Science.gov

Sample records for 15-50 kev band

  1. 46 CFR 168.15-50 - Ventilation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Accommodations § 168.15-50 Ventilation. (a) All quarters must be adequately ventilated in a manner suitable to the purpose of the space and route of the vessel. (b) When mechanical ventilation is provided for... 46 Shipping 7 2010-10-01 2010-10-01 false Ventilation. 168.15-50 Section 168.15-50 Shipping...

  2. Emission from the Local Galactic Halo in the 1/4 keV Band

    NASA Astrophysics Data System (ADS)

    Juda, M.

    1994-12-01

    Pointed observations with the ROSAT PSPC toward clouds at high galactic latitude provide a unique opportunity to probe emission from the local galactic halo in the 1/4 keV band. I present data from five fields toward clouds at |b| > 60(deg) identified through their IRAS 100 microns emission, two in the north galactic hemisphere and three in the south. In four of the five fields significant shadows are detected (2 north, 2 south). The derivation of the brightness of the shadowed component depends strongly on the assumed location and amount of absorbing material. Scaling the IRAS 100 microns emission by 10(20) H atom cm(-2) /MJy sr(-1) and correcting for the difference from the observed average 21 cm derived column density, the implied brightness of the distant emitting component is the same for the two northern latitude fields at { ~ 1.2*E(-3) counts s(-1) arcmin(-2}) ; this brightness is lower than that seen in the direction of Draco (Burrows & Mendenhall 1991, Snowden et al. 1991) and higher than in Ursa Major (Snowden et al. 1994). The two southern fields also have the same derived distant brightness at nearly the same level as the northern fields, { ~ 1.0*E(-3) counts s(-1) arcmin(-2}) . Approximately 20% of this emission may be attributed to an extragalactic background (Hasinger et al. 1993). The remaining emission, { ~ 0.8*E(-3) counts s(-1) arcmin(-2}) , would be provided by the local galactic halo. If these x-rays arise from a collisionally excited plasma at a temperature of 10(6) K the required emission measure is { ~ 0.0033 cm(-6) pc}. Burrows & Mendenhall 1991, Nature, 351, 629. Hasinger et al. 1993, A&A, 275, 1. Snowden et al. 1991, Science, 252, 1529. Snowden et al. 1994, ApJ, 430, 601.

  3. 46 CFR 168.15-50 - Ventilation.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 7 2014-10-01 2014-10-01 false Ventilation. 168.15-50 Section 168.15-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS CIVILIAN NAUTICAL SCHOOL VESSELS... fresh air equal to at least 10 times the volume of the room each hour....

  4. 46 CFR 168.15-50 - Ventilation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 7 2012-10-01 2012-10-01 false Ventilation. 168.15-50 Section 168.15-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS CIVILIAN NAUTICAL SCHOOL VESSELS... fresh air equal to at least 10 times the volume of the room each hour....

  5. 46 CFR 168.15-50 - Ventilation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Ventilation. 168.15-50 Section 168.15-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS CIVILIAN NAUTICAL SCHOOL VESSELS... fresh air equal to at least 10 times the volume of the room each hour....

  6. 46 CFR 168.15-50 - Ventilation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Ventilation. 168.15-50 Section 168.15-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) NAUTICAL SCHOOLS CIVILIAN NAUTICAL SCHOOL VESSELS... fresh air equal to at least 10 times the volume of the room each hour....

  7. Laboratory-based x-ray reflectometer for multilayer characterization in the 15–150 keV energy band

    SciTech Connect

    Windt, David L.

    2015-04-15

    A laboratory-based X-ray reflectometer has been developed to measure the performance of hard X-ray multilayer coatings at their operational X-ray energies and incidence angles. The instrument uses a sealed-tube X-ray source with a tungsten anode that can operate up to 160 kV to provide usable radiation in the 15–150 keV energy band. Two sets of adjustable tungsten carbide slit assemblies, spaced 4.1 m apart, are used to produce a low-divergence white beam, typically set to 40 μm × 800 μm in size at the sample. Multilayer coatings under test are held flat using a vacuum chuck and are mounted at the center of a high-resolution goniometer used for precise angular positioning of the sample and detector; additionally, motorized linear stages provide both vertical and horizontal adjustments of the sample position relative to the incident beam. A CdTe energy-sensitive detector, located behind a third adjustable slit, is used in conjunction with pulse-shaping electronics and a multi-channel analyzer to capture both the incident and reflected spectra; the absolute reflectance of the coating under test is computed as the ratio of the two spectra. The instrument’s design, construction, and operation are described in detail, and example results are presented obtained with both periodic, narrow-band and depth-graded, wide-band hard X-ray multilayer coatings.

  8. Laboratory-based x-ray reflectometer for multilayer characterization in the 15-150 keV energy band

    NASA Astrophysics Data System (ADS)

    Windt, David L.

    2015-04-01

    A laboratory-based X-ray reflectometer has been developed to measure the performance of hard X-ray multilayer coatings at their operational X-ray energies and incidence angles. The instrument uses a sealed-tube X-ray source with a tungsten anode that can operate up to 160 kV to provide usable radiation in the 15-150 keV energy band. Two sets of adjustable tungsten carbide slit assemblies, spaced 4.1 m apart, are used to produce a low-divergence white beam, typically set to 40 μm × 800 μm in size at the sample. Multilayer coatings under test are held flat using a vacuum chuck and are mounted at the center of a high-resolution goniometer used for precise angular positioning of the sample and detector; additionally, motorized linear stages provide both vertical and horizontal adjustments of the sample position relative to the incident beam. A CdTe energy-sensitive detector, located behind a third adjustable slit, is used in conjunction with pulse-shaping electronics and a multi-channel analyzer to capture both the incident and reflected spectra; the absolute reflectance of the coating under test is computed as the ratio of the two spectra. The instrument's design, construction, and operation are described in detail, and example results are presented obtained with both periodic, narrow-band and depth-graded, wide-band hard X-ray multilayer coatings.

  9. Do the O2 Schumann-Runge Bands Participate in keV Collision-Induced Dissociation Experiments?

    NASA Astrophysics Data System (ADS)

    Lin, Yawei; Mayer, Paul M.

    2011-01-01

    In high-energy (keV) CID experiments, oxygen has the unique ability to enhance specific ion fragmentation pathways that lie within a relatively narrow band of activation energy. It has been previously proposed that this oxygen-enhanced dissociation phenomenon is due to the participation of the {{O}_{{2}}}{B}{ ^{{3}}}{Σ_{{u}}}^{ + } - {X}{ ^{{3}}}{Σ_{{g}}}^{ - } (Schumann-Runge) system in the collision complex. During the collision, oxygen is first excited to its {B}{ ^{{3}}}{Σ_{{u}}}^{ + } state before it returns this energy to the projectile ion. This energy drives the nonstatistical dissociation of the projectile provided there is an energetically accessible pathway in resonance with the absorbed radiation. To probe the validity of this hypothesis, a modified VG-ZAB mass spectrometer was used to observe the photon emissions from keV collisions of a selection of projectile ions with O2 target gas. By studying the resulting collision-induced emission (CIE) spectra, a second potential mechanism came to light, one that involves the near-isoenergetic O2 +. A 2Πu→X 2 Πg state transition.

  10. Do the O2 Schumann-Runge bands participate in keV collision-induced dissociation experiments?

    PubMed

    Lin, Yawei; Mayer, Paul M

    2011-01-01

    In high-energy (keV) CID experiments, oxygen has the unique ability to enhance specific ion fragmentation pathways that lie within a relatively narrow band of activation energy. It has been previously proposed that this oxygen-enhanced dissociation phenomenon is due to the participation of the O(2) B(3)Σ(u)(+) - X(3)Σ(g)(-) (Schumann-Runge) system in the collision complex. During the collision, oxygen is first excited to its [Formula: see text] state before it returns this energy to the projectile ion. This energy drives the nonstatistical dissociation of the projectile provided there is an energetically accessible pathway in resonance with the absorbed radiation. To probe the validity of this hypothesis, a modified VG-ZAB mass spectrometer was used to observe the photon emissions from keV collisions of a selection of projectile ions with O(2) target gas. By studying the resulting collision-induced emission (CIE) spectra, a second potential mechanism came to light, one that involves the near-isoenergetic O(2) (+.) A (2)Π(u)→X (2) Π(g) state transition. PMID:21472546

  11. 46 CFR 42.15-50 - Air pipes.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 2 2013-10-01 2013-10-01 false Air pipes. 42.15-50 Section 42.15-50 Shipping COAST... Conditions of Assignment of Freeboard § 42.15-50 Air pipes. (a) Where air pipes to ballast and other tanks.... Satisfactory means permanently attached, shall be provided for closing the openings of the air pipes....

  12. 46 CFR 42.15-50 - Air pipes.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 2 2011-10-01 2011-10-01 false Air pipes. 42.15-50 Section 42.15-50 Shipping COAST... Conditions of Assignment of Freeboard § 42.15-50 Air pipes. (a) Where air pipes to ballast and other tanks.... Satisfactory means permanently attached, shall be provided for closing the openings of the air pipes....

  13. 46 CFR 42.15-50 - Air pipes.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 2 2014-10-01 2014-10-01 false Air pipes. 42.15-50 Section 42.15-50 Shipping COAST... Conditions of Assignment of Freeboard § 42.15-50 Air pipes. (a) Where air pipes to ballast and other tanks.... Satisfactory means permanently attached, shall be provided for closing the openings of the air pipes....

  14. 46 CFR 42.15-50 - Air pipes.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 2 2012-10-01 2012-10-01 false Air pipes. 42.15-50 Section 42.15-50 Shipping COAST... Conditions of Assignment of Freeboard § 42.15-50 Air pipes. (a) Where air pipes to ballast and other tanks.... Satisfactory means permanently attached, shall be provided for closing the openings of the air pipes....

  15. 46 CFR 167.15-50 - Tailshaft examinations.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Tailshaft examinations. 167.15-50 Section 167.15-50... SHIPS Inspections § 167.15-50 Tailshaft examinations. Tailshaft examinations on nautical school ships must conform with the examination requirements in part 61 of this chapter....

  16. 46 CFR 42.15-50 - Air pipes.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Air pipes. 42.15-50 Section 42.15-50 Shipping COAST... Conditions of Assignment of Freeboard § 42.15-50 Air pipes. (a) Where air pipes to ballast and other tanks.... Satisfactory means permanently attached, shall be provided for closing the openings of the air pipes....

  17. 46 CFR 95.15-50 - Lockout valves.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 4 2013-10-01 2013-10-01 false Lockout valves. 95.15-50 Section 95.15-50 Shipping COAST... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 95.15-50 Lockout valves. (a) A lockout valve must... lockout valve must be a manually operated valve located in the discharge manifold prior to the stop...

  18. 46 CFR 95.15-50 - Lockout valves.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 4 2014-10-01 2014-10-01 false Lockout valves. 95.15-50 Section 95.15-50 Shipping COAST... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 95.15-50 Lockout valves. (a) A lockout valve must... lockout valve must be a manually operated valve located in the discharge manifold prior to the stop...

  19. 46 CFR 193.15-50 - Clean agent systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 7 2013-10-01 2013-10-01 false Clean agent systems. 193.15-50 Section 193.15-50 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) OCEANOGRAPHIC RESEARCH VESSELS FIRE PROTECTION EQUIPMENT Carbon Dioxide and Clean Agent Extinguishing Systems, Details § 193.15-50 Clean agent systems. A clean agent system complying with...

  20. 950 keV X-Band Linac For Material Recognition Using Two-Fold Scintillator Detector As A Concept Of Dual-Energy X-Ray System

    SciTech Connect

    Lee, Kiwoo; Natsui, Takuya; Hirai, Shunsuke; Uesaka, Mitsuru; Hashimoto, Eiko

    2011-06-01

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

  1. 9 CFR 50.15-50.16 - [Reserved

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false 50.15-50.16 Section 50.15-50.16 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE COOPERATIVE CONTROL AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF...

  2. 9 CFR 50.15-50.16 - [Reserved

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 1 2011-01-01 2011-01-01 false 50.15-50.16 Section 50.15-50.16 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE COOPERATIVE CONTROL AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF...

  3. 9 CFR 50.15-50.16 - [Reserved

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 1 2013-01-01 2013-01-01 false 50.15-50.16 Section 50.15-50.16 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE COOPERATIVE CONTROL AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF...

  4. 9 CFR 50.15-50.16 - [Reserved

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 1 2012-01-01 2012-01-01 false 50.15-50.16 Section 50.15-50.16 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE COOPERATIVE CONTROL AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF...

  5. 9 CFR 50.15-50.16 - [Reserved

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 1 2014-01-01 2014-01-01 false 50.15-50.16 Section 50.15-50.16 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE COOPERATIVE CONTROL AND ERADICATION OF LIVESTOCK OR POULTRY DISEASES ANIMALS DESTROYED BECAUSE OF...

  6. SIGNIFICANT X-RAY LINE EMISSION IN THE 5-6 keV BAND OF NGC 4051

    SciTech Connect

    Turner, T. J.; Miller, L.; Reeves, J. N.; Lobban, A.; Braito, V.; Kraemer, S. B.; Crenshaw, D. M.

    2010-03-20

    A Suzaku X-ray observation of NGC 4051 taken during 2005 November reveals line emission at 5.44 keV in the rest frame of the galaxy which does not have an obvious origin in known rest-frame atomic transitions. The improvement to the fit statistic when this line is accounted for establishes its reality at >99.9% confidence: we have also verified that the line is detected in the three X-ray Imaging Spectrometer units independently. Comparison between the data and Monte Carlo simulations shows that the probability of the line being a statistical fluctuation is p < 3.3 x 10{sup -4}. Consideration of three independent line detections in Suzaku data taken at different epochs yields a probability p < 3 x 10{sup -11} and thus conclusively demonstrates that it cannot be a statistical fluctuation in the data. The new line and a strong component of Fe Kalpha emission from neutral material are prominent when the source flux is low, during 2005. Spectra from 2008 show evidence for a line consistent with having the same flux and energy as that observed during 2005, but inconsistent with having a constant equivalent width against the observed continuum. The stability of the line flux and energy suggests that it may not arise in transient hotspots, as has been suggested for similar lines in other sources, but could arise from a special location in the reprocessor, such as the inner edge of the accretion disk. Alternatively, the line energy may be explained by spallation of Fe into Cr, as discussed in a companion paper.

  7. 46 CFR 193.15-50 - Clean agent systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... PROTECTION EQUIPMENT Carbon Dioxide and Clean Agent Extinguishing Systems, Details § 193.15-50 Clean agent systems. A clean agent system complying with 46 CFR subpart 95.16 may be used as an alternative to a carbon dioxide fire extinguishing system....

  8. 46 CFR 95.15-50 - Lockout valves.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... EQUIPMENT Carbon Dioxide Extinguishing Systems, Details § 95.15-50 Lockout valves. (a) A lockout valve must be provided on any carbon dioxide extinguishing system protecting a space over 6,000 cubic feet in... the system from the protected space or spaces, making it impossible for carbon dioxide to discharge...

  9. On-site nondestructive inspection by upgraded portable 950 keV/3.95 MeV X-band linac x-ray sources

    NASA Astrophysics Data System (ADS)

    Ueaska, Mitsuru; Dobashi, Katsuhiro; Fujiwara, Takeshi; Pei, Cuixiang; Wu, Wenjing; Kusano, Joichi; Nakamura, Naoki; Yamamoto, Masashi; Tanabe, Eiji; Ohya, Seiji; Hattori, Yukiya; Miura, Itaru; Honma, Hidetaka; Ishida, Masahiro; Kimura, Yoshitomi

    2014-12-01

    We have developed and upgraded portable 950 keV/3.95 MeV X-band (9.3 GHz) linac x-ray sources for on-site nondestructive testing (NDT) for social and industrial infrastructures. We integrated the hardware devices as well as software systems. For the hardware, we established all designed parameters including x-ray intensities of 0.05/2 Gy min-1 at 1 m for 950 keV/3.95 MeV systems, respectively. Concerning the software, we adopted the wavelet analysis for enhanced image contrast and partial angle computed tomography (CT) for a small region of interest. The wavelet analysis is effective to reduce scattered low energy x-ray noise in addition to using physical filters and collimators. The partial CT is inevitable to reconstruct an inner reinforced iron tube in concrete. We successfully performed on-site inspection three times, namely of a nitrogen acid distillation tower, a reinforced concrete pier and a large sample cut from a bridge. We obtained the x-ray images of the inner tube, determined the sizes of reinforced iron parts and evaluated the mechanical tolerance. Moreover, we are developing a new x-ray camera specified for MeV x-rays used for NDT of heavy objects. Then, our system will become a self-consisting and specialized high energy x-ray on-site inspection system. We are going to promote an application to NDT of social and industrial infrastructures in Japan and around the world.

  10. The X-ray behaviour of the high-energy peaked BL Lacertae source PKS 2155-304 in the 0.3-10 keV band

    NASA Astrophysics Data System (ADS)

    Kapanadze, B.; Romano, P.; Vercellone, S.; Kapanadze, S.

    2014-10-01

    We present the results of our monitoring of the high-energy peaked BL Lac object PKS 2155-304 by the Swift/X-Ray Telescope (XRT) during 2005-2012. Our timing study shows that the source was highly variable both on longer (weeks-to-months) and intra-day time-scales, up to a factor of 7 in flux, and 30 per cent in fractional variability amplitudes, with no periodic variations. The X-ray spectra are mainly curved with broad ranges of photon index, curvature parameter, and hardness ratio which exhibit significant variability with the flux on different time-scales. Our study of multi-wavelength cross-correlations has revealed that the one-zone SSC scenario seems to be valid for the most optical-to-gamma-ray flares observed during 2006-2012. An `orphan' X-ray flare with no counterpart in other spectral bands suggests the existence of different electron populations. Based on the absence of a correlation between photon index and curvature parameter (expected from the energy-dependent acceleration probability scenario), the observed distribution of curvature parameter from the XRT spectra peaking at b = 0.37, and the observed anti-correlation between the curvature parameter and the 0.3-10 keV flux (i.e. lower curvatures in flaring states), we conclude that the most likely mechanism responsible for producing X-ray emission during the flares is the stochastic acceleration of the electrons.

  11. 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.

  12. Subarcsecond x-ray telescope for imaging the solar corona in the 0.25- to 1.2-keV band

    NASA Astrophysics Data System (ADS)

    Gallagher, Dennis J.; Cash, Webster C.; Jelsma, Schuyler; Farmer, Jason

    1996-07-01

    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 degree graze angles with tungsten coatings, yielding a bandpass of 0.25-1.5 keV with a peak effective area of 0.8 cm(superscript 2) 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.

  13. Wide-Band KB Optics for Spectro-Microscopy Imaging Applications in the 6-13 keV X-ray Energy Range

    SciTech Connect

    Ziegler, E.; De Panfilis, S.; Peverini, L.; Vaerenbergh, P. van; Rocca, F.

    2007-01-19

    We present a Kirkpatrick-Baez optics (KB) system specially optimized to operate in the 6-13 keV X-ray range, where valuable characteristic lines are present. The mirrors are coated with aperiodic laterally graded (Ru/B4C)35 multilayers to define a 15% energy bandpass and to gain flux as compared to total reflection mirrors. For any X-ray energy selected the shape of each mirror can be optimized with a dynamical bending system so as to concentrate the X-ray beam into a micrometer-size spot. Once the KB mirrors are aligned at the X-ray energy corresponding to the barycenter of the XAS spectrum to be performed they remain in a steady state during the micro-XAS scans to minimize beam displacements. Results regarding the performance of the wideband KB optics and of the spectro-microscopy setup are presented, including beam stability issues.

  14. 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.

  15. 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.

  16. One 17-keV Majorana neutrino?

    NASA Astrophysics Data System (ADS)

    Carlson, Eric; Randall, Lisa

    1991-06-01

    A model is presented accommodating a 17-keV neutrino with 1 percent mixing with the electron neutrino and bounds on the electron-neutrino mass and neutrinoless double-beta decay. However, in contrast to previous models, there is only a single state with mass 17 keV. This model is consistent with cosmological and supernova-cooling constraints, and incorporates the Mikheyev-Smirnov-Wolfenstein explanation of the low solar-neutrino counts. Possible signatures of this model include an excess of muon neutrinos from a supernova explosion, spread over a period of 10-1000 sec, and a Higgs-boson decay signature of leptons plus missing energy.

  17. The Average 0.5-200 keV Spectrum of AGNs at 0

    NASA Astrophysics Data System (ADS)

    Ballantyne, David R.

    2013-04-01

    The X-ray spectra of AGNs span nearly three decades in energy and are comprised of many separate components: a power-law with a high energy cutoff, reflection from the accretion disk as well as distant material, and, in many cases, a soft excess. Aside from a small number of bright sources observed with BeppoSAX, the full energy range of AGN spectra has only been studied in piecemeal by a fleet of X-ray observatories that can only focus on a small part of the entire spectrum. Therefore, while catalogues of the spectral properties of hundreds of AGNs have been published in different energy bands, these results are isolated from one another and a clear picture of the broadband spectral properties of typical AGNs remains elusive. In this work, we make use of the 0 X-ray luminosity functions of AGNs in the 0.5-2 keV, 2-10 keV, 3-20 keV, 15-55 keV and 14-195 keV bands to construct the spectral model of an average AGN that can simultaneously account for all 5 luminosity functions. Enhanced iron abundances, disk reflection, and the presence or absence of the X-ray Baldwin Effect are considered, along with the traditional parameters of photon index and cutoff energy. Applications to X-ray background modelling and AGN physics are discussed.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

    Boynton, R.; Balikhin, M. A.; Sibeck, D. G.; Walker, S. N.; Ganushkina, N. Y.

    2015-12-01

    Forecast models are developed for the electron fluxes measured by the Magnetospheric Electron Detector (MagED) onboard the Geostationary Operational Environmental Satellite (GOES) 13. The models employ solar wind and geomagnetic indices as inputs to produce a forecast of the electron flux at Geostationary Earth Orbit (GEO) for five energy ranges from 30 keV - 600 keV. All of these models will be implemented in real time to forecast the electron fluxes on the PROGRESS project website (https://ssg.group.shef.ac.uk/progress2/html/index.phtml).

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

    SciTech Connect

    Gupta, A.; Galeazzi, M.

    2009-09-01

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

  1. 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.

  2. 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.

  3. The first MAXI/SSC catalog of X-ray sources in 0.7-7.0 keV

    NASA Astrophysics Data System (ADS)

    Tomida, Hiroshi; Uchida, Daiki; Tsunemi, Hiroshi; Imatani, Ritsuko; Kimura, Masashi; Nakahira, Satoshi; Hanayama, Takanori; Yoshidome, Koshiro

    2016-06-01

    We present the first source catalog of the Solid-state Slit Camera (SSC) of the Monitor of All-sky X-ray Image (MAXI) mission on the International Space Station, using the 45-month data from 2010 August to 2014 April in the 0.7-7.0 keV bands. Sources are searched for in two energy bands, 0.7-1.85 keV (soft) and 1.85-7.0 keV (hard), the limiting sensitivity of 3 and 4 mCrab are achieved, and 140 and 138 sources are detected in the soft and hard energy bands, respectively. Combining the two energy bands, 170 sources are listed in the MAXI/SSC catalog. All but 2 sources are identified with 22 galaxies including AGNs, 29 cluster of galaxies, 21 supernova remnants, 75 X-ray binaries, 8 stars, 5 isolated pulsars, and 9 non-categorized objects. Comparing the soft-band fluxes at the brightest end in our catalog with the ROSAT survey, which was performed about 20 years ago, 10% of the cataloged sources are found to have changed flux since the ROSAT era.

  4. The first MAXI/SSC catalog of X-ray sources in 0.7-7.0 keV

    NASA Astrophysics Data System (ADS)

    Tomida, Hiroshi; Uchida, Daiki; Tsunemi, Hiroshi; Imatani, Ritsuko; Kimura, Masashi; Nakahira, Satoshi; Hanayama, Takanori; Yoshidome, Koshiro

    2016-03-01

    We present the first source catalog of the Solid-state Slit Camera (SSC) of the Monitor of All-sky X-ray Image (MAXI) mission on the International Space Station, using the 45-month data from 2010 August to 2014 April in the 0.7-7.0 keV bands. Sources are searched for in two energy bands, 0.7-1.85 keV (soft) and 1.85-7.0 keV (hard), the limiting sensitivity of 3 and 4 mCrab are achieved, and 140 and 138 sources are detected in the soft and hard energy bands, respectively. Combining the two energy bands, 170 sources are listed in the MAXI/SSC catalog. All but 2 sources are identified with 22 galaxies including AGNs, 29 cluster of galaxies, 21 supernova remnants, 75 X-ray binaries, 8 stars, 5 isolated pulsars, and 9 non-categorized objects. Comparing the soft-band fluxes at the brightest end in our catalog with the ROSAT survey, which was performed about 20 years ago, 10% of the cataloged sources are found to have changed flux since the ROSAT era.

  5. Gastric Banding

    MedlinePlus

    ... gastric banding before deciding to have the procedure. Advertisements for a device or procedure may not include ... feeds Follow FDA on Twitter Follow FDA on Facebook View FDA videos on YouTube View FDA photos ...

  6. 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.

  7. Band Together!

    ERIC Educational Resources Information Center

    Olson, Cathy Applefeld

    2011-01-01

    After nearly a decade as band director at St. James High School in St. James, Missouri, Derek Limback knows that the key to building a successful program is putting the program itself above everything else. Limback strives to augment not only his students' musical prowess, but also their leadership skills. Key to his philosophy is instilling a…

  8. The average 0.5-200 keV spectrum of local active galactic nuclei and a new determination of the 2-10 keV luminosity function at z ≈ 0

    NASA Astrophysics Data System (ADS)

    Ballantyne, D. R.

    2014-01-01

    The broad-band X-ray spectra of active galactic nuclei (AGNs) contains information about the nuclear environment from Schwarzschild radii scales (where the primary power law is generated in a corona) to distances of ˜1 pc (where the distant reflector may be located). In addition, the average shape of the X-ray spectrum is an important input into X-ray background synthesis models. Here, local (z ≈ 0) AGN luminosity functions (LFs) in five energy bands are used as a low-resolution, luminosity-dependent X-ray spectrometer in order to constrain the average AGN X-ray spectrum between 0.5 and 200 keV. The 15-55 keV LF measured by Swift-BAT is assumed to be the best determination of the local LF, and then a spectral model is varied to determine the best fit to the 0.5-2 keV, 2-10 keV, 3-20 keV and 14-195 keV LFs. The spectral model consists of a Gaussian distribution of power laws with a mean photon-index <Γ> and cutoff energy Ecut, as well as contributions from distant and disc reflection. The reflection strength is parametrized by varying the Fe abundance relative to solar, AFe, and requiring a specific Fe Kα equivalent width (EW). In this way, the presence of the X-ray Baldwin effect can be tested. The spectral model that best fits the four LFs has <Γ> = 1.85 ± 0.15, E_{cut}=270^{+170}_{-80} keV, A_{Fe}=0.3^{+0.3}_{-0.15}. The sub-solar AFe is unlikely to be a true measure of the gas-phase metallicity, but indicates the presence of strong reflection given the assumed Fe Kα EW. Indeed, parametrizing the reflection strength with the R parameter gives R=1.7^{+1.7}_{-0.85}. There is moderate evidence for no X-ray Baldwin effect. Accretion disc reflection is included in the best-fitting model, but it is relatively weak (broad iron Kα EW < 100 eV) and does not significantly affect any of the conclusions. A critical result of our procedure is that the shape of the local 2-10 keV LF measured by HEAO-1 and MAXI is incompatible with the LFs measured in the hard X

  9. Physics of a 17 keV neutrino.

    NASA Astrophysics Data System (ADS)

    Kayser, B.

    The possible 17 keV neutrino, if real, cannot be νμ but could be essentially ντ. Relic 17 keV neutrinos from the big bang must have disappeared, through a non-Standard-Model decay or annihilation process, before the present epoch. If one assumes that the 17 keV neutrino is not a Dirac neutrino of the conventional kind, then one is led to picture it as a Dirac neutrino of the unconventional Zeldovich-Konopinski-Mahmoud kind. It is then an amalgam of ντ and ν¯μ.

  10. 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.

  11. 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

  12. 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.

  13. Cyclotron side band emissions from magnetospheric electrons

    NASA Technical Reports Server (NTRS)

    Maeda, K.

    1975-01-01

    Very low frequency emissions with subharmonic cyclotron frequency from magnetospheric electrons were detected by the S(3)-A satellite (Explorer 45) whose orbit is close to the magnetic equatorial plane where the wave-particle interaction is most efficient. These emissions were observed during the main phase of a geomagnetic storm in the nightside of the magnetosphere outside of the plasmasphere. During the event of these side-band emissions, the pitch angle distributions of high energy electrons (greater than 50 keV) and of energetic protons (greater than 100 keV) showed remarkable changes with time, whereas those of low energy electrons and protons remained approximately isotropic. In this type of event, emissions consist essentially of two bands, the one below the equatorial electron gyrofrequency, and the other above. The emissions below are whistler mode, and the emissions above are electrostatic mode.

  14. Electron currents associated with an auroral band

    NASA Technical Reports Server (NTRS)

    Spiger, R. J.; Anderson, H. R.

    1975-01-01

    Measurements of electron pitch angle distributions and energy spectra over a broad auroral band were used to calculate net electric current carried by auroral electrons in the vicinity of the band. The particle energy spectrometers were carried by a Nike-Tomahawk rocket launched from Poker Flat, Alaska, at 0722 UT on February 25, 1972. Data are presented which indicate the existence of upward field-aligned currents of electrons in the energy range 0.5-20 keV. The spatial relationship of these currents to visual structure of the auroral arc and the characteristics of the electrons carrying the currents are discussed.

  15. 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.

  16. 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.

  17. 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.

  18. 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…

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

    PubMed

    Conlon, Joseph P; Marsh, M C David

    2013-10-11

    Primordial decays of string theory moduli at z~10(12) naturally generate a dark radiation cosmic axion background with 0.1-1 keV energies. This cosmic axion background can be detected through axion-photon conversion in astrophysical magnetic fields to give quasithermal excesses in the extreme ultraviolet and soft x-ray bands. Substantial and observable luminosities may be generated even for axion-photon couplings <10(-11) GeV(-1). We propose that axion-photon conversion may explain the observed excess emission of soft x rays from galaxy clusters, and may also contribute to the diffuse unresolved cosmic x-ray background. We list a number of correlated predictions of the scenario. PMID:24160588

  20. Effect of 200 keV argon ion implantation on refractive index of polyethylene terepthlate (PET)

    NASA Astrophysics Data System (ADS)

    Kumar, Rajiv; Chawla, Mahak; Rubi, Sharma, Annu; Aggarwal, Sanjeev; Kumar, Praveen; Kanjilal, D.

    2012-06-01

    In the present work, the effect of argon ion implantation has been studied on the refractive index of PET. The specimens were implanted at 200 keV with argon ions in the fluence range of 1×1015 to 1×1017 ions cm-2. The refractive indices have been found to increase with implantation dose and wavelength (in visible region) obtained by using UV-visible spectroscopy. Also a drastic decrease in optical band gap (from 3.63 eV to 1.48eV) and increase in Urbach energy (from 0.29 eV to 3.70 eV) with increase in implantation dose has been observed. The possible correlation between the changes observed in the refractive indices and the Urbachenergyhave been discussed.

  1. 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.

  2. A Simple Band for Gastric Banding.

    PubMed

    Broadbent

    1993-08-01

    The author has noted that flexible gastric bands have occasionally stenosed the gastric stoma or allowed it to dilate. A band was developed using a soft outer silicone rubber tube over a holding mechanism made out of a nylon cable tie passed within the silicone tube. This simple, easily applied band is rigid, resisting scar contracture and dilatation. PMID:10757939

  3. 40-keV electron durable trapping electron

    SciTech Connect

    Feynman, J.; Hardy, D.A.; Mullen, E.G.

    1984-03-01

    The positron and extent of the region in which electrons with energies less than 40-keV are durably trapped in the nightside magnetosphere is found for both normal and disturbed geomagnetic conditions by using data from the P78-2 (SCATHA) satellite. The region of the magnetosphere from 5.3 to 7.9 R/sub E/ was studied. In this region neither solar-magnetic nor geocentric-solar magnetospheric coordinates order the data satisfactorily. A new coordinate systems called composite coordinates is introduced. It takes account of the fact that this region of the magnetosphere is strongly influenced by both the earth's ddipole field and the direction of the solar wind. In composite coordinates when Kp< or =4+, 40-keV electron fluxes were almost continuously present in a region centered on the equatorial palne and 1.2 R/sub E/ in half width. At larger composite coordinate latitudes there is another region more than 1 R/sub E/ thick within which 40-keV electron fluxes routinely appear and disappear on time scales of one hour as the trapping boundary actively moves over the satellite. We have no evidence that SCATHA over entered the tail lobes where no particles are trapped. When Kp> or =6- the region in which 40-keV electron fluxes were always present moved earthward and/or thinned but remained ordered in composite coordinates. We suggest that the new coordinate system will be useful for ordering other data sets taken in this region of the magnetosphere.

  4. 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.

  5. 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).

  6. Slug Test Characterization Results for Multi-Test/Depth Intervals Conducted During the Drilling of CERCLA Operable Unit OU ZP-1 Wells 299-W11-43, 299-W15-50, and 299-W18-16

    SciTech Connect

    Spane, Frank A.; Newcomer, Darrell R.

    2010-06-21

    The following report presents test descriptions and analysis results for multiple, stress level slug tests that were performed at selected test/depth intervals within three Operable Unit (OU) ZP-1 wells: 299-W11-43 (C4694/Well H), 299-W15-50 (C4302/Well E), and 299-W18-16 (C4303/Well D). These wells are located within south-central region of the Hanford Site 200-West Area (Figure 1.1). The test intervals were characterized as the individual boreholes were advanced to their final drill depths. The primary objective of the hydrologic tests was to provide information pertaining to the areal variability and vertical distribution of hydraulic conductivity with depth at these locations within the OU ZP-1 area. This type of characterization information is important for predicting/simulating contaminant migration (i.e., numerical flow/transport modeling) and designing proper monitor well strategies for OU and Waste Management Area locations.

  7. 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

  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. Novel method to study neutron capture of 235U and 238U simultaneously at keV energies.

