation 5 1.8 Conclusions 5 2 Effect of the Troposphere on Microwave Propagation 6 2.1...allowing for transhorizonal communication in the microwave ranges. This study tests the viability of using the higher frequency ranges (the test

  13. Improved 20mm Plastic Rotating Bands

    DTIC Science & Technology

    1976-12-01

    flow into the band and minimize the possibility of weld lines. However, ring gates require a post-molding secondary operation to re- move them, whereas a...however, would tend to produce weld lines on the band surface opposite from the gate entry, a condition potentially deleterious to band and projectile...including ex- cessive flash at the bourrelet and parting line, contamination, mold drag, and band seat voids. The latter was deemed to be a major

  14. Senior Adult Bands: Music's New Horizon.

    ERIC Educational Resources Information Center

    Coffman, Don D.; Levy, Katherine M.

    1997-01-01

    Discusses the success of Iowa City's (Iowa) New Horizons Band that consists of 55 senior adult beginners and former instrumentalists. Describes the organization of the band program, the senior's performance skills and commitment, and the ongoing challenges. Gives a selected listing of the music the band plays at concerts and other events. (CMK)

  15. S and Ku band frequency source development

    NASA Technical Reports Server (NTRS)

    1980-01-01

    The results of the two part S- and Ku-band source development program are described. The S- and Ku-band sources were designed, fabricated, and evaluated. A high performance S- and Ku-band microwave signal source using state-of-the-art oscillator and microwave source technology was developed.

  16. Esophageal motility disorders after gastric banding.

    PubMed

    O'Rourke, R W; Deveney, C W; McConnell, D B; Wolfe, B M; Jobe, B A

    2007-01-01

    The long-term effects of gastric banding on esophageal function are not well described. This report describes a 28-year-old woman who developed signs and symptoms of abnormal esophageal motility and lower esophageal sphincter hypotension after gastric banding for morbid obesity. The current literature addressing the effects of gastric banding on esophageal function in light of this case report is discussed.

  17. Study of the beam-foil excitation mechanism with the use of chlorine projectiles, 2-10 MeV

    NASA Astrophysics Data System (ADS)

    Jupén, C.; Denne, B.; Ekberg, J. O.; Engström, L.; Litzén, U.; Martinson, I.; Tai-Meng, W.; Trigueiros, A.; Veje, E.

    1982-11-01

    Beam-foil excitation of chlorine projectiles has been studied by means of optical spectrometry, at projectile energies ranging from 2 to 10 MeV. The relative populations of various levels in ClV through ClVIII have been measured as functions of the projectile energy. It is concluded that for ClVII and ClVIII, the 3p and 3d terms are populated entirely through molecular-orbital (MO) electron promotions. High-lying levels of these charge states are excited by means of pickup of electrons from the valence band of the solid. Intermediate levels are populated through multiple inner-shell processes as well as from valence-band electron pickup. For ClV and ClVI, most of the levels are excited predominantly by pickup of electrons from the valence band. However, for some of the valence-shell levels in ClVI, fairly strong contributions from MO processes are found at higher projectile energies. No evidence has been observed for direct Coulomb excitation.

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

    NASA Astrophysics Data System (ADS)

    Jeltema, Tesla; Profumo, Stefano

    2016-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

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

    SciTech Connect

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

    2014-11-15

    A high resolution crystal spectrometer utilizing a crystal in transmission geometry has been developed and experimentally optimized to measure the widths of emission lines in the 10–60 keV energy range with eV accuracy. The spectrometer achieves high spectral resolution by utilizing crystal planes with small lattice spacings (down to 2d = 0.099 nm), a large crystal bending radius and Rowland circle diameter (965 mm), and an image plate detector with high spatial resolution (60 μm in the case of the Fuji TR image plate). High resolution W L-shell and K-shell laboratory test spectra in the 10–60 keV range and Ho K-shell spectra near 47 keV recorded at the LLNL Titan laser facility are presented. The Ho K-shell spectra are the highest resolution hard x-ray spectra recorded from a solid target irradiated by a high-intensity laser.

