Science.gov

Sample records for 15-50 kev flux

  1. 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).

  2. 46 CFR 168.15-50 - Ventilation.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 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 2012-10-01 2012-10-01 false Ventilation. 168.15-50 Section 168.15-50 Shipping...

  3. 46 CFR 168.15-50 - Ventilation.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 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 2011-10-01 2011-10-01 false Ventilation. 168.15-50 Section 168.15-50 Shipping...

  4. Low energy (10eV to 10 keV) equatorial particle fluxes and soft particle fluxes near the equator

    NASA Technical Reports Server (NTRS)

    Winningham, J. D.; Heikkila, W. J.

    1974-01-01

    Several spectra are shown that represent one rotation of ISIS-1. Spectra 1, 2, 3, represent particles moving down the field line into northern ionosphere and spectra 4, 5, 6 represent particles moving up field lines towards the magnetic equator. The former are direct fluxes and the latter are albedo fluxes. The spectra observed are remarkably similar to these observed in the auroral zone. The direct fluxes exhibit a relative maximum in the few keV range and the albedo a power low spectrum with increased fluxes at low energies. Examination of concurrent topside sounder data on ISIS-1 revealed a positive correlation between a region of turbulent ionosphere and particle fluxes. This ionospheric condition is referred to as equatorial spread F and has been studied extensively with bottomside ionospheric sounders and backscatter radars. The perigee of ISIS crossed the magnetic equator at four local times (0400, 1000, 1600, 2100) during the lifetime of the particle spectrometer. No fluxes were observed at 0400 and 1000 local time. At 1600 a few instances of particles were observed. At 2100 essentially all passes included detectable equatorial fluxes. This is in agreement with the frequency of occurence of equatorial spread F.

  5. Extreme energetic electron fluxes in low Earth orbit: Analysis of POES E > 30, E > 100, and E > 300 keV electrons

    NASA Astrophysics Data System (ADS)

    Meredith, Nigel P.; Horne, Richard B.; Isles, John D.; Green, Janet C.

    2016-02-01

    Energetic electrons are an important space weather hazard. Electrons with energies less than about 100 keV cause surface charging, while higher-energy electrons can penetrate materials and cause internal charging. In this study we conduct an extreme value analysis of the maximum 3-hourly flux of E > 30 keV, E > 100 keV, and E > 300 keV electrons in low Earth orbit as a function of L∗, for geomagnetic field lines that map to the outer radiation belt, using data from the National Oceanic and Atmospheric Administration Polar Operational Environmental Satellites (POES) from July 1998 to June 2014. The 1 in 10 year flux of E > 30 keV electrons shows a general increasing trend with distance ranging from 1.8 × 107 cm-2 s-1 sr-1 at L∗=3.0 to 6.6 × 107 cm-2 s-1 sr-1 at L∗=8.0. The 1 in 10 year flux of E > 100 keV electrons peaks at L∗=4.5-5.0 at 1.9 × 107 cm-2 s-1 sr-1 decreasing to minima of 7.1 × 106 and 8.7 × 106 cm-2 s-1 sr-1 at L∗=3.0 and 8.0, respectively. In contrast to the E > 30 keV electrons, the 1 in 10 year flux of E > 300 keV electrons shows a general decreasing trend with distance, ranging from 2.4 × 106 cm-2 s-1 sr-1 at L∗=3.0 to 1.2 × 105 cm-2 s-1 sr-1 at L∗=8.0. Our analysis suggests that there is a limit to the E > 30 keV electrons with an upper bound in the range 5.1 × 107 to 8.8 × 107 cm-2 s-1 sr-1. However, the results suggest that there is no upper bound for the E > 100 keV and E > 300 keV electrons.

  6. Flux predictions at geosynchronous orbit (1 eV to 40 keV) based on solar wind conditions at 1 AU.

    NASA Astrophysics Data System (ADS)

    Denton, M.; Jordanova, V.; Henderson, M. G.; Thomsen, M. F.; Borovsky, J.; Woodroffe, J. R.; Hartley, D.; Pitchford, D. A.

    2015-12-01

    Accurate upstream predictions of the flux environment at GEO are highly desirable in order to evaluate the upcoming risk to orbital satellites and instrumentation. Knowledge of the expected flux, in the energy range from 1 eV to 40 keV, with a lead time of ~1 hour, would provide operators with information on the potential risks from surface-charging. Our current model (http://gemelli.spacescience.org/mdenton/) provides the electron and ion flux at any energy between 1 eV and 40 keV, at any local time, and at any value of the Kp index. We will discuss our current model of the electron and ion fluxes at GEO, and also highlight new additions to the model based on LANL/MPA observations ordered with respect to the IMF and solar-wind velocity at 1 AU. We will also discuss other factors (e.g. effects of magnetic latitude) that could potentially improve predictions of fluxes in the inner magnetosphere.

  7. Strong enhancement of 10-100 keV electron fluxes by combined effects of chorus waves and time domain structures

    NASA Astrophysics Data System (ADS)

    Ma, Qianli; Mourenas, Didier; Artemyev, Anton; Li, Wen; Thorne, Richard M.; Bortnik, Jacob

    2016-05-01

    Time domain structures (TDSs) are trains of intense electric field spikes observed in large numbers during plasma injections in the outer radiation belt. Here we explore the question of their importance in energetic electron acceleration and loss in this region. Although the most common TDSs can preaccelerate low-energy electrons up to 1-5 keV energies, they often cannot produce by themselves the seed population of 30-150 keV electrons, which are needed for a subsequent energization up to relativistic energies during storms or substorms. However, we demonstrate by numerical simulations that modifications of the low-energy electron pitch angle and energy distributions due to interactions with TDS lead to more efficient scattering of electrons by chorus waves toward both higher and lower pitch angles, ultimately leading to both significantly higher fluxes in the 10-100 keV energy range and more intense 1-100 keV precipitation into the atmosphere, potentially affecting the outer radiation belt dynamics.

  8. 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....

  9. 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....

  10. 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....

  11. 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....

  12. 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....

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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...

  18. 46 CFR 193.15-50 - Clean agent systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 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... 46 Shipping 7 2012-10-01 2012-10-01 false Clean agent systems. 193.15-50 Section...

  19. The Origin of the Local 1/4-KeV X-Ray Flux in Both Charge Exhange and a Hot Bubble

    NASA Technical Reports Server (NTRS)

    Galeazzi, M.; Chiao, M.; Collier, M. R.; Cravens, T.; Koutroumpa, D.; Kuntz, K. D.; Lallement, R.; Lepri, S. T.; McCammon, D.; Morgan, K.; Porter, F. S.; Robertson, I. P.; Snowden, S. L.; Thomas, N. E.; Uprety, Y.; Ursino, E.; Walsh, B. M.

    2014-01-01

    The solar neighbourhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of easily absorbed 1/4-kiloelectronvolt X-rays coupled with the discovery that interstellar space within about a hundred parsecs of the Sun is almost completely devoid of cool absorbing gas, led to a picture of a 'local cavity' filled with X-ray-emitting hot gas, dubbed the local hot bubble. This model was recently challenged by suggestions that the emission could instead be readily produced within the Solar System by heavy solar-wind ions exchanging electrons with neutral H and He in interplanetary space, potentially removing the major piece of evidence for the local existence of million-degree gas within the Galactic disk. Here we report observations showing that the total solar wind charge-exchange contribution is approximately 40 percent of the 1/4-keV flux in the Galactic plane. The fact that the measured flux is not dominated by charge exchange supports the notion of a million-degree hot bubble extending about a hundred parsecs from the Sun.

  20. The origin of the local 1/4-keV X-ray flux in both charge exchange and a hot bubble.

    PubMed

    Galeazzi, M; Chiao, M; Collier, M R; Cravens, T; Koutroumpa, D; Kuntz, K D; Lallement, R; Lepri, S T; McCammon, D; Morgan, K; Porter, F S; Robertson, I P; Snowden, S L; Thomas, N E; Uprety, Y; Ursino, E; Walsh, B M

    2014-08-14

    The solar neighbourhood is the closest and most easily studied sample of the Galactic interstellar medium, an understanding of which is essential for models of star formation and galaxy evolution. Observations of an unexpectedly intense diffuse flux of easily absorbed 1/4-kiloelectronvolt X-rays, coupled with the discovery that interstellar space within about a hundred parsecs of the Sun is almost completely devoid of cool absorbing gas, led to a picture of a 'local cavity' filled with X-ray-emitting hot gas, dubbed the local hot bubble. This model was recently challenged by suggestions that the emission could instead be readily produced within the Solar System by heavy solar-wind ions exchanging electrons with neutral H and He in interplanetary space, potentially removing the major piece of evidence for the local existence of million-degree gas within the Galactic disk. Here we report observations showing that the total solar-wind charge-exchange contribution is approximately 40 per cent of the 1/4-keV flux in the Galactic plane. The fact that the measured flux is not dominated by charge exchange supports the notion of a million-degree hot bubble extending about a hundred parsecs from the Sun. PMID:25079321

  1. 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...

  2. 46 CFR 193.15-50 - Clean agent systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 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....

  3. 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....

  4. 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

  5. Evidence for electron acceleration up to approximately 300 keV in the magnetic reconnection diffusion region of earth's magnetotail.

    PubMed

    ØIeroset, M; Lin, R P; Phan, T D; Larson, D E; Bale, S D

    2002-11-01

    We report direct measurements of high-energy particles in a rare crossing of the diffusion region in Earth's magnetotail by the Wind spacecraft. The fluxes of energetic electrons up to approximately 300 keV peak near the center of the diffusion region and decrease monotonically away from this region. The diffusion region electron flux spectrum obeys a power law with an index of -3.8 above approximately 2 keV, and the electron angular distribution displays strong field-aligned bidirectional anisotropy at energies below approximately 2 keV, becoming isotropic above approximately 6 keV. These observations indicate significant electron acceleration inside the diffusion region. Ions show no such energization.

  6. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1998-05-01

    In this work we examine the statistical presence of some important features of upstream energetic (>=50 keV) ion events under some special conditions in the upstream region and the magnetosphere. The 125 ion events considered in the statistic were observed by the IMP 7 and IMP 8 spacecraft, at ~35RE from the Earth, during nine long time intervals of a total of 153 hours. The time intervals analyzed were selected under the following restrictions: existence of high proton flux (i.e., >=900 pcm-2s-1sr-1) and of a great number of events (an occurrence frequency of ~10 events per 12 hours in the whole statistics) in the energy range 50-220 keV. The most striking findings are the following: (1) The upstream events were observed during times with high values of the geomagnetic activity index Kp(>=3-) (2) all of the upstream events (100%) have energy spectra extending up to energies E>=290keV (3) 86% of these events are accompanied by relativistic (E>=220keV) electrons; and (4) the majority of the upstream ion events (82%) showed noninverse velocity dispersion during their onset phase (22% of the events showed forward velocity dispersion, and 60% showed no velocity dispersion at all when 5.5-min averaged observations were analyzed). Further statistical analysis of this sample of upstream particle events shows that the 50- to 220-keV proton flux shows a positive correlation with the following parameters: the Kp index of geomagnetic activity and the flux of the high-energy (290-500 keV) protons and (>=220 keV) electrons. More specific findings are the following: (1) The spectral index γ for a power law distribution of ions detected by the National Oceanic and Atmospheric Administration Energetic Particle Experiment (EPE) instrument (50<=E<=220keV) and The Johns Hopkins University Applied Physics Laboratory Charged Particle Measurement Experiment (CPME) instrument (290<=E<=500keV) ranges between 2 and 6, with maximum probability between 4 and 5 and (2) the peak

  8. 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.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1990-08-01

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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

    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.

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

    PubMed

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

    2013-09-01

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

  19. 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.

  20. 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.

  1. Beta decay anomalies and the 17-keV conundrum

    SciTech Connect

    Hime, A.

    1993-03-01

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

  2. Beta decay anomalies and the 17-keV conundrum

    SciTech Connect

    Hime, A.

    1993-01-01

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

  3. Low-energy electrons (5-50 keV) in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Ganushkina, N. Y.; Liemohn, M. W.; Amariutei, O. A.; Pitchford, D.

    2014-01-01

    Transport and acceleration of the 5-50 keV electrons from the plasma sheet to geostationary orbit were investigated. These electrons constitute the low-energy part of the seed population for the high-energy MeV particles in the radiation belts and are responsible for surface charging. We modeled one nonstorm event on 24-30 November 2011, when the presence of isolated substorms was seen in the AE index. We used the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) with the boundary at 10 RE with moment values for the electrons in the plasma sheet. The output of the IMPTAM modeling was compared to the observed electron fluxes in 10 energy channels (from 5 to 50 keV) measured on board the AMC 12 geostationary spacecraft by the Compact Environmental Anomaly Sensor II with electrostatic analyzer instrument. The behavior of the fluxes depends on the electron energy. The IMPTAM model, driven by the observed parameters such as Interplanetary Magnetic Field (IMF) By and Bz, solar wind velocity, number density, dynamic pressure, and the Dst index, was not able to reproduce the observed peaks in the electron fluxes when no significant variations are present in those parameters. We launched several substorm-associated electromagnetic pulses at the substorm onsets during the modeled period. The observed increases in the fluxes can be captured by IMPTAM when substorm-associated electromagnetic fields are taken into account. Modifications of the pulse front velocity and arrival time are needed to exactly match the observed enhancements.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  5. VizieR Online Data Catalog: XMM-Newton Slew Survey in 2-10keV (Warwick+, 2012)

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    Details of the sources which comprise the hard-band selected XSS extragalactic sample are given in the Table. The table provides the following information for each source: the XSS name; whether the source was also detected in the XSS soft band (1=yes, 0=no); the XSS hard band (2-10keV) flux and error on the flux (in units of 10-11ergs/cm2/s) ; the RA and Dec of the proposed counterpart; the name of the counterpart; the type of the counterpart; the redshift (if known). (1 data file).

  6. ) Mold Fluxes

    NASA Astrophysics Data System (ADS)

    Seo, Myung-Duk; Shi, Cheng-Bin; Cho, Jung-Wook; Kim, Seon-Hyo

    2014-10-01

    The effects of basicity (CaO/SiO2), B2O3, and Li2O addition on the crystallization behaviors of lime-silica-based mold fluxes have been investigated by non-isothermal differential scanning calorimetry (DSC), field emission scanning electron microscopy, X-ray diffraction (XRD), and single hot thermocouple technique. It was found that the crystallization temperature of cuspidine increased with increasing the basicity of mold fluxes. The crystallization of wollastonite was suppressed with increasing the mold flux basicity due to the enhancement of cuspidine crystallization. The addition of B2O3 suppresses the crystallization of mold flux. The crystallization temperature of mold flux decreases with Li2O addition. The size of cuspidine increases, while the number of cuspidine decreases with increasing mold flux basicity. The morphology of cuspidine in mold fluxes with lower basicity is largely dendritic. The dendritic cuspidine in mold fluxes is composed of many fine cuspidine crystals. On the contrary, in mold fluxes with higher basicity, the cuspidine crystals are larger in size with mainly faceted morphology. The crystalline phase evolution was also calculated using a thermodynamic database, and compared with the experimental results determined by DSC and XRD. The results of thermodynamic calculation of crystalline phase formation are in accordance with the results determined by DSC and XRD.

  7. Correction in X-ray flux in OJ 287

    NASA Astrophysics Data System (ADS)

    Grupe, Dirk; Komossa, S.; amp; Gomez, J. L.

    2016-10-01

    We noticed an error in the current X-ray flux of OJ 287 that we reported in ATEL #9629: The flux measured by Swift in the 0.3-10 keV band should be 3.2e-14 W/m2. This means that the flux had increased by a factor of 5 compared with the values before the sun-constraint in June.

  8. 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.

  9. 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.

  10. 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

  11. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  13. THE EMISSION OF CYGNUS X-1: OBSERVATIONS WITH INTEGRAL SPI FROM 20 keV TO 2 MeV

    SciTech Connect

    Jourdain, E.; Roques, J. P.; Malzac, J.

    2012-01-01

    We report on Cyg X-1 observations performed by the SPI telescope on board the INTEGRAL mission and distributed over more than 6 years. We investigate the variability of the intensity and spectral shape of this peculiar source in the hard X-ray domain, and more particularly up to the MeV region. We first study the total averaged spectrum which presents the best signal-to-noise ratio (4 Ms of data). Then, we refine our results by building mean spectra by periods and gathering those of similar hardness. Several spectral shapes are observed with important changes in the curvature between 20 and 200 keV, even at the same luminosity level. In all cases, the emission decreases sharply above 700 keV, with flux values above 1 MeV (or upper limits) well below the recently reported polarized flux, while compatible with the MeV emission detected some years ago by the Compton Gamma-ray Observatory/COMPTEL. Finally, we take advantage of the spectroscopic capability of the instrument to seek for spectral features in the 500 keV region with negative results for any significant annihilation emission on 2 ks and day timescales, as well as in the total data set.

  14. 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.

  15. SPECTRAL PROPERTIES OF {approx}0.5-6 keV ENERGETIC NEUTRAL ATOMS MEASURED BY THE INTERSTELLAR BOUNDARY EXPLORER (IBEX) ALONG THE LINES OF SIGHT OF VOYAGER

    SciTech Connect

    Desai, M. I.; Allegrini, F. A.; Dayeh, M. A.; McComas, D. J.; Schwadron, N. A.; De Majistre, B.; Funsten, H.; Heerikhuisen, J.; Pogorelov, N.; Zank, G. P.

    2012-04-20

    Energetic neutral atoms (ENAs) observed by the Interstellar Boundary Explorer (IBEX) provide powerful diagnostics about the origin of the progenitor ion populations and the physical mechanisms responsible for their production. Here we survey the fluxes, energy spectra, and energy dependence of the spectral indices of {approx}0.5-6 keV ENAs measured by IBEX-Hi along the lines of sight of Voyager 1 and 2. We compare the ENA spectra observed at IBEX with predictions of Zank et al. who modeled the microphysics of the heliospheric termination shock to predict the shape and relative contributions of three distinct heliosheath ion populations. We show that (1) the ENA spectral indices exhibit similar energy dependence along V1 and V2 directions-the spectrum hardens to {gamma} {approx} 1 between {approx}1 and 2 keV and softens to {gamma} {approx} 2 below {approx}1 keV and above {approx}2 keV, (2) the observed ENA fluxes agree to within {approx}50% of the Zank et al. predictions and are unlikely to be produced by core solar wind (SW) ions, and (3) the ENA spectra do not exhibit sharp cutoffs at {approx}twice the SW speed as is typically observed for shell-like pickup ion (PUI) distributions in the heliosphere. We conclude that ENAs at IBEX are generated by at least two types of ion populations whose relative contributions depend on the ENA energy: transmitted PUIs in the {approx}0.5-5 keV energy range and reflected PUIs above {approx}5 keV energy. The {approx}0.5-5 keV PUI distribution is probably a superposition of Maxwellian or kappa distributions and partially filled shell distributions in velocity space.

  16. 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…

  17. 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.

  18. 7.1 keV sterile neutrino constraints from X-ray observations of 33 clusters of galaxies with Chandra ACIS

    NASA Astrophysics Data System (ADS)

    Hofmann, F.; Sanders, J. S.; Nandra, K.; Clerc, N.; Gaspari, M.

    2016-08-01

    Context. Recently an unidentified emission line at 3.55 keV has been detected in X-ray spectra of clusters of galaxies. The line has been discussed as a possible decay signature of 7.1 keV sterile neutrinos, which have been proposed as a dark matter (DM) candidate. Aims: We aim to put constraints on the proposed line emission in a large sample of Chandra-observed clusters and obtain limits on the mixing angle in a 7.1 keV sterile neutrino DM scenario. Methods: For a sample of 33 high-mass clusters of galaxies, we merge all observations from the Chandra data archive. Each cluster has more than 100 ks of combined exposure. The resulting high signal-to-noise spectra are used to constrain the flux of an unidentified line emission at 3.55 keV in the individual spectra and a merged spectrum of all clusters. Results: We obtained very detailed spectra around the 3.55 keV range and limits on an unidentified emission line. Assuming all DM were made of 7.1 keV sterile neutrinos, the upper limits on the mixing angle are sin2(2Θ) < 10.1×10-11 from ACIS-I and < 40.3×10-11 from ACIS-S data at 99.7 per cent confidence level. Conclusions: We do not find evidence for an unidentified emission line at 3.55 keV. The sample extends the list of objects searched for an emission line at 3.55 keV and will help to identify the best targets for future studies of the potential DM decay line with upcoming X-ray observatories like Hitomi (Astro-H), eROSITA, and Athena.

  19. Statistical Properties of Local AGNs Inferred from the RXTE 3-20 keV All-Sky Survey

    NASA Astrophysics Data System (ADS)

    Revnivtsev, M.; Sazonov, S. Yu.

    We have recently ([1]) performed an all-sky survey in the 3-20 keV band from the data accumulated during satellite slews in 1996-2002 - the RXTE slew survey (XSS). For 90% of the sky at |b|>10° , a flux limit for source detection of 2.5×10-11 erg/s/sq.cm(3-20 keV) or lower was achieved, while a combined area of 7000 sq.deg was sampled to record flux levels (for such very large-area surveys) below 10-11 erg/s/sq.cm. A catalog contains 294 X-ray sources. 236 of these sources were identified with a single known astronomical object. Of particular interest are 100 identified active galactic nuclei (AGNs) and 35 unidentified sources. The hard spectra of the latter suggest that many of them will probably also prove AGNs when follow-up observations are performed. Most of the detected AGNs belong to the local population (z<0.1). In addition, the hard X-ray band of the XSS (3-20 keV) as compared to most previous X-ray surveys, performed at photon energies below 10 keV, has made possible the detection of a substantial number of X-ray absorbed AGNs (mostly Seyfert 2 galaxies). These properties make the XSS sample of AGNs a valuable one for the study of the local population of AGNs. We carried out a thorough statistical analysis of the above sample in order to investigate several key properties of the local population of AGNs, in particular their distribution in intrinsic absorption column density (NH) and X-ray luminosity function ([2]). Knowledge of these characteristics provides important constraints for AGN unification models and synthesis of the cosmic X-ray background, and is further needed to understand the details of the accretion-driven growth of supermassive black holes in the nuclei of galaxies.

  20. 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.

  1. Spectroscopy from 2 to 200 keV

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  2. Neutral hydrogen flux measured at 100- to 200-km altitude in an electron aurora

    NASA Technical Reports Server (NTRS)

    Iglesias, G. E.; Anderson, H. R.

    1975-01-01

    Neutral hydrogen fluxes were measured at altitudes of 120-200 km by a rocket payload that also measured electron and proton fluxes and vector magnetic fields. An intense electron arc was crossed, while an upper limit to the flux of 0.5- to 20-keV protons was 1,000,000 per sq cm s sr keV. A neutral flux of 50,000,000 per sq cm s sr was observed, assuming hydrogen with greater than 1-keV energy, with greater north-south extent than the electron flux. Its pitch angle distribution was peaked toward 90 deg, tending toward isotropy in the center. This is fitted to a model describing spreading of an initial proton arc above 500 km.

  3. Deep XMM observations of Draco rule out at the 99 per cent confidence level a dark matter decay origin for the 3.5 keV line

    NASA Astrophysics Data System (ADS)

    Jeltema, Tesla; Profumo, Stefano

    2016-06-01

    We searched for an X-ray line at energies around 3.5 keV in deep, ˜1.6 Ms XMM-Newton observations of the dwarf spheroidal galaxy Draco. No line was found in either the Metal Oxide Semi-conductor (MOS) or the p-type/n-type semiconductor (PN) detectors. The data in this energy range are completely consistent with a single, unfolded power-law modelling the particle background, which dominates at these energies, plus instrumental lines; the addition of a ˜3.5 keV line feature gives no improvement to the fit. The corresponding upper limit on the line flux rules out a dark matter decay origin for the 3.5 keV line found in observations of clusters of galaxies and in the Galactic Centre at greater than 99 per cent confidence level.

  4. High flux compact neutron generators

    SciTech Connect

    Reijonen, J.; Lou, T.-P.; Tolmachoff, B.; Leung, K.-N.; Verbeke, J.; Vujic, J.

    2001-06-15

    Compact high flux neutron generators are developed at the Lawrence Berkeley National Laboratory. The neutron production is based on D-D or D-T reaction. The deuterium or tritium ions are produced from plasma using either a 2 MHz or 13.56 MHz radio frequency (RF) discharge. RF-discharge yields high fraction of atomic species in the beam which enables higher neutron output. In the first tube design, the ion beam is formed using a multiple hole accelerator column. The beam is accelerated to energy of 80 keV by means of a three-electrode extraction system. The ion beam then impinges on a titanium target where either the 2.4 MeV D-D or 14 MeV D-T neutrons are generated. The MCNP computation code has predicted a neutron flux of {approximately}10{sup 11} n/s for the D-D reaction at beam intensity of 1.5 A at 150 kV. The neutron flux measurements of this tube design will be presented. Recently new compact high flux tubes are being developed which can be used for various applications. These tubes also utilize RF-discharge for plasma generation. The design of these tubes and the first measurements will be discussed in this presentation.

  5. Detection of 511 keV positron annihilation radiation from the galactic center direction. [gamma ray astronomy

    NASA Technical Reports Server (NTRS)

    Leventhal, M.; Maccallum, C. J.; Stang, P. D.

    1978-01-01

    A balloon-borne gamma ray telescope with an approximately 130 cu cm high purity germanium detector was flown over Australia to detect sharp spectral features from the galactic center direction. A 511 keV positron annihilation line was observed at a flux level of (1.21 plus or minus 0.22) x (10/cu cm) photons/sec/sp cm. Suggestive evidence for the detection of the three-photon positronium continuum is presented. The possible origin of the positrons is discussed.

  6. 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.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Bulbul, Esra; Markevitch, Maxim; Foster, Adam; Miller, Eric; Bautz, Mark; Loewenstein, Mike; Randall, Scott W.; Smith, Randall K.

    2016-11-01

    We perform a detailed study of the stacked Suzaku observations of 47 galaxy clusters, spanning a redshift range of 0.01–0.45, to search for the unidentified 3.5 keV line. This sample provides an independent test for the previously detected line. We detect a 2σ -significant spectral feature at 3.5 keV in the spectrum of the full sample. When the sample is divided into two subsamples (cool-core and non-cool core clusters), the cool-core subsample shows no statistically significant positive residuals at the line energy. A very weak (∼ 2σ confidence) spectral feature at 3.5 keV is permitted by the data from the non-cool-core clusters sample. The upper limit on a neutrino decay mixing angle of {\\sin }2(2θ )=6.1× {10}-11 from the full Suzaku sample is consistent with the previous detections in the stacked XMM-Newton sample of galaxy clusters (which had a higher statistical sensitivity to faint lines), M31, and Galactic center, at a 90% confidence level. However, the constraint from the present sample, which does not include the Perseus cluster, is in tension with previously reported line flux observed in the core of the Perseus cluster with XMM-Newton and Suzaku.

  9. 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.

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

    SciTech Connect

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

    2015-11-01

    In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low-energy component (up to ∼200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons (kT{sub 0} ∼ 7 keV) is introduced. Above this first component, a clear excess extending up to 400–600 keV leads us to investigate a scenario where an additional (cutoff) power law could correspond to the contribution of the jet synchrotron emission, as proposed in Cyg X-1. A search for an annihilation feature did not provide any firm detection, with an upper limit of 2 × 10{sup −4} ph cm{sup −2} s{sup −1} (2σ) for a narrow line centered at 511 keV, on the averaged obtained spectrum.

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

    NASA Astrophysics Data System (ADS)

    Antier, S.; Limousin, O.; Ferrando, P.

    2015-07-01

    X-rays astrophysical sources have been almost characterized through imaging, spectroscopy and timing analysis. Nevertheless, more observational parameters such as polarization are needed because some radiation mechanisms present in gamma-ray sources are still unclear. We have developed a CdTe based fine-pitch imaging spectrometer, Caliste to study polarization. With a 58-micron pitch and 1 keV energy resolution at 60 keV, we are able to accurately reconstruct the polarization angle and fraction of an impinging flux of photons which are scattered by 90° after Compton diffusion within the crystal. In this paper, we present the principles and the results obtained for this kind of measurements: on one hand, we compare simulations results with experimental data taken at ESRF ID15A (European Synchrotron Radiation Facility) using a 35-300 keV mono-energetic polarized beam. Applying a judicious energy selection to our data set, we reach a remarkable sensitivity level characterized by a measured Quality factor of 0.78±0.02 in the 200-300 keV range; and a measured Q factor of 0.64±0.0 at 70 keV where hard X-rays mirrors are already available.

  12. Microdosimetry of a 25 keV electron microbeam.

    PubMed

    Wilson, W E; Lynch, D J; Wei, K; Braby, L A

    2001-01-01

    Electron microbeam experiments are planned or under way to explore in part the question regarding whether the bystander effect is a general phenomenon or is restricted to high-LET radiation. Since low-LET radiations scatter more readily compared to high-LET radiations, identifying bystander cells and assessing the potential dose that they may receive will be crucial to the interpretation of radiobiological results. This paper reports on initial calculations of the basic information needed for a stochastic model of the penetration of energetic electrons in tissue-like matter; the model will be used to predict doses delivered to adjacent regions in which bystander cells may reside. Results are presented of calculations of the stochastics of energy deposition by 25 keV electrons slowing down in a homogeneous water medium. Energy deposition distributions were scored for 1-micrometer spheres located at various penetration and radial distances up to 10 micrometer from the point of origin. The energy of 25 keV was selected because experiments are planned for that energy. At 25 keV there is a high probability that the entire electron track will be contained within a typical mammalian cell. Individual tracks are scored because of their primacy; data for higher doses can be obtained by convoluting single-track distributions. The event frequency decreases approximately exponentially after the first micrometer to 1% at about 8 micrometer of penetration. Radially, the 1% contour extends to 3.5 micrometer at a penetration of 5.5 micrometer. The frequency-mean energy deposited decreases from 1.5 to 1 keV/micrometer at a penetration of 3.5 micrometer, then increases back to about 1.5 at a penetration of 6.5 micrometer. The mean energy increases to about 3 keV/micrometer at a radial distance of 8.5 micrometer.

  13. The precipitation of keV energetic oxygen ions at Mars and their effects during the comet Siding Spring approach

    NASA Astrophysics Data System (ADS)

    Gronoff, Guillaume; Rahmati, Ali; Wedlund, Cyril Simon; Mertens, Christopher J.; Cravens, Thomas E.; Kallio, Esa

    2014-07-01

    Comet Siding Spring C/2013 A1 will pass Mars on 19 October 2014, entailing particle and dust precipitation in the Martian upper atmosphere and a potential dust hazard for orbiters. An estimate of the flux of energetic O+ ions picked up by the solar wind from the cometary coma is shown, with an increase of the O+ flux above 50 keV by 2 orders of magnitude. While the ionization of Mars' upper atmosphere by precipitating O+ ions is expected to be negligible compared to solar EUV-XUV ionization, it is of the same order of magnitude at 110 km altitude during the cometary passage, leading to detectable increases in ionospheric densities. Cometary O+ pickup ion precipitation is expected to be the major nightside ionization source, creating a temporary ionosphere and a global airglow. These effects are dependent on the solar and cometary activities at the time of the encounter.