    PubMed

    Wallner, A; Belgya, T; Bichler, M; Buczak, K; Dillmann, I; Käppeler, F; Lederer, C; Mengoni, A; Quinto, F; Steier, P; Szentmiklosi, L

    2014-05-16

    The neutron capture cross sections of the main uranium isotopes, (235)U and (238)U, were measured simultaneously for keV energies, for the first time by combining activation technique and atom counting of the reaction products using accelerator mass spectrometry. New data, with a precision of 3%-5%, were obtained from mg-sized natural uranium samples for neutron energies with an equivalent Maxwell-Boltzmann distribution of kT ∼ 25 keV and for a broad energy distribution peaking at 426 keV. The cross-section ratio of (235)U(n,γ)/(238)U(n,γ) can be deduced in accelerator mass spectrometry directly from the atom ratio of the reaction products (236)U/(239)U, independent of any fluence normalization. Our results confirm the values at the lower band of existing data. They serve as important anchor points to resolve present discrepancies in nuclear data libraries as well as for the normalization of cross-section data used in the nuclear astrophysics community for s-process studies. PMID:24877933

  10. 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.

  11. 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.

  12. Novel Method to Study Neutron Capture of U235 and U238 Simultaneously at keV Energies

    NASA Astrophysics Data System (ADS)

    Wallner, A.; Belgya, T.; Bichler, M.; Buczak, K.; Dillmann, I.; Käppeler, F.; Lederer, C.; Mengoni, A.; Quinto, F.; Steier, P.; Szentmiklosi, L.

    2014-05-01

    The neutron capture cross sections of the main uranium isotopes, U235 and U238, were measured simultaneously for keV energies, for the first time by combining activation technique and atom counting of the reaction products using accelerator mass spectrometry. New data, with a precision of 3%-5%, were obtained from mg-sized natural uranium samples for neutron energies with an equivalent Maxwell-Boltzmann distribution of kT ˜25 keV and for a broad energy distribution peaking at 426 keV. The cross-section ratio of U235(n ,γ)/U238(n ,γ) can be deduced in accelerator mass spectrometry directly from the atom ratio of the reaction products U236/U239, independent of any fluence normalization. Our results confirm the values at the lower band of existing data. They serve as important anchor points to resolve present discrepancies in nuclear data libraries as well as for the normalization of cross-section data used in the nuclear astrophysics community for s-process studies.

  13. 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…

  14. 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.

  15. 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.

  16. Gel behavior of keV ion irradiated polystyrene

    SciTech Connect

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

    1988-10-17

    Among the chemical and physical modifications induced by ion bombardment of polymers, the solubility changes are very important because of technological application for lithography in microelectronic devices. Solubility changes due to the occurrence of crosslinkings have been followed on monodisperse and polydisperse polystyrene after ion irradiations (10/sup 11/--10/sup 14/ ions/cm/sup 2/, keV energy). By using the Inokuty gel theory (M. Inokuti J. Appl. Phys. 38, 2999 (1963)), the chemical yield (crosslinking/eV) has been determined for different molecular weights and molecular weight distributions.

  17. 511 keV photons from superconducting cosmic strings.

    PubMed

    Ferrer, Francesc; Vachaspati, Tanmay

    2005-12-31

    We show that a tangle of light superconducting strings in the Milky Way could be the source of the observed 511 keV emission from electron-positron annihilation in the Galactic bulge. The scenario predicts a flux that is in agreement with observations if the strings are at the approximately 1 TeV scale, making the particle physics within reach of planned accelerator experiments. The emission is directly proportional to the galactic magnetic field, and future observations should be able to differentiate the superconducting string scenario from other proposals. PMID:16486335

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

    NASA Astrophysics Data System (ADS)

    Bellm, Eric C.; Vaillancourt, John E.

    2005-04-01

    Snowden and coworkers have presented a model for the 1/4 keV soft X-ray diffuse background in which the observed flux is dominated by a ~106 K thermal plasma located in a 100-300 pc diameter bubble surrounding the Sun but has significant contributions from a very patchy Galactic halo. Halo emission provides about 11% of the total observed flux and is responsible for half of the H I anticorrelation. The remainder of the anticorrelation is presumably produced by displacement of disk H I by the varying extent of the Local Hot Bubble (LHB). The ROSAT R1 and R2 bands used for this work had the unique spatial resolution and statistical precision required for separating the halo and local components but provide little spectral information. Some consistency checks had been made with older observations at lower X-ray energies, but we have made a careful investigation of the extent to which the model is supported by existing sounding rocket data in the Be (73-111 eV) and B (115-188 eV) bands, where the sensitivities to the model are qualitatively different from the ROSAT bands. We conclude that the two-component model is well supported by the low-energy data. We find that these combined observations of the local component may be consistent with single-temperature thermal emission models in collisional ionization equilibrium if depleted abundances are assumed. However, different model implementations give significantly different results, offering little support for the conclusion that the astrophysical situation is so simple.

  19. Evidence for Halo Contributions to the 1/4 keV Diffuse Soft X-Ray Background

    NASA Astrophysics Data System (ADS)

    Bellm, E. C.

    2003-12-01

    The 1/4-keV diffuse soft X-ray background (SXRB) apparently originates in a thermal plasma at around 106 K, but the location of this emission has proven to be difficult to determine. The finite flux in the Galactic plane and similarity of the spectrum at all latitudes led to a model where essentially all of the observed flux originated in a local hot bubble (LHB) surrounding the Sun. Snowden et al. (1998) have proposed a three-component model of the SXRB from the ROSAT All-Sky Survey R12 (1/4 keV) map which consists of an unabsorbed local component, an absorbed halo component, and an absorbed power law to represent the known contribution from AGN, which is quite small. We have investigated whether this model is consistent with the lower-energy data available from sounding rocket flights in the B and Be bands. We find that the Snowden model provides better correspondence with the low-energy Wisconsin bands than the pure LHB model. The differences are subtle because the bulk of the intensity variation in the Snowden model is still due to differences in the extent of the local bubble. We have also investigated whether the observed band ratios are fit by the emission models used. We find that with current collisional ionization equilibrium models, depleted abundances are necessary to be consistent with the observed band ratios. We also show that the model predictions depend strongly on the model version, which does little to lend confidence to their predictions. This work was supported by a NSF-REU site grant (AST-0139563) to the University of Wisconsin-Madison.

  20. 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.

  1. X-Band/Ka-Band Dichroic Plate

    NASA Technical Reports Server (NTRS)

    Chen, Jacqueline C.

    1993-01-01

    Dichroic plate designed nearly transparent to circularly polarized microwaves at frequencies between 31.8 and 34.7 GHz (in and near Ka band) and reflective at frequencies between 8.4 and 8.5 GHz (in the X band). Made of electrically conductive material and contains rectangular holes in staggered pattern.

  2. Characteristics of ZnO Wafers Implanted with 60 keV Sn{sup +} Ions at Room Temperature and at 110 K

    SciTech Connect

    Dang, Giang T.; Taniwaki, Masafumi; Kawaharamura, Toshiyuki; Hirao, Takashi; Nitta, Noriko

    2011-01-07

    ZnO wafers implanted with 60 keV Sn{sup +} ions at room temperature (RT) and at 110 K are investigated by means of X-ray diffraction (XRD) and photoluminescence (PL) techniques. The effect of implantation temperature is evident in the XRD and PL data. A yellow-orange (YO) band near 600 nm appears in the PL spectra of the ZnO wafers implanted to the doses of 4x10{sup 14} and 8x10{sup 14} ions/cm{sup 2} at RT. The intensity of this band increases and the peak position blue-shifts after illumination of the samples with the 325 nm line of a He-Cd laser. The PL data suggests that the CB (conduction band){yields}V{sub O}{sup +} and Zn{sub i}{sup +{yields}}V{sub Zn}{sup -} transitions contribute to the photoemission of the YO band.

  3. 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.

  4. Midnight Sector Observations of Auroral Omega Bands

    NASA Astrophysics Data System (ADS)

    Wild, J. A.; Woodfield, E. E.; Donovan, E. F.; Fear, R. C.; Grocott, A.; Lester, M.; Fazakerley, A. N.; Lucek, E. A.; Kadokura, A.; Hosokawa, K.; Carlson, C. W.; McFadden, J. P.; Glassmeier, K.; Angelopoulos, V.; Björnsson, G.

    2010-12-01

    We present observations of auroral omega bands on 28 September 2009. Although generally associated with the substorm recovery phase and typically observed in the morning sector, the omega bands presented here occurred just after expansion phase onset and were observed in the midnight sector, immediately dawnward of the onset region. The Tjörnes “Rainbow” all-sky imager, located in north-eastern Iceland, revealed that the omega bands were ˜200 km in scale and propagated eastward from the onset region at ˜0.4 km/s while a co-located ground magnetometer recorded the simultaneous passage of Ps 6 pulsations. Although somewhat smaller and slower-moving than the majority of previously reported omega bands, the observed structures were clear examples of this phenomenon, albeit in an atypical location and much earlier in the substorm cycle than is usual. During the study interval the THEMIS A and C probes provided detailed measurements of the upstream interplanetary environment while the Cluster spacecraft were located in the tail plasma sheet conjugate to the ground-based all-sky imager. Cluster observed pulsed fluxes of electrons moving parallel to the magnetic field towards the northern hemisphere auroral ionosphere. Despite mapping uncertainties, there is some suggestion that keV electron fluxes in the tail were related to the auroral emissions in the omega bands. We suggest that omega band formation may be linked to expansion phase onset in the midnight sector and that the finite propagation speed through post-midnight and early morning local times may account for the interpretation of omega bands as a morning sector recovery phase phenomenon.

  5. Photonic band gap materials

    SciTech Connect

    Soukoulis, C.M. |

    1993-12-31

    An overview of the theoretical and experimental efforts in obtaining a photonic band gap, a frequency band in three-dimensional dielectric structures in which electromagnetic waves are forbidden, is presented.

  6. CSF oligoclonal banding

    MedlinePlus

    ... the cerebrospinal fluid (CSF). CFS is the clear fluid that flows in the space around the spinal cord and brain. Oligoclonal bands are proteins called immunoglobulins. The ... system. Oligoclonal bands may be a sign of multiple sclerosis.

  7. Study of keV radiation properties of Mo and Ti X-pinch plasma sources using a pinhole transmission grating spectrometer

    SciTech Connect

    Li Jing; Deng Jianjun; Xie Weiping; Huang Xianbin; Yang Libing; Zhou Shaotong; Duan Shuchao; Zhang Siqun; Dan Jiakun; Zhu Xiaoli

    2010-07-15

    The properties of keV x-ray radiations from Mo and Ti X-pinch plasma sources at the current of 800 kA were investigated by a pinhole transmission grating spectrometer. The spectrometer was characterized by a high linear dispersion rate (2.9 A/mm), and from its time-integrated diffraction images, rich information about the X-pinch sources (e.g., source number, source size, and absolute spectra) could be obtained. Multiple hot spots were produced in all the Mo tests with loads made of two or four 25 mum wires with or without a shunt wire, and obvious increases both in the radiation intensity and in the source size around the spectral region of 2.6 keV were observed. In Ti X-pinch tests, a single keV x-ray burst with a source size of approx200 mum and a time duration of approx200 ps in full width at half maximum was obtained using a load made of two 50 mum wires plus a shunt wire. The intensity of x-rays decreased sharply from approx10{sup 11} photon eV{sup -1} sr{sup -1} at 1 keV to approx10{sup 8} photon eV{sup -1} sr{sup -1} at 4 keV. The energy-dependent source size in the band of 1-4 keV is less than 100 mum and seemed to shrink quickly as x-ray energy increases.

  8. Flat Band Quastiperiodic Lattices

    NASA Astrophysics Data System (ADS)

    Bodyfelt, Joshua; Flach, Sergej; Danieli, Carlo

    2014-03-01

    Translationally invariant lattices with flat bands (FB) in their band structure possess irreducible compact localized flat band states, which can be understood through local rotation to a Fano structure. We present extension of these quasi-1D FB structures under incommensurate lattices, reporting on the FB effects to the Metal-Insulator Transition.

  9. Band structures in 98Ru and 99Ru

    NASA Astrophysics Data System (ADS)

    Van Voorthuysen, E. H. Du Marchie; Devoigt, M. J. A.; Blasi, N.; Jansen, J. F. W.

    1981-03-01

    The level schemes of 98, 99Ru were studied with the reactions 98Mo(α, 3nγ) and 98Mo(α, 4nγ) at Eα = 35 to 55 MeV, using a large variety of in-beam γ-ray detection techniques and conversion-electron measurements. A search for the 3 - state was carried out with the reaction 98Ru(p, p'). The ground-state band of 98Ru was excited up to Jπ = (12) + and a negative-parity band up to (15) -. New levels in 98Ru were found at Ex = 2285 ( Jπ = 4 +), 2435 ( Jπ = (3 -, 4 +)), 2671, 3540, 4224, 4847, 4915 ( Jπ = (12) +), 4989 ( Jπ = (12 +)), 5521 ( Jπ = (13) -), 5889, 6591 ( Jπ = (15) -), and 7621 keV. New unambiguous spin and parity assignments were made for the levels at Ex = 2014 and 3852 keV, as Jπ = 3 + and 9 -, respectively. New levels in 99Ru were found at Ex = 1976, 2021 ( J π = ( {15}/{2}+) ), 2393, 2401 ( J π = ( {17}/{2}+) ), 2875 (π = (+)), 3037, 3201 ( J π = ( {23}/{2}) -), 3460 ( J = ( {17}/{2}) ), 3484 ( J π = ( {21}/{2}+) ), 3985, 4224 ( J π = ( {27}/{2}-) ), and 5359 keV. The 1070 keV, J π = {11}/{2}- level in 99Ru has a half-life of 2.8 ns. A strongly excited negative-parity band is built on this level. A positive-parity band based on the ground state was excited up to J π = ( {21}/{2}+) . The level schemes are well reproduced by the interacting boson model in the vibrational limit.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    The active galactic nuclei (AGN) X-ray luminosity function traces actively accreting supermassive black holes and is essential for the study of the properties of the AGN population, black hole evolution, and galaxy-black hole coevolution. Up to now, the AGN luminosity function has been estimated several times in soft (0.5-2 keV) and hard X-rays (2-10 keV). AGN selection in these energy ranges often suffers from identification and redshift incompleteness and, at the same time, photoelectric absorption can obscure a significant amount of the X-ray radiation. We estimate the evolution of the luminosity function in the 5-10 keV band, where we effectively avoid the absorbed part of the spectrum, rendering absorption corrections unnecessary up to NH ~ 1023 cm-2. Our dataset is a compilation of six wide, and deep fields: MAXI, HBSS, XMM-COSMOS, Lockman Hole, XMM-CDFS, AEGIS-XD, Chandra-COSMOS, and Chandra-CDFS. This extensive sample of ~1110 AGN (0.01 < z < 4.0, 41 < log Lx < 46) is 98% redshift complete with 68% spectroscopic redshifts. For sources lacking a spectroscopic redshift estimation we use the probability distribution function of photometric redshift estimation specifically tuned for AGN, and a flat probability distribution function for sources with no redshift information. We use Bayesian analysis to select the best parametric model from simple pure luminosity and pure density evolution to more complicated luminosity and density evolution and luminosity-dependent density evolution (LDDE). We estimate the model parameters that describe best our dataset separately for each survey and for the combined sample. We show that, according to Bayesian model selection, the preferred model for our dataset is the LDDE. Our estimation of the AGN luminosity function does not require any assumption on the AGN absorption and is in good agreement with previous works in the 2-10 keV energy band based on X-ray hardness ratios to model the absorption in AGN up to redshift three

  11. XMM-Newton slew survey hard band sources

    NASA Astrophysics Data System (ADS)

    Saxton, R. D.; Read, A. M.; Warwick, R. S.; Esquej, M. P.

    2010-07-01

    The XMM-Newton slew survey has a flux limit of 4×10-12 ergs s-1 cm-2 in the hard (2-12 keV) energy band. This gives it the potential to fill in the gap in luminosity functions which currently exist between shallow all-sky surveys (HEAO-1 A2, Ariel V) and the medium deep surveys of ASCA, BeppoSax and latterly the 2XMM serendipitous catalogue. In this paper we explore the hard-band source population with a view to constructing luminosity distributions.

  12. Rapid variability of 10-140 keV X-rays from Cygnus X-1

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Gruber, D. E.; Matteson, J. L.; Peterson, L. E.; Rothschild, R. E.; Doty, J. P.; Levine, A. M.; Lewin, W. H. G.; Primini, F. A.

    1981-01-01

    On five occasions in 1977 and 1978, Cygnus X-1 was observed using the low-energy detectors of the UCSD/MIT Hard X-ray and Low-Energy Gamma Ray experiment on the HEAO 1 satellite. Rapid (times between 0.08 and 1000 sec) variability was found in the 10-140 keV band. The power spectrum was white for frequencies between 0.001 and 0.05 Hz and was proportional to the inverse of the frequency for frequencies between 0.05 and 3 Hz, indicating correlations on all time scales less than approximately 20 s. The shape of the energy spectrum was correlated with intensity; it was harder at higher intensity. If the emission is produced by Comptonization of a soft photon flux in a hot cloud, the heating of the cloud cannot be constant; it must vary on time scales up to approximately 20 s. A variable accretion rate could cause the observed effects.

  13. Measurements of total atomic attenuation cross sections of Tm, Yb, Lu, Hf, Ta, W, Re and Os Elements at 122keV and 136keV

    SciTech Connect

    Kaya, N.; Tirasoglu, E.; Apaydin, G.; Kobya, A. I.

    2007-04-23

    The aim of this study was to measure the total atomic attenuation cross sections ({sigma}t) in eighth elements (69{<=}Z{<=}76) at 122 keV and 136 keV. The experimental values of the cross sections were determined using the transmission geometry. Measurements have been performed using an annular source (Co-57) and Ultra-LEGe solid state detector with a resolution of 150 eV at 5.9 keV. Experimental results have been compared with theoretically calculated values and other available experimental results. Good agreement was observed among the experimental, theoretical and other experimental values.

  14. 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.

  15. Narrow-band 5 kHz hiss observed in the vicinity of the plasmapause

    NASA Astrophysics Data System (ADS)

    Ondoh, T.; Nakamura, Y.; Watanabe, S.; Murakami, T.

    1981-01-01

    Latitudinal distributions of narrow-band 5 kHz hisses have been statistically obtained by using VLF electric field data received from the ISIS-1 and -2 at Syowa station, Antarctica and Kashima station, Japan, in order to study an origin of the narrow-band 5 kHz hisses which are often observed on the ground in mid- and low-latitudes. The result shows that the narrow-band 5 kHz hiss occurs most frequently at geomagnetically invariant latitudes from 55 to 63 deg, which are roughly the plasmapause latitudes at various geomagnetic activities, both in the Northern and Southern Hemispheres. The narrow-band 5 kHz hiss seems to be generated by the cyclotron instabilities of several keV to a few ten keV electrons for the most feasible electron density of 10 to 1000 per cu cm in the vicinity of the equatorial plasmapause.

  16. 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.

  17. 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.

  18. Banded ion morphology

    SciTech Connect

    Frahm, R.A.

    1987-01-01

    Bands of ions have been observed at constant pitch angle by the Dynamics Explorer High- and Low-Altitude Plasma Instruments at auroral latitudes. The observed ion-dispersion pattern shows lower-energy ions toward the equatorward side of the band and higher-energy ions toward the poleward side of the band. Ion bands have their highest-energy flux at small pitch angles. The observed bands have been correlated with storm phase (by Dst) and substorm phase (by AE). Bands are more likely to occur during main-storm phase than during recovery storm phase. Substorm correlations are statistically significant, but there is a hint that most bands occur during substorm recovery phase. Two models have the potential of producing ion signatures that are similar to the band feature. They are the time-of-flight mechanism and the convective dispersion mechanism. Under a time-of-flight mechanism, ions are dispersed along a magnetic filed line with higher-energy particles outrunning lower energy particles. Ions are dispersed perpendicular to the magnetic field under convective dispersion. A time-of-flight effect does not explain the band energy-latitude dependence observed in the southern night or northern day very well, whereas the convective dispersion mechanism easily accomplishes this.

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  1. The search for absorption of 1 keV X-rays by the Small Magellanic Cloud

    NASA Technical Reports Server (NTRS)

    Marazas, Brad

    1989-01-01

    The contribution of the extragalactic component of the diffuse background to the 1 keV energy band remains unknown. An effective way to ascertain this contribution is to measure the absorption of the extragalactic component by the neutral hydrogen in the Small Magellanic Cloud (SMC) with an instrument capable of eliminating point sources from the X-ray data that compensate for absorption. The image proportional counter data from the Einstein observatory can be used for this purpose. Additionally, any extended emission must also be eliminated. The resulting source free data can be compared to the neutral hydrogen and the amount of absorption can then be obtained when compared to the diffuse flux away from the SMC. However, due to other types of radiation contaminating the X-ray data, a true measure of the X-ray absorption was not obtained.

  2. 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,…

  3. 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…

  4. 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.

  5. 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.

  6. 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.

  7. HEAO 1 observations of the Perseus cluster above 10 keV

    NASA Technical Reports Server (NTRS)

    Primini, F. A.; Howe, S. K.; Lang, F.; Levine, A. M.; Lewin, W. H. G.; Rothschild, R.; Baity, W. A.; Gruber, D. E.; Knight, F. K.; Basinska, E.

    1981-01-01

    Results are presented of HEAO 1 observations of the Perseus cluster from 10 to 150 keV in 1977 August and 1978 February and August. The spectrum exhibits a previously unknown hard (greater than 25 keV) component in addition to the previously known thermal bremsstrahlung emission. The data presented show no significant evidence of variability from 10.5 keV to 93.5 keV, and a comparison of our results with earlier results indicates no strong evidence for variability above 25 keV over a time scale of 4 yr. If the hard-component excess is due to NGC 1275, the data imply a 2-6 keV X-ray luminosity of 1 x 10 to the 44th ergs/s for the galaxy, or about 15% of the total cluster emission from 2 to 6 keV and a 25-40 keV luminosity of 8 x 10 to the 43rd ergs/s.

  8. 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.

  9. Chiral Bands and Triaxiality

    SciTech Connect

    Petrache, C.M.

    2004-02-27

    The results obtained with the GASP array in the A=130 mass region are reviewed, emphasizing the discovery excited highly-deformed bands and their decay out, the study of the odd-odd Pr nuclei up to high spins, the discovery of stable triaxial bands in Nd nuclei close to the N=82 shell closure. The very recent studies of nuclei near the proton drip line are described. A discussion of the origin of the various doublet bands observed in odd-odd nuclei of the A=130 mass region is presented.

  10. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    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 ɛ = AΕa+BΕb, where ɛ is efficiency, Ε 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.

  12. Laparoscopic gastric banding

    MedlinePlus

    ... gastric banding is not a "quick fix" for obesity. It will greatly change your lifestyle. You must ... panel on weight loss surgery: executive report update. Obesity . 2009;17:842-62. PMID: 19396063 www.ncbi. ...

  13. Laparoscopic gastric banding

    MedlinePlus

    ... lining), heartburn , or stomach ulcers Infection in the port, which may need antibiotics or surgery Injury to ... may not be able to reach the access port to tighten or loosen the band (you would ...

  14. 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.

  15. CSF oligoclonal banding - slideshow

    MedlinePlus

    ... presentations/100145.htm CSF oligoclonal banding - series—Normal anatomy ... Overview The cerebrospinal fluid (CSF) serves to supply nutrients to the central nervous system (CNS) and collect waste products, as well as ...

  16. 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. ...

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-09-01

    Depth graded multilayer designs for hard x-ray telescopes in the 10 keV to 70-80 keV energy range have had either W or Pt as the heavy element. These materials have been chosen because of reasonable optical constants, the possibility to grow smooth interfaces with the spacer material, and the stability over time. On the flip side both W and Pt have an absorption edge -- 69.5 keV (W) and 78.4 keV (Pt) -- which is very close to the two 44Ti lines at 67.9 keV and 78.4 keV that are produced in the envelope of a super nova explosion. Other materials have better optical constants and no absorption edges in this energy range, for example Ni 0.93V 0.07, but are not used because of high interface roughness. By using a WC/SiC multilayer for the bottom and a Ni 0.93V 0.07/SiC multilayer for the thicker top layers of a depth graded multilayer we have made a reflector that doesn't have a clear absorption edge. This reflector has been measured at energies between 8 keV and 130 keV. At a graze angle of 0.11 degree there is still nearly the same reflectivity below the W absorption edge as for a traditional W based coating, and above the W absorption edge there is still 48% reflection at 80 keV.

  19. 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).

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

    NASA Astrophysics Data System (ADS)

    Angelone, M.; Esposito, A.; Chiti, M.; Gentile, A.

    2001-06-01

    The total absorption coefficients for some selected organic compounds relevant to health physics, Triaflol BN (C 3H 4O 2) n, Triaflol TN (C 12H 18O 7) n, Kapton (C 44H 20O 10) n, and Melinex (C 10H 8N 4O 4) n were measured in the X-ray energy range from 13 keV up to about 40 keV using a collimator, high purity germanium detector with thin Be window and variable energy X-ray source. The measured values are compared with the theoretical ones obtained using the XCOM code. The agreement is generally good within a few percent.

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

    NASA Astrophysics Data System (ADS)

    Alarcón, F. B.; Martinez, H.; Fuentes, B. E.; Yousif, F. B.

    2013-08-01

    Absolute electron capture cross sections for the K+-H2 pair, employing beam collision spectroscopy for 0.4-4 keV energy were measured. The capture cross section increased with the increase in collision energy. The results below 2 keV overlap with previously measured data of other investigators and extend down in energy to 400 eV, where no previous data have been reported. Experimental data were compared with calculations employing the Olson model, which were found to agree in behavior as well as with an absolute value above 100 keV.

  2. ROSAT detection of an X-ray shadow in the 1/4-keV diffuse background in the Draco nebula

    NASA Technical Reports Server (NTRS)

    Snowden, S. L.; Mebold, U.; Hirth, W.; Herbstmeier, U.; Schmitt, J. H. M.

    1991-01-01

    The detection by the Roentgen satellite (ROSAT) X-ray telescope of a shadow in the 1/4-keV (C-band, 0.1 to 0.284 keV) cosmic diffuse background is reported. The location and morphology of the local minimum in X-rays are in clear agreement with a discrete H I cloud. The shadow is very deep with a minimum level at 50 percent of the surrounding emission; therefore, a minimum of 50 percent of the observed off-cloud flux must originate on the far side of the cloud. The analysis of H I velocity components links the cloud with the Draco nebula (distance of about 600 parsecs); it then follows that there is significant 1/4-keV X-ray emission at large distance (more than 400 parsecs) from the galactic plane along this line of sight. The extent of the distant emission region is uncertain, and if it indicates the existence of a hot galactic corona, it must be patchy in nature.

  3. Precision Measurements of the 278 keV {sup 14}N(p,{gamma}) and the 151 keV {sup 18}O(p,{alpha}) Resonance Parameters

    SciTech Connect

    Borowski, M.; Lieb, K. P.; Uhrmacher, M.; Bolse, W.

    2009-01-28

    In thin film technology, analytical methods for monitoring the deposition of oxide and nitride coatings and the effects of corrosive, laser and ion-beam treatments have attracted considerable attention. For depth-profiling the concentrations of light isotopes, resonant nuclear reaction analysis is an excellent non-destructive ion-beam analytical tool. We report here on precision measurements of the 278 keV {sup 14}N(p,{gamma}) and the 151 keV {sup 18}O(p,{alpha}) resonances using the high-resolution proton beam of the Goettingen IONAS accelerator. The deduced resonance energies E{sub R} and total widths {gamma}(in the laboratory system) are E{sub R} = 277.60(27) keV and {gamma} = 1115(33) eV for the {sup 14}N(p,{gamma}) resonance, and E{sub R} = 150.97(26) keV and {gamma} = 178(35) eV for the {sup 18}O(p,{alpha}) resonance. These values are significantly more precise than the ones quoted in the literature.

  4. Measurement of photon mass attenuation coefficients of plutonium from 60 to 2615 keV

    NASA Astrophysics Data System (ADS)

    Rettschlag, M.; Berndt, R.; Mortreau, P.

    2007-11-01

    Measurements have been made to determine plutonium photon mass attenuation coefficients by using a collimated-beam transmission method in the energy range from 60 to 2615 keV. These experimental results were compared with previous experimental and theoretical data. Good agreements are observed in the 240-800 keV energy range, whereas differences up to maximum 10% are observed out of these limits.

  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. Synthesizing folded band chaos.

    PubMed

    Corron, Ned J; Hayes, Scott T; Pethel, Shawn D; Blakely, Jonathan N

    2007-04-01

    A randomly driven linear filter that synthesizes Lorenz-like, reverse-time chaos is shown also to produce Rössler-like folded band wave forms when driven using a different encoding of the random source. The relationship between the topological entropy of the random source, dissipation in the linear filter, and the positive Lyapunov exponent for the reverse-time wave form is exposed. The two drive encodings are viewed as grammar restrictions on a more general encoding that produces a chaotic superset encompassing both the Lorenz butterfly and Rössler folded band paradigms of nonlinear dynamics. PMID:17500950

  7. New constraints on the 2-10 keV X-ray luminosity function from the Chandra COSMOS Legacy Survey

    NASA Astrophysics Data System (ADS)

    Marchesi, Stefano; Civano, Francesca M.; Elvis, Martin; Urry, C. Megan; Comastri, Andrea; Chandra Cosmos Legacy Team

    2015-01-01

    In this talk, we present new results on number counts and luminosity function in the 0.5-2 and 2-10 keV bands, obtained in the Chandra COSMOS Legacy Survey. The COSMOS field is the largest (2 deg2) field with a complete coverage at any wavelength, and the Chandra COSMOS-Legacy survey uniformly covers the 1.7 deg2 COSMOS/HST field to ~160 ksec depth, with a total of 2.8 Ms exposure time. This triples the area of the earlier deep C-COSMOS survey (limiting flux ~3e-16 ergs/cm2/s in the 0.5-2 keV band), and together these two projects cover a total area of 2.2 deg2, yielding a sample of ~4100 X-ray sources, ~2300 of which have been detected in the new observations. We describe how the survey improves our knowledge in the galaxy-super massive black hole co-evolution.

  8. Multi-Band-SWIFT

    PubMed Central

    Corum, Curtis A.; Garwood, Michael

    2015-01-01

    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. PMID:25557859

  9. Colloquium: Topological band theory

    NASA Astrophysics Data System (ADS)

    Bansil, A.; Lin, Hsin; Das, Tanmoy

    2016-04-01

    The first-principles band theory paradigm has been a key player not only in the process of discovering new classes of topologically interesting materials, but also for identifying salient characteristics of topological states, enabling direct and sharpened confrontation between theory and experiment. This review begins by discussing underpinnings of the topological band theory, which involve a layer of analysis and interpretation for assessing topological properties of band structures beyond the standard band theory construct. Methods for evaluating topological invariants are delineated, including crystals without inversion symmetry and interacting systems. The extent to which theoretically predicted properties and protections of topological states have been verified experimentally is discussed, including work on topological crystalline insulators, disorder and interaction driven topological insulators (TIs), topological superconductors, Weyl semimetal phases, and topological phase transitions. Successful strategies for new materials discovery process are outlined. A comprehensive survey of currently predicted 2D and 3D topological materials is provided. This includes binary, ternary, and quaternary compounds, transition metal and f -electron materials, Weyl and 3D Dirac semimetals, complex oxides, organometallics, skutterudites, and antiperovskites. Also included is the emerging area of 2D atomically thin films beyond graphene of various elements and their alloys, functional thin films, multilayer systems, and ultrathin films of 3D TIs, all of which hold exciting promise of wide-ranging applications. This Colloquium concludes by giving a perspective on research directions where further work will broadly benefit the topological materials field.

  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. The Steel Band.

    ERIC Educational Resources Information Center

    Weil, Bruce

    1996-01-01

    Describes studying the steel drum, an import from Trinidad, as an instrument of intellectual growth. Describes how developing a steel drum band provided Montessori middle school students the opportunity to experience some important feelings necessary to emotional growth during this difficult age: competence, usefulness, independence, and…

  12. Europa Triple Band

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This picture of Europa, a moon of Jupiter, was obtained on February 20, 1997, by the Solid State Imaging system onboard the Galileo spacecraft during its sixth orbit around Jupiter. The area is centered at 9.3 degrees north latitude, 275.7 degrees west longitude, on the trailing hemisphere of Europa. As Europa moves in its orbit around Jupiter, the trailing hemisphere is the portion which is always on the moon's backside opposite to its direction of motion. The area depicted is about 32 kilometers by 40 kilometers (20 miles by 25 miles). Resolution is 54 meters (59 yards). The Sun illuminates the scene from the right (east).

    A section of a triple band crosses the upper left of the picture and extends for hundreds of miles across the surface. Triple bands derive their name from their appearance at lower resolution as a narrow bright band flanked by a pair of darker bands. At the high resolution of this picture, however, the triple band is much more complex and is composed of a system of ridges 6 kilometers (4 miles) across. Some ridges reach heights of about 180 meters (200 yards). Other features include a hill in the center of the picture about 480 meters (500 yards) high. Two mounds about 6 kilometers across (4 miles) are seen in the bottom of the picture. The ridges, hills and mounds probably all represent uplifts of the icy crust of Europa by processes originating from the interior.

    The Jet Propulsion Laboratory, Pasadena, CA, manages the mission for NASA's Office of Space Science, Washington D.C. This image and other images and data received from Galileo are posted on the World Wide Web Galileo mission home page at: http://galileo.jpl.nasa.gov.

  13. The Yrast Rotational Bands of SELENIUM-74 and KRYPTON-77

    NASA Astrophysics Data System (ADS)

    Gross, Carl J.

    1987-09-01

    New states in the positive parity yrast bands of ^{74}Se and ^{77}Kr have been observed with the reactions ^{52}Cr( ^{28}Si,alpha 2p)^{74}Se and ^{52}Cr(^ {28}Si,2pn)^{77} Kr at 98 MeV. The target consisted of approximately 1 mg/cm^2 natural chromium (84% ^{52}Cr abundance) evaporated on a thick lead backing. The new states extend the known level scheme of ^{74}Se up to I ^{pi} = (22^+ ) and most of the transitions in the other previously reported bands have been seen. For the states I ^{pi} >=q 6^+ the spectrum shows a relatively constant moment of inertia parameter (hbar ^2/2Theta) = 27.8 +/- 0.5 keV. Excited positive parity states up to spin (41/2) have been observed in ^{77}Kr. DeltaI = 1 transitions have been identified throughout the positive parity band. The energies, mixing ratios and B(M1) transition rates for these transitions alternate in size as the spin increases. A cranked shell model analysis was performed along with Strutinsky-Bogolyubov cranking calculations. The observed decrease in the signature splitting of the nug_ {9/2} band has been attributed to a band crossing due to an aligning pair of g_{9/2 } protons. Prolate quadrupole deformations of beta_2 = 0.34 for the ground band and beta_2 = 0.26 for the first excited band are predicted. This band crossing is associated with a shape change caused by the polarization effect of aligned quasiparticles.