  1. CAN THE EXCESS IN THE Fe XXVI Ly{gamma} LINE FROM THE GALACTIC CENTER PROVIDE EVIDENCE FOR 17 keV STERILE NEUTRINOS?

    SciTech Connect

    Prokhorov, Dmitry; Silk, Joseph

    2010-12-20

    Sterile neutrinos (or right-handed neutrinos) are a plausible warm dark matter candidate. We find that the excess of the intensity in the 8.7 keV line (at the energy of the Fe XXVI Ly{gamma} line) in the spectrum of the Galactic center observed by Suzaku cannot be explained by standard ionization and recombination processes. We suggest that the origin of this excess is via decays of sterile neutrinos with a mass of 17.4 keV. The estimated value of the mixing angle sin{sup 2}(2{theta}) = (4.4 {+-} 2.2) x 10{sup -12} lies in the allowed region of the mixing angle for a dark matter sterile neutrino with a mass of 17-18 keV.

  2. Reconfigurable L-Band Radar

    NASA Technical Reports Server (NTRS)

    Rincon, Rafael F.

    2008-01-01

    The reconfigurable L-Band radar is an ongoing development at NASA/GSFC that exploits the capability inherently in phased array radar systems with a state-of-the-art data acquisition and real-time processor in order to enable multi-mode measurement techniques in a single radar architecture. The development leverages on the L-Band Imaging Scatterometer, a radar system designed for the development and testing of new radar techniques; and the custom-built DBSAR processor, a highly reconfigurable, high speed data acquisition and processing system. The radar modes currently implemented include scatterometer, synthetic aperture radar, and altimetry; and plans to add new modes such as radiometry and bi-static GNSS signals are being formulated. This development is aimed at enhancing the radar remote sensing capabilities for airborne and spaceborne applications in support of Earth Science and planetary exploration This paper describes the design of the radar and processor systems, explains the operational modes, and discusses preliminary measurements and future plans.

  3. Minimum cut and shear bands

    NASA Astrophysics Data System (ADS)

    Tordesillas, Antoinette; Cramer, Andrew; Walker, David M.

    2013-06-01

    We explore the efficacy of network optimisation theory for minimum cut to quantify the evolution of granular fabric and its functionality as a transmission medium in deforming dense granular media. Our focus here is on force transmission in a sheared assembly of polydisperse particles, in a biaxial compression test under constant confining pressure. The granular fabric is examined with respect to the material's force-bearing contact network over that regime when the material has reached its residual strength, and is deforming under a near constant volume in the presence of a fully developed shear band. The structural evolution of the fabric is quantitatively characterized using a representative weighted-directed network that is similarly evolving as the sample deforms. The edges or links, representing the interparticle contacts, are each weighted by the capacity of the contact to transmit force: a scalar that depends solely on the relative motion of the contacting grains. In the large strain failure regime, the minimum cut which represents the bottleneck in force transmission is found to lie in the persistent shear band. This study paves the way for the future analysis of flows and force transmission through an evolving contact network and, in turn, the characterisation of the relationship between the material's contact topology and its capacity to transmit forces through its contact network.

  4. V-band IMPATT transmitter

    NASA Technical Reports Server (NTRS)

    Williams, D.; Ying, R. S.

    1983-01-01

    A V-band transmitter for communication application was developed that has 30 dB gain and consists of six stages of IMPATT amplifiers. The low and medium power stages are stable amplifiers while the two high power stages are triggered oscillators. Hybrid couplers in the form of Magic Tees were used for power combining two single diode IMPATT modules in the high driver stage and for a single diode IMPATT modules at the output stage. Output power of 4 watts CW across a 2.5 GHz band centered at 60 GHz was achieved with an input power of 4 mW. Dynamic range of the amplifier chain is in excess of 7 dB. A single diode one watt stable amplifier over a bandwidth greater than 2.5 GHz, a high power ( 1 watt) stable amplifier capable of operating in either the constant current or constant voltage mode and verification of the advantages of the latter mode of operation; and a 10 channel modulator with built in test equipment (specifically protective circuitry, failure monitoring, and mode of failure indicated) were also developed. The performance requirements of circulators/isolators for reflection amplifiers were also defined and verified.