  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. The XMM-Newton slew survey in the 2-10 keV band

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    Context. The on-going XMM-Newton Slew Survey (XSS) provides coverage of a significant fraction of the sky in a broad X-ray bandpass. Although shallow by contemporary standards, in the "classical" 2-10 keV band of X-ray astronomy, the XSS provides significantly better sensitivity than any currently available all-sky survey. Aims: We investigate the source content of the XSS, focussing on detections in the hard 2-10 keV band down to a very low threshold (≥ 4 counts net of background). At the faint end, the survey reaches a flux sensitivity of roughly 3 × 10-12 erg cm-2 s-1 (2-10 keV). Methods: Our starting point was a sample of 487 sources detected in the XSS (up to and including release XMMSL1d2) at high galactic latitude in the hard band. Through cross-correlation with published source catalogues from surveys spanning the electromagnetic spectrum from radio through to gamma-rays, we find that 45% of the sources have likely identifications with normal/active galaxies. A further 18% are associated with other classes of X-ray object (nearby coronally active stars, accreting binaries, clusters of galaxies), leaving 37% of the XSS sources with no current identification. We go on to define an XSS extragalactic sample comprised of 219 galaxies and active galaxies selected in the XSS hard band. We investigate the properties of this extragalactic sample including its X-ray log N - log S distribution. Results: We find that in the low-count limit, the XSS is, as expected, strongly affected by Eddington bias. There is also a very strong bias in the XSS against the detection of extended sources, most notably clusters of galaxies. A significant fraction of the detections at and around the low-count limit may be spurious. Nevertheless, it is possible to use the XSS to extract a reasonably robust sample of extragalactic sources, excluding galaxy clusters. The differential log N - log S relation of these extragalactic sources matches very well to the HEAO-1 A2 all-sky survey

  17. Symmetry of the IBEX Ribbon of Enhanced Energetic Neutral Atom (ENA) Flux

    NASA Astrophysics Data System (ADS)

    Funsten, H. O.; Bzowski, M.; Cai, D. M.; Dayeh, M.; DeMajistre, R.; Frisch, P. C.; Heerikhuisen, J.; Higdon, D. M.; Janzen, P.; Larsen, B. A.; Livadiotis, G.; McComas, D. J.; Möbius, E.; Reese, C. S.; Roelof, E. C.; Reisenfeld, D. B.; Schwadron, N. A.; Zirnstein, E. J.

    2015-01-01

    The circular ribbon of enhanced energetic neutral atom (ENA) emission observed by the Interstellar Boundary Explorer (IBEX) mission remains a critical signature for understanding the interaction between the heliosphere and the interstellar medium. We study the symmetry of the ribbon flux and find strong, spectrally dependent reflection symmetry throughout the energy range 0.7-4.3 keV. The distribution of ENA flux around the ribbon is predominantly unimodal at 0.7 and 1.1 keV, distinctly bimodal at 2.7 and 4.3 keV, and a mixture of both at 1.7 keV. The bimodal flux distribution consists of partially opposing bilateral flux lobes, located at highest and lowest heliographic latitude extents of the ribbon. The vector between the ribbon center and heliospheric nose (which defines the so-called BV plane) appears to play an organizing role in the spectral dependence of the symmetry axis locations as well as asymmetric contributions to the ribbon flux. The symmetry planes at 2.7 and 4.3 keV, derived by projecting the symmetry axes to a great circle in the sky, are equivalent to tilting the heliographic equatorial plane to the ribbon center, suggesting a global heliospheric ordering. The presence and energy dependence of symmetric unilateral and bilateral flux distributions suggest strong spectral filtration from processes encountered by an ion along its journey from the source plasma to its eventual detection at IBEX.

  18. Width of the 3841-keV level in 17O

    NASA Astrophysics Data System (ADS)

    Moreh, R.; Beck, O.; Kneissl, U.; Margraf, J.; Maser, H.; Pitz, H. H.; Herzberg, R.-D.; Pietralla, N.; Zilges, A.

    1994-10-01

    The width of 3841-keV level in 17O was precisely measured in nuclear resonance fluorescence experiments performed at the Stuttgart Dynamitron facility. The result of Γ(3841 keV)=(92+/-6) meV is compared with upper limits quoted in the literature. Possible particle-hole configurations of the 3841-keV level are discussed.

  19. ENHANCEMENT OF THE 6.4 keV LINE IN THE INNER GALACTIC RIDGE: PROTON-INDUCED FLUORESCENCE?

    SciTech Connect

    Nobukawa, K. K.; Nobukawa, M.; Tsuru, T. G.; Tanaka, T.; Koyama, K.; Uchiyama, H.; Torii, K.; Fukui, Y.; Chernyshov, D. O.; Dogiel, V. A.

    2015-07-01

    A common idea for the origin of the Galactic diffuse X-ray emission, particularly that of the iron lines from neutral and highly ionized atoms, is a superposition of many cataclysmic variables and coronally active binaries. In this scenario, the flux should symmetrically distribute between the east and west on the plane with respect to Sagittarius A* because the stellar mass distribution determined by infrared observations is nearly symmetric. This symmetry is confirmed for the highly ionized iron line as well as the continuum emission. However, a clear excess of the neutral iron line in the near east of the Galactic center compared to the near-west side is found. The flux distribution of the excess emission well correlates with the molecular column density. The X-ray spectrum of the excess emission is described by a power-law continuum plus a 6.4 keV line with a large equivalent width of ∼1.3 keV, which is hardly explained by the low-energy electron bombardment scenario. The longitudinal and latitudinal distribution of the excess emission disfavors the X-ray irradiation, either by Sagittarius A* or by nearby X-ray binaries. Then, the low-energy proton bombardment is the most probable origin, although the high-energy density ∼80 eV cm{sup −3} in 0.1–1000 MeV is required and there is no conventional proton source in the vicinity.

  20. 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.

  1. HEXIT-SAT: a mission concept for x-ray grazing incidence telescopes from 0.5 to 70 keV

    NASA Astrophysics Data System (ADS)

    Fiore, Fabrizio; Perola, Giuseppe C.; Pareschi, Giovanni; Citterio, Oberto; Anselmi, Alberto; Comastri, Andrea

    2004-10-01

    While the energy density of the Cosmic X-ray Background (CXB) provides a statistical estimate of the super massive black hole (SMBH) growth and mass density in the Universe, the lack, so far, of focusing instrument in the 20-60 keV (where the CXB energy density peaks), frustrates our effort to obtain a comprehensive picture of the SMBH evolutionary properties. HEXIT-SAT (High Energy X-ray Imaging Telescope SATellite) is a mission concept capable of exploring the hard X-ray sky with focusing/imaging instrumentation, to obtain an unbiased census of accreting SMBH up to the redshifts where galaxy formation peaks, and on extremely wide luminosity ranges. This will represent a leap forward comparable to that achieved in the soft X-rays by the Einstein Observatory in the late 70'. In addition to accreting SMBH, and very much like the Einstein Observatory, this mission would also have the capabilities of investigating almost any type of the celestial X-ray sources. HEXIT-SAT is based on high throughput (>400 cm2 @ 30 keV; >1200 cm2 @ 1 keV), high quality (15 arcsec Half Power Diameter) multi-layer optics, coupled with focal plane detectors with high efficiency in the full 0.5-70keV range. Building on the BeppoSAX experience, a low-Earth, equatorial orbit, will assure a low and stable particle background, and thus an extremely good sensitivity for faint hard X-ray sources. At the flux limits of 1/10 microCrab (10-30 keV) and 1/3 microCrab (20-40 keV) (reachable in one Msec observation) we should detect ~100 and ~40 sources in the 15 arcmin FWHM Field of View respectively, thus resolving >80% and ~65% of the CXB where its energy density peaks.

  2. 46 CFR 168.15-50 - Ventilation.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... the purpose of the space and route of the vessel. (b) When mechanical ventilation is provided for sleeping rooms, washrooms, toilet rooms, hospital spaces, and messrooms, these spaces must be supplied with fresh air equal to at least 10 times the volume of the room each hour....

  3. 46 CFR 168.15-50 - Ventilation.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... the purpose of the space and route of the vessel. (b) When mechanical ventilation is provided for sleeping rooms, washrooms, toilet rooms, hospital spaces, and messrooms, these spaces must be supplied with 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, 2014 CFR

    2014-10-01

    ... the purpose of the space and route of the vessel. (b) When mechanical ventilation is provided for sleeping rooms, washrooms, toilet rooms, hospital spaces, and messrooms, these spaces must be supplied with fresh air equal to at least 10 times the volume of the room each hour....

  5. 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.

  6. Solar Wind ˜20-200 keV Superhalo Electrons at Quiet Times

    NASA Astrophysics Data System (ADS)

    Wang, Linghua; Yang, Liu; He, Jiansen; Tu, Chuanyi; Pei, Zhongtian; Wimmer-Schweingruber, Robert F.; Bale, Stuart D.

    2015-04-01

    High-energy superhalo electrons are present in the interplanetary medium (IPM) even in the absence of any significant solar activity, carrying important information on electron acceleration in the solar wind. We present a statistical survey of ˜20-200 keV superhalo electrons measured at 1 AU by the WIND 3D Plasma & Energetic Particle instrument during quiet-time periods from 1995 January through 2013 December. The selected 242 quiet-time samples mostly occur during the rising, maximum and decay phases of solar cycles. The observed omnidirectional differential flux of these quiet-time superhalo electrons generally fits to a power-law spectrum J=A× {{(\\frac{E}{{{m}e}{{c}2}})}-β }, with β ranging from ˜1.6 to ˜3.7 and the integrated density nsup ranging from 10-8 to 10-5 cm-3. In solar cycle 23 (24), the distribution of β has a broad maximum between 2.4 and 2.8 (2.0 and 2.4). Both β and the logarithm of nsup show no obvious correlation with sunspot number, solar flares, solar wind core population, etc. These superhalo electrons may form a quiet-time energetic electron background/reservoir in the IPM. We propose that they may originate from nonthermal processes related to the acceleration of the solar wind such as nanoflares, or could be formed in the IPM due to further acceleration and/or long-distance propagation effects.

  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. The precipitation of keV energetic oxygen ions at Mars and their effects during the comet Siding Spring approach

    NASA Astrophysics Data System (ADS)

    Gronoff, G.; Rahmati, A.; Simon Wedlund, C.; Mertens, C. J.; Cravens, T.; Kallio, E. J.; Pawlowski, D. J.; Bell, J. M.

    2014-12-01

    On October 19, 2014, the Siding Spring C/2013 A1 comet passed in the vicinity of Mars with a closest approach of ˜sim130,000 km with a heliocentric distance of 1.38 AU.The coma of the comet interacted with Mars, leading to the precipitation of molecules, ions, and dust particles. The most important atmospheric effect was the precipitation of atoms/molecules/ions, and especially atomic oxygen atoms and O+^+ ions. Although the main gas forming the corona of comets is H2_2O, the cometary coronal gas is partially ionized and dissociated by the EUV-XUV solar flux. To understand the atomic and molecular precipitation effects during such an encounter, it is therefore necessary to evaluate the flux of the neutral gas ejected from the comet, and to compute its composition after the dissociation/ionization. We computed the photodissociation of the cometary gas for different solar conditions, and for the conditions of the comet encounter. In addition, using a pickup ion code, we computed the fluxes of the O+^+ ions accelerated by the solar wind at energies greated than a keV. Using the Planetocosmic model, we computed the ionization in the atmosphere of Mars due to these species, and, using the M-GITM model, we computed the associated increase of the ion/electron density.For the first time, an estimate of the flux of energetic O+^+ ions picked up by the solar wind from the cometary coma is shown, with an increase of the O+^+ flux above 50 keV by two orders of magnitude. While the ionization of Mars' upper atmosphere by precipitating O+^+ ions is expected to be negligible compared to solar EUV-XUV ionization, it is of the same order of magnitude at 110 km altitude during the cometary passage.The present work will show both the theoretical results of the ion interaction with the upper atmosphere of Mars and the results of the observations.

  9. Search for Transient gamma -Ray Line Emission Between 400 and 600 keV from the Crab Nebula

    NASA Astrophysics Data System (ADS)

    Harris, M. J.; Share, G. H.; Leising, M. D.

    1992-12-01

    Previous experiments reported transient gamma -ray line emission from the Crab Nebula for periods of several hr, at energies 400-460 keV (Leventhal et al. 1977, Yoshimori et al. 1979, Owens et al. 1985, Massaro et al. 1991) and 545 keV (Sunyaev et al. 1992). We have searched data taken by the SMM Gamma Ray Spectrometer for lines at these energies, using the method of Harris et al. (1991). Line features associated with the pulse period cannot be resolved by this method. We find no evidence of significant line emission at any energy during 1981-1989 on time-scales between ~ 1 d and ~ 1 yr. Our 3 sigma upper limits on the transient flux in any line are characteristically ~ 1.0 times 10(-3) gamma cm(-2) s(-1) over time-scales 12 d or greater, and ~ 2.5 times 10(-3) gamma cm(-2) s(-1) over time-scales ~ 1 d. The duty cycle during 1981-1989 for strong (>> 1times 10(-3) gamma cm(-2) s(-1) ) transient lines on ~ 1 d time-scales, such as those detected by Leventhal et al. (1977), Yoshimori et al. (1979), Owens et al. (1985) and Sunyaev et al. (1992), must have been <1%. We searched our data for the ~ 5 hr on 1981 June 6 coinciding with the transient line at 405 keV detected by Owens et al. (1985). Our null result for this line during that period is inconsistent with the measurement of Owens et al. This work was performed under NASA Grant NAGW-2789. M.J. Harris et al. 1991, Bull AAS 23, 1440. M. Leventhal et al. 1977 ApJ 216, 491. E. Massaro et al. 1991, ApJ 376, L11. A. Owens et al. 1985, Proc. 19th ICRC 1, 145. R. Sunyaev et al. 1992, IAUC 5481. M. Yoshimori et al. 1979, Aust.J. Phys. 32, 375.

  10. 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".

  11. 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.

  12. Statistical evaluation of the flux cross-calibration of the XMM-Newton EPIC cameras

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Saxton, R. D.; Read, A. M.; Sembay, S.

    2009-03-01

    Context: The second XMM-Newton serendipitous source catalogue, 2XMM, provides the ideal data base for performing a statistical evaluation of the flux cross-calibration of the XMM-Newton European Photon Imaging Cameras (EPIC). Aims: We aim to evaluate the status of the relative flux calibration of the EPIC cameras on board the XMM-Newton observatory (MOS1, MOS2, and pn) and investigate the dependence of the calibration on energy (from 0.2 to 12.0 keV), position of the sources in the field of view of the X-ray detectors, and lifetime of the mission. Methods: We compiled the distribution of flux percentage differences for large samples of "good quality" objects detected with at least two of the EPIC cameras. The mean offset of the fluxes and dispersion of the distributions was then found by Gaussian fitting. Count rate to flux conversion was performed with a fixed spectral model. The impact on the results of varying this model was investigated. Results: Excellent agreement was found between the two EPIC MOS cameras to better than 4% over the entire energy range where the EPIC cameras are best calibrated (0.2-12.0 keV). We found that MOS cameras register 7-9% higher flux than EPIC pn below 4.5 keV and a 10-13% flux excess at the highest energies (⪆4.5 keV). No evolution of the flux ratios is seen with time, except at the lowest energies (⪉0.5 keV), where we found a strong decrease in the MOS to pn flux ratio with time. This effect is known to be due to a gradually degrading MOS redistribution function. The flux ratios show some dependence on distance from the optical axis in the sense that the MOS to pn flux excess increases with off-axis angle. Furthermore, in the 4.5-12.0 keV band there is a strong dependence of the MOS to pn excess flux on the azimuthal-angle. These results strongly suggest that the calibration of the Reflection Grating Array (RGA) blocking factors is incorrect at high energies. Finally, we recommend ways to improve the calculation of fluxes in

  13. Fast flux locked loop

    DOEpatents

    Ganther, Jr., Kenneth R.; Snapp, Lowell D.

    2002-09-10

    A flux locked loop for providing an electrical feedback signal, the flux locked loop employing radio-frequency components and technology to extend the flux modulation frequency and tracking loop bandwidth. The flux locked loop of the present invention has particularly useful application in read-out electronics for DC SQUID magnetic measurement systems, in which case the electrical signal output by the flux locked loop represents an unknown magnetic flux applied to the DC SQUID.

  14. Nighttime observations of 0.2- to 26-keV electrons in the South Atlantic anomaly made by Atmosphere Explorer C

    NASA Technical Reports Server (NTRS)

    Gledhill, J. A.; Hoffman, R. A.

    1981-01-01

    Atmosphere Explorer C satellite observations have determined that the flux of low energy ions in the South Atlantic Anomaly is much smaller than that of electrons, allowing the satellite's low-energy ion detector to monitor the high-energy background and correct the low-energy electron detector accordingly. It is shown that the electron spectra can be represented by a power law in the range 0.2-26.0 keV, with the spectral index close to -1.0, and that the mean energy flux carried by electrons in the middle of the anomaly is about 0.003 erg/sq cm/sec and may reach 5 times this value. Maps of the downward energy flux are included.

  15. Nighttime observations of 0.2- to 26-keV electrons in the South Atlantic anomaly made by Atmosphere Explorer C

    NASA Astrophysics Data System (ADS)

    Gledhill, J. A.; Hoffman, R. A.

    1981-08-01

    Atmosphere Explorer C satellite observations have determined that the flux of low energy ions in the South Atlantic Anomaly is much smaller than that of electrons, allowing the satellite's low-energy ion detector to monitor the high-energy background and correct the low-energy electron detector accordingly. It is shown that the electron spectra can be represented by a power law in the range 0.2-26.0 keV, with the spectral index close to -1.0, and that the mean energy flux carried by electrons in the middle of the anomaly is about 0.003 erg/sq cm/sec and may reach 5 times this value. Maps of the downward energy flux are included.

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

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  17. Measurement of low energy neutron spectrum below 10 keV with the slowing down time method

    NASA Astrophysics Data System (ADS)

    Maekawa, F.; Oyama, Y.

    1996-02-01

    No general-purpose method of neutron spectrum measurement in the energy region around eV has been established so far. Neutron spectrum measurement in this energy region was attempted by applying the slowing down time (SDT) method, for the first time, inside two types of shield for fusion reactors, type 316 stainless steel (SS316) and SS316/water layered assemblies, incorporating with pulsed neutrons. In the SS316 assembly, neutron spectra below 1 keV were measured with an accuracy less than 10%. Although application of the SDT method was expected very difficult for SS316/water assembly since it contained lightest atoms of hydrogen, the measurement demonstrated that the SDT method was still effective for such shield assembly. The SDT method was also extended to thermal flux measurement in the SS316/water assembly. The present study demonstrated that the SDT method was effective for neutron spectrum measurement in the energy region around eV.

  18. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  1. Neutron capture cross section measurements for 197Au from 3.5 to 84 keV at GELINA

    NASA Astrophysics Data System (ADS)

    Massimi, C.; Becker, B.; Dupont, E.; Kopecky, S.; Lampoudis, C.; Massarczyk, R.; Moxon, M.; Pronyaev, V.; Schillebeeckx, P.; Sirakov, I.; Wynants, R.

    2014-08-01

    Cross section measurements have been performed at the time-of-flight facility GELINA to determine the average capture cross section for 197Au in the energy region between 3.5 keV and 84 keV. Prompt γ-rays, originating from neutron-induced capture events, were detected by two C6 D6 liquid scintillators. The sample was placed at about 13m distance from the neutron source. The total energy detection principle in combination with the pulse height weighting technique was applied. The energy dependence of the neutron flux was measured with a double Frisch-gridded ionization chamber based on the 10B(n,α) reaction. The data have been normalized to the well-isolated and saturated 197Au resonance at 4.9 eV. Special care was taken to reduce bias effects due to the weighting function, normalization, dead time and background corrections. The total uncertainty due to normalization, neutron flux and weighting function is 1.0%. An additional uncertainty of 0.5% results from the correction for self-shielding and multiple interaction events. Fluctuations due to resonance structures have been studied by complementary measurements at a 30m flight path station. The results reported in this work deviate systematically by more than 5% from the cross section that is recommended as a reference for astrophysical applications. They are about 2% lower compared to an evaluation of the 197Au(n, γ) cross section, which was based on a least squares fit of experimental data available in the literature prior to this work. The average capture cross section as a function of neutron energy has been parameterized in terms of average resonance parameters. Maxwellian average cross sections at different temperatures have been calculated.

  2. Magnetic-flux pump

    NASA Technical Reports Server (NTRS)

    Hildebrandt, A. F.; Elleman, D. D.; Whitmore, F. C. (Inventor)

    1966-01-01

    A magnetic flux pump is described for increasing the intensity of a magnetic field by transferring flux from one location to the magnetic field. The device includes a pair of communicating cavities formed in a block of superconducting material, and a piston for displacing the trapped magnetic flux into the secondary cavity producing a field having an intense flux density.

  3. 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.

  4. Flux-p: automating metabolic flux analysis.

    PubMed

    Ebert, Birgitta E; Lamprecht, Anna-Lena; Steffen, Bernhard; Blank, Lars M

    2012-11-12

    Quantitative knowledge of intracellular fluxes in metabolic networks is invaluable for inferring metabolic system behavior and the design principles of biological systems. However, intracellular reaction rates can not often be calculated directly but have to be estimated; for instance, via 13C-based metabolic flux analysis, a model-based interpretation of stable carbon isotope patterns in intermediates of metabolism. Existing software such as FiatFlux, OpenFLUX or 13CFLUX supports experts in this complex analysis, but requires several steps that have to be carried out manually, hence restricting the use of this software for data interpretation to a rather small number of experiments. In this paper, we present Flux-P as an approach to automate and standardize 13C-based metabolic flux analysis, using the Bio-jETI workflow framework. Exemplarily based on the FiatFlux software, it demonstrates how services can be created that carry out the different analysis steps autonomously and how these can subsequently be assembled into software workflows that perform automated, high-throughput intracellular flux analysis of high quality and reproducibility. Besides significant acceleration and standardization of the data analysis, the agile workflow-based realization supports flexible changes of the analysis workflows on the user level, making it easy to perform custom analyses.

  5. 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.

  6. Soft x-ray (0.2keV) imager for z-pinch plasma radiation sources

    NASA Astrophysics Data System (ADS)

    Failor, B. H.; Qi, N.; Levine, J. S.; Sze, H.; Gullickson, E. M.

    2004-10-01

    Z-pinches can produce intense fluxes of argon K-shell (3 keV) radiation, but typically only a fraction of the load mass near the axis of the pinch radiates in this spectral range. The majority of the mass does not get hot or dense enough to radiate efficiently in the K-shell. We have designed, built, and tested an instrument to image pinch emission, specifically the radial emission profile, at energies below the K-shell in order to track the location of the cooler mass. A gold mirror provides a high-energy cut-off at 2 keV while a transmission grating disperses the incoming radiation and provides a low-energy cutoff at 0.1 keV. A vertical slit images the pinch radiation in the radial direction and the emission profile is recorded with either an extreme ultraviolet-sensitive charge-coupled device camera (time-integrated) or a linear photodiode array (˜1 ns time resolution). We present results for the mirror, grating, and system characterization obtained at the Advanced Light Source synchrotron located at Lawrence Berkeley National Laboratory (Berkeley, CA).

  7. Spatial distribution and broad-band spectral characteristics of the diffuse X-ray background, 0.1 - 1.0 keV

    NASA Technical Reports Server (NTRS)

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

    1979-01-01

    Preliminary maps covering more than 85 percent of the sky are presented for three energy bands: the B band, the C band, and the M band. The study was undertaken to find evidence that most of the diffuse X-ray background at energies less than 1 keV is local to the galaxy and that it is most probably due to thermal radiation from a low density plasma which fills a substantial fraction of interstellar space. A preliminary analysis of the data is provided including a report that most of the B and C band flux has a common origin, probably in a 10 to the 6th power K region surrounding the Sun, and that most of the M band flux does not originate from the same material.

  8. 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.

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

    PubMed

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

    2010-03-01

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

  10. Revisiting the relationship between 6 μm and 2-10 keV continuum luminosities of AGN

    NASA Astrophysics Data System (ADS)

    Mateos, S.; Carrera, F. J.; Alonso-Herrero, A.; Rovilos, E.; Hernán-Caballero, A.; Barcons, X.; Blain, A.; Caccianiga, A.; Della Ceca, R.; Severgnini, P.

    2015-05-01

    We have determined the relation between the AGN luminosities at rest-frame 6 μm associated with the dusty torus emission and at 2-10 keV energies using a complete, X-ray-flux-limited sample of 232 AGN drawn from the Bright Ultra-hard XMM-Newton Survey. The objects have intrinsic X-ray luminosities between 1042 and 1046 erg s-1 and redshifts from 0.05 to 2.8. The rest-frame 6 μm luminosities were computed using data from the Wide-field Infrared Survey Explorer and are based on a spectral energy distribution decomposition into AGN and galaxy emission. The best-fitting relationship for the full sample is consistent with being linear, L6 μm ∝ L_{2-10 keV}^{0.99± 0.03}, with intrinsic scatter, Δ log L6 μm ˜ 0.35 dex. The L_{6 μ m}/L_{2-10 keV} luminosity ratio is largely independent of the line-of-sight X-ray absorption. Assuming a constant X-ray bolometric correction, the fraction of AGN bolometric luminosity reprocessed in the mid-IR decreases weakly, if at all, with the AGN luminosity, a finding at odds with simple receding torus models. Type 2 AGN have redder mid-IR continua at rest-frame wavelengths <12 μm and are overall ˜1.3-2 times fainter at 6 μm than type 1 AGN at a given X-ray luminosity. Regardless of whether type 1 and type 2 AGN have the same or different nuclear dusty toroidal structures, our results imply that the AGN emission at rest-frame 6 μm is not isotropic due to self-absorption in the dusty torus, as predicted by AGN torus models. Thus, AGN surveys at rest-frame ˜6 μm are subject to modest dust obscuration biases.

  11. Patterns of Flux Emergence

    NASA Astrophysics Data System (ADS)

    Title, A.; Cheung, M.

    2008-05-01

    The high spatial resolution and high cadence of the Solar Optical Telescope on the JAXA Hinode spacecraft have allowed capturing many examples of magnetic flux emergence from the scale of granulation to active regions. The observed patterns of emergence are quite similar. Flux emerges as a array of small bipoles on scales from 1 to 5 arc seconds throughout the region that the flux eventually condenses. Because the fields emerging from the underlying flux rope my appear many in small segments and the total flux (absolute sum) is not a conserved quantity the amount of total flux on the surface may vary significantly during the emergence process. Numerical simulations of flux emergence exhibit patterns similar to observations. Movies of both observations and numerical simulations will be presented.

  12. Energetic electron precipitation into the middle atmosphere -- Constructing the loss cone fluxes from MEPED POES

    NASA Astrophysics Data System (ADS)

    Nesse Tyssøy, H.; Sandanger, M. I.; Ødegaard, L.-K. G.; Stadsnes, J.; Aasnes, A.; Zawedde, A. E.

    2016-06-01

    The impact of energetic electron precipitation (EEP) on the chemistry of the middle atmosphere (50-90 km) is still an outstanding question as accurate quantification of EEP is lacking due to instrumental challenges and insufficient pitch angle coverage of current particle detectors. The Medium Energy Proton and Electron Detectors (MEPED) instrument on board the NOAA/Polar Orbiting Environmental Satellites (POES) and MetOp spacecraft has two sets of electron and proton telescopes pointing close to zenith (0°) and in the horizontal plane (90°). Using measurements from either the 0° or 90° telescope will underestimate or overestimate the bounce loss cone flux, respectively, as the energetic electron fluxes are often strongly anisotropic with decreasing fluxes toward the center of the loss cone. By combining the measurements from both telescopes with electron pitch angle distributions from theory of wave-particle interactions in the magnetosphere, a complete bounce loss cone flux is constructed for each of the electron energy channels >50 keV, >100 keV, and >300 keV. We apply a correction method to remove proton contamination in the electron counts. We also account for the relativistic (>1000 keV) electrons contaminating the proton detector at subauroral latitudes. This gives us full range coverage of electron energies that will be deposited in the middle atmosphere. Finally, we demonstrate the method's applicability on strongly anisotropic pitch angle distributions during a weak geomagnetic storm in February 2008. We compare the electron fluxes and subsequent energy deposition estimates to OH observations from the Microwave Limb Sounder on the Aura satellite substantiating that the estimated fluxes are representative for the true precipitating fluxes impacting the atmosphere.

  13. 5.9-keV Mn K-shell X-ray luminosity from the decay of 55Fe in Type Ia supernova models

    NASA Astrophysics Data System (ADS)

    Seitenzahl, I. R.; Summa, A.; Krauß, F.; Sim, S. A.; Diehl, R.; Elsässer, D.; Fink, M.; Hillebrandt, W.; Kromer, M.; Maeda, K.; Mannheim, K.; Pakmor, R.; Röpke, F. K.; Ruiter, A. J.; Wilms, J.

    2015-02-01

    We show that the X-ray line flux of the Mn Kα line at 5.9 keV from the decay of 55Fe is a promising diagnostic to distinguish between Type Ia supernova (SN Ia) explosion models. Using radiation transport calculations, we compute the line flux for two three-dimensional explosion models: a near-Chandrasekhar mass delayed detonation and a violent merger of two (1.1 and 0.9 M⊙) white dwarfs. Both models are based on solar metallicity zero-age main-sequence progenitors. Due to explosive nuclear burning at higher density, the delayed-detonation model synthesizes ˜3.5 times more radioactive 55Fe than the merger model. As a result, we find that the peak Mn Kα line flux of the delayed-detonation model exceeds that of the merger model by a factor of ˜4.5. Since in both models the 5.9-keV X-ray flux peaks five to six years after the explosion, a single measurement of the X-ray line emission at this time can place a constraint on the explosion physics that is complementary to those derived from earlier phase optical spectra or light curves. We perform detector simulations of current and future X-ray telescopes to investigate the possibilities of detecting the X-ray line at 5.9 keV. Of the currently existing telescopes, XMM-Newton/pn is the best instrument for close (≲1-2 Mpc), non-background limited SNe Ia because of its large effective area. Due to its low instrumental background, Chandra/ACIS is currently the best choice for SNe Ia at distances above ˜2 Mpc. For the delayed-detonation scenario, a line detection is feasible with Chandra up to ˜3 Mpc for an exposure time of 106 s. We find that it should be possible with currently existing X-ray instruments (with exposure times ≲5 × 105 s) to detect both of our models at sufficiently high S/N to distinguish between them for hypothetical events within the Local Group. The prospects for detection will be better with future missions. For example, the proposed Athena/X-IFU instrument could detect our delayed

  14. Disappearance and reappearance of particles of energies 50 keV as seen by P78-2 (SCATHA) near geosynchronous orbit

    NASA Technical Reports Server (NTRS)

    Feynman, J.; Saflekos, N. A.; Garrett, H. G.; Hardy, D. A.; Mullen, E. G.

    1980-01-01

    The nightside particle environment as observed by the AFGL Rapid Scan Particle Detector on SCATHA showing large, sudden simultaneous changes in the fluxes of electrons and protons with energies above 50 keV (dropouts) is considered. An interesting feature of SCATHA dropouts is the quasiperiodic behavior of the particle flux amplitudes which often vary with a period of the order of 15 minutes both during the dropout and after the return. A flux return during eclipse caused a major spacecraft charging event of several kilovolts. The SCATHA observations are compared with those reported for other geosynchronous satellites. In agreement with ATS-5, a marked dependence in the frequency of occurrence due to an effect of the orbit is found. ATS-5 experienced few dropouts during quiet geomagnetic conditions. However, for an L shell greater than seven, SCATHA particle dropouts occur routinely during quiet conditions. Thus, for SCATHA's orbit, both the orbital position and geomagnetic conditions must be taken into account in evaluating the potential hazard of flux returns.

  15. Return flux experiment

    NASA Technical Reports Server (NTRS)

    Tveekrem, June L.

    1992-01-01

    All spacecraft emit molecules via outgassing, thruster plumes, vents, etc. The return flux is the portion of those molecules that scatter from the ambient atmosphere and return to the spacecraft. Return flux allows critical spacecraft surfaces to become contaminated even when there is no direct line of sight between the contamination source and the critical surface. Data from the Long Duration Exposure Facility (LDEF) show that contamination of LDEF surfaces could not have come entirely from direct flux. The data suggest significant return flux. Several computer models have been developed to simulate return flux, but the predictions have never been verified in orbit. Large uncertainties in predictions lead to overly conservative spacecraft designs. The purpose of the REturn FLux EXperiment (REFLEX) is to fly a controlled experiment that can be directly compared with predictions from several models.