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

    SciTech Connect

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

    1990-12-01

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

  15. 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.

  16. 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.

  17. Valence-band states of ion-bombarded polystyrene

    SciTech Connect

    Terrasi, A. ); Foti, G. ); Hwu, Y. ); Margaritondo, G. )

    1991-08-01

    Ion-bombarded polystyrene with a 0.5-keV Ar{sup +} beam has been investigated by means of photoelectron spectroscopy performed with synchrotron radiation. After a dose of 10{sup 15} ions/cm{sup 2} the evolution of the valence band of the bombarded sample towards an amorphous carbonlike configuration is reported. From the analysis of valence-band spectra we estimated the out-diffusion of hydrogen and showed that its electronic states remain well identified and stable until the hydrogen presence is about 35% with respect to the pristine sample. Finally, comparison with mass spectroscopy measurements on deuterated polystyrene has been performed to determine hydrogen evolution during the ion irradiation.

  18. TDRS Ku band gateway

    NASA Technical Reports Server (NTRS)

    Collins, Cynthia; Lecha, Javier; Principe, Caleb M.; Ross, Douglas

    1987-01-01

    The Wideband Transport Frame Formatter (WTFF) is the tracking and data relay satellite (TDRS) ku-band return link gateway. The WTFF system is a multiplexing device developed to process and downlink the high rate data generated by a wide variety of users. The WTFF is designed to frame and format high data rate user channels into transport frames and multiplex according to a predefined schedule into two bit streams that are compatible with TDRS Ku I and Q band service. The combined data rate will be 300 Mbps. The WTFF will service up to eight input channels generating data in the range of 10 to 150 Mbps. In addition to these input channels, audio data will be accepted by the WTFF system and inserted in the downlink. A second function of the WTFF is to provide telecommunication coding as assigned to each virtual channel to ensure a given quality of service.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. HEAO 3 upper limits to the expected 1634 KeV line from SS 483

    NASA Technical Reports Server (NTRS)

    Wheaton, W. A.; Ling, J. C.; Mahoney, W. A.; Jacobson, A. S.

    1985-01-01

    A model based on 24 Mg(1369) was developed as the source of the lines in which refractory grains in the jets, containing Mg and 0, are bombarded, by ambient protons in the local ISM. The narrowness of the features results because the recoil Mg nucleus is stopped in the grain before the 1369 keV excited state decays. A consequence of the 24 Mg interpretation is the expected appearance of other emission lines, due to 20 Ne and 20 Na, which are produced by proton bombardment of 24 Mg at the 33 MeV/nucleon energy corresponding to the velocity of the jets. These lines appear at rest energies of 1634 keV and 1636 keV, respectively, and should have essentially the same total flux as that emited at 1369 keV. The HEAO 3 data are examined to search for the 1634 keV (rest) emission. The observation and analysis, the results, and the implications for the understanding of SS 433 are discussed.

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

    NASA Astrophysics Data System (ADS)

    Rudakovskyi, Anton; Iakubovskyi, Dmytro

    2016-06-01

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

  5. 2-165 keV observations of active galaxies and the diffuse background

    NASA Technical Reports Server (NTRS)

    Rothschild, R. E.; Baity, W. A.; Gruber, D. E.; Matteson, J. L.; Peterson, L. E.; Mushotzky, R. F.

    1983-01-01

    HEAO 1 spectral observations of 12 active galaxies in the 12-165 keV and 2-50 keV ranges are reported. The spectra of these galaxies in the 2-165 keV range are well represented by a single power law model; within experimental uncertainties a narrow dispersion in power law index attributable to the individual galaxies is observed, while the 2-165 keV luminosities of these galaxies ranged from 3 x 10 to the 43rd to 3 x 10 to the 45th ergs/s. An apparent universality of the spectral form is found which can be interpreted as due to a common electron distribution with a temperature of tens of keV in the Compton scattering region or as a common nonthermal power-law distribution generating the observed flux through synchrotron-Compton processes. The data indicate that relativistic particles are likely to be responsible for the X-rays from cores of active galaxies through synchroton-Compton processes. In addition, it is noted that only weak number evolution, if any at all, is present in active galaxies.

  6. Spatial distribution of upstream magnetospheric geq50 keV ions

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, G. C.; Argyropoulos, G.; Kaliabetsos, G.

    2000-01-01

    We present for the first time a statistical study of geq50 keV ion events of a magnetospheric origin upstream from Earth's bow shock. The statistical analysis of the 50-220 keV ion events observed by the IMP-8 spacecraft shows: (1) a dawn-dusk asymmetry in ion distributions, with most events and lower intensities upstream from the quasi-parallel pre-dawn side (4 LT-6 LT) of the bow shock, (2) highest ion fluxes upstream from the nose/dusk side of the bow shock under an almost radial interplanetary magnetic field (IMF) configuration, and (3) a positive correlation of the ion intensities with the solar wind speed and the index of geomagnetic index Kp, with an average solar wind speed as high as 620 km s-1 and values of the index Kp > 2. The statistical results are consistent with (1) preferential leakage of sim50 keV magnetospheric ions from the dusk magnetopause, (2) nearly scatter free motion of sim50 keV ions within the magnetosheath, and (3) final escape of magnetospheric ions from the quasi-parallel dawn side of the bow shock. An additional statistical analysis of higher energy (290-500 keV) upstream ion events also shows a dawn-dusk asymmetry in the occurrence frequency of these events, with the occurrence frequency ranging between sim16%-sim34% in the upstream region.

  7. 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.

  8. 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.

  9. Cyclotron side-band emissions from ring-current electrons

    NASA Technical Reports Server (NTRS)

    Maeda, K.

    1976-01-01

    The paper examines temporal variations in electron energy spectra and pitch-angle distributions during a VLF-emission event observed by Explorer 45 in the main phase of a magnetic storm. It is noted that the observed event occurred outside the plasmasphere on the night side of the magnetosphere and that the dusk-side plasmapause had a double structure during the event. It is found that the VLF emissions consisted of two frequency bands, corresponding to the whistler and electrostatic modes, and that there was a sharp band of 'missing emissions' along frequencies equal to half the equatorial electron gyrofrequency. A peculiar pitch-angle distribution for high-energy electrons (50 to 350 keV) is noted. It is concluded that the VLF-producing particles were enhanced low-energy (about 5 keV) ring-current electrons which penetrated into the night side of the magnetosphere from the magnetotail plasma sheet and which drifted eastward after encountering the steep gradient of the geomagnetic field.

  10. 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.

  11. Ion-chain interaction in keV ion-beam-irradiated polystyrene

    SciTech Connect

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

    1987-09-21

    Molecular weight distribution has been measured in monodisperse polystyrene film (MW = 9 000 amu) after ion bombardment, in the ion fluence range 10/sup 11/--10/sup 13/ ions/cm/sup 2/. The chosen beams are 100 keV He, 200 keV Ne, and 400 keV Ar. The experimental data have been interpreted in terms of a simple statistical model for cross-links. The chemical yield is found to be very high and equal to 0.30, about a factor of 10 higher than the values given in the literature for gamma irradiation (M. Dole, in The Radiation Chemistry of Macromolecules (Academic, New York, 1973), Vol. 2, Chap. 5, p. 57).

  12. Width of the 511 keV line from the bulge of the galaxy

    SciTech Connect

    Zhitnitsky, Ariel

    2007-11-15

    In this paper I present the detail estimations for the width of the 511 keV line produced by a mechanism when dark matter is represented by macroscopically large dense nuggets. I argue that the width of 511 keV emission in this mechanism is very narrow (in a few keV range) in agreement with all observations. The dominant mechanism of the annihilation in this case is the positronium formation e{sup +}e{sup -}{yields}{sup 1}S{sub 0}{yields}2{gamma} rather than a direct e{sup +}e{sup -}{yields}2{gamma} annihilation. I also discuss some generic features of the {gamma} rays spectrum (in few MeV range) resulting from this mechanism.

  13. Guidelines for using a 10-keV x-ray source for hardness assurance

    SciTech Connect

    Fleetwood, D.M.

    1986-01-01

    In this paper, work done at Sandia is summarized that demonstrates that it is possible to use a 10-keV x-ray source for hardness assurance. Transistor data is presented that shows that a 10-keV x-ray source can be used as a reliable process monitor, in the sense that Co-60 part response can be predicted easily and reliably from x-ray part response. Further, test structure and functional part data is presented that illustrates how an x-ray source may be employed for wafer lot acceptance for silicon-gate CMOS devices that either employ quardbands or hardened field oxides for device isolation. Finally, a few words are said about the use of high-Z gate metallizations. These results should provide guidelines for implementation of lot acceptance testing with a 10-keV x-ray source.

  14. 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)%.

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

    NASA Astrophysics Data System (ADS)

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

    1988-08-01

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

  16. VizieR Online Data Catalog: 2-10keV luminosity function of AGN (Ranalli+, 2016)

    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.

    2016-02-01

    The XMM-LSS, XMM-CDFS, and XMM-COSMOS are three surveys with complementary properties in terms of luminosity and redshift coverage. We used these three surveys to derive Bayesian estimates of the unabsorbed luminosity function (LF) of AGN in the 2-10keV band. The LF estimates are presented as a set of samples from the posterior probability distribution of the LF parameters. The LF is parameterised as a double power-law, with either the luminosity and density evolution (LADE) model, or the luminosity-dependent density evolution (LDDE) model. The double power-law is described by Eq.(10) in the paper. The LADE and LDDE models are described by Eqs.(11-14) and Eqs.(15-17), respectively. A Fortran 2008 implementation of these models can be found in file src2/lumf_funcs.f90 of the LFTools package, in the classes doublepowerlaw, ladevol, and lddevol (see the paper). (8 data files).

  17. Application of monochromatic keV X-ray source to X-ray drug delivery system

    NASA Astrophysics Data System (ADS)

    Uesaka, Mitsuru; Taguchi, Hiroki; Mori, Azusa; Yusa, Noritaka; Kato, Takamitsu; Okayasu, Ryuichi

    2009-09-01

    X-ray Drug Delivery System (DDS) enhances accumulation of anti-cancer drug or contrast agent by surrounding it with polymer and Enhanced Penetration and Retention (EPR) effect. DDS uses advanced nano-scaled polymers that contain and deliver drug or contrast agent to cancers without side effects. Several X-ray DDSs pose high-Z atoms such as gold to absorb X-rays effectively and used as contrast agent for inspection. Moreover, they have radiation enhancement effect by emission of Auger electron and successive characteristic X-rays. The enhancement factor of gold is more than five. This could be used even for therapy. This new modality must be very important for inspection and therapy of deep cancers. We are making use of our X-band Compton scattering monochromatic keV X-ray source for the inspection. Numerical simulation on monochromatic X-ray CT for possible concentration of gold-colloid DDS considering the X-ray property from the source was done. Enough visibility was confirmed. Furthermore, in vitro experiment analyzed its toxic effect to cells by the Alkaline comet assay and fluorescent immunostaining method for single and double strand breaks of DNA. Availability of clear imaging for the inspection has been confirmed by the numerical simulation and the in-vitro evaluation of the therapy effect is under way.

  18. PACT: a sensitive 100 keV-10 MeV all sky pairs and Compton telescope

    NASA Astrophysics Data System (ADS)

    Laurent, P.; Tatischeff, V.; de Seréville, N.; Limousin, O.; Bertoli, W.; Bréelle, E.; Dolgorouky, Y.; Gostojic, A.; Hamadache, C.; Khalil, M.; Kiener, J.

    2014-07-01

    PACT is a Pair And Compton Telescope that aims to make a sensitive survey of the gamma-ray sky between 100 keV and 100 MeV. It will be devoted to the detection of radioactivity lines from present and past supernova explosions, the observation of thousands of new blazars, and the study of polarized radiations from gamma-ray bursts, pulsars and accreting black holes. It will reach a sensitivity of one to two orders of magnitude lower than COMPTEL/CGRO (e.g. about 50 times lower for the broad-band, survey sensitivity at 1 MeV after 5 years). The concept of PACT will be proposed for the AstroMeV mission in the framework of the M4 ESA Call. It is based upon three main components: a silicon-based gamma-ray tracker, a crystal-based calorimeter (e.g. CeBr3:Sr), and an anticoincidence detector made of plastic scintillator panels. Prototypes of these detector planes are currently tested in the laboratories.

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

    NASA Astrophysics Data System (ADS)

    Boughariou, A.; Blaise, G.; Braga, D.; Kallel, A.

    2004-04-01

    A scanning electron microscope has been equipped to study the fundamental aspects of charge trapping in insulating materials, by measuring the secondary electron emission (SEE) yield σ with a high precision (a few percent), as a function of energy, electron current density, and dose. The intrinsic secondary electron emission yield σ0 of uncharged MgO single crystals annealed at 1000 °C, 2 h, has been studied at four energies 1.1, 5, 15, and 30 keV on three different crystal orientations (100), (110), and (111). At low energies (1.1 and 5 keV) σ0 depends on the crystalline orientation wheras at high energies (30 keV) no differentiation occurs. It is shown that the value of the second crossover energy E2, for which the intrinsic SEE yield σ0=1, is extremely delicate to measure with precision. It is about 15 keV±500 eV for the (100) orientation, 13.5 keV±500 eV for the (110), and 18.5 keV±500 eV for the (111) one. At low current density J⩽105 pA/cm2, the variation of σ with the injected dose makes possible the observation of a self-regulated regime characterized by a steady value of the SEE yield σst=1. At low energies 1.1 and 5 keV, there is no current density effects in MgO, but at high energies ≈30 keV, apparent current density effects come from a bad collect of secondary electrons, due to very high negative surface potential. At 30 keV energy, an intense erratic electron exoemission was observed on the MgO (110) orientation annealed at 1500 °C. This phenomenon is the result of a disruptive process similar to flashover, which takes place at the surface of the material.

  20. 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.

  1. 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.

  2. Realistic Sterile Neutrino Dark Matter with KeV Mass does not Contradict Cosmological Bounds

    SciTech Connect

    Boyarsky, Alexey; Lesgourgues, Julien; Ruchayskiy, Oleg

    2009-05-22

    Previous fits of sterile neutrino dark matter (DM) models to cosmological data ruled out masses smaller than {approx}8 keV, assuming a production mechanism that is not the best motivated from a particle physics point of view. Here we focus on a realistic extension of the standard model with three sterile neutrinos, consistent with neutrino oscillation data and baryogenesis, with the lightest sterile neutrino being the DM particle. We show that for each mass {>=}2 keV there exists at least one model accounting for 100% of DM and consistent with Lyman-{alpha} and other cosmological, astrophysical, and particle physics data.

  3. Observations of 12-200 keV X-rays from GX 339-4

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Gruber, D. E.; Knight, F. K.; Matteson, J. L.; Peterson, L. E.; Levine, A. M.; Lewin, W. H. G.; Primini, F. A.

    1982-01-01

    X-ray spectra of GX 339-4 measured on three occasions in 1977 and 1978 are presented. These are the first reported measurements above 10 keV. The spectra can be described as the superposition of a soft component, which is dominant below about 20 keV, and a hard component at higher energy. Simultaneous measurements at lower energy show that the soft component vanished during the observation in early 1978. The behavior of these two components is similar to that of the spectrum of Cygnus X-1; this reinforces the previously noted resemblance in rapid X-ray variability.

  4. 511 keV line from Q balls in the galactic center

    SciTech Connect

    Kasuya, Shinta; Takahashi, Fuminobu

    2005-10-15

    The 511 keV photons from the galactic center can be explained by positrons produced through Q-ball decay. In the scheme of gauge-mediated supersymmetry breaking, large Q balls with lepton charge are necessarily long-lived. In particular, the lifetime can be as long as (or even longer than) the age of the Universe. If kinematically allowed, such large Q balls decay into positrons, which eventually annihilate with electrons into 511 keV photons. Our scenario is realized within the minimal supersymmetric standard model in the inflationary universe, which is very plausible.

  5. Tomographic scanning microscope for 1-4 KeV x-rays

    SciTech Connect

    McNulty, I.; Feng, Y.P.; Hadda, W.S.; Trebes, J.E.

    1995-12-31

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

  6. 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.

  7. 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.

  8. Electron-impact excitation of the 31. 4-eV band in N sub 2

    SciTech Connect

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

    1990-08-01

    Generalized oscillator strengths (GOS) for the dipole-forbidden 31.4-eV band in N{sub 2} have been determined both experimentally and theoretically. The experimental values for the GOS were obtained using a crossed-beam electron spectrometer at 1-keV impact energy. The theoretical results were determined using the first Born approximation with {ital ab} {ital initio} configuration-interaction target wave functions.

  9. Dual-band relativistic backward wave oscillators based on a single beam and dual beams

    NASA Astrophysics Data System (ADS)

    Ting, Wang; Jian-de, Zhang; Bao-liang, Qian; Xiao-ping, Zhang

    2010-04-01

    Two types of relativistic backward wave oscillators (RBWOs) used to produce dual-band microwaves are proposed and investigated by use of the particle-in-cell (PIC) simulation code KARAT [V. P. Tarakanov, User's Manual for Code Karat (Berkeley Research Associates, Springfield, VA, 1992)]. The first type of RBWO, for generation of C-band and X-band microwaves, is designed based on a single beam and a sectioned structure. With an electron beam of 650 keV and 5.0 kA guided by a magnetic field of 2.0 T, an average power of 380 MW with a total power conversion efficiency of 11.7% is obtained and the frequencies are 5.48 and 9.60 GHz, respectively. By changing the distance between the two sections, single-band oscillations are realized with higher power conversion efficiency than that of the dual-band oscillation. The second type, based on a coaxial structure and dual parallel annular beams, is a dual-band RBWO designed with separated beam-wave interaction regions for generation of C-band and X-band microwaves. With a dual beam of 650 keV and 11.8 kA (the outer beam current is 6.4 kA and inner beam current is 5.4 kA) guided by a magnetic field of 2.0 T, an output power of 1400 MW with a total power conversion efficiency of 18.3% is generated and the frequencies are 4.60 and 8.40 GHz, respectively. PIC simulations demonstrate that the two beam-wave interaction regions operate independently. The two types of dual-band RBWO are also compared and analyzed.

  10. Detection of interplanetary electrons from 18 keV to 1.8 MeV during solar quiet times, 1. On the origin of 200 KeV interplanetary electrons, 2.

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Anderson, K. A.; Cline, T. L.; Ramaty, R.; Fisk, L. A.

    1972-01-01

    A quiet time component of interplanetary electrons having energies above solar wind energies and below those characterized as cosmic radiation was observed. Its energy spectrum falls with energy from 18 keV to 1.8 MeV, but it shows a feature in the 100 to 300 keV range. The observed temporal variations of the intensity suggest that the 18 to 100 keV portion is solar and the 0.3 to 1.8 MeV portion is galactic in origin. Solar and terrestrial neutron decay electrons appear inadequate to explain the 100 to 300 keV feature.

  11. Investigating geomagnetic activity dependent sources of 100s of keV electrons in Earth's inner radiation belt using Van Allen Probes observations

    NASA Astrophysics Data System (ADS)

    Turner, D. L.; O'Brien, T. P., III; Fennell, J. F.; Claudepierre, S. G.; Blake, J. B.; Baker, D. N.; Henderson, M. G.; Reeves, G. D.

    2015-12-01

    By providing an unprecedented level of reliability in particle flux observations at low L-shells, NASA's Van Allen Probes mission has yielded a series of discoveries and unanswered questions concerning the inner electron radiation belt. Two such discoveries are: 1) a sharp cutoff in the energy distribution of electrons at ~900 keV, such that fluxes of electrons with energies greater than ~900 keV are below the detectability threshold of the Van Allen Probes' MagEIS instruments and consistent with upper flux limits of multi-MeV electrons calculated using the Van Allen Probes' REPT instruments, and 2) that impulsive injections of up to several hundred keV electrons may act as an activity-dependent source of electrons in the slot and inner radiation belt. In this presentation, we discuss results from phase space density (PSD) analysis of inner zone electrons. Such analysis, which examines PSD as a function of the three adiabatic invariants, effectively removes adiabatic variations in the particle observations allowing one to better identify source and loss processes ongoing in the system. We demonstrate that impulsive injections do indeed act as a source of inner radiation belt electrons and, when combined with losses in the slot region, can result in peaked radial distributions of electron PSD in the inner zone. We briefly discuss the nature of these low-L injections, which penetrate inside the plasmasphere and display strong energy and species dependencies. By examining such injections throughout the Van Allen Probes era, we also i) determine the occurrence rate of injections as a function of electron energy (and first adiabatic invariant), geomagnetic activity level, and L-shell; ii) estimate the contribution of such injections to the inner belt population; and iii) investigate how such injections disrupt coherent banded flux structures in the inner zone known as "zebra stripes".

  12. Constraining models for keV sterile neutrinos by quasidegenerate active neutrinos

    NASA Astrophysics Data System (ADS)

    Merle, Alexander

    2012-12-01

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

  13. Field aligned currents and the auroral spectrum below 1 keV

    NASA Technical Reports Server (NTRS)

    Arnoldy, R. L.

    1973-01-01

    Measurements during auroral events were conducted with the aid of detectors flown aboard three Nike-Tomahawk rocket flights. The detectors used to measure the auroral spectrum below 1 keV consisted of electrostatic analyzers positioned in the rocket to measure particles moving up and down the magnetic field lines. The analyzers measured electrons and protons simultaneously during a given sweep.

  14. Using a 10-keV x-ray source for hardness assurance

    SciTech Connect

    Fleetwood, D.M.; Beegle, R.W.; Sexton, F.W.; Winokur, P.S.; Miller, S.L.; Schwank, J.R.; Jones, R.V.; McWhorter, P.J.

    1986-01-01

    It is shown that a 10 keV x-ray source can be used to predict the responses of microelectronic circuits to Co-60 irradiation. Guidelines for using an x-ray tester in a hardness assurance program for VLSI CMOS circuits are suggested. 5 refs., 2 figs., 1 tbl.

  15. Interstellar photoelectric absorption cross sections, 0.03-10 keV

    NASA Technical Reports Server (NTRS)

    Morrison, R.; Mccammon, D.

    1983-01-01

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

  16. 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.

  17. 20-keV undulators for a 6-GeV storage ring

    SciTech Connect

    Kim, S.H.; Cho, Y.

    1985-10-01

    The main goal of the future 6-GeV electron storage ring is to provide 20-keV fundamental harmonic radiations from insertion devices. Parameter restrictions of REC-vanadium permendur hybrid undulators have been examined. The critical factor is the achieveable minimum gap of the undulator. Variations of the spectral brilliance for different beam parameters are also shown.

  18. The 20 keV undulators for a 6-GeV storage ring

    NASA Astrophysics Data System (ADS)

    Kim, S. H.; Cho, Y.

    The main goal of the future 6-GeV electron storage ring is to provide 20-keV fundamental harmonic radiations from insertion devices. Parameter restrictions of REC-Vanadium permendur hybrid undulators were examined. The critical factor is the achievable minimum gap of the undulator. Variations of the spectral brilliance for different beam parameters are also shown.

  19. Dynamical framework for KeV Dirac neutrino warm dark matter

    NASA Astrophysics Data System (ADS)

    Robinson, Dean J.; Tsai, Yuhsin

    2014-08-01

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

  20. 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.

  1. Static Electric Quadrupole Moments in the Ground State and K = 4-1 Bands in 168Er

    NASA Astrophysics Data System (ADS)

    Thakur, P.; Behra, M. S.; Dogra, R.; Bhati, A. K.; Bedi, S. C.

    2002-07-01

    The time differential perturbed angular correlation (TDPAC) technique has been used to study the nuclear quadrupole interactions of the first excited state of ground state rotational band (2+, 80 keV, T1/2 = 1.88 ns) and the band head of the = 41- band (41-,1094 keV, T1/2 = 120 ns) in the 168Er nucleus of a polycrystalline Er host. At room temperature we obtained the electric quadrupole interaction frequencies ω0(K= 0) = 457(15) Mrad/s and ω0(K= 4) = 69(2) Mrad/s, respectively, for the 2+ and 4- isomeric states of 168Er. The ratio of the spectroscopic quadrupole moments, i. e. Qs (K= 4)/Qs (K= 0) = 0.69(3), is independent of any model approximation and the electric field gradient at 168Er in the host metal

  2. Energetic electron fluxes (E180 KeV) observed by the Giotto experiment EPA during encounter with Comet Halley

    NASA Astrophysics Data System (ADS)

    Kirsch, E.; McKenna-Lawlor, S.; Thompson, A.; Osullivan, D.; Neubauer, F. M.

    1986-12-01

    The Energetic Particle Detector system EPA/EPONA onboard Giotto detects ions and electrons with energies greater than 20 keV in various energy channels. In this paper, electron fluxes are presented together with data from the Giotto Magnetometer Experiment. Electrons >180 keV were recorded from the transit of the foreshock, inbound, until the last observation outbound at approximately 03:00 UT on 15 March 1986. Energy spectra for the inbound pass are shown. One flux enhancement in the >300 keV channel and several in the >180 keV channel were recorded outbound. Possible acceleration mechanisms for the energetic electrons are considered.

  3. Improvements of the standardization of (134)Cs by the critical window setting for 605keV photopeak.

    PubMed

    Yunoki, Akira; Kawada, Yasushi; Hino, Yoshio

    2016-03-01

    In the standardization of (134)Cs by the 4πβ-γ coincidence method with a γ-window at 605keV, the satellite components of 563keV and 569keV overlapping the 605keV peak cause a steep slope and non-linearity of the efficiency extrapolation function. By shifting the lower threshold of a γ-window higher, the satellite components are eliminated, and the slope tends to horizontal. Nearly flat efficiency curves were obtained by using a CeBr3 scintillator for detecting γ-photons, as well as a NaI(Tl) scintillator. PMID:26702547

  4. Spectral Analysis on Solar Flares with an Emission > 300 keV

    NASA Astrophysics Data System (ADS)

    Vargas, R.; Connaughton, V.

    2013-12-01

    The continuum gamma-ray emission from solar flares is caused when a population of electrons is accelerated to relativistic speeds and interacts with the solar plasma. However, it has been theorized that the gamma-ray emission from some brighter flares comes from two populations of electrons. Using the Gamma-Ray Burst Monitor (GBM), we studied the gamma-ray emission spectra of solar flares and paid special attention to the solar flares that showed emission above 300 keV. We found that the emission above 300 keV was better fit with a broken power-law than a single power-law, evidence that the gamma-ray emission from certain solar flares involved two populations of electrons. Specifically, our best model involved a broken power law that had a steeper slope before the break in energy than after. We studied the spectral parameters as a function of time during the period of the high-energy emission. We also found that solar flares with emission above 300 keV form a small subset (~4%) of flares that trigger GBM above 20 keV. One of the flares with an emission greater than 300 keV was fitted with a Broken Power Law model. Only data from the BGO detector was used in making the plots. Various parameters of the fit have been plotted vs. time with the top two graphs representing the light curves of the flare from different detectors (BGO-0 and NaI-4). A spectral fit for bn100612038 for the time interval of [45s-50s] using only the BGO (0) detector file. Data from this fit was used in creating the other plots.

  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. 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.

  7. 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.

  8. Dark Bands on Europa

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Dark crisscrossing bands on Jupiter's moon Europa represent widespread disruption from fracturing and the possible eruption of gases and rocky material from the moon's interior in this four-frame mosaic of images from NASA's Galileo spacecraft. These and other features suggest that soft ice or liquid water was present below the ice crust at the time of disruption. The data do not rule out the possibility that such conditions exist on Europa today. The pictures were taken from a distance of 156,000 kilometers (about 96,300 miles) on June 27, 1996. Many of the dark bands are more than 1,600 kilometers (1,000 miles) long, exceeding the length of the San Andreas fault of California. Some of the features seen on the mosaic resulted from meteoritic impact, including a 30- kilometer (18.5 mile) diameter crater visible as a bright scar in the lower third of the picture. In addition, dozens of shallow craters seen in some terrains along the sunset terminator zone (upper right shadowed area of the image) are probably impact craters. Other areas along the terminator lack craters, indicating relatively youthful surfaces, suggestive of recent eruptions of icy slush from the interior. The lower quarter of the mosaic includes highly fractured terrain where the icy crust has been broken into slabs as large as 30 kilometers (18.5 miles) across. The mosaic covers a large part of the northern hemisphere and includes the north pole at the top of the image. The sun illuminates the surface from the left. The area shown is centered on 20 degrees north latitude and 220 degrees west longitude and is about as wide as the United States west of the Mississippi River. The Galileo mission is managed by NASA's Jet Propulsion Laboratory.

  9. 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.

  10. 46 CFR 76.15-50 - Lockout valves.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... any carbon dioxide extinguishing system protecting a space over 6,000 cubic feet in volume and... system from the protected space or spaces, making it impossible for carbon dioxide to discharge in the... GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS FIRE PROTECTION EQUIPMENT...

  11. 46 CFR 76.15-50 - Lockout valves.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... any carbon dioxide extinguishing system protecting a space over 6,000 cubic feet in volume and... system from the protected space or spaces, making it impossible for carbon dioxide to discharge in the... GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS FIRE PROTECTION EQUIPMENT...

  12. 46 CFR 76.15-50 - Lockout valves.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... any carbon dioxide extinguishing system protecting a space over 6,000 cubic feet in volume and... system from the protected space or spaces, making it impossible for carbon dioxide to discharge in the... GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) PASSENGER VESSELS FIRE PROTECTION EQUIPMENT...

  13. Development of Wide Band Feeds

    NASA Astrophysics Data System (ADS)

    Ujihara, H.; Ichikawa, R.

    2012-12-01

    Wide Band feeds are being developed at NICT, NAOJ, and some universities in Japan for VLBI2010, SKA, and MARBLE. SKA, the Square Kilometre Array, will comprise thousands of radio telescopes with square kilometer aperture size for radio astronomy. MARBLE consists of small portable VLBI stations developed at NICT and GSI in Japan. They all need wide band feeds with a greater than 1:10 frequency ratio. Thus we have been studying wide band feeds with dual linear polarization for these applications.

  14. 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…

  15. 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.

  16. Measurement of the 330-keV resonance in 18F(p,alpha)15O

    SciTech Connect

    Moazen, Brian; Blackmon, Jeff C; Bardayan, Daniel W; Chae, K. Y.; Chipps, K.; Jones, K. L.; Kozub, R. L.; Matei, Catalin; Nesaraja, Caroline D; Pain, Steven D; ShrinerJr., J. F.; Smith, Michael Scott

    2009-03-01

    While recent measurements have substantially improved our understanding of the {sup 18}F(p, {alpha}){sup 15}O reaction that is important in novae, the production of {sup 18}F is still uncertain by more than 2 orders of magnitude, due in large part to the contribution of a resonance located at E{sub cm} = 330 keV. We developed a new technique to study resonant (p, {alpha}) reactions and employed it to measure properties of the E{sub cm} = 183 keV resonance in {sup 17}O(p, {alpha}){sup 14}N which had been previously reported to decrease {sup 18}F production in ONeMg novae by as much as a factor of 10. The previous results were confirmed using the new technique and we now propose to use this technique to study the {sup 18}F(p, {alpha}){sup 15}O reaction.

  17. Secondary ion emission from V and Al surfaces under keV light ion on bombardment

    NASA Astrophysics Data System (ADS)

    Blauner, Patricia G.; Weller, Martha R.; Kaurin, Michael G.; Weller, Robert A.

    1986-03-01

    Positive secondary ion mass spectra have been measured for oxidized polycrystalline V and Al targets bombarded by H +, H 2+, He + and Ar + ions with beam energies ranging from 25 keV to 275 keV. An enhancement in the relative yield of positive ions of electronegative surface constituents, in particular O + is observed under light ion bombardment. Metallic ion intensities were found to decrease with increasing primary beam energy in proportion to the estimated total sputtering yields for these targets and beams. In contrast, the O + secondary ion intensities were independent of primary beam energy. This behavior is similar to that observed previously with heavy ions of comparable velocities. In addition, for the projectiles and targets used in these measurements, no energy thresholds or collective effects were observed in the emission of any positive ion. Published data on secondary ion emission resulting from electron, photon, and heavy ion bombardment are compared with these results.

  18. One-ampere, 80-keV, long pulse H - source and accelerator

    NASA Astrophysics Data System (ADS)

    Kwan, J. W.; Ackerman, G. D.; Anderson, O. A.; Chan, C. F.; Cooper, W. S.; deVries, G. J.; Lietzke, A. F.; Soroka, L.; Steele, W. F.

    1986-05-01

    The design and operation of the surface-conversion H- ion source and the 80-keV preaccelerator are discussed. Both the source and the preaccelerator, together with the transverse field focusing (TFF) matching and pumping beam transport section (presently being tested), will be parts of a negative-ion-based neutral beam line. Results from testing the source and preaccelerator have shown that the system can accelerate more than 1 A of H- ions at 80 keV continuously; the preaccelerator operates at an optimum perveance which matches the one predicted by WOLF code computer simulation. Deconditioning of the preaccelerator due to cesium contamination is a critical problem. A method has been developed to cope with this problem.

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

    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.

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

    SciTech Connect

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

    2011-12-15

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

  1. 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.

  2. 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.

  3. Design and modeling of 40 keV X-ray optics for Titan experiment

    SciTech Connect

    Bajt, S

    2006-06-22

    In 2004 we designed and fabricated a 40 keV W/SiC multilayer coated mirrors with 2.0 nm period thickness that were tested at RAL (UK) in winter 2004/2005. The mirrors reflected from 35 to 70 keV (different grazing incidence angles) and showed high reflectivity. However, there was not enough beamtime at RAL to obtain quantitative results. Similar experiment will now be performed in Titan facility (LLNL). In this report we design and model multilayers with even shorter period than the ones used in 2004/2005 experiments. Our goal is to fabricate 1 nm period W/SiC multilayers with high reflectivity. This will enable operation at higher angle of grazing incidence and simplified the mounting fixture.

  4. Energetic (>100 keV) 0/sup +/ ions in the plasma sheet

    SciTech Connect

    Ipavich, F.M.; Galvin, A.B.; Gloeckler, G.; Hovestadt, D.; Klecker, B.; Scholer, M.