  5. Narrow-band Imaging In Ihe Cn Band Head

    NASA Astrophysics Data System (ADS)

    Uitenbroek, Han; Tritschler, A.

    2006-06-01

    We report on results of an observing campaign intended to revive an old CN Lyot filter originally built by Bernhard Lyot himself, but modified at Sacramento Peak. The filter has two band-width settings of 0.025 nm and 0.05 nm which can be fine tuned thermally. We characterise the passband of the Lyot filter and the employed prefilter based on osbervations performed with a spectrograph. We also performed an imaging experiment in an attempt to obtain data visualizing the imaging capability of the filter. Our results show that the CN filter is in a surprisingly good condition and is most suited for observations to verify theoretical predictions about the brightness of magnetic elements in the CN bandhead at 388.3\\,nm.

  6. Dust bands in the asteroid belt

    NASA Technical Reports Server (NTRS)

    Sykes, Mark V.; Greenberg, Richard; Dermott, Stanley F.; Nicholson, Philip D.; Burns, Joseph A.

    1989-01-01

    This paper describes the original IRAS observations leading to the discovery of the three dust bands in the asteroid belt and the analysis of data. Special attention is given to an analytical model of the dust band torus and to theories concerning the origin of the dust bands, with special attention given to the collisional equilibrium (asteroid family), the nonequilibrium (random collision), and the comet hypotheses of dust-band origin. It is noted that neither the equilibrium nor nonequilibrium models, as currently formulated, present a complete picture of the IRAS dust-band observations.

  7. WIDE BAND REGENERATIVE FREQUENCY DIVIDER AND MULTIPLIER

    DOEpatents

    Laine, E.F.

    1959-11-17

    A regenerative frequency divider and multiplier having wide band input characteristics is presented. The circuit produces output oscillations having frequencies related by a fixed ratio to input oscillations over a wide band of frequencies. In accomplishing this end, the divider-multiplier includes a wide band input circuit coupled by mixer means to a wide band output circuit having a pass band related by a fixed ratio to that of the input circuit. A regenerative feedback circuit derives a fixed frequency ratio feedback signal from the output circuit and applies same to the mixer means in proper phase relation to sustain fixed frequency ratio oscillations in the output circuit.

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

    SciTech Connect

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

    2008-01-01

    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.

  9. Comparison between MCNP and PENELOPE for the simulation of X-ray spectra in electron microscopy in the keV range

    NASA Astrophysics Data System (ADS)

    Roet, D.; Ceballos, C.; Van Espen, P.

    2006-10-01

    In this paper two Monte Carlo codes, MCNP (version 4C2) and PENELOPE (version 2001), were used in a cluster environment to simulate the X-ray spectra emerging from bombarding pure element bulk targets with mono energetic electrons in the keV range (30 keV). The simulation results were compared to experimental data measured on a JEOL-6300 electron microscope with energy dispersive X-ray detector. The results from both codes were compared amongst each other as to find the best in terms of accuracy, ease of use and speed of the calculations.

  10. Albedo factors of some elements in the atomic number range 26≤Z≤79 for 59.54keV.

    PubMed

    Yılmaz, Demet; Uzunoğlu, Zeynep; Demir, Celalettin

    2017-04-01

    In this study, we aimed to determine the albedo factors for Fe, Co, Ni, Cu, Zr, Mo, Ag, Dy, Yb, and Au. Albedo factors were investigated experimentally for 59.54keV photon energy by using an HPGe detector with a resolution of 182eV at 5.9keV. Albedo number (AN), albedo energy (AE), and albedo dose (AD) were plotted as a function of atomic number of the target. It was observed that albedo factors decreased with increasing atomic number. In addition, there was a good third-order polynomial relationship between the albedo factors and atomic number.