  16. Return flux experiment

    NASA Astrophysics Data System (ADS)

    Tveekrem, June L.

    All spacecraft emit molecules via outgassing, thruster plumes, vents, etc. The return flux is the portion of those molecules that scatter from the ambient atmosphere and return to the spacecraft. Return flux allows critical spacecraft surfaces to become contaminated even when there is no direct line of sight between the contamination source and the critical surface. Data from the Long Duration Exposure Facility (LDEF) show that contamination of LDEF surfaces could not have come entirely from direct flux. The data suggest significant return flux. Several computer models have been developed to simulate return flux, but the predictions have never been verified in orbit. Large uncertainties in predictions lead to overly conservative spacecraft designs. The purpose of the REturn FLux EXperiment (REFLEX) is to fly a controlled experiment that can be directly compared with predictions from several models.

  17. Energetic particle flux experiment (IMP F and G)

    NASA Technical Reports Server (NTRS)

    Anderson, K. A.

    1973-01-01

    The data reduction procedures and programs for analysis of the IMP F and G energetic particle flux experiments are summarized. The IMP-F experiment contained two thin-window Geiger-Mueller detectors and an ionization chamber. There were two IMP-G experiments: one with six Geiger-Mueller detectors and an ionization chamber, and the other with two funnel mouthed channeltrons in a parallel plate electrostatic analyzer. These experiments measured particles in the energy range above 20 keV (IMP-F) and above approximately 5 keV (IMP-G). A bibliography is presented of papers containing the scientific results. These data were predominantly used for the study of low energy solar particles from flares.

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

    SciTech Connect

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

    2014-10-23

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

  19. Heat flux measurements

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.; Weikle, Donald H.

    1989-01-01

    A new automated, computer controlled heat flux measurement facility is described. Continuous transient and steady-state surface heat flux values varying from about 0.3 to 6 MW/sq m over a temperature range of 100 to 1200 K can be obtained in the facility. An application of this facility is the development of heat flux gauges for continuous fast transient surface heat flux measurement on turbine blades operating in space shuttle main engine turbopumps. The facility is useful for durability testing at fast temperature transients.

  20. Aspects of flux compactification

    NASA Astrophysics Data System (ADS)

    Liu, Tao

    In this thesis, we study three main aspects of flux compactifications: (1) classify supergravity solutions from flux compactification; (2) construct flux-deformed geometry and 4D low-energy theory to describe these flux vacua; and (3) study 4D particle phenomenology and cosmology of flux vacua. In the first part, we review G-structure, the basic tool to study supersymmetric flux solutions, and some typical solutions obtained in heterotic, type IIA and type IIB string theories. Then we present a comprehensive classification of supersymmetric vacua of M-theory compactification on 7D manifolds with general four-form fluxes. We analyze the cases where the resulting four-dimensional vacua have N = 1, 2, 3, 4 supersymmetry and the internal space allows for SU(2)-, SU(3)- or G 2-structures. In particular, we find for N = 2 supersymmetry, that the external space-time is Minkowski and the base manifold of the internal space is conformally Kahler for SU(2) structures, while for SU(3) structures the internal space has to be Einstein-Sasaki and no internal fluxes are allowed. Moreover, we provide a new vacuum with N = 1 supersymmetry and SU(3) structure, where all fluxes are non-zero and the first order differential equations are solved. In the second part, we simply review the methods used to construct one subclass of fluxed-deformed geometry or the so-called "twisted manifold", and the associated 4D effective theory describing these flux vacua. Then by employing (generalized) Scherk-Schwarz reduction, we construct the geometric twisting for Calabi-Yau manifolds of Voisin-Borcea type (K 3 x T2)/ Z2 and study the superpotential in a type IIA orientifold based on this geometry. The twists modify the direct product by fibering the K 3 over T2 while preserving the Z2 involution. As an important application, the Voisin-Borcea class contains T6/( Z2 x Z2 ), the usual setting for intersecting D6 brane model building. Past work in this context considered only those twists inherited

  1. 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.

  2. CdZnTe x-ray detector for 30 {endash} 100 keV energy

    SciTech Connect

    Yoo, S.-S.; Rodricks, B.; Shastri, S.D.; Montano, P.A.

    1996-07-01

    High-pressure-Bridgman (HPB) grown CdZnTe x-ray detectors 1.25-1.7 mm thick were tested using monochromatic x-rays of 30 to 100 keV generated by a high energy x-ray generator. The results were compared with a commercially available 5 cm thick NaI detector. A linear dependence of the counting rate versus the x-ray generator tube current was observed at 58.9 keV. The measured pulse height of the photopeaks shows a linear dependence on energy. Electron and hole mobility-lifetime products ({mu}{tau}) were deduced by fitting bias dependent photopeak channel numbers at 30 keV x-ray energy. Values of 2 x 10{sup -3} cm{sup 2}/V and 2 x 10{sup -4}cm{sup 2}/V were obtained for {mu}{tau}{sub e} and {mu}{tau}{sub p}, respectively. The detector efficiency of CdZnTe at a 100 V bias was as high as, or higher than 90 % compared to a NaI detector. At x-ray energies higher than 70 keV, the detection efficiency becomes a dominant factor and decreases to 75 % at 100 keV.

  3. The 0.1-2.5-KEV X-Ray Spectrum of the O4F-STAR Zeta-Puppis

    NASA Astrophysics Data System (ADS)

    Hillier, D. J.; Kudritzki, R. P.; Pauldrach, A. W.; Baade, D.; Cassinelli, J. P.; Puls, J.; Schmitt, J. H. M. M.

    1993-09-01

    We have obtained a high quality ROSAT PSPC spectrum of the bright O4f star ζ Pup. Allowing for the wind X-ray opacity, as computed from detailed non-LTE stellar wind models of ζ Pup, and under the assumption that the X-rays arise from shocks distributed throughout the wind, we have been able to match the observed X-ray spectrum (0.1 to 2.5keV). The best model fit is obtained when He++ recombines to He+ in the outer regions of the stellar wind, as predicted by recent detailed cool wind model calculations. With a single temperature plasma, the best model fit indicates a temperature of log Ts(K) = 6.5 to 6.6 corresponding to shock velocities of around 500 km s-1. A 2 temperature plasma yields a significantly improved fit, and indicates temperatures of log Ts(K) = 6.2 and 6.7 for the 2 components. The hotter component accounts for 55% of the intrinsic (75% of the observed) X-ray flux. Due to absorption by the stellar wind, and to a minor extent stellar occultation, less than 5% of the total emitted X-ray flux escapes the star. The models require significant X-ray emission (particularly at energies less than 0.5 keV) from large radii (r > 100R*). In models without recombination, the fits, even with a 2 temperature plasma, are unacceptable. A significant K shell absorption is predicted by these models, but is definitely not present in the observational data. The analysis suggests that the X-ray flux provides an invaluable diagnostic of the ionization of helium in the stellar wind of stars with low reddening.

  4. Video Meteor Fluxes

    NASA Technical Reports Server (NTRS)

    Campbell-Brown, M. D.; Braid, D.

    2011-01-01

    The flux of meteoroids, or number of meteoroids per unit area per unit time, is critical for calibrating models of meteoroid stream formation and for estimating the hazard to spacecraft from shower and sporadic meteors. Although observations of meteors in the millimetre to centimetre size range are common, flux measurements (particularly for sporadic meteors, which make up the majority of meteoroid flux) are less so. It is necessary to know the collecting area and collection time for a given set of observations, and to correct for observing biases and the sensitivity of the system. Previous measurements of sporadic fluxes are summarized in Figure 1; the values are given as a total number of meteoroids striking the earth in one year to a given limiting mass. The Gr n et al. (1985) flux model is included in the figure for reference. Fluxes for sporadic meteoroids impacting the Earth have been calculated for objects in the centimeter size range using Super-Schmidt observations (Hawkins & Upton, 1958); this study used about 300 meteors, and used only the physical area of overlap of the cameras at 90 km to calculate the flux, corrected for angular speed of meteors, since a large angular speed reduces the maximum brightness of the meteor on the film, and radiant elevation, which takes into account the geometric reduction in flux when the meteors are not perpendicular to the horizontal. They bring up corrections for both partial trails (which tends to increase the collecting area) and incomplete overlap at heights other than 90 km (which tends to decrease it) as effects that will affect the flux, but estimated that the two effects cancelled one another. Halliday et al. (1984) calculated the flux of meteorite-dropping fireballs with fragment masses greater than 50 g, over the physical area of sky accessible to the MORP fireball cameras, counting only observations in clear weather. In the micron size range, LDEF measurements of small craters on spacecraft have been used to

  5. Multi-Kev X-Ray Emission from High-Z Gas Targets Fielded at Omega and NIF

    NASA Astrophysics Data System (ADS)

    May, Mark; Fournier, Kevin; Colvin, Jeff; Kane, Jave

    2010-11-01

    We report on the measured X-ray flux from gas-filled targets shot at both the OMEGA and NIF laser facilities. 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 ˜ 1 atm. The OMEGA experiments heated the gas with 20 kJ of 3φ (˜350 nm) laser energy delivered in a 1 ns square pulse. The NIF targets were thin walled (25 μm), 4 mm long, 4 mm inner-diameter epoxy pipes filled with 1.2 atm of a 65:35 Ar:Xe mixture. The NIF experiments heated these targets with 350 kJ of 3φ (˜350 nm) laser energy delivered in a 5 ns square pulse at up to 75 TW of laser power. 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. The results from both experiments will be compared. This work performed under the auspices of the U. S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  6. Degeneracy at 1871 keV in Cd112 and implications for neutrinoless double electron capture

    NASA Astrophysics Data System (ADS)

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

    2009-09-01

    High-statistics β-decay measurements of Ag112 and In112 were performed to study the structure of the Cd112 nucleus. The precise energies of the doublet of levels at 1871 keV, for which the 0+ member has been suggested as a possible daughter state following neutrinoless double electron capture of Sn112, were determined to be 1871.137(72) keV (04+ level) and 1870.743(54) keV (42+ level). The nature of the 04+ 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.

  7. 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)%.

  8. 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.

  9. 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.

  10. Nanopatterning dynamics on Si(100) during oblique 40-keV Ar+ erosion with metal codeposition: Morphological and compositional correlation

    NASA Astrophysics Data System (ADS)

    Redondo-Cubero, A.; Gago, R.; Palomares, F. J.; Mücklich, A.; Vinnichenko, M.; Vázquez, L.

    2012-08-01

    The formation and dynamics of nanopatterns produced on Si(100) surfaces by 40-keV Ar+ oblique (α = 60°) bombardment with concurrent Fe codeposition have been studied. Morphological and chemical analysis has been performed by ex situ atomic force microscopy, Rutherford backscattering spectrometry, x-ray photoelectron spectroscopy, and scanning and transmission electron microscopies. During irradiation, Fe atoms incorporated into the target surface react with Si to form silicides, a process enhanced at this medium-ion energy range. The silicides segregate at the nanoscale from the early irradiation stages. As the irradiation proceeds, a ripple pattern is formed without any correlation with silicide segregation. From the comparison with the pattern dynamics reported previously for metal-free conditions, it is demonstrated that the metal incorporation alters both the pattern dynamics and the morphology. Although the pattern formation and dynamics are delayed for decreasing metal content, once ripples emerge, the same qualitative pattern of morphological evolution is observed for different metal content, resulting in an asymptotic saw-tooth-like facetted surface pattern. Despite the medium ion energy employed, the nanopatterning process with concurrent Fe deposition can be explained by those mechanisms proposed for low-ion energy irradiations such as shadowing, height fluctuations, silicide formation and segregation, ensuing composition dependent sputter rate, and ion sculpting effects. In particular, the interplay between the ion irradiation and metal flux geometries, differences in sputtering rates, and the surface pattern morphology produces a dynamic compositional patterning correlated with the evolving morphological one.

  11. The angular distribution of solar wind ˜20-200 keV superhalo electrons at quiet times

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Wang, Linghua; Li, Gang; He, Jiansen; Salem, Chadi S.; Tu, Chuanyi; Wimmer-Schweingruber, Robert F.; Bale, Stuart D.

    2016-03-01

    We present a comprehensive study of the angular distribution of ˜20-200 keV superhalo electrons measured at 1 AU by the WIND 3DP instrument during quiet times from 1995 January through 2005 December. According to the interplanetary magnetic field, we re-bin the observed electron pitch angle distributions to obtain the differential flux, Jout (Jin), of electrons traveling outward from (inward toward) the Sun, and define the anisotropy of superhalo electrons as A =2/(Jo u t-Ji n) Jo u t+Ji n at a given energy. We found that for out in ˜96% of the selected quiet-time samples, superhalo electrons have isotropic angular distributions, while for ˜3% (˜1%) of quiet-time samples, superhalo electrons are outward-anisotropic (inward-anisotropic). All three groups of angular distributions show no correlation with the local solar wind plasma, interplanetary magnetic field and turbulence. Furthermore, the superhalo electron spectral index shows no correlation with the spectral index of local solar wind turbulence. These quiet-time superhalo electrons may be accelerated by nonthermal processes related to the solar wind source and strongly scattered/ reflected in the interplanetary medium, or could be formed due to the electron acceleration through the interplanetary medium.

  12. LCLS Spectral Flux Viewer

    2005-10-25

    This application (FluxViewer) is a tool for displaying spectral flux data for the Linac Coherent Light Source (LCLS). This tool allows the user to view sliced spatial and energy distributions of the photons selected for specific energies and positions transverse to the beam axis.

  13. Comparisons of Earthward Poynting flux and the kinetic energy flux of up-flowing transversely heated ions from the Polar spacecraft on cusp magnetic field lines

    NASA Astrophysics Data System (ADS)

    Tian, S.; Wygant, J. R.; Cattell, C. A.; Scudder, J. D.; Mozer, F.; Russell, C. T.

    2013-12-01

    This paper presents estimates of the Poynting flux flowing along magnetic field lines in the Earth's cusp region over altitudes from 0.8 Re to 7 Re using measurements during several passes from the Polar spacecraft. The Poynting flux is calculated from measurements of electric fields from the University of California, Berkeley double probe electric field instrument, and from magnetic field measurements from the U.C.L.A. fluxgate magnetometer. The estimates of Poynting flux are of special interest because the high altitude mapping of the cusp magnetic flux tubes may connect to newly reconnected field lines and the low altitude mapping of these field lines is the scene of powerful acceleration processes, most notably transverse heating and outflow of ions. The data show that the Poynting flux is predominantly downward over the frequency range from 1 mHz to 1 Hz . This frequency range includes the Poynting flux due to steady state convection and field-aligned current systems, Alfven waves, and kinetic Alfven waves. Measurement of transversely heated ions over the energy ranges from 10 eV to several keV and their associated ion kinetic energy flux are presented from the University of Iowa Hydra instrument and compared to the values of the downward Poynting flux. Generally the downward Poynting flux exceeds the upward kinetic energy flux of the ions.

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

    PubMed

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

    2006-07-01

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

  15. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    The first observation of in-flight antiproton-nucleus annihilation at ˜130 keV obtained with the ASACUSA detector has demonstrated that the measurement of the cross section of the process is feasible at such extremely low energies Aghai-Khozani, H., et al., Eur. Phys. J. Plus 127, 55 (2012). Here we present the results of the data analysis with the evaluations of the antiproton annihilation cross sections on carbon, palladium and platinum targets at ˜125 keV.

  17. Simulation study of optimizing the 3-5 keV x-ray emission from pure Ar K-shell vs. Ag L-shell targets on the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    Kemp, G. E.; Colvin, J. D.; Fournier, K. B.; Patel, M. V.; Scott, H. A.; Marinak, M.; Fisher, J. H.; Davis, J. F.

    2014-10-01

    High-flux x-ray sources are desirable for testing the radiation hardness of materials used in various civilian, space and military applications. For this study, there is an interest to design a source with primarily mid-energy (~ 3 keV) but limited soft (< 1 keV) x-ray contributions; we focus on optimizing the 3--5 keV non-LTE emission from targets consisting of pure Ar (K-shell) or Ag (L-shell) at sub-critical densities (~nc / 10) to ensure supersonic, volumetric laser heating with minimal losses to kinetic energy and thermal x rays. However, K and L-shell sources are expected to optimize at different temperatures and densities and it is a priori unclear under what target and laser conditions this will occur. Using HYDRA, a multi-dimensional, arbitrary Lagrangian-Eulerian, radiation-hydrodynamics code, we performed a simulation study by varying initial target density and laser parameters for each material as it would perform on the National Ignition Facility (NIF). We employ a model, benchmarked against Kr data collected on the NIF, that uses flux-limited Lee-More thermal conductivity and implicit Monte-Carlo photonics with non-LTE, detailed configuration accounting opacities from CRETIN. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

  18. Intramolecular Nuclear Flux Densities

    NASA Astrophysics Data System (ADS)

    Barth, I.; Daniel, C.; Gindensperger, E.; Manz, J.; PéRez-Torres, J. F.; Schild, A.; Stemmle, C.; Sulzer, D.; Yang, Y.

    The topic of this survey article has seen a renaissance during the past couple of years. Here we present and extend the results for various phenomena which we have published from 2012-2014, with gratitude to our coauthors. The new phenomena include (a) the first reduced nuclear flux densities in vibrating diatomic molecules or ions which have been deduced from experimental pump-probe spectra; these "experimental" nuclear flux densities reveal several quantum effects including (b) the "quantum accordion", i.e., during the turn from bond stretch to bond compression, the diatomic system never stands still — instead, various parts of it with different bond lengths flow into opposite directions. (c) Wavepacket interferometry has been extended from nuclear densities to flux densities, again revealing new phenomena: For example, (d) a vibrating nuclear wave function with compact initial shape may split into two partial waves which run into opposite directions, thus causing interfering flux densities. (e) Tunneling in symmetric 1-dimensional double-well systems yields maximum values of the associated nuclear flux density just below the potential barrier; this is in marked contrast with negligible values of the nuclear density just below the barrier. (f) Nuclear flux densities of pseudorotating nuclei may induce huge magnetic fields. A common methodologic theme of all topics is the continuity equation which connects the time derivative of the nuclear density to the divergence of the flux density, subject to the proper boundary conditions. (g) Nearly identical nuclear densities with different boundary conditions may be related to entirely different flux densities, e.g., during tunneling in cyclic versus non-cyclic systems. The original continuity equation, density and flux density of all nuclei, or of all nuclear degrees of freedom, may be reduced to the corresponding quantities for just a single nucleus, or just a single degree of freedom.

  19. Directed flux motor

    NASA Technical Reports Server (NTRS)

    Wilson, Andrew (Inventor); Punnoose, Andrew (Inventor); Strausser, Katherine (Inventor); Parikh, Neil (Inventor)

    2011-01-01

    A directed flux motor described utilizes the directed magnetic flux of at least one magnet through ferrous material to drive different planetary gear sets to achieve capabilities in six actuated shafts that are grouped three to a side of the motor. The flux motor also utilizes an interwoven magnet configuration which reduces the overall size of the motor. The motor allows for simple changes to modify the torque to speed ratio of the gearing contained within the motor as well as simple configurations for any number of output shafts up to six. The changes allow for improved manufacturability and reliability within the design.

  20. Heat Flux Sensor

    NASA Technical Reports Server (NTRS)

    1994-01-01

    A heat flux microsensor developed under a NASP Small Business Innovation Research (SBIR) has a wide range of potential commercial applications. Vatell Corporation originally designed microsensors for use in very high temperatures. The company then used the technology to develop heat flux sensors to measure the rate of heat energy flowing in and out of a surface as well as readings on the surface temperature. Additional major advantages include response to heat flux in less than 10 microseconds and the ability to withstand temperatures up to 1,200 degrees centigrade. Commercial applications are used in high speed aerodynamics, supersonic combustion, blade cooling, and mass flow measurements, etc.

  1. Quasidiatomic Approach to the Collisions of Low KEV Molecular Ions with Atoms

    NASA Astrophysics Data System (ADS)

    Yenen, Orhan

    The polarization of L(,(alpha)) radiation is measured in coincidence with a charged particle scattered at specific laboratory angles, resulting from the collision induced dissociation of low keV H(,2)('+) and H(,3)('+) incident on target gases. Coincidence measurements of the polarization pattern are made for a variety of scattering angles for 3.22 keV H(,2)('+) incident on He and Ne, and for 4.83 keV H(,3)('+) incident on He. The molecular states excited during the collision are determined from the alignment of the observed polarization patterns. A quasidiatomic collision model, which is an extension of the electron promotion model of ion-atom collisions at low keV energies to molecule-atom collisional systems, is developed to interpret the experimental results. The rules of building simple quasidiatomic correlation diagrams, to qualitatively estimate the dynamical behavior of molecular collisions, are presented. The general idea of treating the molecule as an atom under certain circumstances, is applied to a molecular two-state calculation of the differential charge-transfer probabilities in H('+)-H(,2) collisions. This calculation reproduces the essential features of previous experiments.

  2. 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.

  3. 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.

  4. Gamma-ray burst spectra and time histories from 2 to 400keV

    NASA Astrophysics Data System (ADS)

    Fenimore, E. E.

    1999-01-01

    The Gamma-Ray burst detector on Ginga consisted of a proportional counter to observe the x-rays and a scintillation counter to observe the gamma-rays. It was ideally suited to study the x-rays associated with gamma-ray bursts (GRBs). Ginga detected ~120 GRBs and 22 of them had sufficient statistics to determine spectra from 2 to 400keV. Although the Ginga and BATSE trigger criteria were very similar, the distribution of spectral parameters was different. Ginga observed bend energies in the spectra down to 2keV and had a larger fraction of bursts with low energy power law indexes greater than zero. The average ratio of energy in the x-ray band (2 to 10keV) compared to the gamma-ray band (50 to 300keV) was 24%. Some events had more energy in the x-ray band than in the gamma-ray band. One Ginga event had a period of time preceding the gamma rays that was effectively pure x-ray emission. This x-ray ``preactivity'' might be due to the penchant for the GRB time structure to be broader at lower energy rather than a different physical process. The x-rays tend to rise and fall slower than the gamma rays but they both tend to peak at about the same time. This argues against models involving the injection of relativistic electrons that cool by synchrotron radiation.

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

    SciTech Connect

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

    2012-06-05

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

  6. Ionization of atomic hydrogen by 30 1000 keV antiprotons

    SciTech Connect

    Knudsen, H.; Mikkelsen, U.; Paludan, K.; Kirsebom, K.; Moller, S.P.; Uggerhoj, E.; Slevin, J.; Charlton, M.; Morenzoni, E.

    1995-06-05

    Ionization in collisions between antiprotons and atomic hydrogen is perhaps the least complicated and most fundamental process that can be treated by atomic-collision theory. We present measurements of the ionization cross section for 30--1000 keV antiprotons colliding with atomic hydrogen.

  7. A STRONG EXCESS IN THE 20-100 keV EMISSION OF NGC 1365

    SciTech Connect

    Risaliti, G.; Elvis, M.; Fabbiano, G.; Wang, J.; Braito, V.; Laparola, V.; Bianchi, S.; Matt, G.; Maiolino, R.; Reeves, J.; Salvati, M.

    2009-11-01

    We present a new Suzaku observation of the obscured active galactic nucleus in NGC 1365, revealing an unexpected excess of X-rays above 20 keV of at least a factor approx2 with respect to the extrapolation of the best-fitting 3-10 keV model. Additional Swift-BAT and Integral-IBIS observations show that the 20-100 keV is concentrated within approx1.5 arcmin from the center of the galaxy, and is not significantly variable on timescales from days to years. A comparison of this component with the 3-10 keV emission, which is characterized by a rapidly variable absorption, suggests a complex structure of the circumnuclear medium, consisting of at least two distinct components with rather different physical properties, one of which covers >80% of the source with a column density N {sub H} approx 3-4x10{sup 24} cm{sup -2}. An alternative explanation is the presence of a double active nucleus in the center of NGC 1365.

  8. Flux measurements using the BATSE spectroscopic detectors

    NASA Technical Reports Server (NTRS)

    Mcnamara, Bernard

    1993-01-01

    Among the Compton Gama-Ray Observatory instruments, the BATSE Spectroscopic Detectors (SD) have the distinction of being able to detect photons of energies less than about 20 keV. This is an interesting energy range for the examination of low mass X-ray binaries (LMXB's). In fact, Sco X-1, the prototype LMXB, is easily seen even in the raw BATSE spectroscopic data. The all-sky coverage afforded by these detectors offers a unique opportunity to monitor this source over time periods never before possible. The aim of this investigation was to test a number of ways in which both continous and discrete flux measurements can be obtained using the BATSE spectroscopic datasets. A instrumental description of a SD can be found in the Compton Workshop of Apr. 1989, this report will deal only with methods which can be used to analyze its datasets. Many of the items discussed below, particularly in regard to the earth occultation technique, have been developed, refined, and applied by the BATSE team to the reduction of BATSE LAD data. Code written as part of this project utilizes portions of that work. The following discussions will first address issues related to the reduction of SD datasets using the earth occultation technique. It will then discuss methods for the recovery of the flux history of strong sources while they are above the earth's limb. The report will conclude with recommended reduction procedures.

  9. Electron energy flux in the solar wind.

    NASA Technical Reports Server (NTRS)

    Ogilvie, K. W.; Scudder, J. D.; Sugiura, M.

    1971-01-01

    Description of studies of electrons between 10 eV and 9.9 keV in the solar wind. The transport of energy in the rest frame of the plasma is evaluated and shown to be parallel to the interplanetary magnetic field. The presence of electrons from solar events causes this energy-flux density to exceed the heat flow due to thermal electrons. In one such event, the observations are shown to be consistent with the solar-electron observations made at higher energies. When observations are made at a point connected to the earth's bow shock by an interplanetary-field line, a comparatively large energy flux along the field toward the sun is observed, but the heat flow remains outwardly directed during this time interval. In either situation the heat flow is found to be consistent with measurements made on Vela satellites by a different method. These values, less than .01 ergs/sq cm/sec, are sufficiently low to require modifications to the Spitzer-Harm conductivity formula for use in solar-wind theories.

  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. 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.

  12. 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.

  13. Dark matter inelastic up-scattering with the interstellar plasma: A new source of x-ray lines, including at 3.5 keV

    NASA Astrophysics Data System (ADS)

    D'Eramo, Francesco; Hambleton, Kevin; Profumo, Stefano; Stefaniak, Tim

    2016-05-01

    We explore the phenomenology of a class of models where the dark matter particle can inelastically up-scatter to a heavier excited state via off-diagonal dipolar interactions with the interstellar plasma (gas or free electrons). The heavier particle then rapidly decays back to the dark matter particle plus a quasimonochromatic photon. For the process to occur at appreciable rates, the mass splitting between the heavier state and the dark matter must be comparable to, or smaller than, the kinetic energy of particles in the plasma. As a result, the predicted photon line falls in the soft x-ray range, or, potentially, at arbitrarily lower energies. We explore experimental constraints from cosmology and particle physics, and present accurate calculations of the dark matter thermal relic density and of the flux of monochromatic x rays from thermal plasma excitation. We find that the model provides a natural explanation for the observed 3.5 keV line from clusters of galaxies and from the Galactic center, and is consistent with null detections of the line from dwarf galaxies. The unique line shape, which will be resolved by future observations with the Hitomi (formerly Astro-H) satellite, and the predicted unique morphology and target-temperature dependence will enable easy discrimination of this class of models versus other scenarios for the generation of the 3.5 keV line or of any other unidentified line across the electromagnetic spectrum.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Li, Zhichao; Jiang, Xiaohua; Liu, Shenye; Huang, Tianxuan; Zheng, Jian; Yang, Jiamin; Li, Sanwei; Guo, Liang; Zhao, Xuefeng; Du, Huabin; Song, Tianming; Yi, Rongqing; Liu, Yonggang; Jiang, Shaoen; Ding, Yongkun

    2010-07-01

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

  16. A Review of X-ray Diagnostic Calibrations in the 2 to 100 keV Region Using the High Energy X-ray Calibration Facility (HEX)

    SciTech Connect

    Ali, Zaheer; Pond, T; Buckles, R A; Maddox, B R; Chen, C D; DeWald, E L; Izumi, N; Stewart, R

    2010-05-19

    The precise and accurate measurement of X-rays in the 2 keV to 100 keV region is crucial to the understanding of HED plasmas and warm dense matter in general. With the emergence of inertially confined plasma facilities as the premier platforms for ICF, laboratory astrophysics, and national security related plasma experiments, the need to calibrate diagnostics in the high energy X-ray regime has grown. At National Security Technologies High Energy X-ray Calibration Facility (HEX) in Livermore, California, X-ray imagers, filter-fluorescer spectrometers, crystal spectrometers, image plates, and nuclear diagnostics are calibrated. The HEX can provide measurements of atomic line radiation, X-ray flux (accuracy within 10%), and X-ray energy (accuracy within 1%). The HEX source is comprised of a commercial 160 kV X-ray tube, a fluorescer wheel, a filter wheel, and a lead encasement. The X-ray tube produces a Tungsten bremsstrahlung spectrum which causes a foil to fluoresce line radiation. To minimize bremsstrahlung in the radiation for calibration we also provide various foils as filters. For experimental purposes, a vacuum box capable of 10{sup -7} Torr, as well as HPGe and CdTe radiation detectors, are provided on an optical table. Most geometries and arrangements can be changed to meet experimental needs.

  17. Reaction rate of the 13C(α,n)16O neutron source using the ANC of the -3 keV resonance measured with the THM

    NASA Astrophysics Data System (ADS)

    La Cognata, M.; Spitaleri, C.; Trippella, O.; Kiss, G. G.; Rogachev, G. V.; Mukhamedzhanov, A. M.; Avila, M.; Guardo, G. L.; Koshchiy, E.; Kuchera, A.; Lamia, L.; Puglia, S. M. R.; Romano, S.; Santiago, D.; Spartà, R.

    2016-01-01

    The s-process is responsible of the synthesis of most of the nuclei in the mass range 90 ≤ A ≤ 208. It consists in a series of neutron capture reactions on seed nuclei followed by β-decays, since the neutron accretion rate is slower than the β-decay rate. Such small neutron flux is supplied by the 13C(α,n)16O reaction. It is active inside the helium-burning shell of asymptotic giant branch stars, at temperatures < 108 K, corresponding to an energy interval of 140-230 keV. In this region, the astrophysical S (E)-factor is dominated by the -3 keV sub-threshold resonance due to the 6.356 MeV level in 17O. In this work, we have applied the Trojan Horse Method (THM) to the 13C(6Li,n16O)d quasi-free reaction to extract the 6.356 MeV level resonance parameters, in particular the asymptotic normalization coefficient . A preliminary analysis of a partial data set has lead to , slightly larger than the values in the literature. However, the deduced 13C(α, n)16O reaction rate is in agreement with most results in the literature at ˜ 108 K, with enhanced accuracy thanks to our innovative approach merging together ANC and THM.

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

    SciTech Connect

    Li Zhichao; Guo Liang; Jiang Xiaohua; Liu Shenye; Huang Tianxuan; Yang Jiamin; Li Sanwei; Zhao Xuefeng; Du Huabin; Song Tianming; Yi Rongqing; Liu Yonggang; Jiang Shaoen; Ding Yongkun; Zheng Jian

    2010-07-15

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

  19. 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.

  20. 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.

  1. Forecasting the arrival of fast coronal mass ejecta at Earth by the detection of 2-20 keV neutral atoms

    NASA Technical Reports Server (NTRS)

    Hsieh, K. C.; Shih, K. L.; Mccomas, D. J.; Wu, S. T.; Wu, C. C.