    1984-05-01

    We present the first measurements of very energetic (112-157 keV) 0/sup +/ ions in the earth's magnetosphere. The observations were made with the UMd/MPE ULECA sensor on ISEE-1 on 5 March 1981 at geocentric distances approx.20 R/sub E/ in the earth's magnetotail. During this time period an Energetic Storm Particle event was observed by our nearly identical sensor on the ISEE-3 space-craft, located approx.250 R/sub E/ upstream of the earth's magnetosphere. The ISEE-1 sensor observed a similar temporal profile except for several sharp intensity enhancements, corresponding to substorm recoveries during which the plasma sheet engulfed the spacecraft. During these plasma sheet encounters we observe 0/sup +//H/sup +/ abundance ratios, at approx.130 keV, as large as 0.35. In between plasma sheet encounters with 0/sup +//H/sup +/ ratio at this energy is consistent with zero.

  5. Experimental results of a dual-beam ion source for 200 keV ion implanter

    SciTech Connect

    Chen, L. H. Cui, B. Q.; Ma, R. G.; Ma, Y. J.; Tang, B.; Huang, Q. H.; Jiang, W. S.; Zheng, Y. N.

    2014-02-15

    A dual beam ion source for 200 keV ion implanter aimed to produce 200 keV H{sub 2}{sup +} and He{sup +} beams simultaneously has been developed. Not suitable to use the analyzing magnet, the purity of beam extracted from the source becomes important to the performance of implanter. The performance of ion source was measured. The results of experiments show that the materials of inlet tube of ion source, the time of arc ionization in ion source, and the amount of gas flow have significant influence on the purity of beam. The measures by using copper as inlet tube material, long time of arc ionization, and increasing the inlet of gas flow could effectively reduce the impurity of beam. And the method using the gas mass flow controller to adjust the proportion of H{sub 2}{sup +} and He{sup +} is feasible.

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

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

    PubMed

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

    2010-07-16

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

  8. Study of photon attenuation coefficients of some multielement materials. [123-1250 keV

    SciTech Connect

    Bhandal, G.S. ); Singh, K. . Dept. of Physics)

    1994-03-01

    Total photon mass attenuation of six multielement shielding materials (concrete, plaster of paris, quick lime, black cement, white cement, and silica) is measured in the 123- to 1,250-keV energy range. The experimental results are analyzed in terms of cross sections, effective atomic numbers, and electron densities. Considerable sensitivity of the total mass attenuation coefficients and effective atomic numbers to variations in oxygen content are found in these multielement materials.

  9. 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.

  10. Picosecond x-ray measurements from 100 eV to 30 keV

    SciTech Connect

    Attwood, D.T.; Kauffman, R.L.; Stradling, G.L.

    1980-10-15

    Picosecond x-ray measurements relevant to the Livermore Laser Fusion Program are reviewed. Resolved to 15 picoseconds, streak camera detection capabilities extend from 100 eV to higher than 30 keV, with synchronous capabilities in the visible, near infrared, and ultraviolet. Capabilities include automated data retrieval using charge coupled devices (CCD's), absolute x-ray intensity levels, novel cathodes, x-ray mirror/reflector combinations, and a variety of x-ray imaging devices.

  11. 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.

  12. 20 keV undulators for a 6-GeV storage ring

    SciTech Connect

    Kim, S.H.; Cho, Y.

    1985-01-01

    The main goal of the future 6-GeV electron storage ring is to provide 20-keV fundamental harmonic radiations from insertion devices. Parameter restrictions of REC-vanadium permendur hybrid undulators have been examined. The critical factor is the achievable minimum gap of the undulator. Variations of the spectral brilliance for different beam parameters are also shown. 6 refs., 5 figs.

  13. Compton polarimeter for 10-30 keV x rays.

    PubMed

    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. PMID:26429432

  14. Polaroid H-sheet as a polarizer for 33 keV X-rays

    NASA Astrophysics Data System (ADS)

    Collins, S. P.

    1997-07-01

    It is shown that Polaroid H-sheet (iodine-doped polyvinyl alcohol) can be used to good effect as a fixed-wavelength polarizer for 33.17 keV X-ray beams. Iodine K-edge dichroic spectra of HN22 and HN38 sheets are presented, and the HN22 is used to demonstrate X-ray polarization analysis and polarization rotation.

  15. 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.

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

    NASA Astrophysics Data System (ADS)

    Zhao, Zilong; Li, Junqin; Zhang, Xuemei

    2013-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

    We describe a new experimental setup for studying the fragmentation dynamics of molecules induced by the impact of keV electrons using the well-known technique of recoil ion momentum spectroscopy. The apparatus consists of mainly a time- and position-sensitive multi-hit particle detector for ion analysis and a channel electron multiplier detector for detecting the ejected electrons. Different components of the setup and the relevant electronics for data acquisition are described in detail with their working principles. In order to verify the reliable performance of the setup, we have recorded the collision-induced ionic spectra of the CO2 molecule by the impact of keV electrons. Information about the ion pairs of CO+:O+, C+:O+ and O+:O+ resulting from dissociative ionizing collisions of 20 and 26 keV electrons with a dilute gaseous target of CO2 molecules has been obtained. Under conditions of the present experiment, the momentum resolutions of the spectrometer for the combined momenta of CO+ and O+ ions in the direction of the time-of-flight axis and perpendicular to the direction of an electron beam are found to be 10.0 ± 0.2 and 15.0 ± 0.3 au, respectively.

  18. Energy loss of tens keV charged particles traveling in the hot dense carbon plasma

    NASA Astrophysics Data System (ADS)

    Fu, ZhenGuo; Wang, ZhiGang; He, Bin; Li, DaFang; Zhang, Ping

    2016-08-01

    The energy loss of charged particles, including electrons, protons, and α-particles with tens keV initial energy E 0, traveling in the hot dense carbon (C) plasma for densities from 2.281 to 22.81 g/cm3 and temperatures from 400 to 1500 eV is systematically and quantitatively studied by using the dimensional continuation method. The behaviors of different charged particles are readily distinguishable from each other. Firstly, because an ion is thousands times heavier than an electron, the penetration distance of the electron is much longer than that of proton and α-particle traveling in the plasma. Secondly, most energy of electron projectile with E 0 < 100 keV deposits into the electron species of C plasma, while for the cases of proton and α-particle with E 0 < 100 keV, about more than half energy transfers into the ion species of C plasma. A simple decreasing law of the penetration distance as a function of the plasma density is fitted, and different behaviors of each projectile particle can be clearly found from the fitted data. We believe that with the advanced progress of the present experimental technology, the findings shown here could be confirmed in ion-stopping experiments in the near future.

  19. Searching for keV Sterile Neutrino Dark Matter with X-Ray Microcalorimeter Sounding Rockets

    NASA Astrophysics Data System (ADS)

    Figueroa-Feliciano, E.; Anderson, A. J.; Castro, D.; Goldfinger, D. C.; Rutherford, J.; Eckart, M. E.; Kelley, R. L.; Kilbourne, C. A.; McCammon, D.; Morgan, K.; Porter, F. S.; Szymkowiak, A. E.; XQC Collaboration

    2015-11-01

    High-resolution X-ray spectrometers onboard suborbital sounding rockets can search for dark matter candidates that produce X-ray lines, such as decaying keV-scale sterile neutrinos. Even with exposure times and effective areas far smaller than XMM-Newton and Chandra observations, high-resolution, wide field of view observations with sounding rockets have competitive sensitivity to decaying sterile neutrinos. We analyze a subset of the 2011 observation by the X-ray Quantum Calorimeter instrument centered on Galactic coordinates l=165°,b=-5° with an effective exposure of 106 s, obtaining a limit on the sterile neutrino mixing angle of {{sin}}22θ < 7.2× {10}-10 at 95% CL for a 7 keV neutrino. Better sensitivity at the level of {{sin}}22θ ∼ 2.1× {10}-11 at 95% CL for a 7 keV neutrino is achievable with future 300-s observations of the galactic center by the Micro-X instrument, providing a definitive test of the sterile neutrino interpretation of the reported 3.56 keV excess from galaxy clusters.

  20. Possible capture of keV sterile neutrino dark matter on radioactive β-decaying nuclei

    NASA Astrophysics Data System (ADS)

    Li, Y. F.; Xing, Zhi-Zhong

    2011-01-01

    There exists an observed “desert” spanning six orders of magnitude between O(0.5) eV and O(0.5) MeV in the fermion mass spectrum. We argue that it might accommodate one or more keV sterile neutrinos as a natural candidate for warm dark matter. To illustrate this point of view, we simply assume that there is one keV sterile neutrino ν and its flavor eigenstate ν weakly mixes with three active neutrinos. We clarify different active-sterile neutrino mixing factors for the radiative decay of ν and β decays in a self-consistent parametrization. A direct detection of this keV sterile neutrino dark matter in the laboratory is in principle possible since the ν component of ν can leave a distinct imprint on the electron energy spectrum when it is captured on radioactive β-decaying nuclei. We carry out an analysis of its signatures in the capture reactions ν+H3→He3+e- and ν+Ru106→Rh106+e- against the β-decay backgrounds, and conclude that this experimental approach might not be hopeless in the long run.

  1. Effective field theory and keV lines from dark matter

    SciTech Connect

    Krall, Rebecca; Reece, Matthew; Roxlo, Thomas E-mail: mreece@physics.harvard.edu

    2014-09-01

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

  2. 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.

  3. 1/4 keV Fluctuations Due to the Local Hot Bubble

    NASA Astrophysics Data System (ADS)

    Kuntz, K. D.; Snowden, S. L.; Warwick, R. S.

    1997-12-01

    As part of a program to characterize 1/4 keV fluctuations at high galactic latitudes, such as those discovered by Barber, Warwick, & Snowden (1995), it is necessary to characterize the fluctuations produced by the principal foreground components of the 1/4 keV background, the Local Hot Bubble. To do so, we are studying a substantial number of deep, overlapping ROSAT PSPC pointings towards the Hyades cluster, a region which has a substantial absorbing column outside the LHB that effectively blocks the distant 1/4 keV emission. Absorption of X-ray emission by clouds within the LHB is thought to be small in this direction and can be determined by modeling the ROSAT response function. The structure of the X-ray emission in this field can be caused by 1.) changes in the pathlength to the LHB boundary, and 2.) variation in emission measure within the LHB. The amplitude of fluctuations can then place limits on these quantities, but cannot separate their effects.

  4. A large scale height galactic component of the diffuse 2-60 keV background

    NASA Technical Reports Server (NTRS)

    Iwan, D.; Marshall, F. E.; Boldt, E. A.; Mushotzky, R.; Shafer, R. A.; Stottlemyer, A.

    1982-01-01

    The diffuse 2-60 keV X-ray background has a galactic component clearly detectable by its strong variation with both galactic latitude and longitude. This galactic component is typically 10 percent of the extragalactic background toward the galactic center, half that strong toward the anticenter, and extrapolated to a few percent of the extragalactic background toward the galactic poles. It is acceptably modeled by a finite radius emission disk with a scale height of several kiloparsecs. The averaged galactic spectrum is best fitted by a thermal spectrum of kT about 9 keV, a spectrum much softer than the about 40 keV spectrum of the extragalactic component. The most likely source of this emission is low luminosity stars with large scale heights such as subdwarfs. Inverse Compton emission from GeV electrons on the microwave background contributes only a fraction of the galactic component unless the local cosmic ray electron spectrum and intensity are atypical.

  5. Solar wind ˜0.1-1.5 keV electrons at quiet times

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND 3-D Plasma & Energetic Particle (3DP) instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. Firstly, we separate strahl (beaming) electrons and halo (isotropic) electrons based on their features in pitch angle distributions. Secondly, we fit the observed energy spectrum of both the strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ, effective temperature Teff and density n0. We also integrate the the measurements over ˜0.1-1.5 keV to obtain the average electron energy Eavg of the strahl and halo. We find a strong positive correlation between κ and Teff for both the strahl and halo, possibly reflecting the nature of the generation of these suprathermal electrons. Among the 245 selected samples, ˜68% have the halo κ smaller than the strahl κ, while ˜50% have the halo Eh larger than the strahl Es.

  6. Band structures extending to very high spin in Xe126

    NASA Astrophysics Data System (ADS)

    Rønn Hansen, C.; Sletten, G.; Hagemann, G. B.; Herskind, B.; Jensen, D. R.; Bringel, P.; Engelhardt, C.; Hübel, H.; Neußer-Neffgen, A.; Singh, A. K.; Carpenter, M. P.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Bednarczyk, P.; Byrski, T.; Curien, D.; Benzoni, G.; Bracco, A.; Camera, F.; Leoni, S.; Clark, R. M.; Fallon, P.; Korichi, A.; Roccaz, J.; Maj, A.; Wilson, J. N.; Lisle, J. C.; Steinhardt, T.; Thelen, O.; Ødegård, S. W.

    2007-09-01

    High-spin states in Xe126 have been populated in the Se82(Ca48,4n)Xe126 reaction in two experiments, one at the VIVITRON accelerator in Strasbourg using the Euroball detector array, and a subsequent one with ATLAS at Argonne using the Gammasphere Ge-detector array. Levels and assignments made previously for Xe126 up to I=20 have been confirmed and extended. Four regular bands extending to a spin of almost I=60, which are interpreted as two pairs of signature partners with opposite parity, are identified for the first time. The α = 0 partner of each pair is connected to the lower-lying levels, whereas the two α = 1 partners remain floating. A fractional Doppler shift analysis of transitions in the strongest populated (π,α)=(-,0) band provides a value of 5.20.50.4 b for the transition quadrupole moment, which can be related to a minimum in the potential-energy surface calculated by the ULTIMATE CRANKER cranked shell-model code at ɛ≈0.35 and γ≈5°. The four lowest bands calculated for this minimum compare well with the two signature pairs experimentally observed over a wide spin range. A sharp upbend at ℏω~1170 keV is interpreted as a crossing with a band involving the j15/2 neutron orbital, for which pairing correlations are expected to be totally quenched. The four long bands extend to within ˜5 spin units of a crossing with an yrast line defined by calculated hyperdeformed transitions and will serve as important stepping stones into the spin region beyond 60ħ for future experiments.

  7. 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.

  8. Energy dependence of the band-limited noise in black hole X-ray binaries★

    NASA Astrophysics Data System (ADS)

    Stiele, H.; Yu, W.

    2015-10-01

    Black hole low-mass X-ray binaries show a variety of variability features, which manifest as narrow peak-like structures superposed on broad noise components in power density spectra in the hard X-ray emission. In this work, we study variability properties of the band-limited noise component during the low-hard state for a sample of black hole X-ray binaries. We investigate the characteristic frequency and amplitude of the band-limited noise component and study covariance spectra. For observations that show a noise component with a characteristic frequency above 1 Hz in the hard energy band (4-8 keV), we found this very same component at a lower frequency in the soft band (1-2 keV). This difference in characteristic frequency is an indication that while both the soft and the hard band photons contribute to the same band-limited noise component, which likely represents the modulation of the mass accretion rate, the origin of the soft photons is actually further away from the black hole than the hard photons. Thus, the soft photons are characterized by larger radii, lower frequencies and softer energies, and are probably associated with a smaller optical depth for Comptonization up-scattering from the outer layer of the corona, or suggest a temperature gradient of the corona. We interpret this energy dependence within the picture of energy-dependent power density states as a hint that the contribution of the up-scattered photons originating in the outskirts of the Comptonizing corona to the overall emission in the soft band is becoming significant.

  9. Paleomagnetic dating of liesegang bands

    SciTech Connect

    Cochran, K.A.; Elmore, R.

    1985-01-01

    Paleomagnetic analysis, in conjunction with petrographic studies, was used to date the formation of hematite liesegang bands in the Ordovician Upper Arbuckle Group in southern Oklahoma. The hematite bands form symmetrical patterns on both sides of calcite-filled fractures in dolomite beds. The bands decrease in abundance and become more diffuse away from the fractures. Dedolomite is common near the fractures. Samples from distinctly banded dolomite near the fractures contain a relatively strong chemical remanent magnetization (CRM) with a southeasterly declination and shallow inclination. Samples farther from the fractures that are less distinctly banded or have no bands contain a weaker and less table CRM. Petrographic evidence and stable demagnetization to 600/sup 0/C indicate that the CRM resides in hematite. Samples were collected from both flanks of the Arbuckle Anticline (late Pennsylvanian folding), and a fold test demonstrates that the CRM is post-folding. The pole position for the CRM corresponds to the Early Permian (approx. 280 Ma) part of the Apparent Polar Wander Path for stable North America. These results suggest that the liesegang bands formed in the Early Permian, probably by rhythmic precipitation of hematite from fluids that moved out from the fractures. The fluids also apparently caused dedolomitization and precipitation of calcite in intercrystalline pore spaces. These fluids were probably the source of iron for the bands, although iron released from dedolimitization of ferroan dolomite may have been a local source.

  10. Orbiter KU-band transmitter

    NASA Technical Reports Server (NTRS)

    Halterman, R.

    1976-01-01

    The design, build, and test of an engineering breadboard Ku band quadraphase shift keyed and wideband frequency modulated transmitter are described. This orbiter Ku band transmitter drawer is to simulate the orbiter transmitter and meet the functional requirements of the orbiter communication link.

  11. 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…

  12. Solar flares X-ray polarimetry in a wide energy band

    NASA Astrophysics Data System (ADS)

    Fabiani, Sergio; Campana, Riccardo; Costa, Enrico; Muleri, Fabio; Bellazzini, Ronaldo; Soffitta, Paolo; Del Monte, Ettore; Rubini, Alda

    2012-07-01

    Polarimetry of solar flares X-ray emission is an additional tool for investigating particles dynamics within the solar atmosphere. Accelerated electrons by magnetic reconnection in the corona produce bremsstrahlung radiation as primary emission in the footpoints of a solar flare which has moreover the possibility to be Compton backscattered resulting in albedo emission. Non-thermal bremsstrahlung emission is expected to be a significant above 15 keV and highly polarized. The albedo component peaks between 20 and 50 keV, its polarization properties depend on the Compton scattering angle. Such a diffusion modifies the spectrum and the polarization of the primary bremsstrahlung emission. Hard X-ray polarimetry, spectroscopy and imaging are therefore necessary to disentangle and modeling the different components in a solar flare. We present a non imaging Compton polarimeter sensitive from 20 keV designed as a single scattering unit surrounded by absorbers of high atomic number. A photelectric polarimeter based on the Gas Pixel Detector technology sensitive in the 15-35 keV energy band can be coupled for imaging.

  13. 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.

  14. 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.

  15. 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.

  16. The neutron star transient 4U 1608-52 has left the hard state

    NASA Astrophysics Data System (ADS)

    Zhang, Wenda; Yu, Wenfei

    2013-05-01

    The neutron star SXT 4U 1608-52 has started an outburst starting from around 2013 May 27 UT (MJD 56439) as indicated by BAT monitoring in 15-50 keV around 2013 May 27 UT (MJD 56439) and MAXI monitoring in all 3 bands on 2013 May 29 UT (MJD 56441; also see MAXI mail alert). On 2013 May 28 UT (MJD 56440), the BAT/15-50 keV intensity was 0.031+/-0.005 Crab and the MAXI/2-10 keV intensity was 0.022+/-0.004 Crab.

  17. 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.

  18. Rotational Bands in 172W

    NASA Astrophysics Data System (ADS)

    Greenberg, J.; Guess, C. J.; Tandel, S.; Chowdhury, P.; Carpenter, M. P.; Hartley, D. J.; Janssens, R. V. F.; Khoo, T. L.; Lauritsen, T.; Lister, C. J.; Seweryniak, D.; Shirwadkar, U.; Wang, X.; Zhu, S.

    2015-10-01

    Studying the structure of rotational bands in 172W is valuable for gaining a better understanding of deformed nuclei. Highly excited states of the isotope were populated from a 230 MeV 50Ti beam incident on a 128Te target at Argonne National Laboratory using the ATLAS accelerator. γ emissions from 172W in the range were measured using Compton suppressed germanium detectors in the Gammasphere array. Using this data, three new rotational bands were found, and several other bands were expanded. Swarthmore College Summer Research Fellowship.

  19. 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.

  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. Construction of low current 30 keV proton accelerator for detection efficiency studies

    NASA Astrophysics Data System (ADS)

    Salas Bacci, Americo; Baessler, Stefan; Ross, Aaron; Roane, Nicholas; Whitaker, C. J.

    2013-10-01

    We have constructed a small ion source and proton accelerator at UVA. This accelerator is needed for the characterization of the detection efficiency of a large area, thick, 127-hexagonal segmented Silicon detector for the neutron beta decay ``Nab'' experiment that will be carried out at SNS, Oak Ridge National Laboratory in search of physics beyond the standard model. We will present the design, simulations, operation, and detection of 30 keV H+ and H2+, as well as our efforts to stabilize and correlate both ion currents.

  2. High-energy recoil-ion emission in keV heavy-ion surface collisions

    NASA Astrophysics Data System (ADS)

    van Someren, B.; Rudolph, H.; Urazgil'din, I. F.; van Emmichoven, P. A. Zeijlmans; Niehaus, A.

    1997-11-01

    For keV Xe +, Kr + and Ar + ions incident at 30° on Cu(110) we have observed the emission of negatively charged particles with energies up to about 40% of the primary energy. By time-of-flight techniques we have found that electrons are emitted with energies up to 80 eV, whereas the negatively charged high-energy particles are Cu - recoil ions. High-energy Cu + ions have also been found. Simple energy and momentum conservation arguments show that such high recoil energies are indeed possible for multiple collision events in which the primary recoil ion scatters off one or more Cu atoms.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

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

    PubMed Central

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

    2010-01-01

    This paper presents the first observation of coincidental emission of photons, electrons and secondary ions from individual C60 keV impacts. An increase in photon, electron and secondary ion yields is observed as a function of C60 projectile energy. The effect of target structure/composition on photon and electron emissions at the nanometer level is shown for a CsI target. The time-resolved photon emission may be characterized by a fast component emission in the UV-Vis range with a short decay time, while the electron and secondary ion emission follow a Poisson distribution. PMID:21218166

  8. 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.

  9. Rise time in 20-32 keV impulsive X-radiation

    NASA Technical Reports Server (NTRS)

    Vorpahl, J. A.; Takakura, T.

    1974-01-01

    A new property of the X-ray impulsive component observed in solar flares is discussed, giving attention to the relation between the slope of the electron power spectrum and the rise time in the 20-32 keV X-ray spike. This particular energy range was chosen because it offered the greatest number of impulsive events while being sufficiently high to avoid contamination by soft X radiation. It is found for the thin-target model that the electron spectrum tends to be softer when the acceleration rate is smaller.

  10. 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.

  11. Radiation safety review for 511-keV emitters in nuclear medicine.

    PubMed

    Dell, M A

    1997-03-01

    With the advent of high-energy collimators and dual-head coincidence cameras, standard nuclear medicine facilities will soon begin imaging with PET isotopes. The use of 511-keV emitters raises new radiation safety concerns for technologists traditionally limited to handling 99mTc and other low-energy isotopes. This article is a basic review of positron emitters, measurement concerns, exposure rates, shielding requirements and external radiation exposure mitigation. Newly developed PET shielding products are presented and regulatory status is discussed briefly. PMID:9239598

  12. Dynamic dependence of interaction potentials for keV atoms at metal surfaces

    SciTech Connect

    Schueller, A.; Adamov, G.; Wethekam, S.; Maass, K.; Mertens, A.; Winter, H.

    2004-05-01

    He and N atoms are scattered with keV energies under a grazing angle of incidence from clean and flat Ag(111) and Al(111) surfaces. For incidence along low index crystallographic directions in the surface plane, atomic projectiles are steered by rows of atoms (''axial surface channeling'') giving rise to characteristic rainbows in their angular distribution. From the analysis of this effect we derive effective scattering potentials which reveal pronounced dynamical effects. We attribute our observation to the embedding energy for penetration of atoms in the electron gas of a metal.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  15. 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.

  16. Isogeometric analysis of shear bands

    NASA Astrophysics Data System (ADS)

    Berger-Vergiat, Luc; McAuliffe, Colin; Waisman, Haim

    2014-08-01

    Numerical modeling of shear bands present several challenges, primarily due to strain softening, strong nonlinear multiphysics coupling, and steep solution gradients with fine solution features. In general it is not known a priori where a shear band will form or propagate, thus adaptive refinement is sometimes necessary to increase the resolution near the band. In this work we explore the use of isogeometric analysis for shear band problems by constructing and testing several combinations of NURBS elements for a mixed finite element shear band formulation. Owing to the higher order continuity of the NURBS basis, fine solution features such as shear bands can be resolved accurately and efficiently without adaptive refinement. The results are compared to a mixed element formulation with linear functions for displacement and temperature and Pian-Sumihara shape functions for stress. We find that an element based on high order NURBS functions for displacement, temperature and stress, combined with gauss point sampling of the plastic strain leads to attractive results in terms of rate of convergence, accuracy and cpu time. This element is implemented with a -bar strain projection method and is shown to be nearly locking free.

  17. 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

  18. 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.

  19. 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.

  20. Precise Determination of the Intensity of 226Ra Alpha Decay to the 186 keV Excited State

    SciTech Connect

    S.P. LaMont; R.J. Gehrke; S.E. Glover; R.H. Filby

    2001-04-01

    There is a significant discrepancy in the reported values for the emission probability of the 186 keV gamma-ray resulting from the alpha decay of 226 Ra to 186 keV excited state of 222 Rn. Published values fall in the range of 3.28 to 3.59 gamma-rays per 100 alpha-decays. An interesting observation is that the lower value, 3.28, is based on measuring the 186 keV gamma-ray intensity relative to the 226 Ra alpha-branch to the 186 keV level. The higher values, which are close to 3.59, are based on measuring the gamma-ray intensity from mass standards of 226 Ra that are traceable to the mass standards prepared by HÓNIGSCHMID in the early 1930''s. This discrepancy was resolved in this work by carefully measuring the 226 Ra alpha-branch intensities, then applying the theoretical E2 multipolarity internal conversion coefficient of 0.692±0.007 to calculate the 186 keV gamma-ray emission probability. The measured value for the alpha branch to the 186 keV excited state was (6.16±0.03)%, which gives a 186 keV gamma-ray emission probability of (3.64±0.04)%. This value is in excellent agreement with the most recently reported 186 keV gamma-ray emission probabilities determined using 226 Ra mass standards.

  1. Estimates of the Compton backscattering feature at approximately 150 keV in the Crab Nebula pulsar

    NASA Astrophysics Data System (ADS)

    Bednarek, W.; Cremonesi, O.; Treves, A.

    1994-04-01

    The Compton backscattering feature at approximately 150 keV from the Crab Nebula pulsar is evaluated in a picture where the 440 keV emission is interpreted as due to positron annihilation in the pulsar crust. Monte Carlo simulations indicate a broad feature the intensity of which is expected in the range 10-5 - 10-4 ph/sq cm/s. The possibility of detection of the feature is discussed.

  2. 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.

  3. Chemically induced compaction bands: Triggering conditions and band thickness

    NASA Astrophysics Data System (ADS)

    Stefanou, Ioannis; Sulem, Jean

    2014-02-01

    During compaction band formation, various mechanisms can be involved at different scales. Mechanical and chemical degradation of the solid skeleton and grain damage are important factors that may trigger instabilities in the form of compaction bands. Here we explore the conditions of compaction band formation in quartz- and carbonate-based geomaterials by considering the effect of chemical dissolution and grain breakage. As the stresses/deformations evolve, the grains of the material break, leading to an increase of their specific surface. Consequently, their dissolution is accelerated and chemical softening is triggered. By accounting for (a) the mass diffusion of the system, (b) a macroscopic failure criterion with dissolution softening, and (c) the reaction kinetics at the microlevel, a model is proposed and the conditions for compaction instabilities are investigated. Distinguishing the microscale (grain level) from the macrolevel (representative elementary volume) and considering the heterogeneous microstructure of the representative elementary volume, it is possible to discuss the thickness and periodicity of compaction bands. Two case studies are investigated. The first one concerns a sandstone rock reservoir which is water flooded and the second one a carbonate rock in which CO2 is injected for storage. It is shown that compaction band instabilities are possible in both cases.

  4. Resolution of the 1,238-keV gamma-ray line from supernova 1987A

    NASA Technical Reports Server (NTRS)

    Teegarden, B. J.; Barthelmy, S. D.; Gehrels, N.; Tueller, J.; Leventhal, M.

    1989-01-01

    Observations of supernova 1987A from the maiden flight of the Gamma-Ray Imaging Spectrometer (GRIS) are reported. SN1987A was observed for a period of 11.1 hours on May 1, 1988. Line emission at 1238 keV and continuum emission from 60-800 keV were detected. A gaussian line profile gives an acceptable fit to the 1238 keV line. The best-fit parameters are: flux = 8.5(+ 2.3, - 2.2) x 10 to the -4th photons/sq cm/s; peak energy = 1235.4 (+ 2.2, - 2.4) keV; FWHM = 16.3 (+ 6.1, - 5.7) keV. No evidence is found for a supernova-produced red- or blueshift in the 1238 keV line. The measured linewidth is a factor of about two greater than model predictions, although the discrepancy represents only two standard deviations. The line profiles are characteristic of optically thin regions, whereas the intensity implies a mean optical depth of about two. Fragmentation or nonspherical geometry of the supernova shell are possible explanations of the data.

  5. Influence of a keV sterile neutrino on neutrinoless double beta decay: How things changed in recent years

    NASA Astrophysics Data System (ADS)

    Merle, Alexander; Niro, Viviana

    2013-12-01

    Earlier studies of the influence of dark matter keV sterile neutrinos on neutrinoless double beta decay concluded that there is no significant modification of the decay rate. These studies have focused only on a mass of the keV sterile neutrino above 2 and 4 keV, respectively, as motivated by certain production mechanisms. On the other hand, alternative production mechanisms have been proposed, which relax the lower limit for the mass, and new experimental data are available, too. For this reason, an updated study is timely and worthwhile. We focus on the most recent data, i.e., the newest Chandra and XMM-Newton observational bounds on the x-ray line originating from radiative keV sterile neutrino decay, as well as the new measurement of the previously unknown leptonic mixing angle θ13. While the previous works might have been a little short-sighted, the new observational bounds do indeed render any influences of keV sterile neutrinos on neutrinoless double beta decay small. This conclusion even holds in case not all the dark matter is made up of keV sterile neutrinos.

  6. Band loss by nestling mourning doves

    USGS Publications Warehouse

    Kaczynski, C.F.; Kiel, W.H.

    1963-01-01

    Nestling mourning doves (Zenaidura macroura) were banded and checked for band loss prior to fledging at Parchman, Mississippi, during the months of June-August, 1960. Three hundred seventy-seven nestlings 4-6 days of age were banded, 117 with size 3 bands, 120 with size 3A bands, and 140 with size 3A bands secured by Dalzoflex tape. Two hundred twenty nestlings 7-9 days of age were banded, 114 with size 3 bands and 106 with size 3A bands. In the 4- to 6-day age group, 66.3 percent of the size 3A bands were lost. This was a statistically significant departure from the 7.7 percent loss of size 3 bands. No taped bands were lost. However, predators ate 13.8 percent of the nestlings with taped bands and significantly fewer of the nestlings banded without tape. In the 4- to 6-day age group, percentages of nestlings known to be available for band recovery at 9 days or older were: size 3, 69.2 percent; size 3A with tape, 59.0 percent; size 3A, 25.8 percent. In the 7-to 9-day age group, there was a 3.3 percent loss of size 3A bands and no loss of size 3 bands. The minimum age at which nestlings were banded without subsequent loss of bands was 6 days for size 3 and 8 days for size 3A.

  7. Estimation of keV submicron ion beam width using a knife-edge method

    NASA Astrophysics Data System (ADS)

    Ishii, Yasuyuki; Isoya, Akira; Kojima, Takuji; Arakawa, Kazuo

    2003-11-01

    A beam width measurement system has been developed for keV submicron ion beams of 0.1 μm or less in width assuming a round shape beam. The system enables to measure beam current change as a function of knife-edge position by cutting a beam focusing point (beam spot) with the sharp edge within a spatial resolution of 0.02 μm. The width of 30 keV order submicron H + ion beam was estimated by fitting current change curves based on three different ion density models: uniform, flat-top and Gaussian. Among these models, the flat-top model provide the most reasonable beam width of 0.56 μm interpreting contribution of halo around the beam spot to beam width estimation. The beam width measurement system with the high spatial resolution and the data analysis based on the flat-top ion density model should contribute to accelerate developments of submicron ion beam production technologies.

  8. Performance improvement of keV Neutrons-based PGNAA setups.

    PubMed

    Naqvi, A A; Abdelmonem, M S; Al-Misned, Ghada; Al-Ghamdi, Hanan

    2006-12-01

    The performance of keV neutrons based Prompt Gamma Ray Neutron Activation Analysis (PGNAA) setups have been observed to improve by enclosing its neutron source inside the moderator. The keV neutrons were produced via (7)Li(p,n) reaction and (3)H(p,n) reactions. For the two PGNAA setups, the maximum intensity of the prompt gamma-ray yield was observed for a 5cm long moderator with the neutron source positioned at a distance of 0.5cm from the moderator-end facing the sample. Due to enclosing the source inside the moderator, the prompt gamma-ray yield from the (7)Li(p,n) reaction and (3)H(p,n) reaction based PGNAA setups have increased by a factor of three as compared to that achieved from these setups with the source outside the moderator. This study provides a theoretical basis for the measurement of performance of (7)Li(p,n) reaction and the (3)H(p,n) reaction based PGNAA setups. PMID:16837206

  9. Magnetic moment of the 2083 keV level of 140Ce

    NASA Astrophysics Data System (ADS)

    Ohkubo, Y.; Taniguchi, A.; Xu, Q.; Tanigaki, M.; Shimizu, N.; Otsuka, T.

    2013-04-01

    For the magnetic moment of the 2083 keV level of 140Ce, there are four published data, all obtained by applying an external magnetic field of less than 5 T to a liquid sample containing 140La using the time-differential perturbed angular correlation (TDPAC) technique. Although these four values are consistent within two times their uncertainties (2σ), the range of values in 2σ extends from μ=+3.0 to +5.2 (in units of nuclear magneton, μN). This time, the TDPAC technique was successfully applied to the 2083 keV level of 140Ce implanted in an Fe foil. The magnetic moment of this level was determined to be μ=+4.00(20)μN, employing the known hyperfine field at 141Ce in Fe, -41(2) T, which agrees very well with one of the values, μ=+4.06(15)μN. The present value is compared with two shell-model calculations.