  11. X-band RF gun and linac for medical Compton scattering X-ray source

    SciTech Connect

    Dobashi, Katsuhito; Uesaka, Mitsuru; Fukasawa, Atsushi; Sakamoto, Fumito; Ebina, Futaro; Ogino, Haruyuki; Urakawa, Junji; Higo, Toshiyasu; Akemoto, Mitsuo; Hayano, Hitoshi; Nakagawa, Keiichi

    2004-12-07

    Compton scattering hard X-ray source for 10-80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U.Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard (10-80 keV) X-rays with the intensities of 108-1010 photons/s (at several stages) and the table-top size. Second important aspect is to reduce noise radiation at a beam dump by adopting the deceleration of electrons after the Compton scattering. This realizes one beamline of a 3rd generation SR source at small facilities without heavy shielding. The final goal is that the linac and laser are installed on the moving gantry. We have designed the X-band (11.424 GHz) traveling-wave-type linac for the purpose. Numerical consideration by CAIN code and luminosity calculation are performed to estimate the X-ray yield. X-band thermionic-cathode RF-gun and RDS(Round Detuned Structure)-type X-band accelerating structure are applied to generate 50 MeV electron beam with 20 pC microbunches (104) for 1 microsecond RF macro-pulse. The X-ray yield by the electron beam and Q-switch Nd:YAG laser of 2 J/10 ns is 107 photons/RF-pulse (108 photons/sec at 10 pps). We design to adopt a technique of laser circulation to increase the X-ray yield up to 109 photons/pulse (1010 photons/s). 50 MW X-band klystron and compact modulator have been constructed and now under tuning. The construction of the whole system has started. X-ray generation and medical application will be performed in the early next year.

  12. Preparation of Pt/Irx(IrO2)10 - x bifunctional oxygen catalyst for unitized regenerative fuel cell

    NASA Astrophysics Data System (ADS)

    Kong, Fan-Dong; Zhang, Sheng; Yin, Ge-Ping; Zhang, Na; Wang, Zhen-Bo; Du, Chun-Yu

    2012-07-01

    Bifunctional Pt/Irx(IrO2)10 - x (x < 10) catalyst for unitized regenerative fuel cell (URFC) has been prepared by depositing Pt on Irx(IrO2)10 - x support which is obtained initially from Adams fusion method. X-ray diffraction and transmission electron microscopy show that ultrafine and narrow distributed Pt/Ir3(IrO2)7 nanocomposites are formed. Electrochemical measurements demonstrate that among the series of catalysts studied, Pt/Ir3(IrO2)7 catalyst possesses the highest electrochemical surface area (24.74 m2 g-1) and the highest activity towards oxygen reduction reaction (ORR) (21.71 mA mg-1 at 0.85 V). Meanwhile, considerably high activity towards oxygen evolution reaction (OER) (42.35 mA mg-1 at 1.55 V) is also observed for Pt/Ir3(IrO2)7 catalyst. Kinetic analyses indicate that ORR on Pt/Ir3(IrO2)7 catalyst follows four-electron mechanism. This work opens a new way to fabricate efficient bifunctional oxygen catalyst for URFC.

  13. The Effects of Band Director Leadership Style and Student Leadership Ability on Band Festival Ratings

    ERIC Educational Resources Information Center

    Davison, P. Dru

    2007-01-01

    This study examined the relationship between band director leadership styles and the strength of student leadership within the bands. This study also examined the differences between leadership styles, student leadership strength, and band festival ratings (marching and concert). Subjects (N = 42) were band directors from Texas and Arkansas who…

  14. A Novel Ku-Band/Ka-Band and Ka-Band/E-Band Multimode Waveguide Couplers for Power Measurement of Traveling-Wave Tube Amplifier Harmonic Frequencies

    NASA Technical Reports Server (NTRS)

    Wintucky, Edwin G.; Simons, Rainee N.