    1992-01-01

    Studies have shown that Earth passages of fast coronal mass ejections (CMEs) trigger geomagnetic storms. Early identification of fast earth-directed CME can help provide storm warnings, but detection of such by coronagraphs is extremely difficult. We suggest that energetic hydrogen atoms (EHA) between 2 and 10 keV produced during the transit phase of an Earth-directed CME by recombination between protons and electrons in the CME can travel ahead of the CME and act as harbingers of a magnetic storm. This forecasting scheme should work if enough EHA are produced, because while CMEs decelerate continuously after their ejection, the EHA fluxes produced in the initial phase of fast CMEs propagate at their initial high speeds. Model simulations support this proposed mechanism.

  2. Modeling Magnetic Flux Ropes

    NASA Astrophysics Data System (ADS)

    Xia, Chun; Keppens, Rony

    2014-01-01

    The magnetic configuration hosting prominences can be a large-scale helical magnetic flux rope. As a necessary step towards future prominence formation studies, we report on a stepwise approach to study flux rope formation. We start with summarizing our recent three-dimensional (3D) isothermal magnetohydrodynamic (MHD) simulation where a flux rope is formed, including gas pressure and gravity. This starts from a static corona with a linear force-free bipolar magnetic field, altered by lower boundary vortex flows around the main polarities and converging flows towards the polarity inversion. The latter flows induce magnetic reconnection and this forms successive new helical loops so that a complete flux rope grows and ascends. After stopping the driving flows, the system relaxes to a stable helical magnetic flux rope configuration embedded in an overlying arcade. Starting from this relaxed isothermal endstate, we next perform a thermodynamic MHD simulation with a chromospheric layer inserted at the bottom. As a result of a properly parametrized coronal heating, and due to radiative cooling and anisotropic thermal conduction, the system further relaxes to an equilibrium where the flux rope and the arcade develop a fully realistic thermal structure. This paves the way to future simulations for 3D prominence formation.

  3. Artificial neural network prediction model for geosynchronous electron fluxes: Dependence on satellite position and particle energy

    NASA Astrophysics Data System (ADS)

    Shin, Dae-Kyu; Lee, Dae-Young; Kim, Kyung-Chan; Hwang, Junga; Kim, Jaehun

    2016-04-01

    Geosynchronous satellites are often exposed to energetic electrons, the flux of which varies often to a large extent. Since the electrons can cause irreparable damage to the satellites, efforts to develop electron flux prediction models have long been made until recently. In this study, we adopt a neural network scheme to construct a prediction model for the geosynchronous electron flux in a wide energy range (40 keV to >2 MeV) and at a high time resolution (as based on 5 min resolution data). As the model inputs, we take the solar wind variables, geomagnetic indices, and geosynchronous electron fluxes themselves. We also take into account the magnetic local time (MLT) dependence of the geosynchronous electron fluxes. We use the electron data from two geosynchronous satellites, GOES 13 and 15, and apply the same neural network scheme separately to each of the GOES satellite data. We focus on the dependence of prediction capability on satellite's magnetic latitude and MLT as well as particle energy. Our model prediction works less efficiently for magnetic latitudes more away from the equator (thus for GOES 13 than for GOES 15) and for MLTs nearer to midnight than noon. The magnetic latitude dependence is most significant for an intermediate energy range (a few hundreds of keV), and the MLT dependence is largest for the lowest energy (40 keV). We interpret this based on degree of variance in the electron fluxes, which depends on magnetic latitude and MLT at geosynchronous orbit as well as particle energy. We demonstrate how substorms affect the flux variance.

  4. Generation mechanism of L-value dependence of oxygen flux enhancements during substorms

    NASA Astrophysics Data System (ADS)

    Nakayama, Y.; Ebihara, Y.; Tanaka, T.; Ohtani, S.; Gkioulidou, M.; Takahashi, K.; Kistler, L. M.; Kletzing, C.

    2015-12-01

    The Van Allen Probes Helium Oxygen Proton Electron (HOPE) instrument measures charged particles with an energy range from ~eV to ~ tens of keV. The observation shows that the energy flux of the particles increases inside the geosynchronous orbit during substorms. For some night-side events around the apogee, the energy flux of O+ ion enhances below ~10 keV at lower L shell, whereas the flux below ~8 keV sharply decreases at higher L shells. This structure of L-energy spectrogram of flux is observed only for the O+ ions. The purpose of this study is to investigate the generation mechanism of the structure by using numerical simulations. We utilized the global MHD simulation developed by Tanaka et al (2010, JGR) to simulate the electric and magnetic fields during substorms. We performed test particle simulation under the electric and magnetic fields by applying the same model introduced by Nakayama et al. (2015, JGR). In the test particle simulation each test particle carries the real number of particles in accordance with the Liouville theorem. Using the real number of particles, we reconstructed 6-dimensional phase space density and differential flux of O+ ions in the inner magnetosphere. We obtained the following results. (1) Just after the substorm onset, the dawn-to-dusk electric field is enhanced to ~ 20 mV/m in the night side tail region at L > 7. (2) The O+ ions are accelerated and transported to the inner region (L > ~5.5) by the large-amplitude electric field. (3) The reconstructed L-energy spectrogram shows a similar structure to the Van Allen Probes observation. (4) The difference in the flux enhancement between at lower L shell and higher L shells is due to two distinct acceleration processes: adiabatic and non-adiabatic. We will discuss the relationship between the particle acceleration and the structure of L-energy spectrogram of flux enhancement in detail.

  5. A statistical approach to determining energetic outer radiation belt electron precipitation fluxes

    NASA Astrophysics Data System (ADS)

    Simon Wedlund, Mea; Clilverd, Mark A.; Rodger, Craig J.; Cresswell-Moorcock, Kathy; Cobbett, Neil; Breen, Paul; Danskin, Donald; Spanswick, Emma; Rodriguez, Juan V.

    2014-05-01

    Subionospheric radio wave data from an Antarctic-Arctic Radiation-Belt (Dynamic) Deposition VLF Atmospheric Research Konsortia (AARDDVARK) receiver located in Churchill, Canada, is analyzed to determine the characteristics of electron precipitation into the atmosphere over the range 3 < L < 7. The study advances previous work by combining signals from two U.S. transmitters from 20 July to 20 August 2010, allowing error estimates of derived electron precipitation fluxes to be calculated, including the application of time-varying electron energy spectral gradients. Electron precipitation observations from the NOAA POES satellites and a ground-based riometer provide intercomparison and context for the AARDDVARK measurements. AARDDVARK radiowave propagation data showed responses suggesting energetic electron precipitation from the outer radiation belt starting 27 July 2010 and lasting ~20 days. The uncertainty in >30 keV precipitation flux determined by the AARDDVARK technique was found to be ±10%. Peak >30 keV precipitation fluxes of AARDDVARK-derived precipitation flux during the main and recovery phase of the largest geomagnetic storm, which started on 4 August 2010, were >105 el cm-2 s-1 sr-1. The largest fluxes observed by AARDDVARK occurred on the dayside and were delayed by several days from the start of the geomagnetic disturbance. During the main phase of the disturbances, nightside fluxes were dominant. Significant differences in flux estimates between POES, AARDDVARK, and the riometer were found after the main phase of the largest disturbance, with evidence provided to suggest that >700 keV electron precipitation was occurring. Currently the presence of such relativistic electron precipitation introduces some uncertainty in the analysis of AARDDVARK data, given the assumption of a power law electron precipitation spectrum.

  6. Study of the storm time fluxes of heavy ions

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The characteristics of the storm time ring current ions in the energy range of 0.5 to 16 keV were investigated. Data were processed and analyzed from the energetic ion mass spectrometer aboard the S3-3 satellite. Results are used for planning and operating the ion mass spectrometer experiment on the ISEE spacecraft, for selecting and processing the ISEE ion data, and for planning and conducting coordinated satellite experiments in support of the International Magnetospheric Study (IMS). It is established from the S3-3 ion data that relatively large fluxes of energetic (keV) 0(+) and H(+) ions are frequently flowing upward from the ionosphere along magnetic field lines in the polar auroral regions. Also, from investigations with the same instrument during the main phase of three moderate (D sub ST approximately 100) magnetic storms, it is found that the number density of 0(+) ions in the ring current was comparable to H(+) ion density the range 0.5 to 15 keV.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The pitch angle distribution (PAD) of energetic electrons in the slot region and inner radiation belt received little attention in the past decades due to the lack of quality measurements. Using the state-of-art pitch-angle-resolved data from the Magnetic Electron Ion Spectrometer (MagEIS) instrument onboard the Van Allen Probes, a detailed analysis of 100s keV electron PADs below L =4 is performed, in which the PADs is categorized into three types: normal (flux peaking at 90°), cap (exceedingly peaking narrowly around 90°) and 90°-minimum (lower flux at 90°) PADs. By examining the characteristics of the PADs of 460 keV electrons for over a year, we find that the 90°-minimum PADs are generally present in the inner belt (L<2), while normal PADs dominate at L~3.5-4. In the region between, 90°-minimum PADs dominate during injection times and normal PADs dominate during quiet times. Cap PADs appear mostly at the decay phase of storms in the slot region and are likely caused by the pitch angle scattering of hiss waves. Fitting the normal PADs into sinnα form, the parameter n is much higher below L=3 than that in the outer belt and relatively constant in the inner belt but changes significantly in the slot region (2

  8. A thin film device as a low energy, high flux charged particle spectrometer

    NASA Astrophysics Data System (ADS)

    Cecil, F. E.; Roy, Brian; Sutton, Christian; Wasinger, Nicole

    2001-01-01

    We are continuing our investigation of the use of stacks of electrically isolated thin metal foils as spectrometers for lost ions from tokamak fusion plasmas. Devices of this type in which the foil thicknesses were a few micrometers were installed on the Joint European Torus during the recent first deuterium-tritium experiment in an effort to observe lost energetic alpha particles. While there was no convincing evidence of lost alpha particles in this experiment, we did observe significant fluxes of low energy (<500 keV) charged particles. In an effort to provide an instrument for the investigation of this phenomenon and of escaping relatively low energy (<100 keV) ions from other fusion plasma devices, we have developed alternative devices with very thin (few hundred nanometers) alternating layers of conductor and insulator. Four such devices have been fabricated and tested for protons with energies between 20 and 160 keV and demonstrated good energy resolution (typically about 10%) for proton bombarding energies between about 40 and 120 keV. One of the devices, consisting of deposited layers of Al, Ti, and SiO2 was operated up to a current density of about 100 m/cm2 at an energy of 100 keV, corresponding to a power volume density of 100 kW/cm3

  9. 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

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

    SciTech Connect

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

    2008-04-30

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

  11. Energetic (greater than 100 keV) O(+) ions in the plasma sheet

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

    The first measurements of very energetic (112 - 157 keV) O(+) ions in the earth's magnetosphere are presented. The observations were made with the UMd/MPE ULECA sensor on ISEE-1 on 5 March 1981 at geocentric distances approximately 20 R(E) in the earth's magnetotail. During this time period an Energetic Storm Particle event was observed by the nearly identical sensor on the ISEE-3 spacecraft, located approximately 250 R(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 O(+)/H(+) abundance ratios, at approximately 130 kev, as large as 0.35. In between plasma sheet encounters the O(+)/H(+) ratio at this energy is consistent with zero.

  12. 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.

  13. 0. 073% (95% C. L. ) upper limit on 17keV neutrino admixture

    SciTech Connect

    Ohshima, T. )

    1992-02-01

    A direct search was made for a threshold kink in [sup 63]Ni [beta]-ray spectrum due possibly to a sizeable admixture of 17keV neutrino. A fine energy scan was performed using a magnetic spectrometer over the specific energy region with very high statistics and a very high signal-to-background ratio. The resultant mixing strength is [vert bar][ital U][vert bar][sup 2]=([minus]0.011[plus minus]0.033(stat.)[plus minus]0.030(sys.) )% and its upper limit [vert bar][ital U][vert bar][sup 2][le]0.073% (95% C.L.). The result clearly excludes neutrinos with [vert bar][ital U][vert bar][sup 2][ge]0.1% for the mass range from 11 to 24keV.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. The 871 keV gamma ray from 17O and the identification of plutonium oxide

    NASA Astrophysics Data System (ADS)

    Peurrung, Anthony; Arthur, Richard; Elovich, Robert; Geelhood, Bruce; Kouzes, Richard; Pratt, Sharon; Scheele, Randy; Sell, Richard

    2001-12-01

    Disarmament agreements and discussions between the United States and the Russian Federation for reducing the number of stockpiled nuclear weapons require verification of the origin of materials as having come from disassembled weapons. This has resulted in the identification of measurable "attributes" that characterize such materials. It has been proposed that the 871 keV gamma ray of 17O can be observed as an indicator of the unexpected presence of plutonium oxide, as opposed to plutonium metal, in such materials. We have shown that the observation of the 871 keV gamma ray is not a specific indicator of the presence of the oxide, but rather indicates the presence of nitrogen.

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

    NASA Astrophysics Data System (ADS)

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

    2011-08-01

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

  20. Superradiance and flux conservation

    NASA Astrophysics Data System (ADS)

    Boonserm, Petarpa; Ngampitipan, Tritos; Visser, Matt

    2014-09-01

    The theoretical foundations of the phenomenon known as superradiance still continue to attract considerable attention. Despite many valiant attempts at pedagogically clear presentations, the effect nevertheless still continues to generate some significant confusion. Part of the confusion arises from the fact that superradiance in a quantum field theory context is not the same as superradiance (superfluorescence) in some condensed matter contexts; part of the confusion arises from traditional but sometimes awkward normalization conventions, and part is due to sometimes unnecessary confusion between fluxes and probabilities. We shall argue that the key point underlying the effect is flux conservation (and, in the presence of dissipation, a controlled amount of flux nonconservation), and that attempting to phrase things in terms of reflection and transmission probabilities only works in the absence of superradiance. To help clarify the situation we present a simple exactly solvable toy model exhibiting both superradiance and damping.

  1. Flux amplification in SSPX

    NASA Astrophysics Data System (ADS)

    Lodestro, Lynda; Hooper, E. B.; Jayakumar, R. J.; Pearlstein, L. D.; Wood, R. D.; McLean, H. S.

    2007-11-01

    Flux amplification---the ratio of poloidal flux enclosed between the magnetic and geometric axes to that between the separatrix and the geometric axis---is a key measure of efficiency for edge-current-driven spheromaks. With the new, modular capacitor bank, permitting flexible programming of the gun current, studies of flux amplification under various drive scenarios can be performed. Analysis of recent results of pulsed operation with the new bank finds an efficiency ˜ 0.2, in selected shots, of the conversion of gun energy to confined magnetic energy during the pulses, and suggests a route toward sustained efficiency at 0.2. Results of experiments, a model calculation of field build-up, and NIMROD simulations exploring this newly suggested scenario will be presented.

  2. 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.

  3. Solar Wind ~0.1-1.5 keV Electrons at Quiet Times

    NASA Astrophysics Data System (ADS)

    Tao, J.; Wang, L.; Zong, Q. G.; Li, G.; He, J.; Tu, C.; Wimmer-Schweingruber, R. F.; Salem, C. S.; Yang, L.

    2015-12-01

    Solar wind halo/strahl electrons carry important information on the formation of suprathermal electrons in the solar wind. Here we present a statistical survey on the energy spectrum of 0.1-1.5 keV electrons observed by WIND/3DP in the solar wind during quiet times at solar minimum and maximum of solar cycle 23 and 24. First, we separate strahl electrons from halo electrons according to their different behaviors in the angular distribution. Secondly, we fit the observed energy spectrum of halo/strahl electrons at 0.1-1.5 keV to a kappa distribution function with an index κ and effective temperature Teff. We also integrate the electron measurements to obtain the number density n of halo/strahl electrons at 0.1-1.5 keV. We find a strong positive correlation between κ and Teff for both halo and strahl electrons. For strahl electrons, the index κ (number density n) appears to decrease (increase) with increasing solar activity. For halo electrons, the index κ also decreases with increasing solar activity, while the number density n shows no clear solar-cycle variation. Based on a simple model, we find that the escape of thermal electrons from the coronal region with a higher temperature T could lead to a larger κ for the 0.1-1.5 keV electrons measured in the solar wind, if T > ~0.73×106 K. These results suggest that strahl electrons are likely related to the escaping thermal electrons from different regions in the hot corona, while halo electrons are probably formed due to the scatter/acceleration of strahl electrons in the interplanetary medium.

  4. 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.

  5. Compton polarimeter for 10-30 keV x rays

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  6. 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.

  7. 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

  8. 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.

  9. Proton collisions with the water dimer at keV energies

    NASA Astrophysics Data System (ADS)

    Quinet, O.; Deumens, E.; Öhrn, Y.

    Proton collisions with the water dimer are studied using a nonadiabatic, direct, time-dependent approach called electron nuclear dynamics (END). Fragmentation of the water dimer in collisions with protons at energies of 5.0, 1.0 keV and 200 eV is the primary aim of this initial study of water clusters using END. We report on the initial fragmentation dynamic, that is, for times less than 200 fs.

  10. 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.

  11. 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.

  12. No 17 keV neutrino: Admixture [lt]0. 073% (95% C. L. )

    SciTech Connect

    Ohshima, T.; Sakamoto, H.; Sato, T.; Shirai, J.; Tsukamoto, T. ); Sugaya, Y.; Takahashi, K. ); Suzuki, T. ); Rosenfeld, C.; Wilson, S. ); Ueno, K. ); Yonezawa, Y. ); Kawakami, H.; Kato, S.; Shibata, S.; Ukai, K. )

    1993-06-01

    To solve the controversial issue concerning the possible existence of a 17 keV neutrino with a 1% admixture in nuclear [beta] decay, we searched directly for any evidence of a production-threshold effect. The [sup 63]Ni [beta] spectrum was measured with a magnetic spectrometer, with very high statistics along with a fine energy scan over a narrow energy region around the expected threshold. The obtained mixing strength was [vert bar][ital U][vert bar][sup 2]=[[minus]0.011[plus minus]0.033(stat)[plus minus]0.030(syst)]%, very consistent with zero, and decisively excluding the existence of a 17 keV neutrino admixing at the 1% level with the electron neutrino. The corresponding upper limit was set at [vert bar][ital U][vert bar][sup 2][lt]0.073% (95% C.L.). A new limit was also obtained for a wider mass range: [vert bar][ital U][vert bar][sup 2][lt]0.15% (95% C.L.) for 10.5 to 25.0 keV neutrinos.

  13. 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.

  14. 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.

  15. 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.

  16. Absolute measurements of x-ray backlighter sources at energies above 10 keV

    SciTech Connect

    Maddox, B. R.; Park, H. S.; Remington, B. A.; Chen, C.; Chen, S.; Prisbrey, S. T.; Comley, A.; Back, C. A.; Szabo, C.; Seely, J. F.; Feldman, U.; Hudson, L. T.; Seltzer, S.; Haugh, M. J.; Ali, Z.

    2011-05-15

    Line emission and broadband x-ray sources with x-ray energies above 10 keV have been investigated using a range of calibrated x-ray detectors for use as x-ray backlighters in high energy density (HED) experiments. The conversion efficiency of short- and long-pulse driven Mo and Ag line-emission backlighters at 17 and 22 keV was measured to investigate the crossover region between short- and long-pulse conversion efficiency. It was found that significant 17 and 22 keV line emissions were observed using a 3 {omega}, 1 ns long-pulse drive for Mo and Ag targets and a comparison between the measured Mo x-ray spectrum and calculations using an atomic physics code suggests that the line emission is due to thermal emission from N-like Mo atoms. Electron temperatures derived from fits to the continuum region of the x-ray spectra agree well with the T{sub hot} scaling as 100x(I{lambda}{sup 2}){sup 1/3}. The continuum emissions from empty and 1 atm Kr-filled imploded CH shell targets were also measured for the use as broadband backlighters.

  17. 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.

  18. Observation of the X-ray source Sco X-1 from Skylab. [radiant flux density

    NASA Technical Reports Server (NTRS)

    Wilson, R. M.

    1977-01-01

    An attempt to observe the discrete X-ray source Sco X-1 on 20 September 1973 between 0856 and 0920 UT is reported. Data obtained with the ATM/S-056 X-ray event analyzer, in particular the flux observed with the 1.71 to 4.96 KeV counter, is analyzed. No photographic image of the source was obtained because Sco X-1 was outside the field of view of the X-ray telescope.

  19. The application of a hierarchical Bayesian spatiotemporal model for forecasting the SAA trapped particle flux distribution

    NASA Astrophysics Data System (ADS)

    Suparta, Wayan; Gusrizal

    2014-08-01

    We implement a hierarchical Bayesian spatiotemporal (HBST) model to forecast the daily trapped particle flux distribution over the South Atlantic Anomaly (SAA) region. The National Oceanic and Atmospheric Administration (NOAA)-15 data from 1-30 March 2008 with particle energies as >30 keV (mep0e1) and >300 keV (mep0e3) for electrons and 80-240 keV (mep0p2) and > 6900 keV (mep0p6) for protons were used as the model input to forecast the flux values on 31 March 2008. Data were transformed into logarithmic values and gridded in a 5∘×5∘ longitude and latitude size to fulfill the modelling precondition. A Monte Carlo Markov chain (MCMC) was then performed to solve the HBST Gaussian Process (GP) model by using the Gibbs sampling method. The result for this model was interpolated by a Kriging technique to achieve the whole distribution figure over the SAA region. Statistical results of the root mean square error (RMSE), mean absolute percentage error (MAPE), and bias (BIAS) showed a good indicator of the HBST method. The statistical validation also indicated the high variability of particle flux values in the SAA core area. The visual validation showed a powerful combination of HBST-GP model with Kriging interpolation technique. The Kriging also produced a good quality of the distribution map of particle flux over the SAA region as indicated by its small variance value. This suggests that the model can be applied in the development of a Low Earth Orbit (LEO)-Equatorial satellite for monitoring trapped particle radiation hazard.

  20. Measurements of x-ray spectral flux and intensity distribution of APS/CHESS undulator radiation

    SciTech Connect

    Ilinski, P.; Yun, W.; Lai, B.; Gluskin, E.; Cai, Z.

    1994-09-01

    Absolute radiation flux and polarization measurements of the APS undulators may have to be made under high thermal loading conditions. A method that may circumvent the high-heat-load problem was tested during a recent APS/CHESS undulator run. The technique makes use of a Si(Li) energy-dispersive detector to measure 5--35 keV x-rays scattered from a well-defined He gas volume at controlled pressure.

  1. Measurements of x-ray spectral flux of high brightness undulators by gas scattering

    SciTech Connect

    Ilinski, P.; Yun, W.; Lai, B.; Gluskin, E.; Cai, Z. )

    1995-02-01

    Absolute radiation flux and polarization measurements of the Advanced Photon Source (APS) undulators may have to be made under high thermal loading conditions. A method that may circumvent the high-heat-load problem was tested during a recent APS/CHESS undulator run. The technique makes use of a Si(Li) energy-dispersive detector to measure 5--35 keV x rays scattered from a well-defined He gas volume at controlled pressure.

  2. Optical heat flux gauge

    DOEpatents

    Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MaCarthur, Charles D.; Cala, Gregory C.

    1991-01-01

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  3. Optical heat flux gauge

    DOEpatents

    Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.

    1991-01-01

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator wherein each thermographic layer comprises a plurality of respective thermographic phosphors. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  4. Optical heat flux gauge

    DOEpatents

    Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.

    1991-01-01

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  5. 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.

  6. [Research advances in ecosystem flux].

    PubMed

    Zhang, Xudong; Peng, Zhenhua; Qi, Lianghua; Zhou, Jinxing

    2005-10-01

    To develop the long-term localized observation and investigation on ecosystem flux is of great importance. On the basis of generalizing the concepts and connotations of ecosystem flux, this paper introduced the construction and development histories of Global Flux Networks, Regional Flux Networks (Ameri-Flux, Euro-Flux and Asia-Flux) and China-Flux, as well as the main methodologies, including micrometeorological methods (such as eddy correlation method, mass balance method, energy balance method and air dynamic method)and chamber methods (static and dynamic chamber methods), and their basic operation principles. The research achievements, approaches and advances of CO2, N2O, CH4, and heat fluxes in forest ecosystem, farmland ecosystem, grassland ecosystem and water ecosystem were also summarized. In accordance with the realities and necessities of ecosystem flux research in China, some suggestions and prospects were put forward.

  7. 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.

  8. Compton scattering for spectroscopic detection of ultra-fast, high flux, broad energy range X-rays

    SciTech Connect

    Cipiccia, S.; Wiggins, S. M.; Brunetti, E.; Vieux, G.; Yang, X.; Welsh, G. H.; Anania, M.; Islam, M. R.; Ersfeld, B.; Jaroszynski, D. A.; Maneuski, D.; Montgomery, R.; Smith, G.; Hoek, M.; Hamilton, D. J.; Shea, V. O.; Issac, R. C.; Lemos, N. R. C.; Dias, J. M.; and others

    2013-11-15

    Compton side-scattering has been used to simultaneously downshift the energy of keV to MeV energy range photons while attenuating their flux to enable single-shot, spectrally resolved, measurements of high flux X-ray sources to be undertaken. To demonstrate the technique a 1 mm thick pixelated cadmium telluride detector has been used to measure spectra of Compton side-scattered radiation from a Cobalt-60 laboratory source and a high flux, high peak brilliance X-ray source of betatron radiation from a laser-plasma wakefield accelerator.

  9. High flux heat exchanger

    NASA Astrophysics Data System (ADS)

    Flynn, Edward M.; Mackowski, Michael J.

    1993-01-01

    This interim report documents the results of the first two phases of a four-phase program to develop a high flux heat exchanger for cooling future high performance aircraft electronics. Phase 1 defines future needs for high flux heat removal in advanced military electronics systems. The results are sorted by broad application categories: (1) commercial digital systems, (2) military data processors, (3) power processors, and (4) radar and optical systems. For applications expected to be fielded in five to ten years, the outlook is for steady state flux levels of 30-50 W/sq cm for digital processors and several hundred W/sq cm for power control applications. In Phase 1, a trade study was conducted on emerging cooling technologies which could remove a steady state chip heat flux of 100 W/sq cm while holding chip junction temperature to 90 C. Constraints imposed on heat exchanger design, in order to reflect operation in a fighter aircraft environment, included a practical lower limit on coolant supply temperature, the preference for a nontoxic, nonflammable, and nonfreezing coolant, the need to minimize weight and volume, and operation in an accelerating environment. The trade study recommended the Compact High Intensity Cooler (CHIC) for design, fabrication, and test in the final two phases of this program.

  10. Radiative Flux Analysis

    DOE Data Explorer

    Long, Chuck [NOAA

    2008-05-14

    The Radiative Flux Analysis is a technique for using surface broadband radiation measurements for detecting periods of clear (i.e. cloudless) skies, and using the detected clear-sky data to fit functions which are then used to produce continuous clear-sky estimates. The clear-sky estimates and measurements are then used in various ways to infer cloud macrophysical properties.

  11. Muon and neutrino fluxes

    NASA Technical Reports Server (NTRS)

    Edwards, P. G.; Protheroe, R. J.

    1985-01-01

    The result of a new calculation of the atmospheric muon and neutrino fluxes and the energy spectrum of muon-neutrinos produced in individual extensive air showers (EAS) initiated by proton and gamma-ray primaries is reported. Also explained is the possibility of detecting atmospheric nu sub mu's due to gamma-rays from these sources.

  12. Incident meteoroid flux density

    NASA Technical Reports Server (NTRS)

    Badadjanov, P. B.; Bibarsov, R. SH.; Getman, V. S.; Kolmakov, V. M.

    1987-01-01

    Complex photographic and radar meteor observations were carried out. Using the available observational data, the density of incident flux of meteoroids was estimated over a wide mass range of 0.001 to 100 g. To avoid the influence of apparatus selectivity a special technique was applied. The main characteristics of this technique are given and discussed.

  13. Field-aligned fluxes of energetic electrons related to the onset of magnetospheric substorms

    NASA Astrophysics Data System (ADS)

    Kremser, G.; Korth, A.; Ullaland, S. L.; Roux, A.; Perraut, S.; Pedersen, A.; Schmidt, R.; Tanskanen, P.

    1987-08-01

    Observations of bidirectional field-aligned fluxes of energetic electrons (16 to 80 keV) at magnetic substorm onset are discussed. The electron fluxes appear 4 min after the onset of the expansion phase, last 1.5 min, and are associated with strong spatial gradients of the ion intensity. The observations are interpreted in terms of a model in which a surface wave develops at the transition from dipolelike to taillike geomagnetic fieldlines. The surface wave couples into kinetic Alfven waves that propagate along the fieldlines, are reflected at the ionosphere, and interact with mirrored electrons on their way back towards the equatorial plane.

  14. Gamma-Ray Line Flux Ratios as Diagnostics of SN Ia Models

    NASA Astrophysics Data System (ADS)

    Lara, Juan; The, Lih-Sin; Leising, Mark

    2004-05-01

    The ^56Ni decay chain that powers the optical output of Type Ia supernovae produces gamma-ray lines at 158, 812 ( ^56Ni decay ) and 847, 1238 keV ( ^56Co decay ). The detection of the line fluxes have been used to show indeed that ^56Ni is produced by explosive nucleosynthesis. We investigate the measurement precision required to use the flux ratios of these lines to each other and to the compton X-ray continuum to distinguish among a variety of SN Ia models. We compare this to using gamma-ray line profiles to distinguish among models.

  15. Long term temporal variations of the hard X-ray flux from the Centaurus region

    NASA Technical Reports Server (NTRS)

    Schwartz, D. A.; Peterson, L. E.; Hudson, H. S.

    1971-01-01

    The X-ray telescope aboard the third Orbiting Solar Observatory (OSO-3) observed the Centaurus region daily from 1967 October to 1968 February, and also for five days in 1968 June. A stable minimum flux of 0.33 + or - 0.03 photons (sq cm sec)/1 between 7.7 and 38 keV from a source around l = 305 deg is derived. Several single days show enhanced fluxes, and two extensive flaring episodes, one with a soft and the other a very hard spectrum, lasting at least ten days.

  16. Optical heat flux gauge

    DOEpatents

    Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.

    1991-04-09

    A heat flux gauge is disclosed comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figures.

  17. NEUTRON FLUX INTENSITY DETECTION

    DOEpatents

    Russell, J.T.

    1964-04-21

    A method of measuring the instantaneous intensity of neutron flux in the core of a nuclear reactor is described. A target gas capable of being transmuted by neutron bombardment to a product having a resonance absorption line nt a particular microwave frequency is passed through the core of the reactor. Frequency-modulated microwave energy is passed through the target gas and the attenuation of the energy due to the formation of the transmuted product is measured. (AEC)

  18. Reconnecting Flux Ropes

    NASA Astrophysics Data System (ADS)

    Gekelman, Walter; van Compernolle, Bart

    2012-10-01

    Magnetic flux ropes are due to helical currents and form a dense carpet of arches on the surface of the sun. Occasionally one tears loose as a coronal mass ejection and its rope structure is detected by satellites close to the earth. Current sheets can tear into filaments and these are nothing other than flux ropes. Ropes are not static, they exert mutual JxB forces causing them to twist about each other and merge. Kink instabilities cause them to violently smash into each other and reconnect at the point of contact. We report on experiments done in the large plasma device (LAPD) at UCLA (L=17m,dia=60cm,0.3<=B0z<=2.5kG,n˜2x10^12cm-3)on three dimensional flux ropes. Two, three or more magnetic flux ropes are generated from initially adjacent pulsed current channels in a background magnetized plasma. The currents and magnetic fields form exotic shapes with no ignorable direction and no magnetic nulls. Volumetric space-time data show multiple reconnection sites with time-dependent locations. The concept of a quasi-separatrix layer (QSL), a tool to understand 3D reconnection without null points. In our experiment the QSL is a narrow ribbon-like region(s) that twists between field lines. Within the QSL(s) field lines that start close to one another rapidly diverge as they pass through one or more reconnection regions. When the field lines are tracked they are observed to slip along the QSL when reconnection occurs. The Heating and other co-existing waves will be presented.