  10. Attenuation of photons at 3 to 14 keV energies in helium

    SciTech Connect

    Azuma, Y.; Berry, H.G.; Gemmell, D.S.

    1995-08-01

    Using X-ray photons at the X24A, X23B and X23A2 beam lines at NSLS, we measured the total photo-attenuation cross section of helium for photons in the energy range of 3 to 14 keV. In this range the photoionization cross section decreases rapidly with energy, so that Compton scattering is significant at 4 keV and dominates at the highest energies. The apparatus consisted of a 1.4-m long helium-absorption tube, 5 cm in diameter, with 75-{mu} thick, 7-mm diameter, kapton end windows. The tube could be filled with helium up to a pressure of 10{sup 6} Pa. We attained a precision of 1-2% in the attenuation cross section. The measurements verify the dominance of Compton scattering in this energy range and its importance in recent measurements of the ratio of double-to-single photoionization of helium. The measured cross sections are close to the combined calculated cross sections for Compton scattering and photoionization, and we are able to distinguish the contributions of the two effects.

  11. A neutron spectrometer for neutron energies between 1 eV and 10 keV

    SciTech Connect

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

    1988-01-01

    In boron neutron capture therapy (BNCT), it is the consensus that epithermal neutron beams have advantages over thermal beams in treating deep-seated brain tumors, and large neutron fields have advantages over narrow beams, since whole-brain irradiations are thought to be necessary in many cases. Epithermal neutron sources for BNCT, which include filtered reactor neutron beams and moderated reactor neutron fields, are currently being developed at many institutions around the world. Neutrons with energies between 1 eV and 10 keV are most suitable for treating brain tumors. However, techniques for measuring neutron spectra in a vacuum in this energy range are not well developed. This paper describes a new type of neutron spectrometer that has a set of response functions that peak at equally spaced intervals on a logarithmic energy scale ranging from 1 eV to 10 keV; therefore, neutron spectra (or histograms) in this energy range can be obtained by properly applying spectrum unfolding techniques to the measured data. The spectrometer is applicable for measurements in a vacuum for both narrow neutron beams and wide neutron fields.

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

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

    There is a pressing need for better electronic detectors to replace film for recording high-resolution images using electron cryomicroscopy. Our previous work has shown that direct electron detection in CMOS sensors is promising in terms of resolution and efficiency at 120 keV [A.R. Faruqi, R. Henderson, M. Prydderch, R. Turchetta, P. Allport, A. Evans, Nucl. Instr. and Meth. 546 (2005) 170], but in addition, the detectors must not be damaged by the electron irradiation. We now present new measurements on the radiation tolerance of a 25 μm pitch CMOS active-pixel sensor, the STAR250, which was designed by FillFactory using radiation-hard technology for space applications. Our tests on the STAR250 aimed to establish the imaging performance at 300 keV following irradiation. The residual contrast, measured on shadow images of a 300 mesh grid, was >80% after corrections for increased dark current, following irradiation with up to 5×10 7 electrons/pixel (equivalent to 80,000 electron/μm 2). A CMOS sensor with this degree of radiation tolerance would survive a year of normal usage for low-dose electron cryomicroscopy, which is a very useful advance.

  13. The repetitive flaking of inconel 625 by 100 keV helium ion bombardment

    NASA Astrophysics Data System (ADS)

    Whitton, J. L.; Chen, Hao Ming; Littmark, U.; Emmoth, B.

    1981-05-01

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

  14. 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.

  15. 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. PMID:16381717

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  17. 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.

  18. Hydroxyapatite-titanium interface reaction induced by keV electron irradiation

    NASA Astrophysics Data System (ADS)

    Torrisi, L.; Foti, G.

    1992-03-01

    Thin films of hydroxyapatite bioceramic, 5-50 Å in thickness, have been deposited on ion cleaned titanium surfaces to study the chemical-physical adhesion of metal-ceramic interfaces of biomedical devices (orthopaedic and dentistry prosthesis). Film deposition was performed in ultrahigh vacuum condition (10 -10 mbar) using 5 keV argon sputtering of hydroxyapatite matrix; the film thickness was measured in situ with Auger electron spectroscopy. The hydroxyapatite-titanium interface was irradiated with an electron beam of 0.5-5 keV energy and 0.2-2 A/cm 2 current density. During electron irradiation, Auger spectra show chemical shifts of phosphorus, titanium and oxygen peaks. The released electron energy induces modifications in the tetraedric phosphorus-oxygen groups with production of new chemical bonds between phosphorus, oxygen and titanium. Oxygen, for example, diffuses into the titanium interface forming titanium oxide. Chemical reactions induced by electron irradiation are driven by the metal-ceramic interface. Near the interface a strong and fast effect is observed while far from the interface a weak and slow effect occurs. Chemical reactions depend on the electron irradiation dose showing an inhibition threshold at about 10 19 e/cm 2 and, near the interface, a saturation condition at about 5 × 10 20 e/cm 2. Titanium-ceramic chemical reactions are inhibited if the substrate titanium surface is rich in oxide.

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

    SciTech Connect

    Sherman, J.; Arvin, A.; Hodgkins, D.

    1997-10-01

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

  20. 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). PMID:22512978

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

    NASA Astrophysics Data System (ADS)

    Bachau, H.; Dondera, M.

    2016-04-01

    This letter addresses the problem of stimulated Raman excitation of a hydrogen atom submitted to an ultrashort and intense laser pulse in the keV regime. The pulse central frequency ω of 55 a.u. (about 1.5 keV) is in the weakly relativistic regime, ω ≤ c/a0 (c is the speed of light in vacuum and a 0 the Bohr radius) and the pulse duration is τ ≈ 18.85 a.u. (about 456 attoseconds). We solve the corresponding time-dependent Schrödinger equation (TDSE) using a spectral approach, retardation (or nondipole) effects are included up to O(1/c) , breaking the conservation of the magnetic quantum number m and forcing the resolution of the TDSE in a three-dimensional space. Due to the laser bandwidth, which is of the order of the ionization potential of hydrogen, stimulated Raman scattering populates nlm excited states (n and l are the principal and azimuthal quantum numbers, respectively). The populations of these excited states are calculated and analyzed in terms of l and m quantum numbers, this showing the contributions of the retardation effects and their relative importance.

  2. Rotational bands in neutron-rich {sup 169,171,172}Er

    SciTech Connect

    Wu, C.Y.; Cline, D.; Simon, M.W.; Teng, R.; Vetter, K.; Carpenter, M.P.; Janssens, R.V.F.; Wiedenhoever, I.

    2004-07-01

    The neutron-rich {sup 169,171,172}Er nuclei were populated by few-neutron transfer reactions between {sup 170}Er and {sup 238}U at a near barrier energy. The spectroscopy of these Er isotopes was studied using prompt {gamma} rays correlated with delayed transitions or events involving at least three prompt transitions. The ground-state band of {sup 172}Er was populated up to spin 22{sup +} at an excitation energy of 5528 keV. Rotational bands built on the 1/2{sup -}[521], 5/2{sup -}[512], and 7/2{sup +}[633] neutron configurations in {sup 169,171}Er were extended to substantially higher spins than previously known. The signature splitting observed in these rotational bands is addressed within the framework of the particle-rotor model in terms of triaxiality and Coriolis attenuation. The signature inversion observed in the 5/2{sup -}[512] band is well reproduced by including the triaxial degree of freedom in the calculation. Attenuating the Coriolis interaction in the calculation is found to be necessary to reproduce the signature splitting observed in the 7/2{sup +}[633] band. A similar Coriolis attenuation also is needed to account for the signature splitting as well as the B(M1)/B(E2) ratios in the 7/2{sup +}[633] ground-state band in the neighboring N=99 isotones, {sup 167}Er and {sup 169}Yb.

  3. 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.

  4. Decay out of the highly deformed bands in the odd Nd isotopes: The {sup 137}Nd nucleus

    SciTech Connect

    Lunardi, S.; Venturelli, R.; Bazzacco, D.; Petrache, C.; Rossi-Alvarez, C.; de Angelis, G.; Vedovato, G.; Bucurescu, D.; Ur, C.

    1995-07-01

    The decay of the highly deformed (HD) band in the nucleus {sup 137}Nd has been studied with the GASP array using the reactions {sup 110}Pd+{sup 30}Si and {sup 123}Sb+{sup 19}F. Four decay paths linking the HD band to the normal-deformed states have been established, which fix {ital I}{sup {pi}}=29/2{sup +} for the lowest state of the HD band lying at {ital E}{sub {ital x}}=4885 keV. The sudden disappearance, at the low spin side, of the HD bands in the {sup 133,135,137}Nd isotopes can be explained by total Routhian surface calculations through a change of the nuclear shape which is microscopically related to the transfer of the valence neutron from a {ital N}=6 to a {ital N}=4 Nilsson orbital.

  5. 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.

  6. Correlations in a Band Insulator

    NASA Astrophysics Data System (ADS)

    Sentef, Michael; Kunes, Jan; Kampf, Arno P.; Werner, Philipp

    2010-03-01

    Using DMFT we find a discontinuous band-to-Mott insulator transition upon an increase in the local Coulomb repulsion in a covalent band insulator [1,2], defined as a band insulator with partially filled local orbitals. The corresponding band gap is a hybridization gap arising from a particular pattern of hopping integrals. Similar characteristics apply to materials such as FeSi, FeSb2 or CoTiSb [3], some of which exhibit temperature dependent magnetic and transport properties reminiscent of Kondo insulators. Both charge and spin gaps in the covalent band insulator shrink with increasing Coulomb repulsion. At moderate interaction strengths the gap renormalization is well described by a renormalization factor analogous to the quasiparticle weight in a Fermi liquid. [4pt] [1] M. Sentef, J. Kunes, P. Werner, and A.P. Kampf, Phys. Rev. B 80, 155116 (2009) [0pt] [2] A.P. Kampf, M. Kollar, J. Kunes, M. Sentef, and D. Vollhardt, arXiv:0910.5126

  7. 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.

  8. Uncover the electroluminescence in wide band gap polymers

    NASA Astrophysics Data System (ADS)

    Qiao, B.; Teyssedre, G.; Laurent, C.

    2015-10-01

    Due to the rapidly increasing demand of electric power, insulating materials used in electrical components are pushed up to their limits, where their electronic properties are of fundamental importance. Electroluminescence provides an elegant way to investigate electronic properties, high field effects and electrical ageing of polymers although the emission spectrum is still poorly understood. Unlike in organic semi-conductors, electroluminescence spectra of large band gap polymers exhibit specific spectral features that cannot be interpreted on the basis of the photo-physical properties of the material. By irradiating polypropylene thin films with electrons up to a few keV and by analyzing the emitted light, we were able to isolate the elementary components of the emission and to reconstruct the electroluminescence spectrum. For the first time, a comprehensive study of electroluminescence in polymers is provided and the underlying mechanisms of the emission are discussed. The results herein provide an univocal demonstration that the electroluminescence from wide band gap polymers results in part from chemical reactions, opening the way to the diagnosis and prognosis of polymeric materials under electrical stress.

  9. 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

  10. A reward band study of mallards to estimate band reporting rates

    USGS Publications Warehouse

    Henny, C.J.; Burnham, K.P.

    1976-01-01

    Reward bands ($10) were placed on 2,122 hatching-year mallards (Anas platyrhynchos), and an additional 11,490 received conventional bands (controls) to estimate band reporting rates. An analysis of band recoveries indicated that the reporting rate was dependent primarily upon three factors: (1) the distance banded birds were recovered from the banding site, (2) band collecting activities of conservation agencies (usually near banding sites), and ( 3) the intensity of banding effort in the region (frequency of banded birds in the population of the region). Reporting rates were uniformly depressed near the banding sites, but they showed an east-west cline at distances greater than 80 km from the banding sites. The reporting rate was highest in the west. Limited data on historical band reporting rates were compiled. Recommendations are given for adjusting band recoveries to account for the nonreporting of bands for 1957-73.

  11. Shear Banding of Complex Fluids

    NASA Astrophysics Data System (ADS)

    Divoux, Thibaut; Fardin, Marc A.; Manneville, Sebastien; Lerouge, Sandra

    2016-01-01

    Even in simple geometries, many complex fluids display nontrivial flow fields, with regions where shear is concentrated. The possibility for such shear banding has been known for several decades, but in recent years, we have seen an upsurge in studies offering an ever-more precise understanding of the phenomenon. The development of new techniques to probe the flow on multiple scales with increasing spatial and temporal resolution has opened the possibility for a synthesis of the many phenomena that could only have been thought of separately before. In this review, we bring together recent research on shear banding in polymeric and soft glassy materials and highlight their similarities and disparities.

  12. Banded Terrain in East Hellas

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-460, 22 August 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) narrow angle camera image shows banded terrain in easternmost Hellas Planitia, between the distal ends of Dao and Harmakhis valleys. These bands probably indicate the location of eroded, layered bedrock that has been covered by a mantling deposit that, itself, became eroded to form the very small pits and bumps that pervade the region. This picture is located near 41.1oS, 275.0oW. Sunlight illuminates the scene from the left/upper left.

  13. Banded structures in electron pitch angle diffusion coefficients from resonant wave-particle interactions

    NASA Astrophysics Data System (ADS)

    Tripathi, A. K.; Singhal, R. P.; Khazanov, G. V.; Avanov, L. A.

    2016-04-01

    Electron pitch angle (Dαα) and momentum (Dpp) 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 (α) 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 Dαα 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 Dαα coefficients. For chorus waves, Dpp coefficients are about an order of magnitude smaller than Dαα coefficients for the case n ≠ 0. In case of Landau resonance, the values of Dpp coefficient are generally larger than the values of Dαα 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° and harmonic resonances n = +1, +2, and +3, whereas for whistler mode waves, the frequencies have been calculated for angle 10° and Landau

  14. 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.

  15. Measurements of anomalous elastic scattering of 59.54-keV photons

    SciTech Connect

    Baraldi, C.; Casnati, E.; Tartari, A.; Andreis, M.; Singh, B.

    1996-12-01

    Coherent scattering cross sections of 59.54-keV photons on target foils of {sup 64}Gd, {sup 66}Dy, {sup 68}Er, {sup 70}Yb, {sup 72}Hf, and {sup 73}Ta at 60{degree}, 90{degree}, and 120{degree} have been measured to provide information on the region of {ital K} anomalous elastic scattering. The results are compared with the values calculated by the second perturbative order {ital S} matrix and by two procedures based on the form-factor approximation corrected by the anomalous scattering factors. Agreement of the {ital S} matrix values is very satisfactory, on the whole, and that of the values given by the form-factor approximations is fairly good. {copyright} {ital 1996 The American Physical Society.}

  16. The study of the guiding process for 10 keV electrons by planar Plexiglass surfaces

    NASA Astrophysics Data System (ADS)

    Vokhmyanina, K. A.; Zhukova, P. N.; Kubankin, A. S.; Thu Hoai, Le; Nazhmudinov, R. M.; Oleinik, A. N.; Pokhil, G. P.

    2014-05-01

    Experimental study of electron beam reflection from a single planar surface of Plexiglas was made. The distinct guiding effect for the part of the beam was observed for 10 keV electrons within angles of incidence from 0 to +3 degrees. The experiments using Poly plates showed a number of features of the process such as the dependence of the reflection on the plate surface quality and material of the surfaces, the divisions of the beam into two parts with different behaviour depend on tilt angle and the beam current value, the effect of an elevation angle of the beam in compare with initial beam trace at negative and zero tilt angles of the plate.

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

    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.

  19. X-ray grating interferometry at photon energies over 180 keV

    NASA Astrophysics Data System (ADS)

    Ruiz-Yaniz, M.; Koch, F.; Zanette, I.; Rack, A.; Meyer, P.; Kunka, D.; Hipp, A.; Mohr, J.; Pfeiffer, F.

    2015-04-01

    We report on the implementation and characterization of grating interferometry operating at an x-ray energy of 183 keV. With the possibility to use this technique at high x-ray energies, bigger specimens could be studied in a quantitative way. Also, imaging strongly absorbing specimens will benefit from the advantages of the phase and dark-field signals provided by grating interferometry. However, especially at these high photon energies the performance of the absorption grating becomes a key point on the quality of the system, because the grating lines need to keep their small width of a couple of micrometers and exhibit a greater height of hundreds of micrometers. The performance of high aspect ratio absorption gratings fabricated with different techniques is discussed. Further, a dark-field image of an alkaline multicell battery highlights the potential of high energy x-ray grating based imaging.

  20. Neutral beam injector for 475 keV MARS sloshing ions

    SciTech Connect

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

    1984-03-01

    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 produce a total system electrical efficiency of about 63% for this design.

  1. 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.

  2. 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)

  3. 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.

  4. The Galactic 511 keV Line and the Intergalactic Positron Density

    NASA Astrophysics Data System (ADS)

    Vincent, Aaron C.; Vecchio, Antonio; Miralda-Escudé, Jordi; Garay, Carlos Peña

    1043 positrons per second annihilate in a compact spherical region around the centre of the Milky Way. At present, known astrophysical sources cannot account for this signal. In Ref. [1] we propose a novel scenario in which extragalactic positron sources such as radio jets of active galactic nuclei (AGN) fill the intergalactic medium (IGM) with MeV-scale e+e- pairs, which are then accreted into galaxies like the Milky Way. Interpreting the diffuse cosmic radio background (CRB) as arising from synchrotron radiation by such sources suggests that the intergalactic positron-to-electron ratio may be as high as 10-6. Assuming a simple spherical accretion model, this could account for the 511 keV emission of the galaxy.

  5. Interatomic potentials from rainbow scattering of keV noble gas atoms under axial surface channeling

    NASA Astrophysics Data System (ADS)

    Schüller, A.; Wethekam, S.; Mertens, A.; Maass, K.; Winter, H.; Gärtner, K.

    2005-04-01

    For grazing scattering of keV Ne and Ar atoms from a Ag(1 1 1) and a Cu(1 1 1) surface under axial surface channeling conditions we observe well defined peaks in the angular distributions for scattered projectiles. These peaks can be attributed to "rainbow-scattering" and are closely related to the geometry of potential energy surfaces which can be approximated by the superposition of continuum potentials along strings of atoms in the surface plane. The dependence of rainbow angles on the scattering geometry provides stringent tests on the scattering potentials. From classical trajectory calculations based on universal (ZBL), adjusted Moliere (O'Connor and Biersack), and individual interatomic potentials we obtain corresponding rainbow angles for comparison with the experimental data. We find good overall agreement with the experiments for a description of trajectories based on adjusted Moliere and individual potentials, whereas the agreement is poorer for potentials with ZBL screening.

  6. Lineshape analysis of keV electrons scattered from hydrogen molecules

    NASA Astrophysics Data System (ADS)

    Vos, Maarten

    2016-07-01

    Accurate measurements of keV electrons scattered elastically from H2 molecules reveal a lineshape that is an intrinsic property of the target. The intrinsic width of the elastic peak is due to the non-zero momentum of a proton bound to a molecule. A more precise analysis of the lineshape shows that it deviates from Gaussian. This deviation is shown to be a consequence of the dominance of the momentum component of the protons along the molecular axis. The mean-kinetic energy of the protons in H2 obtained based on the new peak shape agrees better with theory than the one obtained based on a Gaussian peak shape. These measurements demonstrate the possibility of a new way to study the dynamics of nuclei by electron scattering.

  7. Solution of controversy over 1583-keV levels in sup 204 Pb

    SciTech Connect

    Trzaska, W.H.; Julin, R.; Kantele, J.; Kumpulainen, J. )

    1989-09-01

    Data from {sup 204}Pb({ital p},{ital p}{prime}){sup 204}Pb conversion-electron and gamma-ray experiments, together with previous results, prove the existence of two levels (0{sup +} and 2{sup +}) at 1583-keV excitation energy in {sup 204}Pb. Modified values (limits) of the {rho}{sub 21}{sup 2} and {ital X}{sub 211} are 0.0013{lt}{rho}{sub 21}{sup 2}{lt}0.015 and {ital X}{sub 211}{gt}0.073. New experimental evidence indicates that all the three observed excited {ital O}{sup +} states in {sup 204}Pb can be explained as belonging to the four-neutron-hole valence space and, therefore, there is no clear candidate for the proton 2p-2h intruder state in this nucleus.

  8. 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.

  9. 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.

  10. 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.

  11. Growth of Sn whiskers after low temperature implantation of 20 keV He or H

    SciTech Connect

    Poker, D.B.; Schubert, J.; Alexandrou, A.; Froehlingsdorf, J.; Stritzker, B.

    1986-01-01

    Single crystalline whiskers have been observed to form on thin films (approx.100 nm) of Sn following implantation of 20-keV H or He at temperatures below 15/sup 0/K. Rapid warming prevented the formation of whiskers, indicating that the growth occurs predominatly during the warming, and not during implantation. Samples that had been warmed rapidly did show whisker growth only after several days in air at room temperature. The adhesion of the films to the substrate is remarkably enhanced by the irradiation, as measured by scratch tests. Thicker films produced progressively fewer whiskers, and none were observed on implanted foils, or films of In, Bi, Zn, or Pb. Possible origins of the driving force for whisker growth are discussed. Whiskers grew on Sn films on all of the substrates that were tested: quartz, sapphire, glass, Si, Cu, stainless steel, and NaCl.

  12. The 50 keV Source of Polarized Electrons at ELSA: Past and Future

    NASA Astrophysics Data System (ADS)

    Eberhardt, Maren; Wittschen, Jürgen; Gowin, Michael; Hillert, Wolfgang; Neff, Bernhard

    2007-06-01

    Since 2000, an inverted source for polarized electrons is in operation at the electron stretcher accelerator ELSA of Bonn university. Within several years of operation for the GDH experiment, the gun provided a pulsed beam with high polarization and intensity using a single strained-layer superlattice photocathode. The generation of rectangularly shaped pulses with 100 nC charge is achieved by optical pumping with a flashlamp-pumped titanium sapphire laser and space charge limited emission at 50 keV. Continuous degradation of the photocathode due to oxygen deposition on the surface which could not be removed completely by heat cleaning at moderate temperatures had been observed. In order to enhance the reliability and uptime of the source, a new load-lock system with crystal storage and atomic hydrogen cleaning will be installed in the near future.

  13. 511 keV line and diffuse gamma rays from moduli

    SciTech Connect

    Kasuya, Shinta; Kawasaki, Masahiro

    2006-03-15

    We obtain the spectrum of gamma-ray emissions from the moduli whose decay into e{sup +}e{sup -} accounts for the 511 keV line observed by SPI/INTERGRAL. The moduli emit gamma rays through internal bremsstrahlung, and also decay directly into two gammas via tree and/or one-loop diagrams. We show that the internal bremsstahlung constrains the mass of the moduli below {approx}40 MeV model-independently. On the other hand, the flux of two gammas directly decayed from the moduli through one-loop diagrams will exceed the observed galactic diffuse gamma-ray background if the moduli mass exceeds {approx}20 MeV in the typical situation. Moreover, forthcoming analysis of SPI data in the range of 1-8 MeV may detect the line emisson with the energy half the moduli mass in the near future, which confirms the decaying moduli scenario.

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

    DOE PAGESBeta

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

    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

  15. Simulation of RPC performance for 511 keV photon detection

    NASA Astrophysics Data System (ADS)

    Lippmann, C.; Vincke, H.; Riegler, W.

    2009-05-01

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

  16. 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.

  17. Evolution of nanodot morphology on polycarbonate (PC) surfaces by 40 keV Ar+

    NASA Astrophysics Data System (ADS)

    Goyal, Meetika; Chawla, Mahak; Gupta, Divya; Shekhawat, Nidhi; Sharma, Annu; Aggarwal, Sanjeev

    2016-05-01

    In the present paper we have discussed the effect of 40 keV Ar+ ions irradiation on nanoscale surface morphology of Polycarbonate (PC) substrate. Specimens were sputtered at off normal incidences of 30°, 40° and 50° with the fluence of 1 × 1016 Ar+cm-2. The topographical behaviour of specimens was studied by using Atomic Force Microscopy (AFM) technique. AFM study demonstrates the evolution of nano dot morphology on PC specimens on irradiating with 1 × 1016 Ar+cm-2. Average size of dots varied from 37-95 nm in this specified range of incidence while density of dots varied from 0.17-3.0 × 107 dotscm-2. Such variations in morphological features have been supported by estimation of ion range and sputtering yield through SRIM simulations.

  18. High Spatial Resolution STXM at 6.2 keV Photon Energy

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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.

  19. A Hard Tail in Broad Band Spectrum of Cir X-1: a clue for a Z-source behavior

    NASA Astrophysics Data System (ADS)

    Iaria, R.; Di Salvo, T.; La Barbera, A.; Burderi, L.; Robba, N. R.

    2000-10-01

    We report on the spectral analysis of the peculiar source Cir X--1 observed by the BeppoSAX satellite when the X-ray source was near the periastron. A flare lasting ~ 6 x 103 s is present at the beginning of the observation. The luminosity during the persistent emission is 1 x 1038 erg s-1, while during the flare is 2 x 1038 erg s-1. The broad band (0.1--100 keV) energy spectrum is well fitted by a model consisting of Comptonization of soft photons, with a temperature of ~ 0.4 keV, by electrons at a temperature of ~ 1 keV, and a power-law component, with photon index ~ 3, dominant at energies higher than 10 keV. This component is present out the flare, contributing to ~ 4% of the total luminosity, while during the flare its addition is not statistically significant. An absorption edge at ~ 8.4 keV, with optical depth ~ 1, corresponding to the K-edge of Fe XXIII--XXV, and an iron emission line at 6.7 keV are also present. The iron line energy is in agreement with the ionization level of the absorbtion edge. The hydrogen column deduced from the absorption edge is ~ 1024 cm-2,two order of magnitude larger than the absorption measured in this source. We calculated the radius of the region originating the comptonized seed photons, RW ~ 150 km. We propose a scenario where RW is the inner disk radius, a highly ionized torus surrounds the accretion disk and a magnetospere is large up to RW. The absorption edge, the emission line could originate in the photoionized torus present in the outer edge of the accretion disk, while the comptonized component originates in an inner region of the disk.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Merle, Alexander; Totzauer, Maximilian

    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.

  2. 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.

  3. 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.

  4. Low-energy x-ray dosimetry studies (6 to 16 keV) at SSRL beamline 1-5

    NASA Astrophysics Data System (ADS)

    Ipe, N. E.; Chatterji, S.; Fassò, A.; Kase, K. R.; Seefred, R.; Olko, P.; Bilski, P.; Soares, C.

    1997-07-01

    Synchrotron radiation facilities provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory (SSRL) are described. Polish lithium fluoride thermoluminescent dosemeters (TLDs), MTS-N(LiF:Mg, Ti- 0.4 mm thick), MCP-N (LiF:Mg, Cu, P - 0.4 mm thick) were exposed free in air to monochromatic x-rays (6-16 keV). These exposures were monitored with an SSRL ionization chamber. The responses (counts/Gy) of MTS-N and MCP-N were generally found to increase with increasing energy. The response at 16 keV is about 3 and 4 times higher than the response at 6 keV for MTS-N and MCP-N, respectively. Irradiation at 6 keV indicates a fairly linear dose response for both type of TLDs over a dose range of 0.01 to 0.4 Gy. In addition there appears to be no significant difference in responses between irradiating the TLDs from the front and the back sides. The energy response of the PTW ionization chamber type 23342 relative to the SSRL ionization chamber is within ±4.5% between 6 and 16 keV. Both the TLDs and the PTW ionization chamber can also be used for beam dosimetry.

  5. The X-ray spectrum of AM Herculis from 0.1 to 150 keV

    NASA Technical Reports Server (NTRS)

    Rothschild, R. E.; Gruber, D. E.; Knight, F. K.; Matteson, J. L.; Nolan, P. L.; Swank, J. H.; Holt, S. S.; Serlemitsos, P. J.; Mason, K. O.; Tuohy, I. R.

    1981-01-01

    No significant flux at 100 keV was detected in the observations by the HEAO 1 satellite (March and April of 1978) and in several OSO 7 observations. The spectrum above 2 keV can be fitted by a composite thermal bremsstrahlung model that includes an approximation to the albedo expected from the white dwarf. The bremsstrahlung kT sub e from this model (30.9 + or - 4.5 keV) implies a white dwarf mass in excess of 0.6 solar mass. An emission feature at 6.5 + or - 0.15 keV and equivalent width of 0.8 + or - 0.1 keV is confirmed; it is thought that this might be due to fluorescence from the white dwarf by the bremsstrahlung from a small thin shocked region. It is noted that the continuum could also have been steepened at high energy in scattering in the accretion column, but the line photons cannot have gone through the same optical depths.

  6. Neutron resonance parameters of /sup 79/Br and /sup 81/Br up to 15 keV

    SciTech Connect

    Ohkubo, M.; Kawarasaki, Y.; Mizumoto, M.

    1980-09-01

    Resonance parameters of separated isotopes of bromine were measured using TOF spectrometer of Japan Atomic Energy Research Institute linear accelerator. Transmission and capture measurements were made with /sup 6/Li-glass and Moxon-Rae detectors, on separated isotopes (approx. 98%) of /sup 79/Br and /sup 81/Br. Resonance analyses were made on transmission data with an area analysis code, and on capture data with a Monte-Carlo program CAFIT. For /sup 79/Br gGAMMA/sup 0//sub n/ values for 156 levels below 10 keV are obtained, and for /sup 81/Br 100 levels below 15 keV. Strength functions are obtained: for /sup 79/Br S/sub O/ = (1.27 +- 0.14) x10/sup -4/ below 10 keV, and for /sup 81/Br S/sub O/ = (0.86 +- 0.14)10/sup -4/ below 15 keV. Intermediate structures are observed in the resonances of /sup 81/Br showing clusters of levels at 1.2, 10, 11.5, and 14 keV, where the sum of gGAMMA/sup 0//sub n/ vs. neutron energy shows steep rises.

  7. Sub-arcsecond X-ray Telescope for Imaging the Solar Corona at 1 keV

    NASA Astrophysics Data System (ADS)

    Gallagher, D.; Cash, W.; Jelsma, S.

    1996-05-01

    Over the past several years at the University of Colorado we have been developing an X-ray telescope that uses a new technique for focusing X-rays with grazing incidence optics The telescope uses spherical optics for all its components, thus utilizing the high quality surfaces obtainable when polishing spherical optics as compared to that of aspherical optics. A prototype engineering X-ray telescope has been fabricated and tested using the 300 meter vacuum pipe at White Sands Missile Range, NM. The telescope uses approximately 2 degree graze angles with tungsten coatings which gives a bandpass of 0.25-1.5 keV and a peak effective area of 0.08 cm(2) at 0.83 keV. Results from X-ray testing at energies of 0.25 keV and 0.93 keV (C-K and Cu-L) will be presented which verify 0.5 arcseconds performance at 0.93 keV. Results from modeling the X-ray telescope's response to the sun show that the current optics design would be capable of recording on the order of 10 images of a solar active region during a 300 second NASA sounding rocket flight at resolution of 0.5 arcsecond.

  8. 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.

  9. Resistive band for turbomachine blade

    SciTech Connect

    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.

  10. 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.

  11. 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…

  12. Tolerance bands for functional data.

    PubMed

    Rathnayake, Lasitha N; Choudhary, Pankaj K

    2016-06-01

    Often the object of inference in biomedical applications is a range that brackets a given fraction of individual observations in a population. A classical estimate of this range for univariate measurements is a "tolerance interval." This article develops its natural extension for functional measurements, a "tolerance band," and proposes a methodology for constructing its pointwise and simultaneous versions that incorporates both sparse and dense functional data. Assuming that the measurements are observed with noise, the methodology uses functional principal component analysis in a mixed model framework to represent the measurements and employs bootstrapping to approximate the tolerance factors needed for the bands. The proposed bands also account for uncertainty in the principal components decomposition. Simulations show that the methodology has, generally, acceptable performance unless the data are quite sparse and unbalanced, in which case the bands may be somewhat liberal. The methodology is illustrated using two real datasets, a sparse dataset involving CD4 cell counts and a dense dataset involving core body temperatures. PMID:26574904

  13. 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.

  14. 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....

  15. 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....

  16. 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....

  17. 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....

  18. 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 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND...-805 MHz Bands § 90.531 Band plan. This section sets forth the band plan for the 763-775 MHz and...

  19. 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.

  20. 700 keV Ni+2 ions induced modification in structural, surface, magneto-optic and optical properties of ZnO thin films

    NASA Astrophysics Data System (ADS)

    Fiaz Khan, M.; Siraj, K.; Anwar, M. S.; Irshad, M.; Hussain, J.; Faiz, H.; Majeed, S.; Dosmailov, M.; Patek, J.; Pedarnig, J. D.; Rafique, M. S.; Naseem, S.

    2016-02-01

    We investigate the effect of 700 keV Ni+2 ions irradiation at different ion fluences (1 × 1013, 1 × 1014, 2 × 1014, 5 × 1014 ions/cm2) on the structural, surface, magneto-optic and optical properties of ZnO thin films. The X-ray diffraction (XRD) results show improved crystallinity when ion fluence is increased to 2 × 1014 ions/cm2, while deterioration is observed at the highest ion fluence of 5 × 1014 ions/cm2. Scanning electron micrographs (SEM) show the formation of small grains at ion fluence 1 × 1013 ions/cm2, micro-rods at fluences 1 × 1014 and 2 × 1014 ions/cm2 and ultimate fracturing of thin film surface at ion fluence 5 × 1014 ions/cm2. Faraday rotation measurements are also performed and show a decrease in Verdet constant from 53 to 31 rad/(T-m) when irradiated at 1 × 1013 ions/cm2, increasing up to 45 rad/(T-m) at 2 × 1014 ions/cm2, and then decreasing again to 36 rad/(T-m) at 5 × 1014 ions/cm2. The optical band gap energy of the films is determined using spectroscopic ellipsometry, which shows an increase in optical band gap energy (Eg) from 3.04 eV to 3.19 eV when the fluence increases to 2 × 1014 ions/cm2 and a decrease to 3 eV at fluence 5 × 1014 ions/cm2. We argue that these properties can be explained using ion heating effect of thin films.