    2015-01-01

    This paper presents the design, fabrication and test results for a novel waveguide multimode directional coupler (MDC). The coupler, fabricated from two dissimilar frequency band waveguides, is capable of isolating power at the second harmonic frequency from the fundamental power at the output port of a traveling-wave tube (TWT) amplifier. Test results from proof-of-concept demonstrations are presented for a Ku-band/Ka-band MDC and a Ka-band/E-band MDC. In addition to power measurements at harmonic frequencies, a potential application of the MDC is in the design of a satellite borne beacon source for atmospheric propagation studies at millimeter-wave (mm-wave) frequencies (Ka-band and E-band).

  15. Band models and correlations for infrared radiation

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.

    1975-01-01

    Absorption of infrared radiation by various line and band models are briefly reviewed. Narrow band model relations for absorptance are used to develop 'exact' formulations for total absorption by four wide band models. Application of a wide band model to a particular gas largely depends upon the spectroscopic characteristic of the absorbing-emitting molecule. Seven continuous correlations for the absorption of a wide band model are presented and each one of these is compared with the exact (numerical) solutions of the wide band models. Comparison of these results indicate the validity of a correlation for a particular radiative transfer application. In radiative transfer analyses, use of continuous correlations for total band absorptance provides flexibilities in various mathematical operations.

  16. Dual-band frequency selective surface with large band separation and stable performance

    NASA Astrophysics Data System (ADS)

    Zhou, Hang; Qu, Shao-Bo; Peng, Wei-Dong; Lin, Bao-Qin; Wang, Jia-Fu; Ma, Hua; Zhang, Jie-Qiu; Bai, Peng; Wang, Xu-Hua; Xu, Zhuo

    2012-05-01

    A new technique of designing a dual-band frequency selective surface with large band separation is presented. This technique is based on a delicately designed topology of L- and Ku-band microwave filters. The two band-pass responses are generated by a capacitively-loaded square-loop frequency selective surface and an aperture-coupled frequency selective surface, respectively. A Faraday cage is located between the two frequency selective surface structures to eliminate undesired couplings. Based on this technique, a dual-band frequency selective surface with large band separation is designed, which possesses large band separation, high selectivity, and stable performance under various incident angles and different polarizations.

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

    SciTech Connect

    Derrien, H

    2005-12-05

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

  18. Nucleosynthesis of 92Nb and the relevance of the low-lying isomer at 135.5 keV

    NASA Astrophysics Data System (ADS)

    Mohr, Peter

    2016-06-01

    Background: Because of its half-life of about 35 million years, 92Nb is considered as a chronometer for nucleosynthesis events prior to the birth of our sun. The abundance of 92Nb in the early solar system can be derived from meteoritic data. It has to be compared to theoretical estimates for the production of 92Nb to determine the time between the last nucleosynthesis event before the formation of the early solar system. Purpose: The influence of a low-lying short-lived isomer on the nucleosynthesis of 92Nb is analyzed. The thermal coupling between the ground state and the isomer via so-called intermediate states affects the production and survival of 92Nb. Method: The properties of the lowest intermediate state in 92Nb are known from experiment. From the lifetime of the intermediate state and from its decay branchings, the transition rate from the ground state to the isomer and the effective half-life of 92Nb are calculated as functions of the temperature. Results: The coupling between the ground state and the isomer is strong. This leads to thermalization of ground state and isomer in the nucleosynthesis of 92Nb in any explosive production scenario and almost 100% survival of 92Nb in its ground state. However, the strong coupling leads to a temperature-dependent effective half-life of 92Nb which makes the 92Nb survival very sensitive to temperatures as low as about 8 keV, thus turning 92Nb at least partly into a thermometer. Conclusions: The low-lying isomer in 92Nb does not affect the production of 92Nb in explosive scenarios. In retrospect this validates all previous studies where the isomer was not taken into account. However, the dramatic reduction of the effective half-life at temperatures below 10 keV may affect the survival of 92Nb after its synthesis in supernovae, which are the most likely astrophysical sites for the nucleosynthesis of 92Nb.