  19. Heat Flux Sensor Testing

    NASA Technical Reports Server (NTRS)

    Clark, D. W.

    2002-01-01

    This viewgraph presentation provides information on the following objectives: Developing secondary calibration capabilities for MSFC's (Marshall Space Flight Center) Hot Gas Facility (HGF), a Mach 4 Aerothermal Wind Tunnel; Evaluating ASTM (American Society for Testing and Materials) slug/ thinskin calorimeters against current HGF heat flux sensors; Providing verification of baselined AEDC (Arnold Engineering Development Center) / Medtherm gage calibrations; Addressing future calibration issues involving NIST (National Institute of Standards and Technology) certified radiant gages.

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

    SciTech Connect

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

    2015-03-20

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

  1. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1990-06-01

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

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  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. 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.

  12. 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.

  13. The distribution of solar magnetic fluxes and the nonlinearity of stellar flux-flux relations

    NASA Technical Reports Server (NTRS)

    Schrijver, C. J.; Harvey, K. L.

    1989-01-01

    Synoptic maps for the 1975-1984 period are used to determine the time-dependent distribution function of magnetic flux densities in the solar atmosphere. The distribution function depends only on the global level of magnetic activity, and it is used to study how relations between magnetic flux densities and radiative flux densities from different temperature regimes in the outer atmosphere (derived from spatially resolved solar observations) transform into relations between surface-averaged flux densities. It is found that the transformation to surface-averaged fluxes preserves the power-law character of relations between radiative and magnetic flux densities for spatially resolved data.

  14. 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.

  15. 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.

  16. High order reflectivity of highly oriented pyrolytic graphite crystals for x-ray energies up to 22 keV

    SciTech Connect

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

    2008-10-15

    We used Kr K{alpha} (12.6 keV), Zr K{alpha} (15.7 keV), and Ag K{alpha} (22.2 keV) x-rays, produced by petawatt-class laser pulses, to measure the integrated crystal reflectivity R{sub int} of flat highly oriented pyrolytic graphite (HOPG) up to the fifth order. The maximum R{sub int} was observed in first order (3.7 mrad at 12.6 keV), decreasing by a factor of 3-5 for every successive order, and dropping by a factor of 2-2.5 at 22.2 keV. The current study indicates that HOPG crystals are suitable for measuring scattering signals from high energy x-ray sources (E{>=}20 keV). These energies are required to penetrate through the high density plasma conditions encountered in inertial confinement fusion capsule implosions on the National Ignition Facility.

  17. Stabilization of moduli by fluxes

    SciTech Connect

    Behrndt, Klaus

    2004-12-10

    In order to fix the moduli, non-trivial fluxes might the essential input. We summarize different aspects of compactifications in the presence of fluxes, as there is the relation to generalized Scherk-Schwarz reductions and gauged supergravity but also the description of flux-deformed geometries in terms of G-structures and intrinsic torsion.

  18. 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.

  19. 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.

  20. 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.

  1. Lifetime measurement of the 167.1 keV state in {sup 41}Ar

    SciTech Connect

    White, E. R.; Mach, H.; Fraile, L. M.; Koester, U.; Arndt, O.; Blazhev, A.; Braun, N.; Fransen, C.; Jolie, J.; Boelaert, N.; Borge, M. J. G.; Boutami, R.; Reillo, E.-M.; Tengblad, O.; Bradley, H.; Dlouhy, Z.; Ugryumov, V.; Fynbo, H. O. U.; Hinke, Ch.; Kroell, T.

    2007-11-15

    The Advanced-Time-Delayed method was used to measure lifetimes of the states in {sup 41}Ar populated in the {beta} decay of {sup 41}Cl. The nuclei {sup 41}Cl were produced at ISOLDE by 1.4-GeV proton bombardment of a thick UC{sub x} target and mass-separated as molecular ions, XeCl{sup +}. Our measured half-life of the 167.1-keV state, T{sub 1/2}=315(15) ps, is significantly lower than the previously measured value of 410(30) ps. We have also determined T{sub 1/2}=260(80) ps and T{sub 1/2}{<=}46 ps for the 515.9- and 1867.7-keV states, respectively. These are the shortest lifetimes measured so far with the ultrafast timing method using the new LaBr{sub 3}(Ce) crystals for {gamma}-ray detection.

  2. EMISSION LINES BETWEEN 1 AND 2 keV IN COMETARY X-RAY SPECTRA

    SciTech Connect

    Ewing, Ian; Christian, Damian J.; Bodewits, Dennis; Dennerl, Konrad; Lisse, Carey M.; Wolk, Scott J. E-mail: daman.christian@csun.edu

    2013-01-20

    We present the detection of new cometary X-ray emission lines in the 1.0-2.0 keV range using a sample of comets observed with the Chandra X-Ray Observatory and ACIS spectrometer. We have selected five comets from the Chandra sample with good signal-to-noise spectra. The surveyed comets are C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended version of our solar wind charge exchange (SWCX) emission model. Above 1 keV, we find Ikeya-Zhang to have strong emission lines at 1340 and 1850 eV which we identify as being created by SWCX lines of Mg XI and Si XIII, respectively, and weaker emission lines at 1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV, respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a significant level for the other comets in our sample (LS4, MH, Encke, 8P), and these lines promise additional diagnostics to be included in SWCX models. The silicon lines in the 1700-2000 eV range are detected for all comets, but with the rising background and decreasing cometary emission, we caution that these detections need further confirmation with higher resolution instruments.

  3. 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.

  4. 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.

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

    SciTech Connect

    Hartse, H.E.

    1997-11-01

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

  6. 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.

  7. Prediction Model of the Geosynchronous Electron Fluxes at a Wide Energy Range Based on a Neural Network Scheme

    NASA Astrophysics Data System (ADS)

    Shin, D. K.; Lee, D. Y.; Kim, K. C.

    2014-12-01

    The orbit in the range 2 to 7 Re (earth radii), which include the geosynchronous orbit, is known to be filled with particles of various energies. High flux levels of energetic electrons can cause irreparable damage to the instruments and equipment on satellites. Significant problems in satellite systems due to flux enhancement have promoted development of electron flux prediction model. In this study, we adopted a neural network technique to prediction the electron flux in a geosynchronous orbit. Solar wind data and geomagnetic indices are used for input parameter of neural network. As a result, we present combinations of solar wind and geomagnetic indices that show highest prediction efficiency. Our prediction model can predict the typical substorm-associated energetic (~40-400 keV) and relativistic-energy (> 0.8 MeV, > 2 MeV) electron fluxes up to 24 hours ahead with a reasonably good prediction efficiency.

  8. High flux reactor

    DOEpatents

    Lake, James A.; Heath, Russell L.; Liebenthal, John L.; DeBoisblanc, Deslonde R.; Leyse, Carl F.; Parsons, Kent; Ryskamp, John M.; Wadkins, Robert P.; Harker, Yale D.; Fillmore, Gary N.; Oh, Chang H.

    1988-01-01

    A high flux reactor is comprised of a core which is divided into two symetric segments housed in a pressure vessel. The core segments include at least one radial fuel plate. The spacing between the plates functions as a coolant flow channel. The core segments are spaced axially apart such that a coolant mixing plenum is formed between them. A channel is provided such that a portion of the coolant bypasses the first core section and goes directly into the mixing plenum. The outlet coolant from the first core segment is mixed with the bypass coolant resulting in a lower inlet temperature to the lower core segment.

  9. Thermal flux transfer system

    NASA Technical Reports Server (NTRS)

    Freggens, R. A. (Inventor)

    1973-01-01

    A thermal flux transfer system for use in maintaining the thrust chamber of an operative reaction motor at given temperatures is described. The system is characterized by an hermetically sealed chamber surrounding a thrust chamber to be cooled, with a plurality of parallel, longitudinally spaced, disk-shaped wick members formed of a metallic mesh and employed in delivering a working fluid, in its liquid state, radially toward the thrust chamber and delivering the working fluid, in its vapor state, away from the nozzle for effecting a cooling of the nozzle, in accordance with known principles of an operating heat pipe.

  10. The Angular Distribution of Quiet-time ~20-300 keV Superhalo Electrons in the Solar Wind

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    The angular distribution of solar wind superhalo electrons carries important information on the electron acceleration location and scattering in the interplanetary medium. Here we present a comprehensive study of the angular distribution of ~20-300 keV superhalo electrons measured at 1 AU by the WIND 3DP instrument during quiet-time periods from 1995 January through 2013 December. For quiet-time intervals, we re-bin the observed electron pitch angle distributions into the outward-traveling and inward-traveling bins, according the direction of interplanetary magnetic field (IMF). The inward-outward anisotropy of superhalo electrons at energy E is defined as A = 2(fout - fin)/(fout + fin), where fout (fin) is the average flux of outward-traveling (inward-traveling) electrons. We find that among all the ~640 quiet-time intervals, ~5% have an A > 0.1 (referred to as "outward events"), ~5% have an A < -0.1 (referred to as "inward events"), and ~90% have an |A| ≤ 0.1 (referred to as "isotropic events"). Isotropic events show no clear correlation with solar wind parameters (nSW, Vsw and Tp), IMF and solar wind turbulence spectrum. Inward and outward events also have no association with the IMF and nSW. But the occurrence ratio of outward (inward) events over all the events, α, roughly decreases (increases) with increasing VSW. Moreover, for outward (inward) events, α roughly increases with ρe/ρTp, where ρTp is the solar wind thermal proton gyroradius that is related to the separation between the turbulence inertial and dissipation ranges. These results suggest that quite-time superhalo electrons are generally isotropic due to the wave-particle interaction in the interplanetary medium; outward-traveling (inward-traveling) superhalo electrons may come from the acceleration occurring beyond (within) 1 AU, probably by CIRs or turbulence. We will also present a case study of several quiet-time electron events with the anisotropy A increasing with the electron energy E.

  11. 6 CFR 15.50 - Program accessibility; existing facilities.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... ENFORCEMENT OF NONDISCRIMINATION ON THE BASIS OF DISABILITY IN PROGRAMS OR ACTIVITIES CONDUCTED BY THE... Department shall operate each program or activity so that the program or activity, when viewed in its... result in a fundamental alteration in the nature of a program or activity or in undue financial...

  12. 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...

  13. 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...

  14. 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...

  15. Discovery of soft X-ray flux from 2A 1102+384 = Markarian 421

    NASA Technical Reports Server (NTRS)

    Hearn, D. R.; Marshall, F. J.; Jernigan, J. G.

    1979-01-01

    During April 1976 a soft X-ray flux was detected with SAS 3 from the vicinity of 2A 1102+384. The average flux densities were 4.3 x 10 to the -11th and 14 x 10 to the -11th erg/sq cm per sec in the energy bands 0.1-0.28 keV and 1-6 keV, respectively. There is an indication of variability over about 0.5 day in the lowest energy band. An upper limit of 3 x 10 to the 20th H atoms per sq cm is found for the gas column density to the X-ray source. In May 1978, observations with the modulation collimators of SAS 3 yielded an accurate (40 arcsec error radius) position for the X-ray source (2-6 keV) at right ascension 11 h 1 m 39.7 s, declination + 38 deg 28 min 51 sec (equinox 1950). The earlier tentative identification by Ricketts et al. (1976) with the BL Lacertae object B2 1101+38 = Markarian 421 is thus confirmed.

  16. Flux Rope Acceleration and Enhanced Magnetic Reconnection Rate

    SciTech Connect

    C.Z. Cheng; Y. Ren; G.S. Choe; Y.-J. Moon

    2003-03-25

    A physical mechanism of flares, in particular for the flare rise phase, has emerged from our 2-1/2-dimensional resistive MHD simulations. The dynamical evolution of current-sheet formation and magnetic reconnection and flux-rope acceleration subject to continuous, slow increase of magnetic shear in the arcade are studied by employing a non-uniform anomalous resistivity in the reconnecting current sheet under gravity. The simulation results directly relate the flux rope's accelerated rising motion with an enhanced magnetic reconnection rate and thus an enhanced reconnection electric field in the current sheet during the flare rise phase. The simulation results provide good quantitative agreements with observations of the acceleration of flux rope, which manifests in the form of SXR ejecta or erupting filament or CMEs, in the low corona. Moreover, for the X-class flare events studied in this paper the peak reconnection electric field is about O(10{sup 2} V/m) or larger, enough to accelerate p articles to over 100 keV in a field-aligned distance of 10 km. Nonthermal electrons thus generated can produce hard X-rays, consistent with impulsive HXR emission observed during the flare rise phase.

  17. Flux qubit as a sensor of magnetic flux

    NASA Astrophysics Data System (ADS)

    Il'ichev, E.; Greenberg, Ya. S.

    2007-03-01

    A magnetometer based on the quantum properties of a superconducting flux qubit is proposed. The main advantage of this device is that its sensitivity can be below the so-called "standard quantum limit" (for an oscillator this is half of the Plank constant). Moreover its transfer functions relative to the measured flux can be made to be about 10 mV/Φ0, which is an order of magnitude more than the best value for a conventional DC SQUIDs with a direct readout. We analyze here the voltage-to-flux, the phase-to-flux transfer functions and the main noise sources. We show that the experimental characteristics of a flux qubit, obtained in recent experiments, allow the use of a flux qubit as magnetometer with energy resolution close to the Planck constant.

  18. Deep mantle subduction flux

    NASA Astrophysics Data System (ADS)

    Porter, Katherine A.; White, William M.

    2009-12-01

    We assess the flux of incompatible trace elements into the deep mantle in the Aleutian, Central America, Izu-Bonin, Kurile, Lesser Antilles, Mariana, Sunda, and Tonga subduction zones. We use a simple mass balance approach in which we assume that all of the material lost from the subducting crust and sediment (the "slab") is incorporated into the magmas erupted above the subduction zone, and we use these assumptions to calculate a residual slab composition. The calculated residual slabs are enriched in incompatible elements compared to mid-ocean ridge basalts and highly enriched compared to primitive or depleted mantle. Almost all of the subducted Nb, Ta, and intermediate and heavy rare earths survive into the deep mantle, as do most of the light rare earths. On average, 73% of Th and Pb, 74% of K, 79% of U, 80% of Rb, 80% of Sr, and 82% of Ba survive into the deep mantle. Pb/Ce ratios are systematically lower, and Nb/U ratios are systematically higher, in the deep mantle flux than they are in the flux of material into the trench. Nevertheless, most residual slabs have Pb/Ce and Nb/U ratios outside the typical mantle range. Changes to U/Pb and Th/U ratios tend to be small and are not systematic. Rb/Sr ratios significantly decrease in some subduction zones but increase in others. In contrast, Sm/Nd ratios increase by small but significant amounts in most arcs. Based on these results, we attempt to predict the Sr, Nd, and Pb composition of anciently recycled material now in the mantle. We find that such material would most resemble enriched mantle II-type oceanic island basalts (OIB). None of our calculated residual slabs would evolve to Sr-Nd-Pb isotopic compositions similar to either high 238U/204Pb or enriched mantle I. The range of Sr and Pb isotope ratios in anciently recycled material is similar to that seen in modern OIB, but Nd isotopic compositions do not range to ɛNd values as low as those in some modern OIB. Neither radiogenic nor unradiogenic Pb isotope

  19. 200 keV Xe+ ions irradiation effects on Zr-Ti binary films

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  20. 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

  1. 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.

  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. Point Defect Cluster Formation in Iron Displacement Cascades Up to 50 keV

    SciTech Connect

    Stoller, R.E.

    1998-11-30

    The results of molecular dynamics displacement cascade simulations in iron at energies up to 50 keV and temperatures of 100, 600, and 900K are summarized, with a focus on the characterization of interstitial and vacancy clusters that are formed directly within the cascade. The fraction of the surviving point defects contained in clusters, and the size distributions of these in-cascade clusters have been determined. Although the formation of true vacancy clusters appears to be inhibited in iron, a significant degree of vacancy site correlation was observed. These well correlated arrangements of vacancies can be considered nascent clusters, and they have been observed to coalesce during longer term Monte Carlo simulations which permit short range vacancy diffusion. Extensive interstitial clustering was observed. The temperature and cascade energy dependence of the cluster size distributions are discussed in terms of their relevance to microstructural evolution and mechanical property changes in irradiated iron-based alloys.

  4. A 75-keV, 145-mA proton injector

    SciTech Connect

    Figueroa, T. L.; Hansborough, L. D.; Kerstiens, D. M.; Schneider, J. D.; Smith, H. V.; Stettler, M. W.; Thuot, M. E.; Warren, D. S.; Zaugg, T. J.; Arvin, A. A.; Bolt, A. S.; Sherman, Joseph D.

    2001-01-01

    A dc and pulsed-mode 75-keV proton injector has been developed and is used in characterization of a continuous-wave (cw) 6.7-MeV, 100-mA radio-frequency quadrupole (RFQ). The injector is used frequently at the full RFQ design power (100-mA, 6.7-MeV) where the RFQ admittance (1rms, normalized) is 0.23 ({pi}mm-mrad). The injector includes a 2.45-GHz microwave proton source and a beam space-charge-neutralized, two magnetic-solenoid, low-energy beam-transport system (LEBT). The design RFQ beam transmission of 95% has been demonstrated at 100-mA RFQ output current.

  5. 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.

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

    SciTech Connect

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

    2008-07-08

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

  7. A 9 keV electron-impact liquid-gallium-jet x-ray source

    SciTech Connect

    Otendal, M.; Tuohimaa, T.; Vogt, U.; Hertz, H. M.

    2008-01-15

    We demonstrate a high-brightness compact 9 keV electron-impact microfocus x-ray source based on a liquid-gallium-jet anode. A {approx}30 W, 50 kV electron gun is focused onto the {approx}20 m/s, 30 {mu}m diameter liquid-gallium-jet anode to produce an {approx}10 {mu}m full width at half maximum x-ray spot. The peak spectral brightness is >2x10{sup 10} photons/(s mm{sup 2} mrad{sup 2}x0.1% BW). Calculation and experiments show potential for increasing this brightness by approximately three orders of magnitude, making the source suitable for laboratory-scale x-ray crystallography and hard x-ray microscopy.

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

    PubMed

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

    2014-09-12

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

  9. 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.

  10. Ion Source Development For The Proposed FNAL 750 keV Injector Upgrade

    SciTech Connect

    Bollinger, D. S.

    2011-09-26

    Currently there is a Proposed FNAL 750 keV Injector Upgrade for the replacement of the 40 year old Fermi National Laboratory (FNAL) Cockcroft-Walton accelerators with a new ion source and 200 MHz Radio Frequency Quadruple (RFQ). The slit type magnetron being used now will be replaced with a round aperture magnetron similar to the one used at Brookhaven National Lab (BNL). Operational experience from BNL has shown that this type of source is more reliable with a longer lifetime due to better power efficiency. The current source development effort is to produce a reliable source with >60 mA of H{sup -} beam current, 15 Hz rep-rate, 100 {mu}s pulse width, and a duty factor of 0.15%. The source will be based on the BNL design along with development done at FNAL for the High Intensity Neutrino Source (HINS).

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

    SciTech Connect

    Bollinger, D.S.; /Fermilab

    2010-11-01

    Currently there is a Proposed FNAL 750keV Injector Upgrade for the replacement of the 40 year old Fermi National Laboratory (FNAL) Cockcroft-Walton accelerators with a new ion source and 200MHz Radio Frequency Quadruple (RFQ). The slit type magnetron being used now will be replaced with a round aperture magnetron similar to the one used at Brookhaven National Lab (BNL). Operational experience from BNL has shown that this type of source is more reliable with a longer lifetime due to better power efficiency. The current source development effort is to produce a reliable source with >60mA of H- beam current, 15Hz rep-rate, 100s pulse width, and a duty factor of 0.15%. The source will be based on the BNL design along with development done at FNAL for the High Intensity Neutrino Source (HINS).

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

    DOE PAGES

    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

  13. 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.

  14. Spectroscopy in the 10 keV to 10 MeV range

    NASA Technical Reports Server (NTRS)

    Matteson, J. L.

    1981-01-01

    Spectral lines in the 10 keV to 1 MeV range carry information of fundamental importance on many astronomical objects. Since the lines are directly related to specific physical processes this information is model independent and gives the physical conditions in the objects. At the sensitivities achieved to date, approximately 0.0001 to 0.001 phsq cm. sec for steady sources and approximately 0.01 to 1 ph/sq cm sec for transient sources, lines were detected from the galactic center, gamma-ray bursts and transients, X-ray pulsators, the Crab pulsar and solar flares. Future instruments with a factor of approximately 100 sensitivity improvement will allow detailed spectroscopic study of these classes of objects as well as supernova remnants, active galaxies and the interstellar medium. This sensitivity improvement can be obtained through the use of detector technology already proven in balloon and satellite instruments.

  15. A neutron source with an effective energy of 0-5 keV.

    PubMed

    Harvey, J R; Bending, R C

    1976-01-01

    Calculations indicate that an assembly consisting of an antimony-beryllium source at the centre of a 4 cm radius water sphere surrounded by a 1 mm thick shell of boron-10 will emit neutrons with a broad spectrum at intermediate energies. A device based on this design was constructed using a water-filled, boron-carbide loaded, plastic shell with an antimony-beryllium source located at the centre. The output spectrum was calculated by Monte Carlo program and the computed total yield agreed well with measurements made with a manganese bath system. The main peak has an effective energy of 0-5 keV and the total yield is 18% of the antimony-beryllium source strength. Experience with this source suggests some possible avenues for future development.

  16. Multigap RPC time resolution to 511 keV annihilation photons

    NASA Astrophysics Data System (ADS)

    Belli, G.; Gabusi, M.; Musitelli, G.; Nardò, R.; Ratti, S. P.; Tamborini, A.; Vitulo, P.

    2015-05-01

    The time resolution of Multigap Resistive Plate Chambers (MRPCs) to 511 keV gamma rays has been investigated using a 22Na source and four detectors. The MRPCs time resolution has been derived from the Time-of-Flight information, measured from pairs of space correlated triggered events. A GEANT4 simulation has been performed to analyze possible setup contributions and to support experimental results. A time resolution (FWHM) of 312 ps and 376 ps has been measured for a single MRPC with four 250 μm gas gaps by considering respectively one and two independent pairs of detectors. These values, endorsed by the GEANT4 simulation, represent a good result compared to those reported in the literature.

  17. 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.

  18. 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.

  19. 200 keV electron mini-accelerators for scientific and applied purposes

    NASA Astrophysics Data System (ADS)

    Kazarezov, I. V.

    2006-12-01

    Created in BINP, 200 keV electron mini-accelerators with different types of high voltage generators are described: cascade generator with serial capacitance connection generator with high voltage step-up transformer and voltage-doubling circuit of rectification generators on the base of pulse and Tesla step-up transformers. Described are their circuit and design performance peculiarities and fields of application.

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  1. 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.}

  2. 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.

  3. 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.

  4. Permanent magnet flux-biased magnetic actuator with flux feedback

    NASA Technical Reports Server (NTRS)

    Groom, Nelson J. (Inventor)

    1991-01-01

    The invention is a permanent magnet flux-biased magnetic actuator with flux feedback for adjustably suspending an element on a single axis. The magnetic actuator includes a pair of opposing electromagnets and provides bi-directional forces along the single axis to the suspended element. Permanent magnets in flux feedback loops from the opposing electromagnets establish a reference permanent magnet flux-bias to linearize the force characteristics of the electromagnets to extend the linear range of the actuator without the need for continuous bias currents in the electromagnets.

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

    PubMed

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

    1997-01-01

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

  6. 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.

  7. 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.

  8. Canalization: what the flux?

    PubMed

    Bennett, Tom; Hines, Geneviève; Leyser, Ottoline

    2014-02-01

    Polarized transport of the hormone auxin plays crucial roles in many processes in plant development. A self-organizing pattern of auxin transport--canalization--is thought to be responsible for vascular patterning and shoot branching regulation in flowering plants. Mathematical modeling has demonstrated that membrane localization of PIN-FORMED (PIN)-family auxin efflux carriers in proportion to net auxin flux can plausibly explain canalization and possibly other auxin transport phenomena. Other plausible models have also been proposed, and there has recently been much interest in producing a unified model of all auxin transport phenomena. However, it is our opinion that lacunae in our understanding of auxin transport biology are now limiting progress in developing the next generation of models. Here we examine several key areas where significant experimental advances are necessary to address both biological and theoretical aspects of auxin transport, including the possibility of a unified transport model.

  9. Methods of SREM channel counts to particle fluxes conversion

    NASA Astrophysics Data System (ADS)

    Marinov, Dilyan; Hajdas, Wojtek; Desorgher, Laurent; Buehler, Paul; Evans, Hugh; Nieminen, Petteri

    The ESA Standard Radiation Environment Monitor (SREM) is a particle detector capable of detection of electrons (E > 500 keV) and protons (E > 8 MeV) with fair spectral and angular resolution. Six SREM instruments have already been launched onboard of Proba-1, Rosetta, INTEGRAL, Giove-B, Herschel and Planck missions, providing the opportunity of correlated space weather observations. In this activity, a number of techniques to extract particle spectra, identify proton and electron environments and estimate anisotropy of fluxes have been studied. Several methods based on neural networks and minimization algorithms with various spectral regularizations have been developed and analysed. Detailed performance evaluation including error propagation analysis will be provided. Strengths and weaknesses of different approaches will be compared using both artificially generated data as well as real measurements from space.

  10. Polar cap auroral electron fluxes observed with Isis 1

    NASA Technical Reports Server (NTRS)

    Winningham, J. D.; Heikkila, W. J.

    1974-01-01

    Three types of auroral particle precipitation have been observed over the polar caps, well inside the auroral oval, by means of the soft particle spectrometer on the Isis 1 satellite. The first type is a uniform, very soft (about 100 eV) electron 'polar rain' over the entire polar cap; this may well be present with very weak intensity at all times, but it is markedly enhanced during worldwide geomagnetic storms. A second type of precipitation is a structured flux of electrons with energies near 1 keV, suggestive of localized 'polar showers'; it seems likely that these are the cause of the sun-aligned auroral arcs that have been observed during moderately quiet conditions. During periods of intense magnetic disturbance this precipitation can become very intense and exhibit a characteristic pattern that we have come to call a 'polar squall'.

  11. 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.

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

    SciTech Connect

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

    2015-09-22

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

  13. Interplanetary magnetic field connection to the sun during electron heat flux dropouts in the solar wind

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Kahler, S. W.

    1992-01-01

    The paper discusses observations of 2- to 8.5-keV electrons, made by measurements aboard the ISEE 3 spacecraft during the periods of heat flux decreases (HFDs) reported by McComas et al. (1989). In at least eight of the total of 25 HFDs observed, strong streaming of electrons that were equal to or greater than 2 keV outward from the sun was recorded. In one HFD, an impulsive solar electron event was observed with an associated type III radio burst, which could be tracked from the sun to about 1 AU. It is concluded that, in many HFDs, the interplanetary field is still connected to the sun and that some energy-dependent process may produce HFDs without significantly perturbing electrons of higher energies.

  14. Quantum tunneling in flux compactifications

    NASA Astrophysics Data System (ADS)

    Blanco-Pillado, Jose J.; Schwartz-Perlov, Delia; Vilenkin, Alexander

    2009-12-01

    We identify instantons representing vacuum decay in a 6-dimensional toy model for string theory flux compactifications, with the two extra dimensions compactified on a sphere. We evaluate the instanton action for tunneling between different flux vacua, as well as for the decompactification decay channel. The bubbles resulting from flux tunneling have an unusual structure. They are bounded by two-dimensional branes, which are localized in the extra dimensions. This has important implications for bubble collisions.

  15. SEPARATION OF THE RIBBON FROM GLOBALLY DISTRIBUTED ENERGETIC NEUTRAL ATOM FLUX USING THE FIRST FIVE YEARS OF IBEX OBSERVATIONS

    SciTech Connect

    Schwadron, N. A.; Moebius, E.; Kucharek, H.; Lee, M. A.; Fairchild, K.; Fuselier, S. A.; McComas, D. J.; Allegrini, F.; Dayeh, M.; Livadiotis, G.; Reno, M.; Funsten, H. O.; Janzen, P.; Reisenfeld, D.; Bzowski, M.; Sokół, J. M.; Kubiak, M. A.; Christian, E. R.; DeMajistre, R.; Frisch, P.; and others

    2014-11-01

    The Interstellar Boundary Explorer (IBEX) observes the IBEX ribbon, which stretches across much of the sky observed in energetic neutral atoms (ENAs). The ribbon covers a narrow (∼20°-50°) region that is believed to be roughly perpendicular to the interstellar magnetic field. Superimposed on the IBEX ribbon is the globally distributed flux that is controlled by the processes and properties of the heliosheath. This is a second study that utilizes a previously developed technique to separate ENA emissions in the ribbon from the globally distributed flux. A transparency mask is applied over the ribbon and regions of high emissions. We then solve for the globally distributed flux using an interpolation scheme. Previously, ribbon separation techniques were applied to the first year of IBEX-Hi data at and above 0.71 keV. Here we extend the separation analysis down to 0.2 keV and to five years of IBEX data enabling first maps of the ribbon and the globally distributed flux across the full sky of ENA emissions. Our analysis shows the broadening of the ribbon peak at energies below 0.71 keV and demonstrates the apparent deformation of the ribbon in the nose and heliotail. We show global asymmetries of the heliosheath, including both deflection of the heliotail and differing widths of the lobes, in context of the direction, draping, and compression of the heliospheric magnetic field. We discuss implications of the ribbon maps for the wide array of concepts that attempt to explain the ribbon's origin. Thus, we present the five-year separation of the IBEX ribbon from the globally distributed flux in preparation for a formal IBEX data release of ribbon and globally distributed flux maps to the heliophysics community.

  16. Separation of the Ribbon from Globally Distributed Energetic Neutral Atom Flux Using the First Five Years of IBEX Observations

    NASA Astrophysics Data System (ADS)

    Schwadron, N. A.; Moebius, E.; Fuselier, S. A.; McComas, D. J.; Funsten, H. O.; Janzen, P.; Reisenfeld, D.; Kucharek, H.; Lee, M. A.; Fairchild, K.; Allegrini, F.; Dayeh, M.; Livadiotis, G.; Reno, M.; Bzowski, M.; Sokół, J. M.; Kubiak, M. A.; Christian, E. R.; DeMajistre, R.; Frisch, P.; Galli, A.; Wurz, P.; Gruntman, M.

    2014-11-01

    The Interstellar Boundary Explorer (IBEX) observes the IBEX ribbon, which stretches across much of the sky observed in energetic neutral atoms (ENAs). The ribbon covers a narrow (~20°-50°) region that is believed to be roughly perpendicular to the interstellar magnetic field. Superimposed on the IBEX ribbon is the globally distributed flux that is controlled by the processes and properties of the heliosheath. This is a second study that utilizes a previously developed technique to separate ENA emissions in the ribbon from the globally distributed flux. A transparency mask is applied over the ribbon and regions of high emissions. We then solve for the globally distributed flux using an interpolation scheme. Previously, ribbon separation techniques were applied to the first year of IBEX-Hi data at and above 0.71 keV. Here we extend the separation analysis down to 0.2 keV and to five years of IBEX data enabling first maps of the ribbon and the globally distributed flux across the full sky of ENA emissions. Our analysis shows the broadening of the ribbon peak at energies below 0.71 keV and demonstrates the apparent deformation of the ribbon in the nose and heliotail. We show global asymmetries of the heliosheath, including both deflection of the heliotail and differing widths of the lobes, in context of the direction, draping, and compression of the heliospheric magnetic field. We discuss implications of the ribbon maps for the wide array of concepts that attempt to explain the ribbon's origin. Thus, we present the five-year separation of the IBEX ribbon from the globally distributed flux in preparation for a formal IBEX data release of ribbon and globally distributed flux maps to the heliophysics community.