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

    SciTech Connect

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

    2006-06-15

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

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

    SciTech Connect

    Green, K. L.; Garrett, P. E.; Demand, G. A.; Grinyer, G. F.; Leach, K. G.; Phillips, A. A.; Schumaker, M. A.; Svensson, C. E.; Wong, J.; Austin, R. A. E.; Colosimo, S.; Ball, G. C.; Bandyopadhyay, D. S.; Hackman, G.; Morton, A. C.; Pearson, C. J.; Cross, D.; Kulp, W. D.; Wood, J. L.; Yates, S. W.

    2009-09-15

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

  3. 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.

  4. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2006-06-01

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

  6. Observational Evidences for the Existence of 17.4 keV Decaying Degenerate Sterile Neutrinos Near the Galactic Center

    NASA Astrophysics Data System (ADS)

    Chan, M. H.; Chu, M.-C.

    2011-02-01

    We show that the existence of a degenerate halo of sterile neutrinos with rest mass of 17.4 keV near the Galactic center (GC) can account for both the excess 8.7 keV emission observed by the Suzaku mission and the power needed (1040 erg s-1) to maintain the high temperature of the hot gas (8 keV) near the GC. The required decay rate and mixing angle of the sterile neutrinos are Γ >= 10-19 s-1 and sin22θ ~ 10-3, respectively. These values are consistent with a low reheating temperature, which suppresses the production of sterile neutrinos, resulting in a small sterile neutrino density parameter (Ω s < 10-8). They are also allowed by X-ray background data and the isotope experiment. The large mixing angle leads to the exciting possibility that a sterile-active neutrino oscillation may be visible in near future experiments.

  7. 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.

  8. 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.

  9. 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.

  10. Size saturation in low energy ion beam synthesized nanoparticles in silica glass: 50 keV Ag{sup -} ions implantation, a case study

    SciTech Connect

    Kuiri, P. K.

    2010-09-15

    Fluence-dependent formation of Ag nanoparticles (NPs) in silica glass by 50 keV Ag{sup -} ions implantation has been studied. Samples implanted with fluences of 2x10{sup 16} ions cm{sup -2} and above are found to show an absorption band at around 410 nm, corresponding to the surface plasmon resonance (SPR) of the Ag NPs in silica glass. An increase in SPR peak intensity with increase in fluence has been observed up to a fluence of 7x10{sup 16} ions cm{sup -2} (F7), after which the absorption intensity shows a saturation. Simulations of the optical absorption spectra also indicated an increase in the absorption intensity and hence the size of the NPs with increase in fluence up to F7, beyond which NP size is seen to saturate. The saturation of fluence and the SPR intensity (or NP size) have been explained as coming due to a break up of larger Ag NPs formed near the surface by displacement spikes induced by subsequently incident Ag ions against their regrowth from the movement of Ag atoms toward the surface and their sputtering loss. Further, we have compared our observations with the earlier data on saturation of fluence and size of NPs in cases of Au and Zn, and concluded that the saturation of both fluence and NP size are general phenomena for low energy high fluence metal ion implantation.

  11. Analysis of 6.4 KEV Moessbauer Spectra Obtained with MIMOS II on MER on Cobbles at Meridiani Planum, Mars and Considerations on Penetration Depths

    NASA Technical Reports Server (NTRS)

    Fleischer, I.; Klingelhoefer, G.; Morris, R. V.; Schroder, C.; Rodionov, D.; deSouza, P.

    2008-01-01

    The miniaturized Moessbauer (MB) spectrometers MIMOS II [1] on board of the two Mars Exploration Rovers Spirit and Opportunity have obtained more than 600 spectra of more than 300 different rock and soil targets [2-7]. Both instruments have simultaneously collected 6.4 keV X-ray and 14.4 keV .-ray spectra in backscattering geometry [1]. With Spirit's MB spectrometer, 6.4 keV and 14.4 keV spectra have been obtained for all targets through sol 461. After this date, only 14.4 keV spectra were collected. With Opportunity's spectrometer, 6.4 keV and 14.4 keV spectra have been collected for all targets to date. The Fe-mineralogy of rock and soil targets at both landing sites reported to date has been exclusively extracted from 14.4 keV spectra [2-5]. The comparison of 6.4 keV and 14.4 keV spectra provides depth selective information about a sample, but interpretation is not always straightforward [8].

  12. The composite broad band spectrum of Cir X-1 at the periastron: a peculiar Z-source

    NASA Astrophysics Data System (ADS)

    Iaria, R.; di Salvo, T.; Burderi, L.; La Barbera, N.; Robba, N. R.

    2001-09-01

    We report on the spectral analysis of the peculiar source Cir X-1 observed by the BeppoSAX satellite when the X-ray source was near the periastron. A flare lasting ~6×103s is present at the beginning of the observation. We produced broad band (0.1 - 100 keV) energy spectra during the flare and the persistent emission. At low energies the continuum is well fitted by a model consisting of Comptonization of soft photons, with a temperature of ~0.4 keV, by electrons at a temperature of ~1 keV. Out of the flare a power-law component, with photon index ~3, is dominant at energies higher than 10 keV. This component contributes to ~4% of the total luminosity. During the flare its addition is not statistically significant. Similar hard components have been recently observed in other Z-sources, sometimes related to the position of the source in the color-color diagram. An interesting possibility is that these components are due to the presence of jet emission.

  13. Spectrum response and analysis of 77 GHz band collective Thomson scattering diagnostic for bulk and fast ions in LHD plasmas

    NASA Astrophysics Data System (ADS)

    Nishiura, M.; Kubo, S.; Tanaka, K.; Seki, R.; Ogasawara, S.; Shimozuma, T.; Okada, K.; Kobayashi, S.; Mutoh, T.; Kawahata, K.; Watari, T.; LHD Experiment Group; Saito, T.; Tatematsu, Y.; Korsholm, S. B.; Salewski, M.

    2014-02-01

    A collective Thomson scattering (CTS) diagnostic was developed and used to measure the bulk and fast ions originating from 180 keV neutral beams in the Large Helical Device (LHD). Electromagnetic waves from a gyrotron at 77 GHz with 1 MW power output function as both the probe and electron cyclotron heating beam. To clarify the diagnostic applicability of the gyrotron in the 77 GHz frequency band, we investigated the dependence of the probe and receiver beam trajectories in plasmas with high electron densities of (4-5) × 1019 m-3 and low electron densities of (1-2) × 1019 m-3. At high density, a stray radiation component was observed in the CTS spectrum whereas it was negligibly small at low density. The CTS spectrum was measured and analysed after the in situ beam alignment using a beam scan. Qualitatively, the CTS spectrogram shows consistent response to ion temperatures of 1-2 keV for electron densities of (1-2) × 1019 m-3 and electron temperatures of 2-4 keV. The measured CTS spectrum shows an asymmetric shape at the foot of the bulk-ion region during the injection of 180 keV fast ions. This shape is explained by the fast-ion distribution in the velocity space (v‖, v⊥) based on Monte Carlo simulation results. The analysis method of the CTS spectra is used to evaluate the ion temperature and fast-ion velocity distribution from the measured CTS data.

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

    NASA Astrophysics Data System (ADS)

    Mohan, Harsh; Jain, Arvind Kumar; Kaur, Mandeep; Singh, Parjit S.; Sharma, Sunita

    2014-08-01

    In performing ion beam analysis, cross section for induced L X-ray emission plays a crucial role. There are different approaches by which these can be found experimentally or can be calculated theoretically based on various models. L X-ray production cross sections for Bi with protons in the energy range 260-400 keV at the interval of 20 keV are measured. These are compared with calculations obtained on the basis of current prevailing theories ECPSSR and ECPSSR-UA. Their importance in understanding this phenomenon and existing arguments in this regard will be highlighted.

  15. Relative dissociation fractions of CF4 under 15–30 keV H‑, C‑ and O‑ negative ion impact

    NASA Astrophysics Data System (ADS)

    Wang, Dedong; Fan, Yikui; Zhao, Zilong; Min, Guangxin; Zhang, Xuemei

    2016-08-01

    The relative dissociation fractions to produce the fragments of CF4 molecule are studied under the impact of 15 keV to 30 keV H‑, C‑ and O‑ negative ions. By using a time-of-flight mass spectrometer, the recoil ions and ion pairs originating from the target molecule CF4 are detected and identified in coincidence with scattered ions in q = 0 and q = +1 charge states. The fractions for the production of the fragment ions are obtained relative to the {\\text{CF} }3+ yield, while that of the ion pairs relative to the (C+, F+) coincidence yield.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. 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.

  18. 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.

  19. Ultrafast band-structure variations induced by fast Au ions in BeO

    NASA Astrophysics Data System (ADS)

    Schiwietz, G.; Czerski, K.; Grande, P. L.; Koteski, V.; Staufenbiel, F.

    2011-05-01

    Auger-electron spectra associated with Be atoms in the pure metal lattice and in an oxide have been investigated for 1.8 MeV/u 129Au 41+ ions and 2.7 keV primary electrons. The excitation and local energy transfer by such fast primary particles in solids is dominated by electronic processes. The electron-induced spectrum is compared to calculated band-structure results and it is relatively well understood. For the heavy-ion case, however, we observe a significant variation of the Auger electron spectrum, related to a variation of the electronic band structure. This spectrum points to a formation of a metal-like meta-stable electronic density of states.

  20. 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.

  1. High-Power Operation of a Three-Cavity X-Band Coaxial Gyroklystron

    NASA Astrophysics Data System (ADS)

    Lawson, W.; Cheng, J.; Calame, J. P.; Castle, M.; Hogan, B.; Granatstein, V. L.; Reiser, M.; Saraph, G. P.

    1998-10-01

    Experimental studies of high-power amplification in a novel three-cavity X-band gyroklystron are reported. The electron gun produces a 520 A beam of 470 keV electrons. The voltage flat top is nearly 2 μs and the beam's average velocity ratio is about 1. All cavities are designed to operate in the TE011 coaxial mode near 8.6 GHz. Peak powers of 75-85 MW are measured. The resultant efficiency is near 32% and the gain is near 30 dB. This performance is in good agreement with simulations and represents nearly a threefold increase in the peak power capability of pulsed X-band gyroklystrons.

  2. Septic complications of hemorrhoidal banding.

    PubMed

    Quevedo-Bonilla, G; Farkas, A M; Abcarian, H; Hambrick, E; Orsay, C P

    1988-05-01

    Rubber band ligation is an efficacious and cost-effective alternative to conventional hemorrhoidectomy for symptomatic internal hemorrhoids. Even though the well-recognized complications of bleeding and thrombosis occur infrequently, far more serious septic complications have only recently been described, as evidenced in five of our patients: four cases were serious enough to necessitate surgical intervention, and one patient died. Pain followed by urinary dysfunction with or without toxic symptoms should alert the physician to the probability of localized perianal or systemic sepsis. Acute awareness of these rare but potentially life-threatening complications and immediate aggressive treatment is mandatory if death is to be prevented. Rubber band ligation of internal hemorrhoids need not be abandoned; however, the indications should be clear, the technique mastered, and a close patient follow-up maintained. PMID:3358691

  3. Ku-band miniature modulators

    NASA Technical Reports Server (NTRS)

    Ernst, R. L.

    1973-01-01

    Ku-band microminiature modulators were designed to convert a 10 mW signal at 400 MHz to a 10 mW signal at 15 GHz. The designs incorporate gallium arsenide Schottky barrier varactors used in upper-sideband up-converters. The use of Ku-band microstrip circulators and hairpin resonator bandpass filters at 2.1 GHz and 2.5 GHz is included. The design and fabrication of a single up-conversion unit with a double up-conversion unit are compared. Various filter configurations are studies, and the use of both alumina and quartz substrates are considered. The various impedance matching networks are evaluated using computer aided design techniques.

  4. ALMA Band 5 Cartridge Performance

    NASA Astrophysics Data System (ADS)

    Billade, Bhushan; Lapkin, I.; Nystrom, O.; Sundin, E.; Fredrixon, M.; Finger, R.; Rashid, H.; Desmaris, V.; Meledin, D.; Pavolotsky, A.; Belitsky, Victor

    2010-03-01

    Work presented here concerns the design and performance of the ALMA Band 5 cold cartridge, one of the 10 frequency channels of ALMA project, a radio interferometer under construction at Atacama Desert in Chile. The Band 5 cartridge is a dual polarization receiver with the polarization separation performed by orthomode transducer (OMT). For each polarization, Band 5 receiver employs sideband rejection (2SB) scheme based on quadrature layout, with SIS mixers covering 163-211 GHz with 4-8 GHz IF. The LO injection circuitry is integrated with mixer chip and is implemented on the same substrate, resulting in a compact 2SB assembly. Amongst the other ALMA bands, the ALMA Band 5 being the lowest frequency band that uses all cold optics, has the largest mirror. Consequently, ALMA Band 5 mirror along with its support structure leaves very little room for placing OMT, mixers and IF subsystems. The constraints put by the size of cold optics and limited cartridge space, required of us to revise the original 2SB design and adopt a design where all the components like OMT, mixer, IF hybrid, isolators and IF amplifier are directly connected to each other without using any co-ax cables in-between. The IF subsystem uses the space between 4 K and 15 K stage of the cartridge and is thermally connected to 4 K stage. Avoiding co-ax cabling required use of custom designed IF hybrid, furthermore, due to limited cooling capacity at 4 K stage, resistive bias circuitry for the mixers is moved to 15 K stage and the IF hybrid along with an integrated bias-T is implemented using superconducting micro-strip lines. The E-probes for both LO and RF waveguide-to-microstrip transitions are placed perpendicular to the wave direction (back-piece configuration). The RF choke at the end of the probes provides a virtual ground for the RF/LO signal, and the choke is DC grounded to the chassis. The on-chip LO injection is done using a microstrip line directional coupler with slot-line branches in the

  5. 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. PMID:17758893

  6. 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

  7. Nonzero Quadrupole Moments of Candidate Tetrahedral Bands

    SciTech Connect

    Bark, R. A.; Lawrie, E. A.; Lawrie, J. J.; Mullins, S. M.; Murray, S. H. T.; Ncapayi, N. J.; Smit, F. D.; Sharpey-Schafer, J. F.; Lindsay, R.

    2010-01-15

    Negative-parity bands in the vicinity of {sup 156}Gd and {sup 160}Yb have been suggested as candidates for the rotation of tetrahedral nuclei. We report the observation of the odd and even-spin members of the lowest energy negative-parity bands in {sup 160}Yb and {sup 154}Gd. The properties of these bands are similar to the proposed tetrahedral band of {sup 156}Gd and its even-spin partner. Band-mixing calculations are performed and absolute and relative quadrupole moments deduced for {sup 160}Yb and {sup 154}Gd. The values are inconsistent with zero, as required for tetrahedral shape, and the bands are interpreted as octupole vibrational bands. The failure to observe the in-band E2 transitions of the bands at low spins can be understood using the measured B(E1) and B(E2) values.

  8. 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.

  9. Band-selective radiofrequency pulses

    NASA Astrophysics Data System (ADS)

    Geen, Helen; Freeman, Ray

    A theoretical treatment is given of the general problem of designing amplitude-modulated radiofrequency pulses that will excite a specified band of frequencies within a high-resolution NMR spectrum with uniform intensity and phase but with negligible excitation elsewhere. First a trial pulse envelope is defined in terms of a finite Fourier series and its frequency-domain profile calculated through the Bloch equations. The result is compared with the desired target profile to give a multidimensional error surface. The method of simulated annealing is then used to find the global minimum on this surface and the result refined by standard gradient-descent optimization. In this manner, a family of new shaped radio-frequency pulses, known as BURP ( band-selective, uniform response, pure-phase) pulses, has been created. These are of two classes—pulses that excite or invert z magnetization and those that act as general-rotation πr/2 or π pulses irrespective of the initial condition of the nuclear magnetization. It was found convenient to design the latter class as amplitude-modulated time-symmetric pulses. Tables of Fourier coefficients and pulse-shape ordinates are given for practical implementation of BURP pulses, together with the calculated frequency-domain responses and experimental verifications. Examples of the application of band-selective pulses in conventional and multidimensional spectroscopy are given. Pure-phase pulses of this type should also find applications in magnetic resonance imaging where refocusing schemes are undesirable.

  10. 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

  11. Nonabelian dark matter models for 3.5 keV X-rays

    NASA Astrophysics Data System (ADS)

    Cline, James M.; Frey, Andrew R.

    2014-10-01

    A recent analysis of XXM-Newton data reveals the possible presence of an X-ray line at approximately 3.55 keV, which is not readily explained by known atomic transitions. Numerous models of eV-scale decaying dark matter have been proposed to explain this signal. Here we explore models of multicomponent nonabelian dark matter with typical mass ~ 1-10 GeV (higher values being allowed in some models) and eV-scale splittings that arise naturally from the breaking of the nonabelian gauge symmetry. Kinetic mixing between the photon and the hidden sector gauge bosons can occur through a dimension-5 or 6 operator. Radiative decays of the excited states proceed through transition magnetic moments that appear at one loop. The decaying excited states can either be primordial or else produced by upscattering of the lighter dark matter states. These models are significantly constrained by direct dark matter searches or cosmic microwave background distortions, and are potentially testable in fixed target experiments that search for hidden photons. We note that the upscattering mechanism could be distinguished from decays in future observations if sources with different dark matter velocity dispersions seem to require different values of the scattering cross section to match the observed line strengths.

  12. The 3 H(d , γ) Reaction at Ec . m . <= 300 keV

    NASA Astrophysics Data System (ADS)

    Parker, C. E.; Brune, C. R.; Massey, T. N.; O'Donnell, J. E.; Richard, A. L.; Sayre, D. B.

    2015-04-01

    The 3 H(d , γ) 5He reaction has been measured using a 500-keV pulsed deuteron beam incident on a stopping titanium tritide target at the Edwards Accelerator Laboratory. The time-of-flight technique has been used to distinguish the γ-rays from neutrons in the bismuth germinate (BGO) γ-ray detector. A stilbene scintillator and an NE-213 scintillator have been used to detect the neutrons from the 3 H(d , n) α reaction using both the pulse-shape discrimination and time-of-flight techniques. A newly designed target holder with a silicon surface barrier detector to simultaneously measure α-particles to normalize the number of neutrons, along with a new titanium tritide target, was incorporated for subsequent measurements. The γ-rays have been measured at laboratory angles of 0 °, 45 °, 90 °, and 135 °. Information about the γ-ray energy distribution for the unbound ground state and first excited state of 5He can be obtained experimentally by comparing the BGO data to Monte Carlo simulations. The 3 H(d , γ) /3 H(d , n) branching ratio has also been measured. Data analysis is currently underway for the subsequent measurements. This work is supported in part by Lawrence Livermore National Laboratory and the U.S. D.O.E. (NNSA) through Grant No. DE-NA0001837.

  13. 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.

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

    NASA Astrophysics Data System (ADS)

    Delcorte, Arnaud; Garrison, Barbara J.

    2007-02-01

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

  15. 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.

  16. 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.

  17. Optima MDxt: A high throughput 335 keV mid-dose implanter

    SciTech Connect

    Eisner, Edward; David, Jonathan; Justesen, Perry; Kamenitsa, Dennis; McIntyre, Edward; Rathmell, Robert; Ray, Andrew; Rzeszut, Richard

    2012-11-06

    The continuing demand for both energy purity and implant angle control along with high wafer throughput drove the development of the Axcelis Optima MDxt mid-dose ion implanter. The system utilizes electrostatic scanning, an electrostatic parallelizing lens and an electrostatic energy filter to produce energetically pure beams with high angular integrity. Based on field proven components, the Optima MDxt beamline architecture offers the high beam currents possible with singly charged species including arsenic at energies up to 335 keV as well as large currents from multiply charged species at energies extending over 1 MeV. Conversely, the excellent energy filtering capability allows high currents at low beam energies, since it is safe to utilize large deceleration ratios. This beamline is coupled with the >500 WPH capable endstation technology used on the Axcelis Optima XEx high energy ion implanter. The endstation includes in-situ angle measurements of the beam in order to maintain excellent beam-to-wafer implant angle control in both the horizontal and vertical directions. The Optima platform control system provides new generation dose control system that assures excellent dosimetry and charge control. This paper will describe the features and technologies that allow the Optima MDxt to provide superior process performance at the highest wafer throughput, and will provide examples of the process performance achievable.

  18. Oxygen incorporation in polyethylene implanted with 150 keV Sb+ ions

    NASA Astrophysics Data System (ADS)

    Hnatowicz, V.; Kvítek, J.; Švorčík, V.; Rybka, V.; Popok, V.

    1994-06-01

    Samples of polyethylene (PE) loaded with carbon black up to 8 wt.% and implanted with 150 keV Sb+ ions to the doses from 2×1013-2×1015 cm-2 were studied using standard Rutherford Back Scattering (RBS) technique. On the PE samples implanted to the doses above 2×1014 cm-2, a considerable surface carbonization is observed. The measured parameters of the Sb depth profile are compared with theoretical TRIM estimations. The projected range is by 25% lower than the theoretical one and the range straggling is about twice of that predicted. The differences are explained by stepwise polymer degradation during the ion bombardment. Strong oxidation of the ion implanted polymers is also observed. The oxygen depth profiles from the sample surface up to the depth comparable with Sb+ ion range evolve from nearly uniform one for low ion doses to highly non-uniform one for doses above 1×1015 cm-2. The total oxygen content in the sample surface layer 300 nm thick reaches a maximum for the doses of (1-2)×1014 cm-2.

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

    NASA Astrophysics Data System (ADS)

    Emery, Deanna Lily; Bogdan, Akos; Kraft, Ralph P.; Forman, William R.; Jones, Christine; Santos, Felipe A.

    2016-06-01

    We present results of deep 153 ks Chandra observations of the hot, 11 keV, galaxy cluster associated with the radio galaxy 3C 438. By mapping the morphology of the hot gas and analyzing its surface brightness and temperature distribution, we argue that the cluster is undergoing a major merger between two massive sub-clusters. To the southeast of 3C 438, we detect two jumps in surface brightness, at 90” (400 kpc) and at 180” (800 kpc). The inner jump corresponds to an increase in density by a factor of two, while the outer jump implies a decrease in density by a factor of almost four. Combining these density jumps with the temperature distribution within the cluster, we establish that the pressure of the hot gas is continuous at the inner jump, while there is a significant pressure increase at the outer jump. From the magnitude of the outer pressure jump, we determine that one sub-cluster is moving with a relative velocity of approximately 2300 km/s with respect to the intracluster medium of the second sub-cluster, creating a bow shock. Based on these findings, we conclude that the discontinuity is likely the result of an ongoing major merger between two massive sub-clusters.

  20. 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. PMID:20097973

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

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

    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 thetav<=45° with respect to the global surface normal using 2 keV Kr+ and fluences of ≈ 2 × 1022 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°<=thetav<=83° 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. Ion-induced photon emission of magnesium aluminate spinel during 60 keV Cu - implantation

    NASA Astrophysics Data System (ADS)

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

    2001-04-01

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

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  5. 800-keV Electron Induction Injector with High Average Power

    NASA Astrophysics Data System (ADS)

    Mamaev, G. L.; Glazov, A. I.; Krasnopolsky, V. A.; Latypov, T. A.; Mamaev, S. L.; Puchkov, S. N.; Shcherbakov, A. M.; Tenyakov, I. E.; Terechkin, Y. M.; Vlasenko, S. I.

    1997-05-01

    Design parameters of the induction injector are 800 keV beam energy, 2...5 kA current, 80 ns pulse flat top and 100 Hz repetition rate. The average beam power of the series of pulses is 40 kW. The injector modules use metglass cores. The electron source mounted on the stem consists of a 80 mm diameter velvet cathode placed on a field forming electrode. The tapered insulator assembly separates the oil-filled induction modules from the vacuum diode. The magnetic field necessary for beam extraction is generated by two magntic cores. 150 kV, 40 kA, 100 ns, 100 Hz pulse generator has been designed in Radiotechnical institute. The generator is a two-stage magnetic power compressor with a thyratron switch. The voltage pulse is produced by the water-filled pulse forming line (PFL) with the impedance of 3.3 ohm. The calculated parameters of the injector, the design features of its modules and the experimental results of their testing are presented.

  6. LUCIA - a new 1-7 keV {mu}-XAS Beamline

    SciTech Connect

    Janousch, M.; Schmidt, Th.; Wetter, R.; Grolimund, G.; Scheidegger, A.M.; Flank, A.-M.; Lagarde, P.; Cauchon, G.; Bac, S.; Dubuisson, J.M.

    2004-05-12

    LURE-SOLEIL (France) and the Swiss Light Source (SLS) are building together a new micro focused beamline for micro x-ray absorption spectroscopy and micro imaging. This line is designed to deliver a photon flux of the order of 1012 ph/sec on a 1 x 1 {mu}m spot within the energy domain of 0.8 to 7 keV. This beam line is being installed on the X07M straight section of SLS. The source is an APPLE II undulator with a period of 54 mm. The main advantage of this device lies in the delivery of any degree of polarization, linear or circular, over the whole energy range, without the need of a sample-position change. The monochromator will be a fixed exit double crystal equipped with 5 sets of crystals, thanks to the very narrow photon beam from the undulator ( Beryl, KTP, YB66, InSb(111), Si(111) ). The optics includes a first horizontal focusing mirror (spherical), which produces an intermediate source for the horizontal mirror of a Kirkpatrick-Baez (KB) system. The vertical mirror of the KB directly images the source. Finally, a low-pass double mirror filter insures a proper harmonic rejection.

  7. MULTI-KEV X-RAY YIELDS FROM HIGH-Z GAS TARGETS FIELDED AT OMEGA

    SciTech Connect

    Kane, J O; Fournier, K B; May, M J; Colvin, J D; Thomas, C A; Marrs, R E; Compton, S M; Moody, J D; Bond, E J; Davis, J F

    2010-11-04

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

  8. Dynamics of charge evolution in glass capillaries for 230-keV Xe23+ ions

    NASA Astrophysics Data System (ADS)

    Cassimi, A.; Ikeda, T.; Maunoury, L.; Zhou, C. L.; Guillous, S.; Mery, A.; Lebius, H.; Benyagoub, A.; Grygiel, C.; Khemliche, H.; Roncin, P.; Merabet, H.; Tanis, J. A.

    2012-12-01

    We have measured the transmission of 230-keV (10-keV/q) Xe23+ ions through insulating tapered glass capillaries of microscopic dimensions. The dynamics of charging and discharging processes have been investigated, evidencing an unexpected slow alignment of the beam along the capillary axis. Oscillations of the exiting beam position have been observed during the charging process associated to the formation of charge patches on the capillary inner walls. The emerging ions are guided with a characteristic guiding angle falling on a universal curve proposed for PET polymer nanocapillaries. This result, very similar to the channeling process, is somewhat surprising in view of the significant differences between the straight nanocapillary polymer foils and the tapered microscopic single glass capillary used here. The transmitted ions show no evidence of energy loss or charge changing except for the production of a small neutral fraction that was determined to be due to ions that had become neutralized to form atoms rather than due to photon emission. These results thus test and confirm the validity of transmission and guiding and provide insight into the dynamics of higher-energy ions than have been previously studied in this regard, allowing a determination of the maximum energy for which the guiding process might occur.

  9. Nonabelian dark matter models for 3.5 keV X-rays

    SciTech Connect

    Cline, James M.; Frey, Andrew R. E-mail: a.frey@uwinnipeg.ca

    2014-10-01

    A recent analysis of XXM-Newton data reveals the possible presence of an X-ray line at approximately 3.55 keV, which is not readily explained by known atomic transitions. Numerous models of eV-scale decaying dark matter have been proposed to explain this signal. Here we explore models of multicomponent nonabelian dark matter with typical mass ∼ 1-10 GeV (higher values being allowed in some models) and eV-scale splittings that arise naturally from the breaking of the nonabelian gauge symmetry. Kinetic mixing between the photon and the hidden sector gauge bosons can occur through a dimension-5 or 6 operator. Radiative decays of the excited states proceed through transition magnetic moments that appear at one loop. The decaying excited states can either be primordial or else produced by upscattering of the lighter dark matter states. These models are significantly constrained by direct dark matter searches or cosmic microwave background distortions, and are potentially testable in fixed target experiments that search for hidden photons. We note that the upscattering mechanism could be distinguished from decays in future observations if sources with different dark matter velocity dispersions seem to require different values of the scattering cross section to match the observed line strengths.

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

    NASA Astrophysics Data System (ADS)

    Chatzidimitriou-Dreismann, C. A.

    2006-11-01

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

  11. 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.

  12. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  14. Tri-axial Shape Coexistence and a New Aligned Band in 178Os

    NASA Astrophysics Data System (ADS)

    Govil, I. M.

    2009-03-01

    The Os nuclei lie in the beginning of the transitional region between the well deformed rare earth and spherical lead isotopes. The nuclei in this region are believed to be soft to changes in gamma deformation due to the softness of nuclear potential which may result in the shape coexistence. The neutron Fermi levels in Os nuclei from A = 170 to A = 186 lie in the middle of i13/2 orbital so that their shape in the ground state tends to take an appreciable prolate deformation. Hence collective bands with the well defined moment of inertia occur and the effect of different proton orbitals is observed as a modulation of the prolate structure. The anomalies in the yrast sequence, an effect attributed to change in moment of inertia of the ground state rotational band and the band crossing phenomena, are very important and vary strongly with neutron number in case of Os nuclei. The nuclear structure of 178Os nucleus has been studied using the reaction 165Ho (20Ne, p6n) 178Os. Indian National Gamma Array (INGA) consisting of six Clover detectors with anti Compton shields was used for the detection of resulting gamma rays. The Direction Correlation of γ-rays de-exciting Oriented states (DCO) ratio and polarization of gamma rays were measured to assign spin, parity and multipolarity of transitions. Twenty one new transitions belonging to the 178Os nucleus have been identified. The sudden and rather strong gain in aligned angular momentum is observed in the yrast band of 178Os. A new aligned rotational band similar to 180Os is also discovered in this nucleus. This band exhibits a very complex decay pattern with a single linking transition of 1778 keV to the ground state band. The tri-axial shape co-existence is also observed in this nucleus at higher excitation. The experimental results are compared with the Microscopic Hartree-Fock model calculations.

  15. Athermal design of hybrid refractive/harmonic diffractive optical system for far-infrared multi-band

    NASA Astrophysics Data System (ADS)

    Liu, Ying; Sun, Qiang; Lu, Zhenwu; Yue, Jinying; Zhang, Hu; Zhu, Rui

    2009-05-01

    In order to get enough information about the target, avoid big chromatic aberration as a result of wide spectrum and the complexity of optical system and adapt different special environment temperature, a hybrid refractive/ harmonic diffractive optical system in far-infrared multi-band is described in the paper. This diffractive optical system has been designed an athermalized multi-band imaging system with harmonic diffractive element in 15-50μm spectrum, based on larger 1dispersion capability and particular thermal dispersive power of harmonic diffractive element. Then, at the temperature range from 0°C to 40°C, this design can simultaneously meet with all requirements of the imaging system in five harmonic wave bands, including15.8-16.2μm, 18.5-20μm, 23-25μm, 30.5-33.5μm and 46-50μm. In each harmonic wave band, the magnification changes as a function of wavelength, which creates image registration error. To compensate this shortcoming, a zoom optical system is designed with three lenses by means of optical two- component method. The design results show that the hybrid refractive/harmonic diffractive optical system can realize athermalized and achromatic design, and the zoom optical system makes half image height at 3.53mm in every harmonic wave band and still realizes aberration compensation action. In the five harmonic wave bands, each optical transfer function approaches the diffraction limit at ambient temperature range of 0°C to 40°C. Finally, the system realizes the requirements of portability, mini-type and ease for fabrication.

  16. 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.

  17. 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

  18. 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

  19. Metastable dark matter mechanisms for INTEGRAL 511 keV γ rays and DAMA/CoGeNT events

    NASA Astrophysics Data System (ADS)

    Cline, James M.; Frey, Andrew R.; Chen, Fang

    2011-04-01

    We explore dark matter mechanisms that can simultaneously explain the galactic 511 keV gamma rays observed by INTEGRAL/SPI, the DAMA/LIBRA annual modulation, and the excess of low-recoil dark matter candidates observed by CoGeNT. It requires three nearly degenerate states of dark matter in the 4-7 GeV mass range, with splittings, respectively, of order MeV and a few keV. The top two states have the small mass gap and transitions between them, either exothermic or endothermic, and can account for direct detections. Decays from one of the top states to the ground state produce low-energy positrons in the Galaxy whose associated 511 keV gamma rays are seen by INTEGRAL. This decay can happen spontaneously, if the excited state is metastable (longer lived than the age of the Universe), or it can be triggered by inelastic scattering of the metastable states into the shorter-lived ones. We focus on a simple model where the dark matter is a triplet of an SU(2) hidden sector gauge symmetry, broken at the scale of a few GeV, giving masses of order ≲1GeV to the dark gauge bosons, which mix kinetically with the standard model hypercharge. The purely decaying scenario can give the observed angular dependence of the 511 keV signal with no positron diffusion, while the inelastic scattering mechanism requires transport of the positrons over distances ˜1kpc before annihilating. We note that an x-ray line of several keV in energy, due to single-photon decays involving the top dark matter states, could provide an additional component to the diffuse x-ray background. The model is testable by proposed low-energy fixed-target experiments.

  20. Model-independent analysis of dark matter points to a particle mass at the keV scale

    NASA Astrophysics Data System (ADS)

    de Vega, H. J.; Sanchez, N. G.

    2010-05-01

    We present a model-independent analysis of dark matter (DM) decoupling both ultrarelativistically (UR) and non-relativistically (NR) based on the DM phase-space density . We derive explicit formulae for the DM particle mass m and for the number of ultrarelativistic degrees of freedom gd at decoupling. We find that for DM particles decoupling UR both at local thermal equilibrium (LTE) and out of LTE, m turns out to be in the keV scale. For example, for DM Majorana fermions decoupling at LTE the resulting mass is m ~= 0.85 keV. For DM particles decoupling NR, results in the keV scale (Td is the decoupling temperature) and the value of m is consistent with the keV scale. In all cases, DM turns out to be cold DM (CDM). In addition, lower and upper bounds on the DM annihilation cross-section for NR decoupling are derived. We evaluate the free-streaming (Jeans) wavelength and Jeans mass: they are independent of the type of DM except for the DM self-gravity dynamics. The free-streaming wavelength today turns to be in the kpc range. These results are based on our theoretical analysis, on astronomical observations of dwarf spheroidal satellite galaxies in the Milky Way and on N-body numerical simulations. We analyse and discuss the results for from analytic approximate formulae for both linear fluctuations and the (non-linear) spherical model and from N-body simulations results. In this way we obtain upper bounds for the DM particle mass, which are all below the 100-keV range.