  19. New XAFS spectroscopic investigations in the 1-2 keV region. Final report on LDRD program

    SciTech Connect

    Wong, J.; Froba, M.; Tamura, E.

    1996-03-01

    Until recently x-ray absorption fine structure (XAFS) measurements in the 1-2 keV region remained a challenging experimental task. This was primarily due to the lack of an adequate monochromator crystal that possessed both the required x-ray properties (large d-spacing, high resolution and reflectivity) and materials properties (ultra-high vacuum (UHV) capability, damage resistance in a synchrotron radiation beam, absence of constituent element absorption edges and stability, both thermal and mechanical). Traditionally, XAFS spectra in this photon energy range have been measured in a piece-wise fashion using a combination of monochromator crystals. Very recently, we have an experimental breakthrough in XAFS spectroscopy in this soft x-ray region. This energy region is of great importance for materials and basic research since the K-edges of Na (1070 eV), Mg (1303 eV), Al (1557 eV) and Si (1839 eV), the L-edges of some 4p elements from Ga to Sr and the M-edges of the rare-earth elements fall within this energy window of the electromagnetic spectrum. YB{sub 66}, a complex binary semiconducting yttrium boride having a cubic crystal structure with a lattice constant of 23.44 {angstrom} has been singled out as a candidate monochromator material for synchrotron radiation in the 1-2 keV region. There is no intrinsic absorption by the constituent elements in this region, which can adequately be dispersed by the (400) reflection having a 2d value of 11.76 {angstrom}. In terms of vacuum compatibility, resistance to radiation damage, thermal and mechanical stability, YB{sub 66} satisfies all the material requirements for use as a monochromator in a synchrotron beam. In the past few years, LLNL in collaboration with a number of other research institutes has pioneered the development of this unique man-made crystal for use as soft x-ray monochromator with synchrotron light sources for materials science studies. 23 refs., 4 figs.

  20. Relic gravity waves and 7 keV dark matter from a GeV scale inflaton

    NASA Astrophysics Data System (ADS)

    Bezrukov, F. L.; Gorbunov, D. S.

    2014-09-01

    We study the mechanism of generation of 7 keV sterile neutrino Dark Matter (DM) in the model with light inflaton χ, which serves as a messenger of scale invariance breaking. In this model the inflaton, in addition to providing reheating to the Standard Model (SM) particles, decays directly into sterile neutrinos. The latter are responsible for the active neutrino oscillations via seesaw type I mechanism. While the two sterile neutrinos may also produce the lepton asymmetry in the primordial plasma and hence explain the baryon asymmetry of the Universe, the third one being the lightest may be of 7 keV and serve as DM. For this mechanism to work, the mass of the inflaton is bound to be light (0.1-1 GeV) and uniquely determines its properties, which allows to test the model. For particle physics experiments these are: inflaton lifetime (10-5-10-12 s), branching ratio of B-meson to kaon and inflaton (10-6-10-4) and inflaton branching ratios into light SM particles like it would be for the SM Higgs boson of the same mass. For cosmological experiments these are: spectral index of scalar perturbations (ns≃0.957-0.967), and amount of tensor perturbations produced at inflation (tensor-to-scalar ratio r≃0.15-0.005). β and ξ are related from the CMB normalization. mχ and β are related by the requirement of the generation of proper abundance of DM (given DM mass M1 or coupling f1 is known). ξ can be determined from the measurement of the tensor-to-scalar ratio r of the primordial perturbations. α is bound from below from the requirement of sufficient reheating, α is bound from above not to spoil the inflationary potential by radiative corrections, certain region in mχ and θ (or, equivalently β) is constrained from particle physics experiments. We show below that the first two are automatically satisfied with the parameters, leading to the proper DM generation, and the latter one leads to significant bound on the inflaton mass mχ (and hence effective upper bound