  17. Heat-Flux-Measuring Facility

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.; Weikle, Donald H.

    1990-01-01

    Apparatus simulates conditions in turbine engines. Automated facility generates and measures transient and steady-state heat fluxes at flux densities from 0.3 to 6 MW/m(Sup2) and temperatures from 100 to 1,200 K. Positioning arm holds heat-flux gauge at focal point of arc lamp. Arm previously chilled gauge in liquid nitrogen in Dewar flask. Cooling water flows through lamp to heat exchanger. Used to develop heat-flux gauges for turbine blades and to test materials for durability under rapidly changing temperatures.

  18. Measuring surface fluxes in CAPE

    NASA Technical Reports Server (NTRS)

    Kanemasu, E. T.; D-Shah, T.; Nie, Dalin

    1992-01-01

    Two stations (site 1612 and site 2008) were operated by the University of Georgia group from 6 July 1991 to 18 August 1991. The following data were collected continuously: surface energy fluxes (i.e., net radiation, soil heat fluxes, sensible heat flux and latent heat flux), air temperature, vapor pressure, soil temperature (at 1 cm depth), and precipitation. Canopy reflectance and light interception data were taken three times at each site between 6 July and 18 August. Soil moisture content was measured twice at each site.

  19. 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.

  20. 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.

  1. KoFlux: Korean Regional Flux Network in AsiaFlux

    NASA Astrophysics Data System (ADS)

    Kim, J.

    2002-12-01

    AsiaFlux, the Asian arm of FLUXNET, held the Second International Workshop on Advanced Flux Network and Flux Evaluation in Jeju Island, Korea on 9-11 January 2002. In order to facilitate comprehensive Asia-wide studies of ecosystem fluxes, the meeting launched KoFlux, a new Korean regional network of long-term micrometeorological flux sites. For a successful assessment of carbon exchange between terrestrial ecosystems and the atmosphere, an accurate measurement of surface fluxes of energy and water is one of the prerequisites. During the 7th Global Energy and Water Cycle Experiment (GEWEX) Asian Monsoon Experiment (GAME) held in Nagoya, Japan on 1-2 October 2001, the Implementation Committee of the Coordinated Enhanced Observing Period (CEOP) was established. One of the immediate tasks of CEOP was and is to identify the reference sites to monitor energy and water fluxes over the Asian continent. Subsequently, to advance the regional and global network of these reference sites in the context of both FLUXNET and CEOP, the Korean flux community has re-organized the available resources to establish a new regional network, KoFlux. We have built up domestic network sites (equipped with wind profiler and radiosonde measurements) over deciduous and coniferous forests, urban and rural rice paddies and coastal farmland. As an outreach through collaborations with research groups in Japan, China and Thailand, we also proposed international flux sites at ecologically and climatologically important locations such as a prairie on the Tibetan plateau, tropical forest with mixed and rapid land use change in northern Thailand. Several sites in KoFlux already begun to accumulate interesting data and some highlights are presented at the meeting. The sciences generated by flux networks in other continents have proven the worthiness of a global array of micrometeorological flux towers. It is our intent that the launch of KoFlux would encourage other scientists to initiate and

  2. Learning to Apply Metrology Principles to the Measurement of X-ray Intensities in the 500 eV to 110 keV Energy Range

    SciTech Connect

    Haugh, M. J.; Pond, T.; Silbernagel, C.; Torres, P.; Marlett, K.; Goldin, F.; Cyr, S.

    2011-02-08

    National Security Technologies, LLC (NSTec), Livermore Operations, has two optical radiation calibration laboratories accredited by “the National Voluntary Laboratories Accreditation Program (NVLAP) which is the accrediting body of” the National Institute of Standards and Technology (NIST), and is now working towards accreditation for its X-ray laboratories. NSTec operates several laboratories with X-ray sources that generate X-rays in the energy range from 50 eV to 115 keV. These X-ray sources are used to characterize and calibrate diagnostics and diagnostic components used by the various national laboratories, particularly for plasma analysis on the Lawrence Livermore National Laboratory (LLNL) National Ignition Facility (NIF). Because X-ray photon flux measurement methods that can be accredited, i.e., traceable to NIST, have not been developed for sources operating in these energy ranges, NSTec, NIST, and the National Voluntary Accreditation Program (NVLAP) together have defined a path toward the development and validation of accredited metrology methods for X-ray energies. The methodology developed for the high energy X-ray (HEX) Laboratory was NSTec’s starting point for X-ray metrology accreditation and will be the basis for the accredited processes in the other X-ray laboratories. This paper will serve as a teaching tool, by way of this example using the NSTec X-ray sources, for the process and methods used in developing an accredited traceable metrology.

  3. International Fusion Materials Irradiation Facility injector acceptance tests at CEA/Saclay: 140 mA/100 keV deuteron beam characterization.

    PubMed

    Gobin, R; Bogard, D; Cara, P; Chauvin, N; Chel, S; Delferrière, O; Harrault, F; Mattei, P; Mosnier, A; Senée, F; Shidara, H; Okumura, Y

    2014-02-01

    In the framework of the ITER broader approach, the International Fusion Materials Irradiation Facility (IFMIF) deuteron accelerator (2 × 125 mA at 40 MeV) is an irradiation tool dedicated to high neutron flux production for future nuclear plant material studies. During the validation phase, the Linear IFMIF Prototype Accelerator (LIPAc) machine will be tested on the Rokkasho site in Japan. This demonstrator aims to produce 125 mA/9 MeV deuteron beam. Involved in the LIPAc project for several years, specialists from CEA/Saclay designed the injector based on a SILHI type ECR source operating at 2.45 GHz and a 2 solenoid low energy beam line to produce such high intensity beam. The whole injector, equipped with its dedicated diagnostics, has been then installed and tested on the Saclay site. Before shipment from Europe to Japan, acceptance tests have been performed in November 2012 with 100 keV deuteron beam and intensity as high as 140 mA in continuous and pulsed mode. In this paper, the emittance measurements done for different duty cycles and different beam intensities will be presented as well as beam species fraction analysis. Then the reinstallation in Japan and commissioning plan on site will be reported.

  4. International Fusion Materials Irradiation Facility injector acceptance tests at CEA/Saclay: 140 mA/100 keV deuteron beam characterization

    SciTech Connect

    Gobin, R. Bogard, D.; Chauvin, N.; Chel, S.; Delferrière, O.; Harrault, F.; Mattei, P.; Senée, F.; Mosnier, A.; Shidara, H.

    2014-02-15

    In the framework of the ITER broader approach, the International Fusion Materials Irradiation Facility (IFMIF) deuteron accelerator (2 × 125 mA at 40 MeV) is an irradiation tool dedicated to high neutron flux production for future nuclear plant material studies. During the validation phase, the Linear IFMIF Prototype Accelerator (LIPAc) machine will be tested on the Rokkasho site in Japan. This demonstrator aims to produce 125 mA/9 MeV deuteron beam. Involved in the LIPAc project for several years, specialists from CEA/Saclay designed the injector based on a SILHI type ECR source operating at 2.45 GHz and a 2 solenoid low energy beam line to produce such high intensity beam. The whole injector, equipped with its dedicated diagnostics, has been then installed and tested on the Saclay site. Before shipment from Europe to Japan, acceptance tests have been performed in November 2012 with 100 keV deuteron beam and intensity as high as 140 mA in continuous and pulsed mode. In this paper, the emittance measurements done for different duty cycles and different beam intensities will be presented as well as beam species fraction analysis. Then the reinstallation in Japan and commissioning plan on site will be reported.

  5. Statistical properties of local active galactic nuclei inferred from the RXTE 3-20 keV all-sky survey

    NASA Astrophysics Data System (ADS)

    Sazonov, S. Yu.; Revnivtsev, M. G.

    2004-08-01

    We compiled a sample of 95 AGNs serendipitously detected in the 3-20 keV band at Galactic latitude |b|>10o during the RXTE slew survey (XSS, Revnivtsev et al. 2004), and utilize it to study the statistical properties of the local population of AGNs, including the X-ray luminosity function and absorption distribution. We find that among low X-ray luminosity (L3-20< 1043.5 erg s-1) AGNs, the ratio of absorbed (characterized by intrinsic absorption in the range 1022 cm-21041 erg s-1 estimated here is smaller than the earlier estimated total X-ray volume emissivity in the local Universe, suggesting that a comparable X-ray flux may be produced together by lower luminosity AGNs, non-active galaxies and clusters of galaxies. Finally, we present a sample of 35 AGN candidates, composed of unidentified XSS sources. Tables 1 and 2 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/423/469

  6. Carbon Dioxide Flux Measurement Systems (CO2Flux) Handbook

    SciTech Connect

    Fischer, M

    2005-01-01

    The Southern Great Plains (SGP) carbon dioxide flux (CO2 flux) measurement systems provide half-hour average fluxes of CO2, H2O (latent heat), and sensible heat. The fluxes are obtained by the eddy covariance technique, which computes the flux as the mean product of the vertical wind component with CO2 and H2O densities, or estimated virtual temperature. A three-dimensional sonic anemometer is used to obtain the orthogonal wind components and the virtual (sonic) temperature. An infrared gas analyzer is used to obtain the CO2 and H2O densities. A separate sub-system also collects half-hour average measures of meteorological and soil variables from separate 4-m towers.

  7. Comprehensive Flux Occurrence Statistics at Geosynchronous Orbit

    NASA Astrophysics Data System (ADS)

    Thomsen, M. F.; Denton, M. H.; Bodeau, M.

    2005-12-01

    Geosynchronous orbit, the distance at which the orbital period around the Earth is 24 hours, is home to more than 200 satellites. From a space weather perspective, the environment in this orbit is highly variable and far from benign. Satellites exposed to these harsh conditions are subject to episodes of deep dielectric charging, surface charging, solar panel degradation, single event upsets, radiation degradation of optical coatings and paints, and other deleterious effects. Either suddenly or gradually over time, such effects can cause catastrophic or simply lifetime-shortening consequences for satellite systems. To protect against these environmental effects, spacecraft designers need to know quantitatively what the nature of the environment is likely to be over the design lifetime of their satellites. In recent years a number of such statistical analyses have been conducted, demonstrating the systematic dependence of geosynchronous plasma properties on orbital position, geomagnetic activity, and phase of the solar cycle. These studies have helped illuminate the physical processes that govern the nature of the plasma at geosynchronous orbit, but they do not provide a condensed description of the environment that is suitable for use by spacecraft designers. We report here a definitive statistical characterization of the geosynchronous environment that will be more useful for such purposes. The analysis is based on the LANL MPA geosynchronous plasma dataset, which now comprises more than 70 satellite-years of measurements extending well over a full solar cycle. We present the flux occurrence statistics of ions and electrons with energies in the range from ~1 eV to ~45 keV, covering the populations that are responsible for satellite surface charging and radiation damage to surface materials, and that provide the source for the higher-energy ring current and radiation belts. Significant differences have been found in long-term averages compared to the AE-8, AP-8

  8. 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.

  9. 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.

  10. Flux Compression Magnetic Nozzle

    NASA Technical Reports Server (NTRS)

    Thio, Y. C. Francis; Schafer, Charles (Technical Monitor)

    2001-01-01

    In pulsed fusion propulsion schemes in which the fusion energy creates a radially expanding plasma, a magnetic nozzle is required to redirect the radially diverging flow of the expanding fusion plasma into a rearward axial flow, thereby producing a forward axial impulse to the vehicle. In a highly electrically conducting plasma, the presence of a magnetic field B in the plasma creates a pressure B(exp 2)/2(mu) in the plasma, the magnetic pressure. A gradient in the magnetic pressure can be used to decelerate the plasma traveling in the direction of increasing magnetic field, or to accelerate a plasma from rest in the direction of decreasing magnetic pressure. In principle, ignoring dissipative processes, it is possible to design magnetic configurations to produce an 'elastic' deflection of a plasma beam. In particular, it is conceivable that, by an appropriate arrangement of a set of coils, a good approximation to a parabolic 'magnetic mirror' may be formed, such that a beam of charged particles emanating from the focal point of the parabolic mirror would be reflected by the mirror to travel axially away from the mirror. The degree to which this may be accomplished depends on the degree of control one has over the flux surface of the magnetic field, which changes as a result of its interaction with a moving plasma.

  11. Errors in airborne flux measurements

    NASA Astrophysics Data System (ADS)

    Mann, Jakob; Lenschow, Donald H.

    1994-07-01

    We present a general approach for estimating systematic and random errors in eddy correlation fluxes and flux gradients measured by aircraft in the convective boundary layer as a function of the length of the flight leg, or of the cutoff wavelength of a highpass filter. The estimates are obtained from empirical expressions for various length scales in the convective boundary layer and they are experimentally verified using data from the First ISLSCP (International Satellite Land Surface Climatology Experiment) Field Experiment (FIFE), the Air Mass Transformation Experiment (AMTEX), and the Electra Radome Experiment (ELDOME). We show that the systematic flux and flux gradient errors can be important if fluxes are calculated from a set of several short flight legs or if the vertical velocity and scalar time series are high-pass filtered. While the systematic error of the flux is usually negative, that of the flux gradient can change sign. For example, for temperature flux divergence the systematic error changes from negative to positive about a quarter of the way up in the convective boundary layer.

  12. 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

  13. On Deriving Incident Auroral Particle Fluxes in the Daytime Using Combined Ground-Based Optical and Radar Measurements

    NASA Technical Reports Server (NTRS)

    Pallamraju, Duggirala; Chakrabarti, Supriya; Solomon, Stanley C.

    2011-01-01

    Particle energies and fluxes have predominantly been measured from instruments onboard satellites. In this study, we use daytime ground-based oxygen redline emission measurements, along with the ionospheric electron density, and electron temperature profiles measured from the incoherent scatter radar, and a physics-based modeling approach to derive the energy and flux of particles incident over Boston during the storm of 30 October 2003. We find that the characteristic energy and the associated flux vary between 0.07.5.7 keV and 0.5.130 mW/sq m, respectively, during the intense magnetic disturbance that brought aurora to midlatitudes. Such an approach not only offers another method to estimate the incident particle energies and fluxes but also enhances our understanding on the channels of energy deposition in the upper atmospheric region, especially during magnetic disturbances, about which database is poor.

  14. Designing with null flux coils

    SciTech Connect

    Davey, K.R.

    1997-09-01

    Null flux were suggested by Danby and Powell in the late 1960`s as a useful means for realizing induced lift with little drag. As an array of alternating magnets is translated past a set of null flux coils, the currents induced in these coils act to vertically center the magnets on those coils. At present, one Japanese MAGLEV system company and two American-based companies are employing either null flux or flux eliminating coils in their design for high speed magnetically levitated transportation. The principle question addressed in paper is: what is the proper choice of coil length to magnet length in a null flux system? A generic analysis in the time and frequency domain is laid out with the intent of showing the optimal design specification in terms of coil parameters.

  15. An empirical model of electron and ion fluxes derived from observations at geosynchronous orbit

    SciTech Connect

    Denton, M. H.; Thomsen, M. F.; Jordanova, V. K.; Henderson, M. G.; Borovsky, J. E.; Denton, J. S.; Pitchford, D.; Hartley, D. P.

    2015-04-01

    Knowledge of the plasma fluxes at geosynchronous orbit is important to both scientific and operational investigations. We present a new empirical model of the ion flux and the electron flux at geosynchronous orbit (GEO) in the energy range ~1 eV to ~40 keV. The model is based on a total of 82 satellite-years of observations from the Magnetospheric Plasma Analyzer instruments on Los Alamos National Laboratory satellites at GEO. These data are assigned to a fixed grid of 24 local-times and 40 energies, at all possible values of Kp. Bi-linear interpolation is used between grid points to provide the ion flux and the electron flux values at any energy and local-time, and for given values of geomagnetic activity (proxied by the 3-hour Kp index), and also for given values of solar activity (proxied by the daily F10.7 index). Initial comparison of the electron flux from the model with data from a Compact Environmental Anomaly Sensor II (CEASE-II), also located at geosynchronous orbit, indicate a good match during both quiet and disturbed periods. The model is available for distribution as a FORTRAN code that can be modified to suit user-requirements.

  16. An empirical model of electron and ion fluxes derived from observations at geosynchronous orbit

    NASA Astrophysics Data System (ADS)

    Denton, M. H.; Thomsen, M. F.; Jordanova, V. K.; Henderson, M. G.; Borovsky, J. E.; Denton, J. S.; Pitchford, D.; Hartley, D. P.

    2015-04-01

    Knowledge of the plasma fluxes at geosynchronous orbit is important to both scientific and operational investigations. We present a new empirical model of the ion flux and the electron flux at geosynchronous orbit (GEO) in the energy range ~1 eV to ~40 keV. The model is based on a total of 82 satellite years of observations from the magnetospheric plasma analyzer instruments on Los Alamos National Laboratory satellites at GEO. These data are assigned to a fixed grid of 24 local times and 40 energies, at all possible values of Kp. Bilinear interpolation is used between grid points to provide the ion flux and the electron flux values at any energy and local time, and for given values of geomagnetic activity (proxied by the 3 h Kp index), and also for given values of solar activity (proxied by the daily F10.7 index). Initial comparison of the electron flux from the model with data from a Compact Environmental Anomaly Sensor II, also located at geosynchronous orbit, indicates a good match during both quiet and disturbed periods. The model is available for distribution as a FORTRAN code that can be modified to suit user requirements.

  17. An empirical model of electron and ion fluxes derived from observations at geosynchronous orbit

    DOE PAGES

    Denton, M. H.; Thomsen, M. F.; Jordanova, V. K.; Henderson, M. G.; Borovsky, J. E.; Denton, J. S.; Pitchford, D.; Hartley, D. P.

    2015-04-01

    Knowledge of the plasma fluxes at geosynchronous orbit is important to both scientific and operational investigations. We present a new empirical model of the ion flux and the electron flux at geosynchronous orbit (GEO) in the energy range ~1 eV to ~40 keV. The model is based on a total of 82 satellite-years of observations from the Magnetospheric Plasma Analyzer instruments on Los Alamos National Laboratory satellites at GEO. These data are assigned to a fixed grid of 24 local-times and 40 energies, at all possible values of Kp. Bi-linear interpolation is used between grid points to provide the ionmore » flux and the electron flux values at any energy and local-time, and for given values of geomagnetic activity (proxied by the 3-hour Kp index), and also for given values of solar activity (proxied by the daily F10.7 index). Initial comparison of the electron flux from the model with data from a Compact Environmental Anomaly Sensor II (CEASE-II), also located at geosynchronous orbit, indicate a good match during both quiet and disturbed periods. The model is available for distribution as a FORTRAN code that can be modified to suit user-requirements.« less

  18. PHLUX: Photographic Flux Tools for Solar Glare and Flux

    2010-12-02

    A web-based tool to a) analytically and empirically quantify glare from reflected light and determine the potential impact (e.g., temporary flash blindness, retinal burn), and b) produce flux maps for central receivers. The tool accepts RAW digital photographs of the glare source (for hazard assessment) or the receiver (for flux mapping), as well as a photograph of the sun for intensity and size scaling. For glare hazard assessment, the tool determines the retinal irradiance (W/cm2)more » and subtended source angle for an observer and plots the glare source on a hazard spectrum (i.e., low-potential for flash blindness impact, potential for flash blindness impact, retinal burn). For flux mapping, the tool provides a colored map of the receiver scaled by incident solar flux (W/m2) and unwraps the physical dimensions of the receiver while accounting for the perspective of the photographer (e.g., for a flux map of a cylindrical receiver, the horizontal axis denotes receiver angle in degrees and the vertical axis denotes vertical position in meters; for a flat panel receiver, the horizontal axis denotes horizontal position in meters and the vertical axis denotes vertical position in meters). The flux mapping capability also allows the user to specify transects along which the program plots incident solar flux on the receiver.« less

  19. Flux growth utilizing the reaction between flux and crucible

    NASA Astrophysics Data System (ADS)

    Yan, J.-Q.

    2015-04-01

    Flux growth involves dissolving the components of the target compound in an appropriate flux at high temperatures and then crystallizing under supersaturation controlled by cooling or evaporating the flux. A refractory crucible is generally used to contain the high temperature melt. The reaction between the melt and crucible materials can modify the composition of the melt, which typically results in growth failure, or contaminates the crystals. Thus one principle in designing a flux growth is to select suitable flux and crucible materials thus to avoid any reaction between them. In this paper, we review two cases of flux growth in which the reaction between flux and Al2O3 crucible tunes the oxygen content in the melt and helps the crystallization of desired compositions. For the case of La5Pb3O, the Al2O3 crucible oxidizes La to form a passivating La2O3 layer which not only prevents further oxidization of La in the melt but also provides [O] to the melt. For the case of La0.4Na0.6Fe2As2, it is believed that the Al2O3 crucible reacts with NaAsO2 and the reaction consumes oxygen in the melt thus maintaining an oxygen-free environment.

  20. Flux growth utilizing the reaction between flux and crucible

    DOE PAGES

    Yan, J. -Q.

    2015-01-22

    Flux growth involves dissolving the components of the target compound in an appropriate flux at high temperatures and then crystallizing under supersaturation controlled by cooling or evaporating the flux. A refractory crucible is generally used to contain the high temperature melt. Moreover, the reaction between the melt and crucible materials can modify the composition of the melt, which typically results in growth failure, or contaminates the crystals. Thus one principle in designing a flux growth is to select suitable flux and crucible materials thus to avoid any reaction between them. In this paper, we review two cases of flux growthmore » in which the reaction between flux and Al2O3 crucible tunes the oxygen content in the melt and helps the crystallization of desired compositions. For the case of La5Pb3O, the Al2O3 crucible oxidizes La to form a passivating La2O3 layer which not only prevents further oxidization of La in the melt but also provides [O] to the melt. Finally, in the case of La0.4Na0.6Fe2As2, it is believed that the Al2O3 crucible reacts with NaAsO2 and the reaction consumes oxygen in the melt thus maintaining an oxygen-free environment.« less

  1. PHLUX: Photographic Flux Tools for Solar Glare and Flux

    SciTech Connect

    2010-12-02

    A web-based tool to a) analytically and empirically quantify glare from reflected light and determine the potential impact (e.g., temporary flash blindness, retinal burn), and b) produce flux maps for central receivers. The tool accepts RAW digital photographs of the glare source (for hazard assessment) or the receiver (for flux mapping), as well as a photograph of the sun for intensity and size scaling. For glare hazard assessment, the tool determines the retinal irradiance (W/cm2) and subtended source angle for an observer and plots the glare source on a hazard spectrum (i.e., low-potential for flash blindness impact, potential for flash blindness impact, retinal burn). For flux mapping, the tool provides a colored map of the receiver scaled by incident solar flux (W/m2) and unwraps the physical dimensions of the receiver while accounting for the perspective of the photographer (e.g., for a flux map of a cylindrical receiver, the horizontal axis denotes receiver angle in degrees and the vertical axis denotes vertical position in meters; for a flat panel receiver, the horizontal axis denotes horizontal position in meters and the vertical axis denotes vertical position in meters). The flux mapping capability also allows the user to specify transects along which the program plots incident solar flux on the receiver.

  2. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

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

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

    PubMed

    Tan, Zhenyu; Liu, Wei

    2014-05-01

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

  5. Teflon impregnated anatase TiO2 nanoparticles irradiated by 80 keV Xe+ ions

    NASA Astrophysics Data System (ADS)

    Khanam, Rizwin; Paul, Nibedita; Kumar, P.; Kanjilal, D.; Ahmed, Gazi A.; Mohanta, Dambarudhar

    2014-10-01

    We report the effect of 80 keV Xe+ ion irradiation on the morphological and optical responses of TiO2 nanoparticles spread over commercially available polytetrafluoroethylene (PTFE, Teflon). These nanoparticles were synthesized via a convenient, sol-gel approach with titanium isopropoxide as the main precursor. From X-ray diffraction (XRD) studies we found that, the nanoparticles crystallize in anatase phase and with a preferential orientation of crystallites along (1 0 1) plane. Upon irradiation at a fluence of 1.25 × 1017 ions/cm2, the nanoparticle dimension was found to increase from a value of ∼9 nm to ∼20-30 nm. Essentially, particle growth is predicted as a consequence of swelling behavior accompanied by the formation of Xe van der Waal crystals in isolated regions of nano-titania. Evidence of nanoripples was also witnessed on the surface of the irradiated nano-titania. The morphological evolution was assessed both by atomic force and transmission electron microscopies (AFM and TEM) independently. From the UV-Vis optical absorption studies, the estimated optical band gap was found to drop with increasing fluence, while refractive index exhibited a remarkable improvement. Photoluminescence (PL) studies have revealed that, the band edge emission and those due to the self trapped excitons (STE) and other oxygen vacancy related ones were manifested considerably as a result of Xe ion irradiation.

  6. High-accuracy x-ray line standards in the 3-keV region

    NASA Astrophysics Data System (ADS)

    Schlesser, S.; Boucard, S.; Covita, D. S.; dos Santos, J. M. F.; Fuhrmann, H.; Gotta, D.; Gruber, A.; Hennebach, M.; Hirtl, A.; Indelicato, P.; Le Bigot, E.-O.; Simons, L. M.; Stingelin, L.; Trassinelli, M.; Veloso, J. F. C. A.; Wasser, A.; Zmeskal, J.

    2013-08-01

    A set of 14 high-accuracy x-ray transition energies in the 2.4-3.1 keV range is presented, which can be used as x-ray standards. They were measured in two- to four-electron sulfur, chlorine, and argon ions produced in an electron-cyclotron resonance ion source, using a single spherically bent crystal spectrometer. The results include the first measurement of six transitions and improve the accuracy of six other experimental values. These measurements considerably extend the set of high-accuracy x-ray energies reported for highly charged ions. Their relative uncertainties range from 1 to 10 ppm. Theory only reaches such a precision in one- and two-electron ions. Our results thus have two distinct applications. On the one hand, they test predictions in two-electron ions [Artemyev, Shabaev, Yerokhin, Plunien, and Soff, Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.71.062104 71, 062104 (2005)], at the precision level of some two-photon QED contributions. We observe an agreement with theory for most of the transitions. On the other hand, the three- and four-electron ion transitions provide new benchmark energies for the calculation of missing theoretical contributions, such as Auger shifts or electronic correlations. Spectra were analyzed with an x-ray tracing simulation that contains all the relevant physics of the spectrometer.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

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

    1997-05-01

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

  10. Relief evolution of HOPG under high-fluence 30 keV argon ion irradiation

    NASA Astrophysics Data System (ADS)

    Andrianova, N. N.; Borisov, A. M.; Mashkova, E. S.; Shemukhin, A. A.; Shulga, V. I.; Virgiliev, Yu. S.

    2015-07-01

    The results of the experimental study of sputtering and erosion of the basal plane of HOPG under irradiation with 30-keV Ar+ in the range from RT to 400 °C are presented. It has been found that developed at elevated (⩾250 °C) temperatures needle-like microscopic relief results in twofold sputtering yield increase (Y ≈ 2) in comparison with sputtering of a surface with an etch pits microscopic relief at the temperatures less than the ion-induced texture transition temperature Tt ≈ 150 °C. The effects of ion-induced graphite relief on high-dose sputtering have been studied using binary-collision computer simulation. The relief was modeled as a sine function surface along two mutually perpendicular surface axes. The simulation has shown that at some parameters of the relief the essential part of the bombarding ions undergoes inclined incidence on the walls of surface hillocks, which increases the density of ion-atom collisions near the surface and, correspondingly, the ejection of atoms. This effect leads to non-monotonic behavior of the sputtering yield on the relief aspect ratio (amplitude/period). The sputtering yield decreases upon reaching the maximum at aspect ratio of 4, and becomes lower than that for a flat surface. The simulation permits to estimate the relation of amplitude to period of relief at T < Tt.

  11. 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.

  12. Monochromatic 8.05-keV Flash Radiography of Imploded Cone-in-Shell Targets

    NASA Astrophysics Data System (ADS)

    Theobald, W.; Solodov, A. A.; Stoeckl, C.; Glebov, V. Yu.; Ivancic, S.; Marshall, F. J.; McKiernan, G.; Mileham, C.; Sangster, T. C.; Beg, F. N.; Jarrott, C.; Giraldez, E.; Stephens, R. B.; Wei, M. S.; Key, M. H.; McLean, H.; Santos, J.

    2012-10-01

    Fast ignition has the potential of high fusion gains through the ignition of massive DT fuel assemblies. The cone-in-shell target concept might be one way of achieving this goal. Integrated experiments on OMEGA have demonstrated ˜4% coupling efficiency of short-pulse laser energy into the compressed target.footnotetextW. Theobald et al., Phys. Plasmas 18, 056305 (2011). An improved target design has been developed with a low-Z cone tip. The goal was to validate 2-D radiation--hydrodynamic modeling predictions of the new target design. The technique used was flash radiography from a monochromatic 8.05-keV x-ray source.footnotetext J. A. King et al., Appl. Phys. Lett. 86, 191501 (2005). Cu foils were irradiated by the 1.5-kJ, 10-ps OMEGA EP short-pulse laser to generate a bright Cu Kα area backlighter source, which was used in combination with monochromatic imaging with a spherical Bragg crystal to backlight the cone-in-shell implosions at various times around peak compression. Flash radiography provides high-quality images of the fuel assembly with ˜10-ps time resolution and ˜10-μm spatial resolution. This work was supported by the U.S. Department of Energy under Cooperative Agreement Nos. DE-FC52-08NA28302 and DE-FC02-04ER54789.

  13. 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.

  14. Two-color ionization of hydrogen close to threshold with keV photons

    NASA Astrophysics Data System (ADS)

    Dondera, Mihai; Florescu, Viorica; Bachau, Henri

    2014-09-01

    In a recent Letter [H. Bachau, M. Dondera, and V. Florescu, Phys. Rev. Lett. 112, 073001 (2014), 10.1103/PhysRevLett.112.073001] we considered the hydrogen atom in interaction with an electromagnetic field consisting in the coherent superposition of two keV pulses centered around two frequencies ω1 and ω2 that differ by a few atomic units. The analysis of the results obtained from the resolution of the time-dependent Schrödinger equation focused on stimulated Compton scattering (SCS). We have developed in parallel an approach based on perturbation theory and it proved to be an appropriate and useful tool in complement to the nonperturbative approach. In this paper we present a detailed analysis of the electron spectra obtained for ℏω1= 55 a.u. and two values of ℏω2, 50 and 54 a.u. Emphasis is put on the case ℏω2=54 a.u., where the electron emitted through SCS has the lowest energy, showing in particular that in the vicinity of the ionization threshold the cross section increases as ℏω1-ℏω2 decreases. We calculate photoelectron energy and angular distributions at various relative directions of propagation of the pulses. We discuss the limitations of the approximations underlying the numerical and analytical approaches used in this work.

  15. 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.

  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. VARIATIONS IN THE HELIOSPHERIC POLAR ENERGETIC NEUTRAL ATOM FLUX OBSERVED BY THE INTERSTELLAR BOUNDARY EXPLORER

    SciTech Connect

    Reisenfeld, D. B.; Janzen, P. H.; Allegrini, F.; McComas, D. J. E-mail: paul.janzen@umontana.edu E-mail: dmccomas@swri.org; and others

    2012-03-10

    The ecliptic poles are observed continuously by the Interstellar Boundary Explorer (IBEX); thus, it is possible to discern temporal variations in the energetic neutral atoms (ENAs) from the outer heliosphere on timescales much shorter than the time it takes for IBEX to generate a full sky map (six months). Observations indicate that the ENA flux from the polar directions incident at Earth has been steadily decreasing for the two-year period from 2008 December through 2011 February. Over the IBEX-Hi energy range, the decrease in flux is energy dependent, varying at the south ecliptic pole from no drop at 0.71 keV, to 70% at 1.1 keV. At higher energies the drop ranges between 10% and 50%. The decline observed at the north ecliptic pole is as high as 48%, also at 1.1 keV. The trend correlates with the steady decline in solar wind dynamic pressure observed at 1 AU between 2005 and 2009, the likely period when solar wind protons that provide the source for ENAs observed by IBEX would have been outbound from the Sun. We propose a method by which the correlation between the 1 AU solar wind dynamic pressure and the ENA-derived pressure within the inner heliosheath (IHS) can be used to estimate the distance to the termination shock and the thickness of the IHS in the direction of the ecliptic poles. Our new analysis based on IBEX data shows the TS distances to be 110 AU and 134 AU at the south and north poles, respectively, and the corresponding IHS thicknesses to be 55 AU and 82 AU. Our analysis is consistent with the notion that the observed ENA fluxes originate in the IHS and their variations are driven by the solar wind as it evolves through the solar cycle.