  1. Metastable dark matter mechanisms for INTEGRAL 511 keV {gamma} rays and DAMA/CoGeNT events

    SciTech Connect

    Cline, James M.; Frey, Andrew R.; Chen, Fang

    2011-04-15

    We explore dark matter mechanisms that can simultaneously explain the galactic 511 keV gamma rays observed by INTEGRAL/SPI, the DAMA/LIBRA annual modulation, and the excess of low-recoil dark matter candidates observed by CoGeNT. It requires three nearly degenerate states of dark matter in the 4-7 GeV mass range, with splittings, respectively, of order MeV and a few keV. The top two states have the small mass gap and transitions between them, either exothermic or endothermic, and can account for direct detections. Decays from one of the top states to the ground state produce low-energy positrons in the Galaxy whose associated 511 keV gamma rays are seen by INTEGRAL. This decay can happen spontaneously, if the excited state is metastable (longer lived than the age of the Universe), or it can be triggered by inelastic scattering of the metastable states into the shorter-lived ones. We focus on a simple model where the dark matter is a triplet of an SU(2) hidden sector gauge symmetry, broken at the scale of a few GeV, giving masses of order < or approx. 1 GeV to the dark gauge bosons, which mix kinetically with the standard model hypercharge. The purely decaying scenario can give the observed angular dependence of the 511 keV signal with no positron diffusion, while the inelastic scattering mechanism requires transport of the positrons over distances {approx}1 kpc before annihilating. We note that an x-ray line of several keV in energy, due to single-photon decays involving the top dark matter states, could provide an additional component to the diffuse x-ray background. The model is testable by proposed low-energy fixed-target experiments.

  2. 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.

  3. The DSS-14 C-band exciter

    NASA Astrophysics Data System (ADS)

    Rowan, D. R.

    1989-05-01

    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.

  4. Lessons Learned from Laparoscopic Gastric Banding.

    PubMed

    Broadbent

    1993-11-01

    The author reviews 27 laparoscopic gastric banding operations, of which 19 cases were completed. Of the 27 operations, eight were revisions of earlier laparoscopic banding. The lessons learned from these cases are highlighted. PMID:10757955

  5. Identification of the UIR bands

    NASA Astrophysics Data System (ADS)

    Johnson, Fred M.

    2016-06-01

    Starlight undergoing multiple scattering processes within fluffy grains results in extinction, UV 2175A bump, DIBs and the UIR bands. Spectroscopic lab and DIB data has identified the highly fluorescent molecule Dipyridyl Magnesium Tetrabenzoporphyrin (MgTBP). Reflection and Raman scattering experimental data will be presented which designates this molecule as the primary source for UIR signals. MgTBP sublimes at about 500OC. It is produced via high temperature plasma synthesis within and subsequently ejected from comets which in turn are by-products of solar system-planetary development. Interstellar dust is the left-over refuse which implies prodigious solar system evolution in each galaxy.

  6. When a Standard Candle Flickers: Crab Nebula Variations in Hard X-rays

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Collen A.; Cherry, M. L.; Case, G. L.; Baumgartner, W. H.; Beklen, E.; Bhat, P. N.; Briggs, M. S.; Camero-Arranz, A.; Chaplin, V.; Connaughton, V.; Finger, M. H.; Gehrels, N.; Greiner, J.; Jahoda, K.; Jenke, P.; Kippen, R. M.; Kouveliotou, C.; Krimm, H. A.; Kuulkers, E.; Lund, N.; Meegan, C. A.; Natalucci, L.; Paciesas, W. S.; Preece, R.; Rodi, J. C.

    2012-01-01

    RXTE played a crucial role in our surprising discovery that the Crab Nebula is variable in hard X-rays. In the first two years of science operations of the Fermi Gamma-ray Burst Monitor (GBM), August 2008-2010, a approx.7% (70 mcrab) decline was discovered in the overall Crab Nebula flux in the 15 - 50 keV band, measured with the Earth occultation technique. This decline was independently confirmed in the 15-50 keV band with four other instruments: the RXTE/PCA, Swift/BAT, INTEGRAL/IBIS, and INTEGRAL/SPI. The pulsed flux measured with RXTE/PCA from 1999-2010 was consistent with the pulsar spin-down, indicating that the observed changes were nebular. From 2001 to 2010, the Crab nebula flux measured with RXTE/PCA was particularly variable, changing by up to approx.3.5% per year in the 15-50 keV band. These variations were confirmed with INTEGRAL/SPI starting in 2003 and Swift/BAT starting in 2005. Before 2001 and since 2010, the Crab nebula 15-50 keV flux measured with RXTE/PCA appeared more stable, varying by less than 2% per year. In this talk I will present Crab light curves including RXTE data for the entire 16-year mission in multiple energy bands.

  7. Black Scholes’ model and Bollinger bands

    NASA Astrophysics Data System (ADS)

    Liu, Wei; Huang, Xudong; Zheng, Weian

    2006-11-01

    Bollinger bands are well-known in stock market as a popular technical analysis tool. We found that Black-Scholes stock price model had this Bollinger bands property also. In this paper, we give the proof of this phenomenon, and give a new distribution of a statistics generated by the Bollinger bands.

  8. Nylon cable band reactions in ovariohysterectomized bitches.

    PubMed

    Werner, R E; Straughan, A J; Vezin, D

    1992-01-01

    Nylon cable bands used as ligatures caused postsurgical complications in 5 ovariohysterectomized bitches. Clinical signs included fever, stiffness, strangury, draining fistulae, vaginal discharge, and tenesmus. Most signs first appeared several years after surgery, and all signs were resolved after removal of the bands. On the basis of our experience, we suggest that nylon cable bands not be used for ovariohysterectomy ligations. PMID:1537693

  9. Prenatal diagnosis of amniotic band syndrome

    PubMed Central

    Padmanabhan, Laxmi Devi; Hamza, Zareena V; Thampi, Madhavan Venugopalan; Nampoothiri, Sheela

    2016-01-01

    Amniotic band can cause a broad spectrum of anomalies ranging from simple band constrictions to major craniofacial and visceral defects. It can cause significant neonatal morbidity. Accurate diagnosis will help in the management of the present pregnancy and in counseling with regard to future pregnancies. Here we report three cases of amniotic band syndrome detected in the prenatal period. PMID:27081225

  10. 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.

  11. Tap Teens' Curiosity with Lab Band.

    ERIC Educational Resources Information Center

    Saunders, Jane

    2002-01-01

    Describes the Lab Band project used with 12th grade students at the Westgate Collegiate and Vocational Institute in Thunder Bay, Ontario (Canada). Explains that each band student taught a peer how to play their instrument which created versatility in the band. States that all students kept a reflective journal. (CMK)

  12. Collision quenching effects in nitrogen and helium excited by a 30-keV electron beam

    NASA Technical Reports Server (NTRS)

    Lillicrap, D. C.

    1973-01-01

    The quenching cross section for the 0-0 first negative band of nitrogen is determined for temperatures between 78 K and 300 K. As the temperature increases above 78 K, the quenching reaches a maximum at approximately 140 K and then decreases as 300 K is approached. At temperatures on the order of 5000 K, quenching is reported to increase with temperature and must therefore reach a minimum at some intermediate temperature between 300 K and 5000 K. By comparison, quenching of the 5016 A helium line increases continuously over the temperature range 78 K to 300 K.

  13. Maskless implants of 20 keV Ga{sup +} in thin crystalline silicon on insulator

    SciTech Connect

    Mio, A. M.; D'Arrigo, G.; Rimini, E.; Spinella, C.; Milazzo, R. G.; Peto, L.; Nadzeyka, A.; Bauerdick, S.

    2013-01-28

    A nano-sized ion beam apparatus has been used as maskless lithography to implant 20 keV Ga{sup +} ions into a 26 nm thick silicon crystalline film on insulator. The ion beam, with about 5 nm standard deviation, delivered few hundred ions during a single shot. Circular areas with nominal diameter of 20 or 50 nm were irradiated to a fluence of 5 Multiplication-Sign 10{sup 14}/cm{sup 2}. Transmission electron microscopy evidenced that the damaged regions are characterized by an irregular contour with many disordered filaments. Damage extends across the layer thickness and fast Fourier transform analysis indicates that implantation causes the amorphization of a region which extends beyond the nominal diameter. In situ annealing experiments demonstrated that the disordered filamentary regions disappear in the 250-450 Degree-Sign C temperature range and the interfaces with the surrounding crystalline regions sharpen. A temperature as high as 600 Degree-Sign C is required to fully re-crystallize the amorphous core of the implanted dots. Reordering occurs by multi-orientation lateral solid-phase epitaxial growth and the breaking of (111) and (101) interfaces, due to the formation of twins, triggers a fast crystallization kinetics. Rapid thermal annealing (890 Degree-Sign C-10 s) completely crystallizes the amorphous regions, twins are absent and small cluster of defects remains instead. Preliminary scanning capacitance measurements indicate that the implanted atoms, after crystallization, are electrically active. The implant method is then a viable processing step for the doping of non-bulk fully depleted ultra-thin-body MOSFET.

  14. 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.

  15. 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.

  16. 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.

  17. Band structure of 235U

    NASA Astrophysics Data System (ADS)

    Ward, D.; Macchiavelli, A. O.; Clark, R. M.; Cline, D.; Cromaz, M.; Deleplanque, M. A.; Diamond, R. M.; Fallon, P.; Görgen, A.; Hayes, A. B.; Lane, G. J.; Lee, I.-Y.; Nakatsukasa, T.; Schmidt, G.; Stephens, F. S.; Svensson, C. E.; Teng, R.; Vetter, K.; Wu, C. Y.

    2012-12-01

    Over a period of several years we have performed three separate experiments at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron in which 235U (thick target) was Coulomb-excited. The program involved stand-alone experiments with Gammmasphere and with the 8pi Spectrometer using 136Xe beams at 720 MeV, and a CHICO-Gammasphere experiment with a 40Ca beam at 184 MeV. In addition to extending the known negative-parity bands to high spin, we have assigned levels in some seven positive-parity bands which are in some cases (e.g., [631]1/2, [624]7/2, and [622]5/2) strongly populated by E3 excitation. The CHICO data have been analyzed to extract E2 and E3 matrix elements from the observed yields. Additionally, many M1 matrix elements could be extracted from the γ-ray branching ratios. A number of new features have emerged, including the unexpected attenuation of magnetic transitions between states of the same Nilsson multiplet, the breakdown of Coriolis staggering at high spin, and the effect of E3 collectivity on Coriolis interactions.

  18. 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.

  19. Thematic mapper studies band correlation analysis

    NASA Technical Reports Server (NTRS)

    Ungar, S. G.; Kiang, R.

    1976-01-01

    Spectral data representative of thematic mapper candidate bands 1 and 3 to 7 were obtained by selecting appropriate combinations of bands from the JSC 24 channel multispectral scanner. Of all the bands assigned, only candidate bands 4 (.74 mu to .80 mu) and 5 (.80 mu to .91 mu) showed consistently high intercorrelation from region to region and time to time. This extremely high correlation persisted when looking at the composite data set in a multitemporal, multilocation domain. The GISS investigations lend positive confirmation to the hypothesis, that TM bands 4 and 5 are redundant.

  20. 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.

  1. Detection of energetic electron (E greater than KeV) and ion fluxes (E greater than 97 KeV) from comet P/Halley by the Giotto experiment EPA on 1986 March 13/14

    NASA Astrophysics Data System (ADS)

    Kirsch, E.; McKenna-Lawlor, S.; Thompson, A.; O'Sullivan, D.; Neubauer, F. M.

    1988-03-01

    Relativistic electron fluxes (greater than 220, greater than 300 KeV) were recorded during the Giotto encounter with comet P/Halley from the inbound to the outbound bowshock. A strong enhancement in the greater than 300 KeV electron flux was measured about 1 hr after the outbound crossing of the bow shock. It is suggested that the electrons were strongly beamed by the magnetic field since they could only be detected in the hemisphere backward to the flight direction. Possible acceleration mechanisms for the relativistic particle population include magnetic field line reconnection at the front side of the magnetic pile-up region, induced electric fields and resonance processes of electrons with electrostatic lower hybrid waves or Langmuir waves. Also acceleration of ions and electrons by a quasiperpendicular shock formed downstream at the outbound bowshock must be considered.

  2. 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.

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

    SciTech Connect

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

    2006-06-14

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

  4. 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…

  5. 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).

  6. 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.

  7. Compressive asymmetry evaluation for M-Band Radiation generated from the interaction of high energy laser and the hohlraum

    NASA Astrophysics Data System (ADS)

    Jiang, Shaoen; Huang, Yunbao; Li, Liling; Jing, Longfei; Lin, Zhiwei

    2015-11-01

    In indirect drive inertial confinement fusion, intense laser interacts with high-Z materials in the hohlraum and X-rays are generated to heat and drive the centrally located capsule. Most of these X-rays emitted from the wall of hohlraum are soft x-rays, but also a comparable fraction of them are high-energy X-rays (mainly from M band of wall material, >2keV for Au), which may lead to preheat and compressive asymmetry on the capsule, and affect final ignition result. Therefore, such preheat and compressive asymmetry needs to be characterized and evaluated, to enable it restrained or controlled. In this paper, by using one-dimensional multi-group radiation hydrodynamic codes and view-factor based radiation transport codes, we evaluate the compressive asymmetry on the centrally located capsule for various fractions of M-band X-rays. The result shows that: 1) The M-band X-rays may lead to significant compressive asymmetry when the thermal flux is symmetric,2) More fractions of M-band X-rays tends to result in more compressing asymmetry, and 3) 15% of M-band X-rays may result in 50% compressive asymmetry. Base on the above analysis, such significant compressive asymmetry due to M-band radiation may decrease the compressibility of the fuel or the capsule performance. Therefore, it motivates us to validate and measure such quantity of compressive asymmetry occurred on the capsule in recent experiments.

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

    NASA Astrophysics Data System (ADS)

    Iakubovskyi, Dmytro

    2015-11-01

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

  9. S-band transponder experiment

    NASA Technical Reports Server (NTRS)

    Sjogren, W. L.; Gottlieb, P.; Muller, P. M.; Wollenhaupt, W. R.

    1972-01-01

    The experiment which derives data from three lunar-orbiting objects, the command-service module (CSM), the lunar module (LM), and the subsatellite in the S-band is described. Each provides detailed information on the near-side lunar gravitational field. The primary emphasis is on the low-altitude (20 km) CSM data. The LM data cover a very short time span and are somewhat redundant with the CSM data. The resolution of the high-altitude (100 km) CSM data is not as great as that of the low altitude data. The low-altitude CSM and LM data coverage and the complementary coverage obtained during the Apollo 14 mission are presented. The experiment uses the same technique of gravity determination employed on the Lunar Orbiter, in the data of which the large anomalies called mascons were first observed. The data consist of variations in the spacecraft speed as measured by the Earth-based radio tracking system.

  10. Circular birefringence of banded spherulites.

    PubMed

    Cui, Xiaoyan; Shtukenberg, Alexander G; Freudenthal, John; Nichols, Shane; Kahr, Bart

    2014-04-01

    Crystal optical properties of banded spherulites of 21 different compounds--molecular crystals, polymers, and minerals--with helically twisted fibers were analyzed with Mueller matrix polarimetry. The well-established radial oscillations in linear birefringence of many polycrystalline ensembles is accompanied by oscillations in circular birefringence that cannot be explained by the natural optical activity of corresponding compounds, some of which are centrosymmetric in the crystalline state. The circular birefringence is shown to be a consequence of misoriented, overlapping anisotropic lamellae, a kind of optical activity associated with the mesoscale stereochemistry of the refracting components. Lamellae splay as a consequence of space constraints related to simultaneous twisting of anisometric lamellae. This mechanism is supported by quantitative simulations of circular birefringence arising from crystallite twisting and splaying under confinement. PMID:24625095

  11. Photonic band gap structure simulator

    DOEpatents

    Chen, Chiping; Shapiro, Michael A.; Smirnova, Evgenya I.; Temkin, Richard J.; Sirigiri, Jagadishwar R.

    2006-10-03

    A system and method for designing photonic band gap structures. The system and method provide a user with the capability to produce a model of a two-dimensional array of conductors corresponding to a unit cell. The model involves a linear equation. Boundary conditions representative of conditions at the boundary of the unit cell are applied to a solution of the Helmholtz equation defined for the unit cell. The linear equation can be approximated by a Hermitian matrix. An eigenvalue of the Helmholtz equation is calculated. One computation approach involves calculating finite differences. The model can include a symmetry element, such as a center of inversion, a rotation axis, and a mirror plane. A graphical user interface is provided for the user's convenience. A display is provided to display to a user the calculated eigenvalue, corresponding to a photonic energy level in the Brilloin zone of the unit cell.

  12. The average GeV-band emission from gamma-ray bursts

    NASA Astrophysics Data System (ADS)

    Lange, J.; Pohl, M.

    2013-03-01

    Aims: We analyze the emission in the 0.3-30 GeV energy range of gamma-ray bursts detected with the Fermi Gamma-ray Space Telescope. We concentrate on bursts that were previously only detected with the Gamma-Ray Burst Monitor in the keV energy range. These bursts will then be compared to the bursts that were individually detected with the Large Area Telescope at higher energies. Methods: To estimate the emission of faint GRBs we used nonstandard analysis methods and sum over many GRBs to find an average signal that is significantly above background level. We used a subsample of 99 GRBs listed in the Burst Catalog from the first two years of observation. Results: Although most are not individually detectable, the bursts not detected by the Large Area Telescope on average emit a significant flux in the energy range from 0.3 GeV to 30 GeV, but their cumulative energy fluence is only 8% of that of all GRBs. Likewise, the GeV-to-MeV flux ratio is less and the GeV-band spectra are softer. We confirm that the GeV-band emission lasts much longer than the emission found in the keV energy range. The average allsky energy flux from GRBs in the GeV band is 6.4 × 10-4 erg cm-2 yr-1 or only ~4% of the energy flux of cosmic rays above the ankle at 1018.6 eV.

  13. Topics in topological band systems

    NASA Astrophysics Data System (ADS)

    Huang, Zhoushen

    The discovery of integer quantum Hall effect and its subsequent theoretical formulation heralded a new paradigm of thinking in condensed matter physics, which has by now blossomed into the rapidly growing field of topological phases. In this work we investigate several mutually related topics in the framework of topological band theory. In Chapter 2, we study solutions to boundary states on a lattice and see how they are related to the bulk topology. To elicit a real space manifestation of the non-trivial topology, the presence of a physical edge is not strictly necessary. We study two other possibilities, namely the entanglement spectrum associated with an imaginary spatial boundary, and the localization centers of Wannier functions, in Chapters 3,4, and 5. Topological classification through discrete indices is so far possible only for systems described by pure quantum states---in the existing scheme, quantization is lost for systems in mixed states. In Chapter 6, we present a program through which discrete topological indices can be defined for topological band systems at finite temperature, based on Uhlmann's parallel transport of density matrices. The potential of topologocal insulators in realistic applications lies in the existence of Dirac nodes on its surface spectrum. Dirac physics, however, is not exclusive to TI surfaces. In a recently discovered class of materials known as Weyl semimetals, energy nodes which emit linear dispersions also occur in the bulk material. In Chapter 7, we study the possibility of resonance states induced by localized impurities near the nodal energy in Weyl semimetals, which will help us in understanding the stability of density-of-state suppression at the energy nodes. Finally, in Chapter 8, we apply the topological characterization developed for noninteracting particles to a class of interacting spin models in 3D, which are generalizations of Kitaev's honeycomb model, and identify several exotic quantum phases such as spin

  14. Experimental investigation of the multiple scatter peak of gamma rays in portland cement in the energy range 279-1332 keV

    NASA Astrophysics Data System (ADS)

    Singh, Tejbir; Singh, Parjit S.

    2011-12-01

    The pulse height spectra for different thicknesses of portland cement in the reflected geometry has been recorded with the help of a NaI(Tl) scintillator detector and 2 K MCA card using different gamma-ray sources such as Hg203 (279 keV), Cs137 (662 keV) and Co60 (1173 and 1332 keV). It has been observed that the multiple scatter peak for portland cement appears at 110 (±7) keV in all the spectra irrespective of different incident photon energies in the range 279-1332 keV from different gamma-ray sources. Further, the variation in the intensity of the multiple scatter peak with the thickness of portland cement in the backward semi-cylinders has been investigated.

  15. Studies of polarization bremsstrahlung and ordinary bremsstrahlung from 89Sr beta particles in metallic targets in the photon energy region of 1-100 keV

    NASA Astrophysics Data System (ADS)

    Singh, Amrit; Dhaliwal, A. S.

    2015-06-01

    Studies of polarization bremsstrahlung (PB) and ordinary bremsstrahlung (OB) produced by the 89Sr beta emitter in Al, Ti, Sn and Pb targets were undertaken at photon energies of 1-100 keV. The experimental results are compared with the Elwert corrected (non-relativistic) Bethe-Heitler (EBH) theory and the modified Elwert factor (relativistic) Bethe-Heitler (Fmod BH) theory for OB and with the Avdonina and Pratt (Fmod BH + PB) theory for total bremsstrahlung (BS). These results are in agreement with the Fmod BH + PB theory up to 13 keV, 16 keV, 22 keV and 28 keV energies for Al, Ti, Sn and Pb targets, respectively; Fmod BH theory is more accurate at higher energies.

  16. Improved energy of the 21.5 keV M1 + E2 nuclear transition in 151Eu

    NASA Astrophysics Data System (ADS)

    Inoyatov, A. Kh.; Kovalík, A.; Filosofov, D. V.; Ryšavý, M.; Perevoshchikov, L. L.; Baimukhanova, A.

    2016-05-01

    Using internal conversion electron spectroscopy, improved energy 21 541.5±0.5 eV was determined for the 21.5keV M1 + E2 nuclear transition in 151Eu populated in the electron capture decay of 151Gd . This value was found to agree well with the present adopted value but is much more accurate. A value of 0.0305±0.0011 derived for the E2 admixture parameter \\vertδ(E2/M1)\\vert from the measured conversion electron line intensities corresponds to the present adopted value. A possible effect of nuclear structure on the multipolarity of the 21.5 keV transition was also investigated.

  17. Neutron total cross section measurements in the energy region from 47 keV to 20 MeV

    SciTech Connect

    Poenitz, W.P.; Whalen, J.F.

    1983-05-01

    Neutron total cross sections were measured for 26 elements. Data were obtained in the energy range from 47 keV to 20 MeV for 11 elements in the range of light-mass fission products. Previously reported measurements for eight heavy and actinide isotopes were extended to 20 MeV. Data were also obtained for Cu (47 keV to 1.4 MeV) and for Sc, Zn, Nd, Hf, and Pt (1.8 to 20 MeV). The present work is part of a continuing effort to provide accurate neutron total cross sections for evaluations and for optical-model parameteriztions. The latter are required for the derivation of other nuclear-data information of importance to applied programs. 37 references.

  18. Electron-positron pair production near the Galactic Centre and the 511 keV emission line

    NASA Astrophysics Data System (ADS)

    Chan, Man Ho

    2016-02-01

    Recent observations indicate that a high production rate of positrons (strong 511 keV line) and a significant amount of excess GeV gamma-ray exist in our Galactic bulge. The latter issue can be explained by ˜40 GeV dark matter annihilation through b bar{b} channel while the former one remains a mystery. On the other hand, recent studies reveal that a large amount of high-density gas might exist near the Galactic Centre million years ago to account for the young, massive stars extending from 0.04-7 pc. In this Letter, I propose a new scenario and show that the 40 GeV dark matter annihilation model can also explain the required positron production rate (511 keV line) in the bulge due to the existence of the high-density gas cloud near the supermassive black hole long time ago.

  19. 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.

  20. 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. PMID:19384056

  1. The energy spectrum of 20 keV-20 MeV electrons accelerated in large solar flares

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Mewaldt, R. A.; Van Hollebeke, M. A. I.

    1982-01-01

    IMP 6, 7, and 8 measurements of the energy spectrum of 20 keV to 20 MeV electrons observed from large solar flares are presented. To minimize propagation effects, only events from flares at W30 deg to W90 deg solar longitude are considered. The energy spectra are constructed using the maximum flux observed at each energy. It is shown that these spectra are representative of the spectra of the electrons escaping from the sun over this range of energies. It is found that every event shows the same spectral shape: a double power law with a smooth transition around 100-200 keV and power law exponents of 0.6-2.0 below and 2.4-4.3 above. The more intense the event, the harder the observed spectrum; in certain cases, the spectra are observed to steepen above 3 MeV.

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

    NASA Astrophysics Data System (ADS)

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

    2004-02-01

    We have determined experimentally optical constants for eight thin film materials that can be used in hard X-ray multilayer coatings. Thin film samples of Ni.97V.03, Mo, W, Pt, C, B4C, Si and SiC were deposited by magnetron sputtering onto superpolished optical flats. Optical constants were determined from fits to reflectance-vs-incidence angle measurements made using synchrotron radiation over the energy range E=35 180 keV. We have also measured the X-ray reflectance of a prototype W/SiC multilayer coating over the energy range E=35 100 keV, and we compare the measured reflectance with a calculation using the newly derived optical constants.

  3. 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.

  4. Self-attenuation correction factors for bioindicators measured by γ spectrometry for energies <100 keV

    NASA Astrophysics Data System (ADS)

    Manduci, L.; Tenailleau, L.; Trolet, J. L.; De Vismes, A.; Lopez, G.; Piccione, M.

    2010-01-01

    The mass attenuation coefficients for a number of marine and terrestrial bioindicators were measured using γ spectrometry for energies between 22 and 80 keV. These values were then used to find the correction factor k for the apparent radioactivity. The experimental results were compared with a Monte Carlo simulation performed using PENELOPE in order to evaluate the reliability of the simplified calculation and to determine the correction factors.

  5. Cross section measurements of the B10(d,n0)C11 reaction below 160 keV

    NASA Astrophysics Data System (ADS)

    Stave, S.; Ahmed, M. W.; Antolak, A. J.; Blackston, M. A.; Crowell, A. S.; Doyle, B. L.; Henshaw, S. S.; Howell, C. R.; Kingsberry, P.; Perdue, B. A.; Rossi, P.; Prior, R. M.; Spraker, M. C.; Weller, H. R.

    2008-05-01

    New data were taken at the Triangle Universities Nuclear Laboratory to investigate the plausibility of using low energy deuterons and the B10(d,n)C11 reaction as a portable source of 6.3 MeV neutrons. Analysis of the data at and below incident deuteron energies of 160 keV indicates an n0 neutron cross section that is lower than previous estimates by at least three orders of magnitude. In separate runs, deuterons with two different energies (160 and 140 keV) were stopped in a B10 target. The resulting n0 neutrons of approximately 6.3 MeV were detected at angles between 0° and 150°. The angle integrated yields were used to determine the astrophysical S factor for this reaction assuming a constant value for the S factor below 160 keV. The cross sections reported between 130 and 160 keV were calculated using the extracted value of the S factor. The measured n0 cross section is several orders of magnitude smaller than previous results, thus eliminating B10(d,n)C11 as a portable source of intense neutrons with low energy deuteron beams on the order of tens of microamps. In order to gain insight into the reaction dynamics at these low energies the cross section results have been compared with results from calculations using the distorted wave Born approximation (DWBA) and a detailed Hauser-Feshbach calculation performed by the authors. The angular distribution is consistent with the Hauser-Feshbach calculation suggesting a statistical compound nucleus reaction rather than a direct reaction.

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

    NASA Astrophysics Data System (ADS)

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

    2012-11-01

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

  7. The Electron Excitation Function of H Lyman-(alpha) from Threshold to 1.8 keV

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

    The excitation function of prompt Lyman-(alpha) radiation, produced by electron impact excitation of atomic hydrogen, has been measured for the first time over an extended energy range from threshold to 1.8 keV. Measurments were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source.

  8. TIME-RESOLVED 1-10 keV CRYSTAL SPECTROMETER FOR THE Z MACHINE AT SANDIA NATIONAL LABORATORIES

    SciTech Connect

    D. V. Morgan; S. Gardner; R. Liljestrand; M. Madlener; S. Slavin; M. Wu

    2003-06-01

    We have designed, fabricated, calibrated, and fielded a fast, time-resolved 1-10 keV crystal spectrometer to observe the evolution of wire pinch spectra at the Z machine at Sandia National Laboratories. The instrument has two convex cylindrical crystals (PET and KAP). Both crystals Bragg reflect x-rays into an array of ten silicon diodes, providing continuous spectral coverage in twenty channels from 1.0 to 10 keV. The spectral response of the instrument has been calibrated from 1.0 to 6.3 keV at beamline X8A at the National Synchrotron Light Source. The time response of the 1-mm2 silicon detectors was measured with the Pulsed X-ray Source at Bechtel Nevada's Los Alamos Operations, where 2-nanosecond full-width half-maximum (FWHM) waveforms with 700-picosecond rise times typically were observed. The spectrometer has been fielded recently on several experimental runs at the Z Machine. In this paper, we present the time-resolved spectra resulting from the implosions of double-nested tungsten wire arrays onto 5-mm diameter foam cylinders. We also show the results obtained for a double-nested stainless steel wire array with no target cylinder. The spectrometer was located at the end of a 7.1-meter beamline on line-of sight (LOS)21/22, at an angle 12{sup o} above the equatorial plane, and was protected from the debris field by a customized dual-slit fast valve. The soft detector channels below 2.0 keV recorded large signals at pinch time coinciding with signals recorded on vacuum x-ray diodes (XRDs). On experiment Z993, the spectrometer channels recorded a second pulse with a hard x-ray emission spectrum several nanoseconds after pinch time.

  9. OBSERVATIONAL EVIDENCES FOR THE EXISTENCE OF 17.4 keV DECAYING DEGENERATE STERILE NEUTRINOS NEAR THE GALACTIC CENTER

    SciTech Connect

    Chan, M. H.; Chu, M.-C. E-mail: mcchu@phy.cuhk.edu.h

    2011-02-01

    We show that the existence of a degenerate halo of sterile neutrinos with rest mass of 17.4 keV near the Galactic center (GC) can account for both the excess 8.7 keV emission observed by the Suzaku mission and the power needed (10{sup 40} erg s{sup -1}) to maintain the high temperature of the hot gas (8 keV) near the GC. The required decay rate and mixing angle of the sterile neutrinos are {Gamma} {>=} 10{sup -19} s{sup -1} and sin{sup 2}2{theta} {approx} 10{sup -3}, respectively. These values are consistent with a low reheating temperature, which suppresses the production of sterile neutrinos, resulting in a small sterile neutrino density parameter ({Omega}{sub s} < 10{sup -8}). They are also allowed by X-ray background data and the isotope experiment. The large mixing angle leads to the exciting possibility that a sterile-active neutrino oscillation may be visible in near future experiments.

  10. Radiation effects on optical and structural properties of GG17 Glasses induced by 170 keV electrons and protons

    NASA Astrophysics Data System (ADS)

    Wang, Qingyan; Geng, Hongbin; Sun, Chengyue; Li, Xingji; Zhao, Haifa; Liu, Weilong; Xiao, Jingdong; Hu, Zhaochu

    2016-01-01

    The effects of 170 keV electron and proton irradiation are investigated on the optical property and the structure of GG17-type borosilicate glasses for the purpose of assessing the suitability of this material for the rubidium lamp envelope, based on GEANT4 simulating calculation, using electron paramagnetic resonance and Fourier transform infrared spectra and optical-transmittance measurements. The Micro-mechanisms on damage of GG17 Glasses are clarified for electron and proton, respectively. For the electron with the energy of 170 keV, defect creation is due to ionization energy losses and the center is mainly boron oxygen hole center (BOHC) formed by one hole trapped on a bridge oxygen structure with [BO4]-. As a result the number of BOHCs grows as the electron fluence increases. However, for the proton with the energy of 170 keV, the creation of structural defects dominates by means of debonding as a result of an atom having been kicked off the structural chain (displacement effect). This leads to the intensive generation of silicon oxygen hole centers, as well as BOHCs, by the holes trapped on non-bridge oxygen.

  11. The X-Ray Line Feature at 3.5 KeV in Galaxy Cluster Spectra

    NASA Astrophysics Data System (ADS)

    Phillips, K. J. H.; Sylwester, B.; Sylwester, J.

    2015-08-01

    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 & 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.

  12. 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.

  13. The Crossroads between the Galactic Disk and Interstellar Space, Ablaze in 3/4 keV Light

    NASA Astrophysics Data System (ADS)

    Shelton, Robin L.

    2016-04-01

    The halo is the crossroads between the Galactic disk and intergalactic space. This region is inhabited by hot gas that has risen from the disk, gas heated in situ, and hot material that has fallen in from intergalactic space. Owing to high spectral resolution observations made by by XMM-Newton, Suzaku, and Chandra of the hot plasma's 3/4 keV emission and absorption, increasingly sophisticated and CPU intensive computer modeling, and an awareness that charge exchange can contaminate 3/4 keV observations, we are now better able to understand the hot halo gas than ever before.Spectral analyses indicate that the 3/4 keV emission comes from T ~ 2.2 million Kelvin gas. Although observations suggest that the gas may be convectively unstable and the spectra's temperature is similar to that predicted by recent sophisticated models of the galactic fountain, the observed emission measure is significantly brighter than that predicted by fountain models. This brightness disparity presents us with another type of crossroads: should we continue down the road of adding physics to already sophisticated modeling or should we seek out other sources? In this presentation, I will discuss the galactic fountain crossroads, note the latitudinal and longitudinal distribution of the hot halo gas, provide an update on charge exchange, and explain how shadowing observations have helped to fine tune our understanding of the hot gas.

  14. 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.

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

    SciTech Connect

    Pellegrini, C.; Wu, J.; /SLAC

    2011-08-17

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

  16. Analysis of experimental data on neutron-proton scattering in the energy range between 0 and 150 keV

    SciTech Connect

    Babenko, V. A. Petrov, N. M.

    2009-04-15

    Experimental data on neutron-proton scattering in the energy range between 0 and 150 keV are analyzed by using various sets of effective-range parameters. It is shown that, in contrast to the parameters corresponding to the phase shifts of a Nijmegen group, the parameters corresponding to the experimental phase shifts reported by a group from George Washington University (GWU group) lead to very good agreement between the calculated cross sections and their experimental counterparts in the energy region under consideration. On the basis of the experimental value of the cross section for neutron-proton scattering at an energy of 2 keV, the total cross section for neutron-proton scattering at zero energy was found to be {sigma}{sub 0} = 20.428(16) b, which is in very good agreement with a value of {sigma}{sub 0} = 20.423(9) b, which was obtained as the weighted mean of the cross sections presented by Houke and Hurst. It is shown that, in the energy region around several tens of keV units, the effective-range parameters matched with Dilg's cross-section value of {sigma}{sub 0} = 20.491(14) b lead to calculated cross sections whose values are in excess of their experimental counterparts.

  17. Analysis of experimental data on neutron-proton scattering in the energy range between 0 and 150 keV

    NASA Astrophysics Data System (ADS)

    Babenko, V. A.; Petrov, N. M.

    2009-04-01

    Experimental data on neutron-proton scattering in the energy range between 0 and 150 keV are analyzed by using various sets of effective-range parameters. It is shown that, in contrast to the parameters corresponding to the phase shifts of a Nijmegen group, the parameters corresponding to the experimental phase shifts reported by a group from George Washington University (GWU group) lead to very good agreement between the calculated cross sections and their experimental counterparts in the energy region under consideration. On the basis of the experimental value of the cross section for neutron—proton scattering at an energy of 2 keV, the total cross section for neutron-proton scattering at zero energy was found to be σ 0 = 20.428(16) b, which is in very good agreement with a value of σ 0 = 20.423(9) b, which was obtained as the weighted mean of the cross sections presented by Houke and Hurst. It is shown that, in the energy region around several tens of keV units, the effective-range parameters matched with Dilg’s cross-section value of σ 0 = 20.491(14) b lead to calculated cross sections whose values are in excess of their experimental counterparts.

  18. Centaurus A /NGC 5128/ at 2 keV-2.3 MeV - HEAO 1 observations and implications

    NASA Technical Reports Server (NTRS)

    Baity, W. A.; Rothschild, R. E.; Lingenfelter, R. E.; Stein, W. A.; Nolan, P. L.; Gruber, D. E.; Knight, F. K.; Matteson, J. L.; Peterson, L. E.; Mushotzky, R. F.

    1981-01-01

    The active-nucleus galaxy Centaurus A has been studied at 2 keV-2.3 MeV using data from the UCSD/MIT hard X-ray and low-energy gamma-ray instrument and the GSFC/CIT cosmic X-ray experiment on HEAO-1. It is found that an E exp -1.60 + or - 0.03 power law spectrum breaking to E exp -2.0 + or - 0.2 at 140 keV best describes the January and July 1978 data. The average intensity was 50% higher during the January observations. Upper limits to unresolved lines at 511 keV and 1.6 MeV were found to be 6.5 x 10 to the -4th photons/sq cm-s and 2.2 x 10 to the -4th photons/sq cm-s, respectively, at the 90% confidence level. The present data are consistent with the detailed calculations of the synchrotron self-Compton mechanism; they may also agree, marginally, with the predictions of emission from spherical accretion onto black holes.

  19. 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.

  20. Anomalous scattering of keV neutrons from H2O and D2O : I. Single scattering events

    NASA Astrophysics Data System (ADS)

    Chatzidimitriou-Dreismann, C. A.; Krzystyniak, M.

    2006-05-01

    Scattering of neutrons in the 24-150 keV incident energy range from H2O relative to that of D2O and H2O-D2O mixtures was reported recently by Moreh et al. This work is related to neutron Compton scattering experiments regarding the 'anomalous' scattering from protons, observed earlier at ISIS by Chatzidimitriou-Dreismann et al in the 5-100 eV range. Here we provide the complete data reduction scheme of time-of-flight integrated intensities measured at keV energy transfers, within the impulse approximation of standard theory and for single scattering events. Current investigations of multiple scattering events and the associated preliminary results are mentioned. Direct application of the theoretical results to the new keV scattering data reveals an anomalous ratio of scattering intensity of H2O relative to that of D2O of about 20%, thus being in good agreement with the earlier results of the original experiment at ISIS.

  1. Spectroscopy of 201At including the observation of a shears band and the 29 /2+ isomeric state

    NASA Astrophysics Data System (ADS)

    Auranen, K.; Uusitalo, J.; Juutinen, S.; Jakobsson, U.; Grahn, T.; Greenlees, P. T.; Hauschild, K.; HerzáÅ, A.; Julin, R.; Konki, J.; Leino, M.; Pakarinen, J.; Partanen, J.; Peura, P.; Rahkila, P.; Ruotsalainen, P.; Sandzelius, M.; Sarén, J.; Scholey, C.; Sorri, J.; Stolze, S.

    2015-02-01

    The excited states of 201At were studied and an isomeric 29 /2+ state [T½=3.39 (9 ) μ s ] was identified by using a fusion-evaporation reaction, a gas-filled recoil separator, and recoil gating techniques. The 29 /2+ state is suggested to originate from the π (h9 /2) ⊗| 200Po ;11-> configuration, and it decays through the 269- and 339-keV E 2 - and E 3 -type transitions, respectively. Moreover, a cascade of magnetic dipole transitions that is suggested to originate from a shears band was observed by using recoil-gated γ -γ (-γ ) coincidence techniques.

  2. Adaptive Confidence Bands for Nonparametric Regression Functions

    PubMed Central

    Cai, T. Tony; Low, Mark; Ma, Zongming

    2014-01-01

    A new formulation for the construction of adaptive confidence bands in non-parametric function estimation problems is proposed. Confidence bands are constructed which have size that adapts to the smoothness of the function while guaranteeing that both the relative excess mass of the function lying outside the band and the measure of the set of points where the function lies outside the band are small. It is shown that the bands adapt over a maximum range of Lipschitz classes. The adaptive confidence band can be easily implemented in standard statistical software with wavelet support. Numerical performance of the procedure is investigated using both simulated and real datasets. The numerical results agree well with the theoretical analysis. The procedure can be easily modified and used for other nonparametric function estimation models. PMID:26269661

  3. Shuttle Ku-band and S-band communications implementations study

    NASA Technical Reports Server (NTRS)

    Huth, G. K.; Nessibou, T.; Nilsen, P. W.; Simon, M. K.; Weber, C. L.

    1979-01-01

    The interfaces between the Ku-band system and the TDRSS, between the S-band system and the TDRSS, GSTDN and SGLS networks, and between the S-band payload communication equipment and the other Orbiter avionic equipment were investigated. The principal activities reported are: (1) performance analysis of the payload narrowband bent-pipe through the Ku-band communication system; (2) performance evaluation of the TDRSS user constraints placed on the S-band and Ku-band communication systems; (3) assessment of the shuttle-unique S-band TDRSS ground station false lock susceptibility; (4) development of procedure to make S-band antenna measurements during orbital flight; (5) development of procedure to make RFI measurements during orbital flight to assess the performance degradation to the TDRSS S-band communication link; and (6) analysis of the payload interface integration problem areas.

  4. Assessment of Thematic Mapper Band-to-band Registration by the Block Correlation Method

    NASA Technical Reports Server (NTRS)

    Card, D. H.; Wrigley, R. C.; Mertz, F. C.; Hall, J. R.

    1985-01-01

    Rectangular blocks of pixels from one band image were statistically correlated against blocks centered on identical pixels from a second band image. The block pairs were shifted in pixel increments both vertically and horizontally with respect to each other and the correlation coefficient to the maximum correlation was taken as the best estimate of registration error for each block pair. For the band combinations of the Arkansas scene studied, the misregistration of TM spectral bands within the noncooled focal plane lie well within the 0.2 pixel target specification. Misregistration between the middle IR bands is well within this specification also. The thermal IR band has an apparent misregistration with TM band 7 of approximately 3 pixels in each direction. The TM band 3 has a misregistration of approximately 0.2 pixel in the across-scan direction and 0.5 pixel in the along-scan direction, with both TM bands 5 and 7.

  5. Assessment of Thematic Mapper band-to-band registration by the block correlation method

    NASA Technical Reports Server (NTRS)

    Card, D. H.; Wrigley, R. C.; Mertz, F. C.; Hall, J. R.

    1983-01-01

    Rectangular blocks of pixels from one band image were statistically correlated against blocks centered on identical pixels from a second band image. The block pairs were shifted in pixel increments both vertically and horizontally with respect to each other and the correlation coefficient to the maximum correlation was taken as the best estimate of registration error for each block pair. For the band combinations of the Arkansas scene studied, the misregistration of TM spectral bands within the noncooled focal plane lie well within the 0.2 pixel target specification. Misregistration between the middle IR bands is well within this specification also. The thermal IR band has an apparent misregistration with TM band 7 of approximately 3 pixels in each direction. The TM band 3 has a misregistration of approximately 0.2 pixel in the across-scan direction and 0.5 pixel in the along-scan direction, with both TM bands 5 and 7.

  6. 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.

  7. Josephson systems based on ballistic point contacts between single-band and multi-band superconductors

    NASA Astrophysics Data System (ADS)

    Yerin, Y. S.; Kiyko, A. S.; Omelyanchouk, A. N.; Il'ichev, E.

    2015-11-01

    The Josephson effect in ballistic point contacts between single-band and multi-band superconductors was investigated. It was found that in the case of Josephson junctions formed by a single-band and an s±-wave two-band superconductor as well as by a single-band and a three-band superconductor the junctions become frustrated, showing the φ-contact properties. Depending on the ground state of a three-band superconductor with time-reversal symmetry breaking, the Josephson junction can have from one to three energy minima, some of which can be locally stable. We also study the behavior of a dc SQUID based on the Josephson junctions between single-band and multi-band superconductors. Some features on the dependences of the critical current and the total magnetic flux on the applied flux of a dc SQUID based on the Josephson point contacts between a single-band superconductor and an s±-wave superconductor, three-band superconductor with broken time-reversal symmetry and three-band superconductor without broken time-reversal symmetry as compared to the conventional dc SQUIDs based on single-band superconductors were found. The results can be used as an experimental tool to detect the existence of multi-band structure and time-reversal symmetry breaking.

  8. Topological Raman band in the carbon nanohorn.

    PubMed

    Sasaki, Ken-ichi; Sekine, Yoshiaki; Tateno, Kouta; Gotoh, Hideki

    2013-09-13

    Raman spectroscopy has been used in chemistry and physics to investigate the fundamental process involving light and phonons. The carbon nanohorn introduces a new subject to Raman spectroscopy, namely topology. We show theoretically that a photoexcited carrier with a nonzero winding number activates a topological D Raman band through the Aharonov-Bohm effect. The topology-induced D Raman band can be distinguished from the ordinary D Raman band for a graphene edge by its peak position. PMID:24074113

  9. Fade Mitigation Techniques at Ka-Band

    NASA Technical Reports Server (NTRS)

    Dissanayake, Asoka (Editor)

    1996-01-01

    Rain fading is the dominant propagation impairment affecting Ka-band satellite links and rain fade mitigation is a key element in the design of Ka-band satellite networks. Some of the common fade mitigation techniques include: power control, diversity, adaptive coding, and resource sharing. The Advanced Communications Technology Satellite (ACTS) provides an excellent opportunity to develop and test Ka-band rain impairment amelioration techniques. Up-link power control and diversity are discussed in this paper.

  10. X-BAND KLYSTRON DEVELOPMENT AT SLAC

    SciTech Connect

    Vlieks, Arnold E.; /SLAC

    2009-08-03

    The development of X-band klystrons at SLAC originated with the idea of building an X-band Linear Collider in the late 1980's. Since then much effort has been expended in developing a reliable X-band Power source capable of delivering >50 MW RF power in pulse widths >1.5 {micro}s. I will report on some of the technical issues and design strategies which have led to the current SLAC klystron designs.

  11. Band engineering of thermoelectric materials.

    PubMed

    Pei, Yanzhong; Wang, Heng; Snyder, G J

    2012-12-01

    Lead chalcogenides have long been used for space-based and thermoelectric remote power generation applications, but recent discoveries have revealed a much greater potential for these materials. This renaissance of interest combined with the need for increased energy efficiency has led to active consideration of thermoelectrics for practical waste heat recovery systems-such as the conversion of car exhaust heat into electricity. The simple high symmetry NaCl-type cubic structure, leads to several properties desirable for thermoelectricity, such as high valley degeneracy for high electrical conductivity and phonon anharmonicity for low thermal conductivity. The rich capabilities for both band structure and microstructure engineering enable a variety of approaches for achieving high thermoelectric performance in lead chalcogenides. This Review focuses on manipulation of the electronic and atomic structural features which makes up the thermoelectric quality factor. While these strategies are well demonstrated in lead chalcogenides, the principles used are equally applicable to most good thermoelectric materials that could enable improvement of thermoelectric devices from niche applications into the mainstream of energy technologies. PMID:23074043

  12. Broad-band beam buncher

    DOEpatents

    Goldberg, D.A.; Flood, W.S.; Arthur, A.A.; Voelker, F.

    1984-03-20

    A broad-band beam bunther 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-

  13. Proportion of recovered waterfowl bands reported

    USGS Publications Warehouse

    Geis, A.D.; Atwood, E.L.

    1961-01-01

    Data from the annual mail survey of waterfowl hunters in the United States were used to estimate the total numbers of banded waterfowl that were shot. These estimates were compared with Banding Office records to estimate the proportion of recovered bands that was reported. On the average, about two banded birds were recovered for each one reported. The proportion reported was higher for some areas and for some species than for others. The proportion reported was higher when more of the reports came through employees of conservation agencies.

  14. Possible chiral bands in {sup 194}Tl

    SciTech Connect

    Masiteng, P. L.; Ramashidzha, T. M.; Maliage, S. M.; Sharpey-Schafer, J. F.; Vymers, P. A.; Lawrie, E. A.; Lawrie, J. J.; Bark, R. A.; Mullins, S. M.; Murray, S. H. T.; Kau, J.; Komati, F.; Lindsay, R.; Matamba, I.; Mutshena, P.; Zhang, Y.

    2011-10-28

    High spin states in {sup 194}Tl, excited through the {sup 181}Ta({sup 18}O,5n) fusion evaporation reaction, were studied using the AFRODITE array at iThemba LABS. Candidate chiral bands built on the {pi}h{sub 9/2} x {nu}i{sub 13/2}{sup 1} configuration were found. Furthermore these bands were observed through a band crossing caused by the excitation of a {nu}i{sub 13/2} pair. Above the band crossing the excitation energies remain close, suggesting that chirality may persist for the four quasiparticle configuration too.

  15. Diffuse interstellar bands in reflection nebulae

    NASA Technical Reports Server (NTRS)

    Fischer, O.; Henning, Thomas; Pfau, Werner; Stognienko, R.

    1994-01-01

    A Monte Carlo code for radiation transport calculations is used to compare the profiles of the lambda lambda 5780 and 6613 Angstrom diffuse interstellar bands in the transmitted and the reflected light of a star embedded within an optically thin dust cloud. In addition, the behavior of polarization across the bands were calculated. The wavelength dependent complex indices of refraction across the bands were derived from the embedded cavity model. In view of the existence of different families of diffuse interstellar bands the question of other parameters of influence is addressed in short.

  16. Flat-band engineering of mobility edges

    NASA Astrophysics Data System (ADS)

    Danieli, Carlo; Bodyfelt, Joshua D.; Flach, Sergej

    2015-06-01

    Properly modulated flat-band lattices have a divergent density of states at the flat-band energy. Quasiperiodic modulations are known to host a metal-insulator transition already in one space dimension. Their embedding into flat-band geometries consequently allows for a precise engineering and fine tuning of mobility edges. We obtain analytic expressions for singular mobility edges for two flat-band lattice examples. In particular, we engineer cases with arbitrarily small energy separations of mobility edge, zeroes, and divergencies.

  17. Metal band drives in spacecraft mechanisms

    NASA Technical Reports Server (NTRS)

    Maus, Daryl

    1993-01-01

    Transmitting and changing the characteristics of force and stroke is a requirement in nearly all mechanisms. Examples include changing linear to rotary motion, providing a 90 deg change in direction, and amplifying stroke or force. Requirements for size, weight, efficiency and reliability create unique problems in spacecraft mechanisms. Flexible metal band and cam drive systems provide powerful solutions to these problems. Band drives, rack and pinion gears, and bell cranks are compared for effectiveness. Band drive issues are discussed including materials, bend radius, fabrication, attachment and reliability. Numerous mechanisms are shown which illustrate practical applications of band drives.

  18. Density of States for Warped Energy Bands

    PubMed Central

    Mecholsky, Nicholas A.; Resca, Lorenzo; Pegg, Ian L.; Fornari, Marco

    2016-01-01

    Warping of energy bands can affect the density of states (DOS) in ways that can be large or subtle. Despite their potential for significant practical impacts on materials properties, these effects have not been rigorously demonstrated previously. Here we rectify this using an angular effective mass formalism that we have developed. To clarify the often confusing terminology in this field, “band warping” is precisely defined as pertaining to any multivariate energy function E(k) that does not admit a second-order differential at an isolated critical point in k-space, which we clearly distinguish from band non-parabolicity. We further describe band “corrugation” as a qualitative form of band warping that increasingly deviates from being twice differentiable at an isolated critical point. These features affect the density-of-states and other parameters ascribed to band warping in various ways. We demonstrate these effects, providing explicit calculations of DOS and their effective masses for warped energy dispersions originally derived by Kittel and others. Other physical and mathematical examples are provided to demonstrate fundamental distinctions that must be drawn between DOS contributions that originate from band warping and contributions that derive from band non-parabolicity. For some non-degenerate bands in thermoelectric materials, this may have profound consequences of practical interest. PMID:26905029

  19. Density of States for Warped Energy Bands

    NASA Astrophysics Data System (ADS)

    Mecholsky, Nicholas A.; Resca, Lorenzo; Pegg, Ian L.; Fornari, Marco

    2016-02-01

    Warping of energy bands can affect the density of states (DOS) in ways that can be large or subtle. Despite their potential for significant practical impacts on materials properties, these effects have not been rigorously demonstrated previously. Here we rectify this using an angular effective mass formalism that we have developed. To clarify the often confusing terminology in this field, “band warping” is precisely defined as pertaining to any multivariate energy function E(k) that does not admit a second-order differential at an isolated critical point in k-space, which we clearly distinguish from band non-parabolicity. We further describe band “corrugation” as a qualitative form of band warping that increasingly deviates from being twice differentiable at an isolated critical point. These features affect the density-of-states and other parameters ascribed to band warping in various ways. We demonstrate these effects, providing explicit calculations of DOS and their effective masses for warped energy dispersions originally derived by Kittel and others. Other physical and mathematical examples are provided to demonstrate fundamental distinctions that must be drawn between DOS contributions that originate from band warping and contributions that derive from band non-parabolicity. For some non-degenerate bands in thermoelectric materials, this may have profound consequences of practical interest.

  20. X-band RF gun and linac for medical Compton scattering X-ray source

    NASA Astrophysics Data System (ADS)

    Dobashi, Katsuhito; Uesaka, Mitsuru; Fukasawa, Atsushi; Sakamoto, Fumito; Ebina, Futaro; Ogino, Haruyuki; Urakawa, Junji; Higo, Toshiyasu; Akemoto, Mitsuo; Hayano, Hitoshi; Nakagawa, Keiichi

    2004-12-01

    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.

  1. Possible Contrast Media Reduction with Low keV Monoenergetic Images in the Detection of Focal Liver Lesions: A Dual-Energy CT Animal Study

    PubMed Central

    Chung, Yong Eun; You, Je Sung; Lee, Hye-Jeong; Lim, Joon Seok; Lee, Hye Sun; Baek, Song-Ee; Kim, Myeong-Jin

    2015-01-01

    Objective To investigate the feasibility of dual-energy CT for contrast media (CM) reduction in the diagnosis of hypervascular and hypovascular focal liver lesions (FLL). Subjects and Methods The Institutional Animal Care and Use Committee approved this study. VX2 tumors were implanted in two different segments of the liver in 13 rabbits. After 2 weeks, two phase contrast enhanced CT scans including the arterial phase (AP) and portal-venous phase (PVP) were performed three times with 24-hour intervals with three different concentrations of iodine, 300 (I300), 150 (I150) and 75 mg I/mL (I75). The mean HU and standard deviation (SD) were measured in the liver, the hypervascular portion of the VX2 tumor which represented hypervascular tumors, and the central necrotic area of the VX2 tumor which represented hypovascular tumors in 140kVp images with I300 as a reference standard and in monoenergetic images (between 40keV and 140keV) with I150 and I75. The contrast-to-noise ratio (CNR) for FLLs and the ratio of the CNRs (CNRratio) between monoenergetic image sets with I150 and I75, and the reference standard were calculated. Results For hypervascular lesions, the CNRratio was not statistically different from 1.0 between 40keV and 70keV images with I150, whereas the CNRratio was significantly lower than 1.0 in all keV images with I75. For hypovascular lesions, the CNRratio was similar to or higher than 1.0 between 40keV and 80keV with I150 and between 40keV and 70keV with I75. Conclusions With dual-energy CT, the total amount of CM might be halved in the diagnosis of hypervascular FLLs and reduced to one-fourth in the diagnosis of hypovascular FLLs, while still preserving CNRs. PMID:26203652

  2. Comparison of X-Band, L-Band and C-Band Radar Images in Monitoring Subsidence in Agricultural Regions

    NASA Astrophysics Data System (ADS)

    Motagh, Mahdi; Haghshenas Haghighi, Mahmud; Shamshiri, Roghaye; Esmaeili, Mustapha

    2015-05-01

    The ongoing pattern of groundwater induced land subsidence in major valleys and agricultural regions of Iran has been recently documented by several studies (e.g. [1-4]) using C-band Interferometric Synthetic Aperture Radar (InSAR) observations. In this article we present the results of our research in which we evaluated the performance of C-band, L-band and X-band SAR data, using time-series method of small baseline subset (SBAS), to retrieve long time series of ground subsidence in agricultural regions in the country. Two major groundwater basins have been selected for this purpose: (1) Rafsanjan Valley in the Kerman province of central Iran and (2) Tehran Plain (capital of Iran). We also report on our experience using dualpolarimetry (HH/VV) X-band SAR data for Persistent Scatterer (PS) deformation analysis in natural terrains subject to high rate of deformation.

  3. Correlated Multi-Wave Band Variability in the Blazar 3C 279 from 1996 to 2007

    NASA Astrophysics Data System (ADS)

    Chatterjee, Ritaban; Jorstad, Svetlana G.; Marscher, Alan P.; Oh, Haruki; McHardy, Ian M.; Aller, Margo F.; Aller, Hugh D.; Balonek, Thomas J.; Miller, H. Richard; Ryle, Wesley T.; Tosti, Gino; Kurtanidze, Omar; Nikolashvili, Maria; Larionov, Valeri M.; Hagen-Thorn, Vladimir A.

    2008-12-01

    We present the results of extensive multi-wave band monitoring of the blazar 3C 279 between 1996 and 2007 at X-ray energies (2-10 keV), optical R band, and 14.5 GHz, as well as imaging with the Very Long Baseline Array (VLBA) at 43 GHz. In all bands the power spectral density corresponds to "red noise" that can be fit by a single power law over the sampled timescales. Variations in flux at all three wave bands are significantly correlated. The time delay between high- and low-frequency bands changes substantially on timescales of years. A major multifrequency flare in 2001 coincided with a swing of the jet toward a more southerly direction, and in general the X-ray flux is modulated by changes in the position angle of the jet near the core. The flux density in the core at 43 GHz—increases in which indicate the appearance of new superluminal knots—are significantly correlated with the X-ray flux. We decompose the X-ray and optical light curves into individual flares, finding that X-ray leads optical variations (XO) in six flares, the reverse (OX) occurs in three flares, and there is essentially zero lag in four flares. Upon comparing theoretical expectations with the data, we conclude that (1) XO flares can be explained by gradual acceleration of radiating electrons to the highest energies, (2) OX flares can result from either light-travel delays of the seed photons (synchrotron self-Compton scattering) or gradients in maximum electron energy behind shock fronts, and (3) events with similar X-ray and optical radiative energy output originate well upstream of the 43 GHz core, while those in which the optical radiative output dominates occur at or downstream of the core.

  4. 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.

    2005-07-15

    Indirectly driven double-shell implosions are being investigated as a possible noncryogenic path to ignition on the National Ignition Facility [J. A. Paisner, J. D. Boyes, S. A. Kumpan, W. H. Lowdermilk, and M. S. Sorem, Laser Focus World 30, 75 (1994)]. 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.

  5. Whistler anisotropy instabilities as the source of banded chorus: Van Allen Probes observations and particle-in-cell simulations

    PubMed Central

    Fu, Xiangrong; Cowee, Misa M; Friedel, Reinhard H; Funsten, Herbert O; Gary, S Peter; Hospodarsky, George B; Kletzing, Craig; Kurth, William; Larsen, Brian A; Liu, Kaijun; MacDonald, Elizabeth A; Min, Kyungguk; Reeves, Geoffrey D; Skoug, Ruth M; Winske, Dan

    2014-01-01

    Magnetospheric banded chorus is enhanced whistler waves with frequencies ωr<Ωe, where Ωe is the electron cyclotron frequency, and a characteristic spectral gap at ωr≃Ωe/2. This paper uses spacecraft observations and two-dimensional particle-in-cell simulations in a magnetized, homogeneous, collisionless plasma to test the hypothesis that banded chorus is due to local linear growth of two branches of the whistler anisotropy instability excited by two distinct, anisotropic electron components of significantly different temperatures. The electron densities and temperatures are derived from Helium, Oxygen, Proton, and Electron instrument measurements on the Van Allen Probes A satellite during a banded chorus event on 1 November 2012. The observations are consistent with a three-component electron model consisting of a cold (a few tens of eV) population, a warm (a few hundred eV) anisotropic population, and a hot (a few keV) anisotropic population. The simulations use plasma and field parameters as measured from the satellite during this event except for two numbers: the anisotropies of the warm and the hot electron components are enhanced over the measured values in order to obtain relatively rapid instability growth. The simulations show that the warm component drives the quasi-electrostatic upper band chorus and that the hot component drives the electromagnetic lower band chorus; the gap at ∼Ωe/2 is a natural consequence of the growth of two whistler modes with different properties. PMID:26167433

  6. Assessment of Thematic Mapper Band-to-band Registration by the Block Correlation Method

    NASA Technical Reports Server (NTRS)

    Card, D. H.; Wrigley, R. C.; Mertz, F. C.; Hall, J. R.

    1984-01-01

    The design of the Thematic Mapper (TM) multispectral radiometer makes it susceptible to band-to-band misregistration. To estimate band-to-band misregistration a block correlation method is employed. This method is chosen over other possible techniques (band differencing and flickering) because quantitative results are produced. The method correlates rectangular blocks of pixels from one band against blocks centered on identical pixels from a second band. The block pairs are shifted in pixel increments both vertically and horizontally with respect to each other and the correlation coefficient for each shift position is computed. The displacement corresponding to the maximum correlation is taken as the best estimate of registration error for each block pair. Subpixel shifts are estimated by a bi-quadratic interpolation of the correlation values surrounding the maximum correlation. To obtain statistical summaries for each band combination post processing of the block correlation results performed. The method results in estimates of registration error that are consistent with expectations.

  7. Getting Elementary Students Involved in Band

    ERIC Educational Resources Information Center

    Moore, Patience

    2009-01-01

    The author discusses getting elementary students involved in a band. The goals of an elementary band instructor should include introduction of good practice habits, working within an ensemble, and rehearsal procedures, along with the focusing on the essentials of music. Instructors should let students use the basic instruments: flute, clarinet,…

  8. 47 CFR 90.1213 - Band plan.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 47 Telecommunication 5 2014-10-01 2014-10-01 false Band plan. 90.1213 Section 90.1213 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND... § 90.1213 Band plan. (a) The following channel center frequencies are permitted to be aggregated...

  9. 47 CFR 90.1213 - Band plan.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 5 2011-10-01 2011-10-01 false Band plan. 90.1213 Section 90.1213 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND... § 90.1213 Band plan. The following channel center frequencies are permitted to be aggregated...

  10. 47 CFR 90.1213 - Band plan.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 5 2012-10-01 2012-10-01 false Band plan. 90.1213 Section 90.1213 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND... § 90.1213 Band plan. (a) The following channel center frequencies are permitted to be aggregated...

  11. 47 CFR 90.1213 - Band plan.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 47 Telecommunication 5 2013-10-01 2013-10-01 false Band plan. 90.1213 Section 90.1213 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND... § 90.1213 Band plan. (a) The following channel center frequencies are permitted to be aggregated...

  12. Hazing in the College Marching Band

    ERIC Educational Resources Information Center

    Silveira, Jason M.; Hudson, Michael W.

    2015-01-01

    The purpose of this study was to investigate hazing in collegiate marching bands. Specifically, the researchers were interested in marching band students' experiences with hazing behaviors, to whom they were reported, attitudes toward hazing, and level of awareness of institutional hazing policies. Using a multistage cluster sampling approach, we…

  13. And the Band Played on--Almost

    ERIC Educational Resources Information Center

    Allen, Ann

    2009-01-01

    High school band teacher, Mr. Alex Smith, received a request from the Republican presidential campaign for the marching band to perform at an upcoming local rally at which both the presidential and vice-presidential candidates would appear. With support from the principal and superintendent, Mr. Smith moved forward with plans for a Monday…

  14. Nucleation of shear bands in amorphous alloys

    PubMed Central

    Perepezko, John H.; Imhoff, Seth D.; Chen, Ming-Wei; Wang, Jun-Qiang; Gonzalez, Sergio

    2014-01-01

    The initiation and propagation of shear bands is an important mode of localized inhomogeneous deformation that occurs in a wide range of materials. In metallic glasses, shear band development is considered to center on a structural heterogeneity, a shear transformation zone that evolves into a rapidly propagating shear band under a shear stress above a threshold. Deformation by shear bands is a nucleation-controlled process, but the initiation process is unclear. Here we use nanoindentation to probe shear band nucleation during loading by measuring the first pop-in event in the load–depth curve which is demonstrated to be associated with shear band formation. We analyze a large number of independent measurements on four different bulk metallic glasses (BMGs) alloys and reveal the operation of a bimodal distribution of the first pop-in loads that are associated with different shear band nucleation sites that operate at different stress levels below the glass transition temperature, Tg. The nucleation kinetics, the nucleation barriers, and the density for each site type have been determined. The discovery of multiple shear band nucleation sites challenges the current view of nucleation at a single type of site and offers opportunities for controlling the ductility of BMG alloys. PMID:24594599

  15. Low-Noise Band-Pass Amplifier

    NASA Technical Reports Server (NTRS)

    Kleinberg, L.

    1982-01-01

    Circuit uses standard components to overcome common limitation of JFET amplifiers. Low-noise band-pass amplifier employs JFET and operational amplifier. High gain and band-pass characteristics are achieved with suitable choice of resistances and capacitances. Circuit should find use as low-noise amplifier, for example as first stage instrumentation systems.

  16. Highly Deformed Rotational Bands in ^65Zn

    NASA Astrophysics Data System (ADS)

    Yu, C.-H.; Baktash, C.; Paul, S. D.; Radford, D. C.; Cameron, J. A.; Haslip, D. S.; Lampman, T.; Svensson, C. E.; Waddington, J. C.; Wilson, J. N.; Lafosse, D. R.; Lerma, F.; Sarantites, D. G.; Rudolph, D.; Eberth, J.; Lee, I. Y.; Macchiavelli, A. O.

    1998-04-01

    High spin states of ^65Zn were populated using the ^40Ca(^29Si, 4p) reaction at a beam energy of 130 MeV. The experiment was performed at the LBL 88" cyclotron using the Gammasphere in conjunction with the Microball. A total of about 88 million 4-proton gated events were collected from the experiment. Two highly deformed rotational bands were established in ^65Zn. Among the two bands, band 1 is more strongly populated and has only one signature. Band 2 is much weaker and has two signatures connected by M1 transitions. These highly deformed rotational bands are consistent with the excitation of the g_9/2 orbitals, which previously were associated(C.E. Svensson et al.,) Phys. Rev. Lett. 79, 1233 (1997). with the superdeformed band in ^62Zn. Lifetimes were also extracted for these bands in ^65Zn using the Centroid Shift Method. Average Qt values of the two bands were determined and will be compared with the Q_t's of the neighboring nuclei.

  17. Apparatus for loading a band saw blade

    DOEpatents

    Reeves, Steven R.

    1990-01-01

    A band saw blade is loaded between pairs of guide wheels upon tensioning the blade by guiding the blade between pairs of spaced guide plates which define converging slots that converge toward the guide wheels. The approach is particularly useful in loading blades on underwater band saw machines used to cut radioactive materials.

  18. Shuttle S-band communications technical concepts

    NASA Technical Reports Server (NTRS)

    Seyl, J. W.; Seibert, W. W.; Porter, J. A.; Eggers, D. S.; Novosad, S. W.; Vang, H. A.; Lenett, S. D.; Lewton, W. A.; Pawlowski, J. F.

    1985-01-01

    Using the S-band communications system, shuttle orbiter can communicate directly with the Earth via the Ground Spaceflight Tracking and Data Network (GSTDN) or via the Tracking and Data Relay Satellite System (TDRSS). The S-band frequencies provide the primary links for direct Earth and TDRSS communications during all launch and entry/landing phases of shuttle missions. On orbit, S-band links are used when TDRSS Ku-band is not available, when conditions require orbiter attitudes unfavorable to Ku-band communications, or when the payload bay doors are closed. the S-band communications functional requirements, the orbiter hardware configuration, and the NASA S-band communications network are described. The requirements and implementation concepts which resulted in techniques for shuttle S-band hardware development discussed include: (1) digital voice delta modulation; (2) convolutional coding/Viterbi decoding; (3) critical modulation index for phase modulation using a Costas loop (phase-shift keying) receiver; (4) optimum digital data modulation parameters for continuous-wave frequency modulation; (5) intermodulation effects of subcarrier ranging and time-division multiplexing data channels; (6) radiofrequency coverage; and (7) despreading techniques under poor signal-to-noise conditions. Channel performance is reviewed.

  19. 47 CFR 90.1213 - Band plan.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 5 2010-10-01 2010-10-01 false Band plan. 90.1213 Section 90.1213 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND SPECIAL RADIO SERVICES PRIVATE LAND... § 90.1213 Band plan. The following channel center frequencies are permitted to be aggregated...

  20. Solid state ku-band power amplifier

    NASA Technical Reports Server (NTRS)

    Bowers, H. C.; Lockyear, W. H.

    1972-01-01

    The design, fabrication, and testing of two types of IMPATT diode reflection amplifiers and a transmission amplifier are given. The Ku-band IMPATT diode development is discussed. Circuitry and electrical performance of the final version of the Ku-band amplifier is described. Construction details and an outline and mounting drawing are presented.