  18. SEPARATION OF THE INTERSTELLAR BOUNDARY EXPLORER RIBBON FROM GLOBALLY DISTRIBUTED ENERGETIC NEUTRAL ATOM FLUX

    SciTech Connect

    Schwadron, N. A.; Kucharek, H.; Moebius, E. E-mail: harald.kucharek@unh.edu

    2011-04-10

    The Interstellar Boundary Explorer (IBEX) observes a remarkable feature, the IBEX ribbon, which has energetic neutral atom (ENA) flux over a narrow region {approx}20{sup 0} wide, a factor of 2-3 higher than the more globally distributed ENA flux. Here, we separate ENA emissions in the ribbon from the distributed flux by applying a transparency mask over the ribbon and regions of high emissions, and then solve for the distributed flux using an interpolation scheme. Our analysis shows that the energy spectrum and spatial distribution of the ribbon are distinct from the surrounding globally distributed flux. The ribbon energy spectrum shows a knee between {approx}1 and 4 keV, and the angular distribution is approximately independent of energy. In contrast, the distributed flux does not show a clear knee and more closely conforms to a power law over much of the sky. Consistent with previous analyses, the slope of the power law steepens from the nose to tail, suggesting a weaker termination shock toward the tail as compared to the nose. The knee in the energy spectrum of the ribbon suggests that its source plasma population is generated via a distinct physical process. Both the slope in the energy distribution of the distributed flux and the knee in the energy distribution of the ribbon are ordered by latitude. The heliotail may be identified in maps of globally distributed flux as a broad region of low flux centered {approx}44{sup 0}W of the interstellar downwind direction, suggesting heliotail deflection by the interstellar magnetic field.

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  20. 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.

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

    SciTech Connect

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

    1982-11-01

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

  2. 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

  3. 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

  4. Generation of large-amplitude electric field and subsequent enhancement of O+ ion flux in the inner magnetosphere during substorms

    NASA Astrophysics Data System (ADS)

    Nakayama, Y.; Ebihara, Y.; Tanaka, T.

    2015-06-01

    Energetic O+ ions are rapidly enhanced in the inner magnetosphere because of abrupt intensification of the dawn-to-dusk electric field and significantly contribute to the ring current during substorms. Here we examine the generation mechanism of the dawn-to-dusk electric field that accelerates the O+ ions and the spatial and temporal evolution of the differential flux of the O+ ions by using a test particle simulation in the electric and magnetic fields that are provided by a global magnetohydrodynamics (MHD) simulation. In the MHD simulation, strong dawn-to-dusk electric field appears in the near-Earth tail region by a joint action of the earthward tension force and pileup of magnetic flux near an onset of substorm expansion. The peak of the electric field is ~9-13 mV/m and is located ~1-2 RE earthward of the peak of the plasma bulk speed because of the pileup. O+ ions coming from the lobe are accelerated from ~eV to >100 keV in ~10 min. The reconstructed flux of the O+ ions shows that at ~7 RE near midnight, the flux has a peak near a few tens of keV and the flux below ~10 keV is small. This structure, called a "void" structure, is consistent with the Polar observation and can be regarded as a manifestation of the acceleration of unmagnetized ions perpendicular to the magnetic field. In the inner magnetosphere (at 6.0 RE), reconstructed energy-time spectrograms show the nose dispersion structure that is also consistent with satellite observations.

  5. Magnetospheric-ionospheric Poynting flux

    NASA Technical Reports Server (NTRS)

    Thayer, Jeffrey P.

    1994-01-01

    Over the past three years of funding SRI, in collaboration with the University of Texas at Dallas, has been involved in determining the total electromagnetic energy flux into the upper atmosphere from DE-B electric and magnetic field measurements and modeling the electromagnetic energy flux at high latitudes, taking into account the coupled magnetosphere-ionosphere system. This effort has been very successful in establishing the DC Poynting flux as a fundamental quantity in describing the coupling of electromagnetic energy between the magnetosphere and ionosphere. The DE-B satellite electric and magnetic field measurements were carefully scrutinized to provide, for the first time, a large data set of DC, field-aligned, Poynting flux measurement. Investigations describing the field-aligned Poynting flux observations from DE-B orbits under specific geomagnetic conditions and from many orbits were conducted to provide a statistical average of the Poynting flux distribution over the polar cap. The theoretical modeling effort has provided insight into the observations by formulating the connection between Poynting's theorem and the electromagnetic energy conversion processes that occur in the ionosphere. Modeling and evaluation of these processes has helped interpret the satellite observations of the DC Poynting flux and improved our understanding of the coupling between the ionosphere and magnetosphere.

  6. Interpreting Flux from Broadband Photometry

    NASA Astrophysics Data System (ADS)

    Brown, Peter J.; Breeveld, Alice; Roming, Peter W. A.; Siegel, Michael

    2016-10-01

    We discuss the transformation of observed photometry into flux for the creation of spectral energy distributions (SED) and the computation of bolometric luminosities. We do this in the context of supernova studies, particularly as observed with the Swift spacecraft, but the concepts and techniques should be applicable to many other types of sources and wavelength regimes. Traditional methods of converting observed magnitudes to flux densities are not very accurate when applied to UV photometry. Common methods for extinction and the integration of pseudo-bolometric fluxes can also lead to inaccurate results. The sources of inaccuracy, though, also apply to other wavelengths. Because of the complicated nature of translating broadband photometry into monochromatic flux densities, comparison between observed photometry and a spectroscopic model is best done by forward modeling the spectrum into the count rates or magnitudes of the observations. We recommend that integrated flux measurements be made using a spectrum or SED which is consistent with the multi-band photometry rather than converting individual photometric measurements to flux densities, linearly interpolating between the points, and integrating. We also highlight some specific areas where the UV flux can be mischaracterized.

  7. Monte Carlo surface flux tallies

    SciTech Connect

    Favorite, Jeffrey A

    2010-11-19

    Particle fluxes on surfaces are difficult to calculate with Monte Carlo codes because the score requires a division by the surface-crossing angle cosine, and grazing angles lead to inaccuracies. We revisit the standard practice of dividing by half of a cosine 'cutoff' for particles whose surface-crossing cosines are below the cutoff. The theory behind this approximation is sound, but the application of the theory to all possible situations does not account for two implicit assumptions: (1) the grazing band must be symmetric about 0, and (2) a single linear expansion for the angular flux must be applied in the entire grazing band. These assumptions are violated in common circumstances; for example, for separate in-going and out-going flux tallies on internal surfaces, and for out-going flux tallies on external surfaces. In some situations, dividing by two-thirds of the cosine cutoff is more appropriate. If users were able to control both the cosine cutoff and the substitute value, they could use these parameters to make accurate surface flux tallies. The procedure is demonstrated in a test problem in which Monte Carlo surface fluxes in cosine bins are converted to angular fluxes and compared with the results of a discrete ordinates calculation.

  8. 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.

  9. 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.

  10. A high flux source of swift oxygen atoms

    NASA Technical Reports Server (NTRS)

    Fink, M.; Kohl, D. A.; Keto, J. W.; Antoniewicz, P.

    1987-01-01

    A source of swift oxygen atoms is described which has several unique features. A high current ion beam is produced by a microwave discharge, accelerated to 10 keV and the mass selected by a modified Du Pont 21-110 mass spectrometer. The O(+) beam exciting the mass spectrometer is focused into a rectangular shape with an energy spread of less than 1 eV. The next section of the machine decelerates the ion beam into a counterpropagating electron beam in order to minimize space charge effects. After deceleration, the ion beam intersects at 90 deg, a neutral oxygen atom beam, which via resonant charge exchange produces a mixture of O(+) and O. Any remaining O(+) are swept out of the beam by an electric field and differentially pumped away while the desired O beam, collimated by slits, impinges on the target. In situ monitoring of the target surface is done by X-ray photoelectron or Auger spectroscopy. Faraday cups provide flux measurements in the ion sections while the neutral flux is determined by a special torsion balance or by a quadrupole mass spectrometer specially adapted for swift atoms. While the vacuum from the source through the mass spectrometer is maintained by diffusion pumps, the rest of the machine is UHV.

  11. Van Allen Probes observations of magnetic field dipolarization and its associated O+ flux variations in the inner magnetosphere at L < 6.6

    NASA Astrophysics Data System (ADS)

    Nosé, M.; Keika, K.; Kletzing, C. A.; Spence, H. E.; Smith, C. W.; MacDowall, R. J.; Reeves, G. D.; Larsen, B. A.; Mitchell, D. G.

    2016-08-01

    We investigate the magnetic field dipolarization in the inner magnetosphere and its associated ion flux variations, using the magnetic field and energetic ion flux data acquired by the Van Allen Probes. From a study of 74 events that appeared at L = 4.5-6.6 between 1 October 2012 and 31 October 2013, we reveal the following characteristics of the dipolarization in the inner magnetosphere: (1) its time scale is approximately 5 min; (2) it is accompanied by strong magnetic fluctuations that have a dominant frequency close to the O+ gyrofrequency; (3) ion fluxes at 20-50 keV are simultaneously enhanced with larger magnitudes for O+ than for H+; (4) after a few minutes of the dipolarization, the flux enhancement at 0.1-5 keV appears with a clear energy-dispersion signature only for O+; and (5) the energy-dispersed O+ flux enhancement appears in directions parallel or antiparallel to the magnetic field. From these characteristics, we discuss possible mechanisms that can provide selective acceleration to O+ ions at >20 keV. We conclude that O+ ions at L = 5.4-6.6 undergo nonadiabatic local acceleration caused by oscillating electric field associated with the magnetic fluctuations and/or adiabatic convective transport from the plasma sheet to the inner magnetosphere by the impulsive electric field. At L = 4.5-5.4, however, only the former acceleration is plausible. We also conclude that the field-aligned energy-dispersed O+ ions at 0.1-5 keV originate from the ionosphere and are extracted nearly simultaneously to the onset of the dipolarization.

  12. Flux Emergence at the Photosphere

    NASA Astrophysics Data System (ADS)

    Cheung, M. C. M.; Schüssler, M.; Moreno-Insertis, F.

    2006-12-01

    To model the emergence of magnetic fields at the photosphere, we carried out 3D magneto-hydrodynamics (MHD) simulations using the MURaM code. Our simulations take into account the effects of compressibility, energy exchange via radiative transfer and partial ionization in the equation of state. All these physical ingredients are essential for a proper treatment of the problem. In the simulations, an initially buoyant magnetic flux tube is embedded in the upper layers of the convection zone. We find that the interaction between the flux tube and the external flow field has an important influence on the emergent morphology of the magnetic field. Depending on the initial properties of the flux tube (e.g. field strength, twist, entropy etc.), the emergence process can also modify the local granulation pattern. The inclusion of radiative transfer allows us to directly compare the simulation results with real observations of emerging flux.

  13. Conical electromagnetic radiation flux concentrator

    NASA Technical Reports Server (NTRS)

    Miller, E. R.

    1972-01-01

    Concentrator provides method of concentrating a beam of electromagnetic radiation into a smaller beam, presenting a higher flux density. Smaller beam may be made larger by sending radiation through the device in the reverse direction.

  14. 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.

  15. Short and long term flux variability of the BL Lacertae object 1ES 2200+420, in the MeV - GeV range

    NASA Astrophysics Data System (ADS)

    Herath, Mahesh; Abeysekara, Anushka; Jayaratne, Chandana

    2016-03-01

    Blazars are a class of Active Galactic Nuclei (AGN) that exhibit variable flux states across the electromagnetic spectrum, from radio to TeV. Current measurements show that the MeV-GeV flux of a Blazar could have a variability time scale as small as few hours or as long as several months. In this talk I will report the MeV-GeV flux variability patterns of the BL Lacertae object (1ES 2200+420). The data has been obtained from the Fermi-LAT archival database, and analysed using the recently released Pass 8 Fermi Science Tools. The cross correlations between MeV-GeV flux and KeV flux observed by Swift-XRT will also be reported, which is an important measurement to constraint the Synchrotron models.

  16. Flux tubes at finite temperature

    NASA Astrophysics Data System (ADS)

    Cea, Paolo; Cosmai, Leonardo; Cuteri, Francesca; Papa, Alessandro

    2016-06-01

    The chromoelectric field generated by a static quark-antiquark pair, with its peculiar tube-like shape, can be nicely described, at zero temperature, within the dual superconductor scenario for the QCD confining vacuum. In this work we investigate, by lattice Monte Carlo simulations of the SU (3) pure gauge theory, the fate of chromoelectric flux tubes across the deconfinement transition. We find that, if the distance between the static sources is kept fixed at about 0.76 fm˜eq 1.6/√{σ } and the temperature is increased towards and above the deconfinement temperature T c , the amplitude of the field inside the flux tube gets smaller, while the shape of the flux tube does not vary appreciably across deconfinement. This scenario with flux-tube "evaporation" above T c has no correspondence in ordinary (type-II) superconductivity, where instead the transition to the phase with normal conductivity is characterized by a divergent fattening of flux tubes as the transition temperature is approached from below. We present also some evidence about the existence of flux-tube structures in the magnetic sector of the theory in the deconfined phase.

  17. Methane flux from Minnesota peatlands

    SciTech Connect

    Crill, P.M.; Bartlett, K.B.; Harriss, R.C.; Gorham, E.; Verry, E.S. )

    1988-12-01

    Northern (> 40 deg N) wetlands have been suggested as the largest natural source of methane (CH{sub 4}) to the troposphere. To refine the authors estimates of source strengths from this region and to investigate climatic controls on the process, fluxes were measured from a variety of Minnesota peatlands during May, June, and August 1986. Late spring and summer fluxes ranged from 11 to 866 mg CH{sub 4}/sq/m/day, averaging 207 mg CH{sub 4} sq/m/day overall. At Marcell Forest, forested bogs and fen sites had lower fluxes than open bogs. In the Red Lake peatland, circumneutral fens, with standing water above the peat surface, produced more methane than acid bog sites in which the water table was beneath the moss surface. Peat temperature was an important control. Methane flux increased in response to increasing soil temperature. It is estimated that the methane flux from all peatlands north of 40 deg may be on the order of 70 to 90 Tg/yr though estimates of this sort are plagued by uncertainties in the areal extent of peatlands, length of the CH{sub 4} producing season, and the spatial and temporal variability of the flux. 60 refs., 7 figs., 5 tabs.

  18. Flux growth utilizing the reaction between flux and crucible

    SciTech Connect

    Yan, J. -Q.

    2015-01-22

    Flux growth involves dissolving the components of the target compound in an appropriate flux at high temperatures and then crystallizing under supersaturation controlled by cooling or evaporating the flux. A refractory crucible is generally used to contain the high temperature melt. Moreover, the reaction between the melt and crucible materials can modify the composition of the melt, which typically results in growth failure, or contaminates the crystals. Thus one principle in designing a flux growth is to select suitable flux and crucible materials thus to avoid any reaction between them. In this paper, we review two cases of flux growth in which the reaction between flux and Al2O3 crucible tunes the oxygen content in the melt and helps the crystallization of desired compositions. For the case of La5Pb3O, the Al2O3 crucible oxidizes La to form a passivating La2O3 layer which not only prevents further oxidization of La in the melt but also provides [O] to the melt. Finally, in the case of La0.4Na0.6Fe2As2, it is believed that the Al2O3 crucible reacts with NaAsO2 and the reaction consumes oxygen in the melt thus maintaining an oxygen-free environment.

  19. Applicability of the Ge(n,γ) Reaction for Estimating Thermal Neutron Flux

    NASA Astrophysics Data System (ADS)

    Nikolov, J.; Medić, Ž.; Jovančević, N.; Hansman, J.; Todorović, N.; Krmar, M.

    A simple experimental setup was used to measure gamma lines appearing in spectra after interactions of neutrons with Ge in the active volume of a high-purity germanium detector placed in a low-background shield. As source of neutrons a 252Cf spontaneous fission source and different thicknesses of PVC plates were used to slow down neutrons. A cadmiumenvelope was placed over the detector dipstick to identify the effect from slow and fast neutrons. Intensities of several characteristic γ-lines were measured, including intensity of the 139.9 keV γ-line from the reaction 74Ge(n,γ)75mGe, usually used for estimation of thermal neutron flux. Obtained results signify that only a part of the detected 139.9 keV γ-rays originate from thermal neutron capture. Some preliminary results indicate that in our detection setup thermal neutron capture contributes with 30% to 50% to the total intensity of the 139.9 keV γ-line, depending on the thickness of the PVC plates.

  20. 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.

  1. 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.

  2. Estimating the energy deposition in the mesosphere from anisotropic electron fluxes during REP events

    NASA Astrophysics Data System (ADS)

    Stadsnes, Johan; Sandanger, Marit; Nesse Tyssoy, Hilde; Odegaard, Linn-Kristine; Asnes, Arne

    Data from the MEPED particle spectrometers on the Polar Orbiting Operational Environmental Satellites (POES) are often used for estimating the energy deposition in the upper atmosphere from electrons in the energy range 30 keV - 2.5 MeV. MEPED includes two collimated electron detectors, which are pointing approximately towards zenith (0 degree detector) and in the horizontal plane (90 degree detector). At medium and high geomagnetic latitudes the 0 degree detector measures particles within a limited part of the bounce loss cone and the 90 degree detector measures particles outside or near the edge of the loss cone. The electron fluxes often show strong pitch angle anisotropy which causes large uncertainty in the estimate of energy deposition based on these measurements. An upper estimate is derived from the 90 degree detector and a lower estimate from the 0 degree detector. The electron anisotropy is to a large extent determined by wave-particle interactions causing pitch angle diffusion driving electrons into the bounce loss cone. The pitch angle anisotropy is dependent on the strength of the diffusion. We are developing a method for calculating the flux versus pitch angle in the loss cone based on the measured electron fluxes and modeled flux profiles from pitch angle scattering by whistler mode waves. We will present results from calculation of the energy deposition using the derived anisotropic flux distribution during a REP event in 2008.

  3. Simulation study of 3-5 keV x-ray conversion efficiency from Ar K-shell vs. Ag L-shell targets on the National Ignition Facility laser

    NASA Astrophysics Data System (ADS)

    Kemp, G. E.; Colvin, J. D.; Fournier, K. B.; May, M. J.; Barrios, M. A.; Patel, M. V.; Scott, H. A.; Marinak, M. M.

    2015-05-01

    Tailored, high-flux, multi-keV x-ray sources are desirable for studying x-ray interactions with matter for various civilian, space and military applications. For this study, we focus on designing an efficient laser-driven non-local thermodynamic equilibrium 3-5 keV x-ray source from photon-energy-matched Ar K-shell and Ag L-shell targets at sub-critical densities (˜nc/10) to ensure supersonic, volumetric laser heating with minimal losses to kinetic energy, thermal x rays and laser-plasma instabilities. Using Hydra, a multi-dimensional, arbitrary Lagrangian-Eulerian, radiation-hydrodynamics code, we performed a parameter study by varying initial target density and laser parameters for each material using conditions readily achievable on the National Ignition Facility (NIF) laser. We employ a model, benchmarked against Kr data collected on the NIF, that uses flux-limited Lee-More thermal conductivity and multi-group implicit Monte-Carlo photonics with non-local thermodynamic equilibrium, detailed super-configuration accounting opacities from Cretin, an atomic-kinetics code. While the highest power laser configurations produced the largest x-ray yields, we report that the peak simulated laser to 3-5 keV x-ray conversion efficiencies of 17.7% and 36.4% for Ar and Ag, respectively, occurred at lower powers between ˜100-150 TW. For identical initial target densities and laser illumination, the Ag L-shell is observed to have ≳10× higher emissivity per ion per deposited laser energy than the Ar K-shell. Although such low-density Ag targets have not yet been demonstrated, simulations of targets fabricated using atomic layer deposition of Ag on silica aerogels (˜20% by atomic fraction) suggest similar performance to atomically pure metal foams and that either fabrication technique may be worth pursuing for an efficient 3-5 keV x-ray source on NIF.

  4. 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.

  5. 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.

  6. 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

  7. Kirkpatrick-Baez microscope with spherical multilayer mirrors around 2.5keV photon energy

    NASA Astrophysics Data System (ADS)

    An, Ning; Du, Xuewei; Wang, Qiuping; Cao, Zhurong; Jiang, Shaoen; Ding, Yongkun

    2014-09-01

    A Kirkpatrick-Baez (KB) x-ray microscope has been developed for the diagnostics of inertial confinement fusion (ICF). The KB microscope system works around 2.5keV with the magnification of 20. It consists of two spherical multilayer mirrors. The grazing angle is 3.575° at 2.5keV. The influence of the slope error of optical components and the alignment errors is simulated by SHADOW software. The mechanical structure which can perform fine tuning is designed. Experiment result with Manson x-ray source shows that the spatial resolution of the system is about 3-4μm over a field of view of 200μm.

  8. 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.

  9. 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.

  10. Development of a 110-m-mA, 75-keV proton injector for high-current, CW linacs

    SciTech Connect

    Sherman, J.D.; Bolme, G.O.; Hansborough, L.D.

    1996-09-01

    A dc proton injector is being developed for a 6.7 MeV CW RFQ at Los Alamos. The RFQ input beam requirements are 75 keV energy, 110 mA dc proton current, and 0.20 {pi}mm-mrad rms normalized emittance. The injector has now produced a 75-keV, 117-mA dc proton beam (130 mA total current) with the required emittance. The emittance has been measured after a 2.1 m long two-solenoid beam transport system. The measured emittance can be explained in terms of the ion source emittance and beam transport through the focusing elements. Measured proton fractions are 90-92% of the beam current. Engineering of the accelerating column high-voltage design is being improved to increase the injector reliability. Injector design details and status are presented.

  11. YAP imager and its application with high-energy X-ray beams up to 150 keV

    NASA Astrophysics Data System (ADS)

    Hirota, K.; Toyokawa, H.; Suzuki, M.; Kudo, T.; Nomachi, M.; Sugaya, Y.; Yosoi, M.; Gorin, A.; Manuilov, I.; Riazantsev, A.; Kuroda, K.

    2003-09-01

    An X-ray imaging detector called YAP imager has been developed for high-energy X-ray region at the SPring-8 facility. It possesses a [128×128] matrix of YAlO 3:Ce crystals, each element having a volume of 1×1×6 mm 3. A NIM logic module using programmable logic device chip was also developed as a position encoder. The YAP imager has been applied for some applications with a thermal barrier coating material and multi-layer metal sheets targets in the incident X-ray energy region of 70-150 keV. Direct X-ray beam profile at 100 keV was also measured.

  12. Construction of a 300-keV compact ion microbeam system with a three-stage acceleration lens

    NASA Astrophysics Data System (ADS)

    Ishii, Yasuyuki; Ohkubo, Takeru; Kojima, Takuji; Kamiya, Tomihiro

    2014-08-01

    Hydrogen ion microbeams were experimentally formed at beam energies below 150 keV using a 300-keV compact microbeam system that was constructed at the Japan Atomic Energy Agency. This paper is a preliminary report on the performance of the three-stage acceleration lens used in the compact microbeam system. This system consists of a three-stage acceleration lens and a plasma-type ion source. Since the three-stage acceleration lens was designed to simultaneously accelerate and focus the ion beam, the compact microbeam system is only about 1-m high and can be placed in a small experimental room. To evaluate the effectiveness of the three-stage acceleration lens, experimentally measured beam sizes are compared with theoretically calculated ones. The calculated and measured beam sizes were consistent within 10%. This shows that the three-stage acceleration lens is effective as a focusing lens for forming microbeams.

  13. High-accuracy determination of the neutron flux at n_TOF

    NASA Astrophysics Data System (ADS)

    Barbagallo, M.; Guerrero, C.; Tsinganis, A.; Tarrío, D.; Altstadt, S.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Bécares, V.; Bečvář, F.; Belloni, F.; Berthoumieux, E.; Billowes, J.; Boccone, V.; Bosnar, D.; Brugger, M.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Carrapiço, C.; Cerutti, F.; Chiaveri, E.; Chin, M.; Colonna, N.; Cortés, G.; Cortés-Giraldo, M. A.; Diakaki, M.; Domingo-Pardo, C.; Duran, I.; Dressler, R.; Dzysiuk, N.; Eleftheriadis, C.; Ferrari, A.; Fraval, K.; Ganesan, S.; García, A. R.; Giubrone, G.; Göbel, K.; Gómez-Hornillos, M. B.; Gonçalves, I. F.; González-Romero, E.; Griesmayer, E.; Gunsing, F.; Gurusamy, P.; Hernández-Prieto, A.; Jenkins, D. G.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karadimos, D.; Kivel, N.; Koehler, P.; Kokkoris, M.; Krtička, M.; Kroll, J.; Lampoudis, C.; Langer, C.; Leal-Cidoncha, E.; Lederer, C.; Leeb, H.; Leong, L. S.; Losito, R.; Manousos, A.; Marganiec, J.; Martınez, T.; Massimi, C.; Mastinu, P. F.; Mastromarco, M.; Meaze, M.; Mendoza, E.; Mengoni, A.; Milazzo, P. M.; Mingrone, F.; Mirea, M.; Mondalaers, W.; Papaevangelou, T.; Paradela, C.; Pavlik, A.; Perkowski, J.; Plompen, A.; Praena, J.; Quesada, J. M.; Rauscher, T.; Reifarth, R.; Riego, A.; Roman, F.; Rubbia, C.; Sabate-Gilarte, M.; Sarmento, R.; Saxena, A.; Schillebeeckx, P.; Schmidt, S.; Schumann, D.; Steinegger, P.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Valenta, S.; Vannini, G.; Variale, V.; Vaz, P.; Ventura, A.; Versaci, R.; Vermeulen, M. J.; Vlachoudis, V.; Vlastou, R.; Wallner, A.; Ware, T.; Weigand, M.; Weiß, C.; Wright, T.; Žugec, P.

    2013-12-01

    The neutron flux of the n_TOF facility at CERN was measured, after installation of the new spallation target, with four different systems based on three neutron-converting reactions, which represent accepted cross sections standards in different energy regions. A careful comparison and combination of the different measurements allowed us to reach an unprecedented accuracy on the energy dependence of the neutron flux in the very wide range (thermal to 1 GeV) that characterizes the n_TOF neutron beam. This is a pre-requisite for the high accuracy of cross section measurements at n_TOF. An unexpected anomaly in the neutron-induced fission cross section of 235U is observed in the energy region between 10 and 30keV, hinting at a possible overestimation of this important cross section, well above currently assigned uncertainties.

  14. Statistics of broad relativistic lines in AGN: a counts- and flux-limited sampl

    NASA Astrophysics Data System (ADS)

    Guainazzi, Matteo

    2006-10-01

    We propose to observe 10 X-ray unabsorbed Active Galactic Nuclei (AGN) extracted from the RXTE Slew Survey (XSS). We aim at completing the XMM-Newton coverage of a flux-limited [2-10 keV flux > 1 mCrab] sub-sample of the XSS with enough statistical quality to unambiguously establish the presence of a relativistically broadened K-alpha iron line in the spectrum of each individual object. Measuring the fraction of local universe AGN where effects due to a relativistic accretion disk are detected, along with the accurate determination of the accretion flow physical properties, will allow us to tell if and how the standard paradigm needs to be modified to explain the origin of the energy output in AGN. The total requested time is 975 ks

  15. Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013

    DOE PAGES

    Su, Zhenpeng; Gao, Zhonglei; Reeves, Geoffrey D.; Funsten, Herbert O.; Zhu, Hui; Li, Wen; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; et al

    2016-07-15

    Radiation belt electron flux dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt electron fluxes exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (L > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ αe ≤ 180°). STEERB simulations show that the relativistic electron loss in the region L = 4.5–6.0 was primarily caused bymore » the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.« less

  16. 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.

  17. 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.

  18. Viscous Heating of Ions through Saturated Fine-Scale MHD Instabilities in a Z-Pinch at 200-300 KeV Temperature

    NASA Astrophysics Data System (ADS)

    Haines, Malcolm; Coverdale, Christine; Deeney, Chris; Lepell, P. David; Jones, Brent; Apruzese, J. P.

    2006-10-01

    Pulsed power driven Z-pinches yield large X-ray powers at stagnation, the energy of which can exceed by up to factors of 3 or 4, the estimated kinetic energy of the implosion. Furthermore, when electron temperatures are measured at stagnation similar in temperatures would not lead to pressure balance. These problems can be resolved by a theoretical model in which short wavelength (ka >> 1, and viscous Lundquist number ˜ 1), fast growing, m=O MHD instabilities reach a saturated amplitude, and the associated viscous dissipation of the vortices leads to ion heating. Equating this heating rate to the equipartition of energy to electrons leads to an estimate of the ion temperature and pinch radius at pressure balance. Extremely high ion temperatures in the range of 200-300 KeV are predicted from this model for stainless steel wire array experiments on Z at Sandia. These have been confirmed from time-resolved Doppler broadening spectroscopic measurements of the optically thin Fe He-δ line. This conversion of magnetic energy into ion thermal energy occurs on the nanosecond timescale, and can prevent radiative collapse. Any accompanying loss of magnetic flux in this highly conducting plasma can be explained by the occurrence of a large number of hot spots along the axis, with electron density and temperature variating not exactly in phase. This leads to a significant value of the integral of E.dl. Dl along the axis due to the grad Pe term in Ohm's law, analogous to the magnetic field generating term found in laser-plasma interactions. Ref 1. M.G. Haines, et al; Phys. Rev. Lett. 96, 075003 (2006) Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-ACO4-94AL85000.

  19. Discovery of a 6.4 keV Emission Line in a Burst from SGR 1900+14

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod E.; Ibrahim, Alaa I.

    2000-01-01

    We present evidence of a 6.4 key emission line during a burst from the soft gamma repeater SGR 1900+14. The Rossi X-Ray Timing Explorer (RXTE) monitored this source extensively during its outburst in the summer of 1998. A strong burst observed on 1998 August 29 revealed a number of unique properties. The burst exhibits a precursor and is followed by a long (approx. 10(exp 3) s) tail modulated at the 5.16 s stellar rotation period. The precursor has a duration of approx. equals 0.85 s and shows both significant spectral evolution as well as an emission feature centered near 6.4 keV during the first 0.3 s of the event, when the X-ray spectrum was hardest. The continuum during the burst is well fit with an optically thin thermal bremsstrahlung spectrum with the temperature ranging from approx. equals 40 to 10 keV. The line is strong, with an equivalent width of approx. 400 eV, and is consistent with Fe K(alpha) fluorescence from relatively coot material. If the rest-frame energy is indeed 6.4 keV, then the lack of an observed redshift indicates that the source is at least approx. 80 km above the neutron star surface. We discuss the implications of the line detection in the context of models for SGRs.

  20. 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.

  1. 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.

  2. THE X-RAY LINE FEATURE AT 3.5 KeV IN GALAXY CLUSTER SPECTRA

    SciTech Connect

    Phillips, K. J. H.; Sylwester, B.; Sylwester, J. E-mail: bs@cbk.pan.wroc.pl

    2015-08-10

    Recent work by Bulbul et al. and Boyarsky et al. has suggested that a line feature at ∼3.5 keV in the X-ray spectra of galaxy clusters and individual galaxies seen with XMM-Newton is due to the decay of sterile neutrinos, a dark matter candidate. This identification has been criticized by Jeltema and Profumo on the grounds that model spectra suggest that atomic transitions in helium-like potassium (K xviii) and chlorine (Cl xvi) are more likely to be the emitters. Here it is pointed out that the K xviii lines have been observed in numerous solar flare spectra at high spectral resolution with the RESIK crystal spectrometer and also appear in Chandra HETG spectra of the coronally active star σ Gem. In addition, the solar flare spectra at least indicate a mean coronal potassium abundance, which is a factor between 9 and 11 higher than the solar photospheric abundance. This fact, together with the low statistical quality of the XMM-Newton spectra, completely account for the ∼3.5 keV feature and there is therefore no need to invoke a sterile neutrino interpretation of the observed line feature at ∼3.5 keV.

  3. 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.

  4. 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.

  5. 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.

  6. Applications of non-periodic multilayer optics for high-resolution x-ray microscopes below 30 keV.

    PubMed

    Troussel, Ph; Dennetiere, D; Rousseau, A; Darbon, S; Høghøj, P; Hedacq, S; Krumrey, M

    2012-10-01

    Multilayer mirrors with enhanced bandwidth were developed with special performances for dense plasma diagnostics and mainly for high spatial resolution x-ray imaging. The multilayer coatings are designed to provide broadband x-ray reflectance at low grazing incidence angles. They are deposited onto toroidal mirror substrates. Our research is directed at the development of non-periodic (depth graded) W∕Si multilayer specifically designed for use in the 1 to 30 keV photon energy band. First, we present a study for a 5 to 22 keV x-ray spectral window at 0.45° grazing angle. The goal is to obtain a high and constant reflectivity. Second, we have modeled a broadband mirror coating for harder x-rays in the range from 10 to 30 keV, with a non-periodic structure containing 300 W∕SiC layers with periods in the range from 0.8 to 4 nm, designed for 0.35° grazing incidence angle.

  7. 0.5-keV Soft X-ray attosecond continua

    PubMed Central

    Teichmann, S. M.; Silva, F.; Cousin, S. L.; Hemmer, M.; Biegert, J.

    2016-01-01

    Attosecond light pulses in the extreme ultraviolet have drawn a great deal of attention due to their ability to interrogate electronic dynamics in real time. Nevertheless, to follow charge dynamics and excitations in materials, element selectivity is a prerequisite, which demands such pulses in the soft X-ray region, above 200 eV, to simultaneously cover several fundamental absorption edges of the constituents of the materials. Here, we experimentally demonstrate the exploitation of a transient phase matching regime to generate carrier envelope controlled soft X-ray supercontinua with pulse energies up to 2.9±0.1 pJ and a flux of (7.3±0.1) × 107 photons per second across the entire water window and attosecond pulses with 13 as transform limit. Our results herald attosecond science at the fundamental absorption edges of matter by bridging the gap between ultrafast temporal resolution and element specific probing. PMID:27167525

  8. Ideal flux field dielectric concentrators.

    PubMed

    García-Botella, Angel

    2011-10-01

    The concept of the vector flux field was first introduced as a photometrical theory and later developed in the field of nonimaging optics; it has provided new perspectives in the design of concentrators, overcoming standard ray tracing techniques. The flux field method has shown that reflective concentrators with the geometry of the field lines achieve the theoretical limit of concentration. In this paper we study the role of surfaces orthogonal to the field vector J. For rotationally symmetric systems J is orthogonal to its curl, and then a family of surfaces orthogonal to the lines of J exists, which can be called the family of surfaces of constant pseudopotential. Using the concept of the flux tube, it is possible to demonstrate that refractive concentrators with the shape of these pseudopotential surfaces achieve the theoretical limit of concentration. PMID:22016201

  9. Pickup Ion Production in the Global Heliosphere and Heliosheath and Their Diagnostics by Fluxes of Energetic Neutral Atoms

    NASA Astrophysics Data System (ADS)

    Wu, Y.

    2015-12-01

    An anisotropic particle transport model, based on an expansion of a focused transport equation in Legendre polynomials, is used here as a tool to analyze the distributions of pickup ions (PUIs) in the heliosphere and heliosheath. A three-dimensional, MHD-kinetic model for flows of a thermal plasma, neutral atoms and PUIs has been developed. The preliminary results from our model are in qualitative agreement with observations made by New Horizons, Ulysses, Voyager 1 and 2. All-sky maps of energetic neutral atoms (ENA) fluxes with energies of about 0.2-6 keV based on our current PUI model are qualitatively similar to IBEX-Hi distributed ENA maps. Also, simulated spectra of ENA fluxes nearly match IBEX-Hi spectra of distributed ENA fluxes. It is demonstrated that preserving some pitch-angle information of the PUI distribution is important for correctly interpreting the data.

  10. CIRCULARITY OF THE INTERSTELLAR BOUNDARY EXPLORER RIBBON OF ENHANCED ENERGETIC NEUTRAL ATOM (ENA) FLUX

    SciTech Connect

    Funsten, H. O.; Higdon, D. M.; Larsen, B. A.; Möbius, E. E-mail: dhigdon@lanl.gov; and others

    2013-10-10

    As a sharp feature in the sky, the ribbon of enhanced energetic neutral atom (ENA) flux observed by the Interstellar Boundary Explorer (IBEX) mission is a key signature for understanding the interaction of the heliosphere and the interstellar medium through which we are moving. Over five nominal IBEX energy passbands (0.7, 1.1, 1.7, 2.7, and 4.3 keV), the ribbon is extraordinarily circular, with a peak location centered at ecliptic (λ{sub RC}, β{sub RC}) = (219.°2 ± 1.°3, 39.°9 ± 2.°3) and a half cone angle of φ{sub C} = 74.°5 ± 2.°0. A slight elongation of the ribbon, generally perpendicular to the ribbon center-heliospheric nose vector and with eccentricity ∼0.3, is observed over all energies. At 4.3 keV, the ribbon is slightly larger and displaced relative to lower energies. For all ENA energies, a slice of the ribbon flux peak perpendicular to the circular arc is asymmetric and systematically skewed toward the ribbon center. We derive a spatial coherence parameter δ{sub C} ≤ 0.014 that characterizes the spatial uniformity of the ribbon over its extent in the sky and is a key constraint for understanding the underlying processes and structure governing the ribbon ENA emission.

  11. Magnetopause shadowing effects on the GEO flux dropout during a very weak magnetic storm: RBE results

    NASA Astrophysics Data System (ADS)

    Hwang, J.; Choi, E.; Park, J.; Kim, K.; Lee, D.; Fok, M. H.; Usanova, M.

    2013-12-01

    We investigate a geosynchronous flux dropout event during a weak storm of which Sym-H minimum value is -37 nT on November 7, 2008. During this event period, two dropouts are observed by GOES observation. Interestingly we found that there is local time dependence by THEMIS SST observation such that the GEO flux dropout starts first from noon-dusk MLT and recovers from midnight-dawn MLT in a few hundreds of keV electrons. This tendency is confirmed with RBE simulation results for both lower and higher energies' electrons; a few hundreds of keV and ~Me V. There is no observed atmospheric precipitation during the first dropout period and there are just negligible atmospheric precipitations during the second dropout by all available NOAA POES satellites' observations. We also check wave activities can provide the indirect proof of the atmospheric precipitation through wave-particle interactions, Chorus wave power from THEMIS exists just only during the second dropout period. EMIC waves do not appear from THEMIS observations while ground observations by CARISMA network show that there are clear EMIC waves during both dropouts. Finally we conclude that the first dropout event is caused by purely magnetopause shadowing effect and the second one might be the result of the combination of magnetopause shadowing and atmospheric precipitation into the earth's atmosphere by wave-particle interaction.

  12. 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.

  13. Surface flux evolution constraints for flux transport dynamos

    NASA Astrophysics Data System (ADS)

    Cameron, R. H.; Schmitt, D.; Jiang, J.; Işık, E.

    2012-06-01

    The surface flux transport (SFT) model of solar magnetic fields involves empirically well-constrained velocity and magnetic fields. The basic evolution of the Sun's large-scale surface magnetic field is well described by this model. The azimuthally averaged evolution of the SFT model can be compared to the surface evolution of the flux transport dynamo (FTD), and the evolution of the SFT model can be used to constrain several near-surface properties of the FTD model. We compared the results of the FTD model with different upper boundary conditions and diffusivity profiles against the results of the SFT model. Among the ingredients of the FTD model, downward pumping of magnetic flux, related to a positive diffusivity gradient, has a significant effect in slowing down the diffusive radial transport of magnetic flux through the solar surface. Provided the pumping was strong enough to give rise to a downflow of a magnetic Reynolds number of 5 in the near-surface boundary layer, the FTD using a vertical boundary condition matches the SFT model based on the average velocities above the boundary layer. The FTD model with a potential field was unable to match the SFT results.

  14. Beta ray flux measuring device

    DOEpatents

    Impink, Jr., Albert J.; Goldstein, Norman P.

    1990-01-01

    A beta ray flux measuring device in an activated member in-core instrumentation system for pressurized water reactors. The device includes collector rings positioned about an axis in the reactor's pressure boundary. Activated members such as hydroballs are positioned within respective ones of the collector rings. A response characteristic such as the current from or charge on a collector ring indicates the beta ray flux from the corresponding hydroball and is therefore a measure of the relative nuclear power level in the region of the reactor core corresponding to the specific exposed hydroball within the collector ring.

  15. ASGASEX, a comprehensive flux experiment

    SciTech Connect

    Oost, W.A.

    1994-12-31

    Among scientists working on CO{sub 2} exchange between air and sea there is a controversy between methods based on concentration measurements and transport coefficients on one hand and direct measurements of CO{sub 2} fluxes with the eddy correlation technique on the other. The controversy is caused by a gap of often more than an order of magnitude between the results of the two methods, in the transfer velocity k. The author decided to use the expertise gained during the HEXOS program to try to contribute to a solution of this problem by measuring all fluxes involved.

  16. High flux solar energy transformation

    DOEpatents

    Winston, R.; Gleckman, P.L.; O'Gallagher, J.J.

    1991-04-09

    Disclosed are multi-stage systems for high flux transformation of solar energy allowing for uniform solar intensification by a factor of 60,000 suns or more. Preferred systems employ a focusing mirror as a primary concentrative device and a non-imaging concentrator as a secondary concentrative device with concentrative capacities of primary and secondary stages selected to provide for net solar flux intensification of greater than 2000 over 95 percent of the concentration area. Systems of the invention are readily applied as energy sources for laser pumping and in other photothermal energy utilization processes. 7 figures.

  17. Simulations of Magnetic Flux Emergence

    NASA Astrophysics Data System (ADS)

    Stein, Robert; Nordlund, Aake

    Magnetic flux emerges from the solar surface on a wide range of scales. We review recent simulations of both large and small scale flux emergence. In our own simulations, we represent the magnetic flux produced by the global dynamo as uniform, untwisted, horizontal field advected into the simulation domain by supergranule scale inflows at the bottom. Our computational domain extends from the temperature minimum (half a megameter above the visible surface) to 20 Mm below the surface, which is 10% of the depth of the convection zone, but contains 2/3 of its scale heights. We investigate how magnetic flux rises through the upper solar convection zone and emerges through the surface. Convective up-flows and magnetic buoyancy bring field toward the surface. Convective down-flows pin down field and prevent its rise. Most of the field gets pumped downward by the convection, but some field rises to the surface. The convective motions both confine the flux concentrations (without the need for twist) and shred them. This process creates a hierarchy of magnetic loops with smaller loops riding "piggy-back", in a serpentine pattern, on larger loops. As a result, magnetic flux emerges in a mixed polarity, "pepper and salt" pattern. The small loops appear as horizontal field over granules with their vertical legs in the bounding intergranular lanes. The fields are quickly swept into the intergranular lanes. As the larger, parent, flux concentrations reach the surface with their legs rooted in the the downflow boundaries of the underlying, supergranule-scale, convective cells near the bottom of the simulation domain, the surface field counter-streams into separate, opposite polarity concentrations, creating pores and spots. The subsurface magnetic field lines of the pores and spots formed by the magneto-convection (without being imposed as an initial condition) are braided, some tightly, some loosely and they connect in complicated ways to the surrounding field at large depths

  18. High flux solar energy transformation

    DOEpatents

    Winston, Roland; Gleckman, Philip L.; O'Gallagher, Joseph J.

    1991-04-09

    Disclosed are multi-stage systems for high flux transformation of solar energy allowing for uniform solar intensification by a factor of 60,000 suns or more. Preferred systems employ a focusing mirror as a primary concentrative device and a non-imaging concentrator as a secondary concentrative device with concentrative capacities of primary and secondary stages selected to provide for net solar flux intensification of greater than 2000 over 95 percent of the concentration area. Systems of the invention are readily applied as energy sources for laser pumping and in other photothermal energy utilization processes.

  19. Spectral Modulation of the IBEX Ribbon Flux by the Dynamic Draping of the Interstellar Medium over the Heliosphere

    NASA Astrophysics Data System (ADS)

    Funsten, H. O.; Pittman, K. T.; Frisch, P. C.; Heerikhuisen, J.; Janzen, P. H.; McComas, D. J.; Reisenfeld, D. B.; Schwadron, N.; Zirnstein, E.

    2015-12-01

    The bright energetic neutral atom (ENA) emission in the circular ribbon observed by the Interstellar Boundary Explorer (IBEX) ribbon is a key ordering parameter of the interaction region between the heliosphere and the insterstellar medium. The ribbon is hypothesized to result from the condition in which the interstellar magnetic field, which is draped over the heliosphere and is the emission location in the "secondary" reibbon hypothesis, is oriented perpendicular to the line-of-sight view from IBEX. Here, we consider the relative motion of the draped magnetic field line for modulating ribbon intensity. Using the 0.7 keV and 1.1 keV ENA maps from the IBEX-Hi instrument, we find that this relative motion may significantly contribute to the variation of ribbon flux around the ribbon. We discuss the implications of this relative motion on our understanding the global structure and dynamics of the heliosphere-insterstellar medium interaction.

  20. The structure of photospheric flux tubes

    NASA Technical Reports Server (NTRS)

    Thomas, John H.

    1990-01-01

    Basic physical mechanisms for producing the observed intense magnetic flux tubes in the solar photosphere are reviewed. The mechanism of flux expulsion by convective cells can concentrate magnetic flux up to the equipartition field strength, which is only about 200 G at the solar surface for the observed granular convection. Other mechanisms that partially evacuate the flux tube are needed to produce further concentration of magnetic flux to the observed values of 1000-1500 G. Two such mechanisms are discussed: concentration by convective collapse of a vertical flux tube in the superadiabatic layer just below the solar surface, and concentration by a siphon flow in an arched, isolated flux tube.

  1. 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.

  2. Properties of electron flux spectra around the plasmapause in the chorus and hiss regions using POES.

    NASA Astrophysics Data System (ADS)

    Whittaker, Ian; Rodger, Craig; Clilverd, Mark

    2014-05-01

    The European FP7 PLASMON project aims to provide observations of plasmaspheric densities, and link the plasmaspheric variations to relativistic electron precipitation from the radiation belts. This is intended to assist in the estimation and prevent damage of space assets from space weather events as well as to improve forecasting (http://plasmon.elte.hu). As part of the PLASMON project, electron fluxes from the POES series of satellites are being used to determine the link between energetic electron precipitation energy spectra and magnitude to the position of the plasmapause. The MEPED instrument onboard POES measures electron flux from 90° (trapped particles) and 0° (losscone) telescopes, in 3 integral energy channels (>30, >100 and >300 keV). These fluxes have been compared to the DEMETER/IDP instrument to confirm that published geometric factor corrections (Yando et al. 2011) can be accurately applied to the POES data to produce as accurate as possible fluxes. These global fluxes have then been separated into regions in which Chorus (23:00-11:00 MLT) and Hiss (11:00-16:00 MLT) whistler mode waves are expected to occur, in 0.2 L-shell bins with a 20 minute temporal resolution. The plasmapause locations have been determined from the O'Brien and Moldwin (2003) models based on Kp, Ae and Dst peaks. We are currently comparing the POES spectral gradient and flux magnitude with plasmapause location and geomagnetic activity for the locations in which chorus and hiss are known to occur. This presentation will focus on the electron flux spectral gradient behaviour either side of the plasmapause, a value that is difficult to measure from ground based techniques.

  3. The soft gamma-ray spectrum of A0535+26: Detection of an absorption feature at 110 keV by OSSE

    NASA Technical Reports Server (NTRS)

    Grove, J. E.; Strickman, M. S.; Johnson, W. N.; Kurfess, J. D.; Kinzer, R. L.; Starr, C. H.; Jung, G. V.; Kendziorra, E.; Maisack, M.; Staubert, R.

    1995-01-01

    We present soft gamma-ray observations by the Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma Ray Observatory (GRO) of the transient X-ray binary pulsar A0535+26. The observations were made 1994 February 8-17, immediately prior to the peak of a giant outburst. The phase averaged spectrum is complex and cannot be described by a single-component model. We find that structure in the spectrum above 100 keV can best be modeled by an absorption feature near 110 keV, which we interepret as the signature of cyclotron resonant scattering. Because of OSSE's 45 keV threshold, we are unable to make a definitive statement on the presence of a 55 keV absorption line; however, we can conclude that if this line does exist, it must have a smaller optical depth than the line at 110 keV. A first harmonic (=fundamental) cyclotron resonance at 110 keV corresponds to a magnetic field strength at the surface of the neutron star of approximately 1 x 10(exp 13) G (approximately 5 x 10(exp 12) G if the first harmonic is at 55 keV).

  4. Van Allen Probes observations of dipolarization and its associated O+ flux variations in the inner magnetosphere

    NASA Astrophysics Data System (ADS)

    Nose, M.; Keika, K.; Kletzing, C.; Smith, C. W.; MacDowall, R. J.; Reeves, G. D.; Spence, H. E.

    2015-12-01

    Recent study employing the MDS-1 satellite reveals that magnetic field dipolarization in the deep inner magnetosphere is not unusual. When the MDS-1 satellite was located at L=3.5-5.0 near the auroral onset longitude (MLT difference of ≤2.5 h), the occurrence probability of local dipolarization was about 16%. Surprisingly, an event was found at L~3.6, far inside the geosynchronous altitude. It was also shown that after the dipolarization, the oxygen ENA flux in the nightside ring current region measured by the IMAGE satellite was predominantly enhanced by a factor of 2-5 and stayed at an enhanced level for more than 1 h, while clear enhancement was scarcely seen in the hydrogen ENA flux. To better understand mechanisms of the selective acceleration of O+ ions during dipolarization, an in-situ measurement of ion fluxes is needed. However, there are few studies investigating H+ and O+ flux variations during dipolarization in the deep inner magnetosphere. In this study we investigate magnetic field dipolarization and its associated ion flux variations in the deep inner magnetosphere, using magnetic field and ion flux data obtained by the Van Allen Probes. From the magnetic field data recorded on the nightside (1800-0600 MLT) in the inner magnetosphere (L=3.0-6.6) in VDH coordinates, we select substorm-related dipolarization events in which the H component increases by more than 20 nT and the absolute value of the V component decreases by more than 8 nT in 5 minutes. About 150 dipolarization events are identified from 1 October 2012 to 30 June 2015. We find that the dipolarization mostly occurs at L=4.5-6.5 in the premidnight sector (2100-0000 MLT). No events are found at L<4.0. Some dipolarization events are accompanied by O+ flux enhancements in the energy range higher than a few keV, which have the pitch angle distribution peaked around 45 or 135 degrees. We also find that low energy O+ ions often appear after dipolarization with an energy dispersion starting from

  5. Flux distribution---pipeline flaws

    SciTech Connect

    Lord, W.

    1989-03-16

    The physical basis for gas pipeline inspection with flux leakage pigs is the interaction of a magnetostatic (d.c.) excitation field with defects in the pipeline wall. Such an interaction produces a leakage field which is characteristic of the defect type, and can be detected with any flux density sensitive device such as a Hall plate. Predictions of defect leakage field profiles are necessary in order to optimize the design of flux leakage pigs, and also aid in the development of reliable defect characterization schemes. In order to carry out generic leakage field studies without reference to a specific flux leakage pig structure, finite element studies were made out on a 1.5-inch diameter carbon steel pipe excited by a central d.c. current carrying conductor. This report gives finite element predictions as well as experimental measurements for a wide variety of defect shapes. Some difficulty was encountered in obtaining an appropriate mesh discretization for the finite element studies. The background to this is given in detail because of its importance to 3-D modeling work. 15 refs., 40 figs.

  6. Mass fluxes for hot stars

    NASA Astrophysics Data System (ADS)

    Lucy, L. B.

    2010-03-01

    In an attempt to understand the extraordinarily small mass-loss rates of late-type O dwarfs, mass fluxes in the relevant part of (Teff, g)-space are derived from first principles using a previously-described code for constructing moving reversing layers. From these mass fluxes, a weak-wind domain is identified within which a star's rate of mass loss by a radiatively-driven wind is less than that due to nuclear burning. The five weak-wind stars recently analysed by Marcolino et al. (2009, A&A, 498, 837) fall within or at the edge of this domain. But although the theoretical mass fluxes for these stars are ≈1.4 dex lower than those derived with the formula of Vink et al. (2000), the observed rates are still not matched, a failure that may reflect our poor understanding of low-density supersonic outflows. Mass fluxes are also computed for two strong-wind O4 stars analysed by Bouret et al. (2005, A&A, 438, 301). The predictions agree with the sharply reduced mass loss rates found when Bouret et al. take wind clumping into account.

  7. Superconducting flux flow digital circuits

    DOEpatents

    Hietala, V.M.; Martens, J.S.; Zipperian, T.E.

    1995-02-14

    A NOR/inverter logic gate circuit and a flip flop circuit implemented with superconducting flux flow transistors (SFFTs) are disclosed. Both circuits comprise two SFFTs with feedback lines. They have extremely low power dissipation, very high switching speeds, and the ability to interface between Josephson junction superconductor circuits and conventional microelectronics. 8 figs.

  8. Superconducting flux flow digital circuits

    DOEpatents

    Hietala, Vincent M.; Martens, Jon S.; Zipperian, Thomas E.

    1995-01-01

    A NOR/inverter logic gate circuit and a flip flop circuit implemented with superconducting flux flow transistors (SFFTs). Both circuits comprise two SFFTs with feedback lines. They have extremely low power dissipation, very high switching speeds, and the ability to interface between Josephson junction superconductor circuits and conventional microelectronics.

  9. Measurement of the Ec.m. = 184 keV resonance strength in the 26gAl (p, gamma)27 Si reaction.

    PubMed

    Ruiz, C; Parikh, A; José, J; Buchmann, L; Caggiano, J A; Chen, A A; Clark, J A; Crawford, H; Davids, B; D'Auria, J M; Davis, C; Deibel, C; Erikson, L; Fogarty, L; Frekers, D; Greife, U; Hussein, A; Hutcheon, D A; Huyse, M; Jewett, C; Laird, A M; Lewis, R; Mumby-Croft, P; Olin, A; Ottewell, D F; Ouellet, C V; Parker, P; Pearson, J; Ruprecht, G; Trinczek, M; Vockenhuber, C; Wrede, C

    2006-06-30

    The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae.

  10. Measurement of the Ec.m.=184keV Resonance Strength in the Al26g(p,γ)Si27 Reaction

    NASA Astrophysics Data System (ADS)

    Ruiz, C.; Parikh, A.; José, J.; Buchmann, L.; Caggiano, J. A.; Chen, A. A.; Clark, J. A.; Crawford, H.; Davids, B.; D'Auria, J. M.; Davis, C.; Deibel, C.; Erikson, L.; Fogarty, L.; Frekers, D.; Greife, U.; Hussein, A.; Hutcheon, D. A.; Huyse, M.; Jewett, C.; Laird, A. M.; Lewis, R.; Mumby-Croft, P.; Olin, A.; Ottewell, D. F.; Ouellet, C. V.; Parker, P.; Pearson, J.; Ruprecht, G.; Trinczek, M.; Vockenhuber, C.; Wrede, C.

    2006-06-01

    The strength of the Ec.m.=184keV resonance in the Al26g(p,γ)Si27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF’s ISAC facility. We measure a value of ωγ=35±7μeV and a resonance energy of Ec.m.=184±1keV, consistent with p-wave proton capture into the 7652(3) keV state in Si27, and discuss the implications of these values for Al26g nucleosynthesis in typical oxygen-neon white-dwarf novae.

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

    PubMed

    Camargo Moreira, Anderson; Roberto Appoloni, Carlos

    2006-09-01

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

  12. Measurement of the Ec.m. = 184 keV resonance strength in the 26gAl (p, gamma)27 Si reaction.

    PubMed

    Ruiz, C; Parikh, A; José, J; Buchmann, L; Caggiano, J A; Chen, A A; Clark, J A; Crawford, H; Davids, B; D'Auria, J M; Davis, C; Deibel, C; Erikson, L; Fogarty, L; Frekers, D; Greife, U; Hussein, A; Hutcheon, D A; Huyse, M; Jewett, C; Laird, A M; Lewis, R; Mumby-Croft, P; Olin, A; Ottewell, D F; Ouellet, C V; Parker, P; Pearson, J; Ruprecht, G; Trinczek, M; Vockenhuber, C; Wrede, C

    2006-06-30

    The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae. PMID:16907298

  13. VizieR Online Data Catalog: AGNs from RXTE 3-20keV All-Sky Survey (Sazonov+, 2004)

    NASA Astrophysics Data System (ADS)

    Sazonov, S. Yu.; Revnivtsev, M. G.

    2004-05-01

    Catalog of 95 identified AGNs serendipitously detected at |b|>10deg during the RXTE slew survey (XSS, ) is presented. Most of these AGNs belong to the local population (z<0.1). For each source the following information is provided: AGN class, count rate in two energy bands 3-8keV and 8-20keV, observed and intrinsic (absorption-corrected) luminosity in the 3-20keV band, intrinsic absorption column density. Also a catalog of 35 AGN candidates, composed of unidentified XSS sources is presented. (2 data files).

  14. Rapid increase in relativistic electron flux controlled by nonlinear phase trapping of whistler chorus elements

    NASA Astrophysics Data System (ADS)

    Saito, Shinji; Miyoshi, Yoshizumi; Seki, Kanako

    2016-07-01

    Wave-particle interactions with whistler chorus waves are believed to provide a primary acceleration for electrons in the outer radiation belt. Previous models for flux enhancement of the radiation belt have assumed the stochastic process as a diffusion manner of successive random-phase interactions, but physical mechanisms for the acceleration are not fully incorporated in these models because of the lack of a nonlinear scattering process. Here we report rapid increase in relativistic electron flux by using an innovative computer simulation model that incorporates not only diffusive process but also nonlinear scattering processes. The simulations show that three types of scattering simultaneously occur, which are diffusive, phase trapping, and phase bunching. It is found that the phase trapping is the most efficient mechanism to produce the MeV electrons rapidly in the scattering processes. The electrons are accelerated from 400 keV to over 1 MeV in time scale less than 60 s. On the other hand, as the phase trapping is suppressed by the breaking of relative phase angle between waves and gyrating electrons during the interaction, the increase of electron flux at MeV energy is clearly reduced. Our simulations conclude that the phase-trapping process causes a significant effect for the increase in relativistic electron flux and suggest that a quasi-linear diffusion model is not always valid to fully describe the relativistic electron acceleration.

  15. Determination of Cosmological Parameters from GRB Correlation between E_iso (gamma) and Afterglow Flux

    NASA Astrophysics Data System (ADS)

    Hannachi, Zitouni; Guessoum, Nidhal; Azzam, Walid

    2016-07-01

    Context: We use the correlation relations between the energy emitted by the GRBs in their prompt phases and the X-ray afterglow fluxes, in an effort to constrain cosmological parameters and construct a Hubble diagram at high redshifts, i.e. beyond those found in Type Ia supernovae. Methods: We use a sample of 128 Swift GRBs, which we have selected among more than 800 ones observed until July 2015. The selection is based on a few observational constraints: GRB flux higher than 0.4 photons/cm^2/s in the band 15-150 keV; spectrum fitted with simple power law; redshift accurately known and given; and X-ray afterglow observed and flux measured. The statistical method of maximum likelihood is then used to determine the best cosmological parameters (Ω_M, Ω_L) that give the best correlation between the isotropic gamma energies E_{iso} and the afterglow fluxes at the break time t_{b}. The χ^2 statistical test is also used as a way to compare results from two methods. Results & Conclusions: Although the number of GRBs with high redshifts is rather small, and despite the notable dispersion found in the data, the results we have obtained are quite encouraging and promising. The values of the cosmological parameters obtained here are close to those currently used.

  16. Dynamics of electron fluxes in the near-rocket region in the ARAKS experiment

    NASA Astrophysics Data System (ADS)

    Izhovkina, N. I.

    2012-05-01

    In the ARAKS experiment, electron pulses were injected into the ionosphere from onboard a rocket. For different series of pulses, the initial energy of electrons was 27 and 15 keV and the current strength was ˜0.5 A. On board the rocket, the distributions of electron fluxes directed toward the rocket were measured using the retarding potential by the electron energy up to 3000 eV. In this work, it is shown that the appearance of extreme values of the intensity of electron fluxes higher than 200 eV at the tail of the electron energy distribution can be explained by the nonmonotonic acceleration of electrons in the fields of electrostatic turbulence. The dynamics of electron and ion fluxes can be influenced by the polarization drift. It should be noted that extreme values of the flux intensities were not observed at heights lower than 130 km. This can be connected with the suppression of electrostatic oscillations by collisions of electrons with ionospheric components.

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

    SciTech Connect

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

    2015-06-20

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

  18. Calculations of stopping powers of 100 eV-30 keV electrons in 31 elemental solids

    SciTech Connect

    Tanuma, S.; Powell, C. J.; Penn, D. R.

    2008-03-15

    We present calculated electron stopping powers (SPs) for 31 elemental solids (Li, Be, glassy C, graphite, diamond, Na, Mg, K, Sc, Ti, V, Fe, Y, Zr, Nb, Mo, Ru, Rh, In, Sn, Cs, Gd, Tb, Dy, Hf, Ta, W, Re, Os, Ir, and Bi). These SPs were determined with an algorithm previously used for the calculation of electron inelastic mean free paths and from energy-loss functions (ELFs) derived from experimental optical data. The SP calculations were made for electron energies between 100 eV and 30 keV and supplement our earlier SP calculations for ten additional solids (Al, Si, Cr, Ni, Cu, Ge, Pd, Ag, Pt, and Au). Plots of SP versus atomic number for the group of 41 solids show clear trends. Multiple peaks and shoulders are seen that result from the contributions of valence-electron and various inner-shell excitations. Satisfactory agreement was found between the calculated SPs and values from the relativistic Bethe SP equation with recommended values of the mean excitation energy (MEE) for energies above 10 keV. We determined effective MEEs versus maximum excitation energy from the ELFs for each solid. Plots of effective MEE versus atomic number showed the relative contributions of valence-electron and different core-electron excitations to the MEE. For a maximum excitation energy of 30 keV, our effective MEEs agreed well for Be, graphite, Na, Al, and Si with recommended MEEs; a difference for Li was attributed to sample oxidation in the SP measurements for the recommended MEE. Substantially different effective MEEs were found for the three carbon allotropes (graphite, diamond, and glassy C)

  19. 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.

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

    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 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ and effective temperature Teff. We also calculate the number density n and average energy Eavg of strahl and halo electrons by integrating the electron measurements between ˜0.1 and 1.5 keV. We find a strong positive correlation between κ and Teff for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity).

  1. Motion of 3-6 keV Nonthermal Sources Along the Legs of a Flare Loop

    NASA Technical Reports Server (NTRS)

    Sui, Linhui; Holman, Gordon D.; Dennis, Brian R.

    2007-01-01

    Observations of nonthermal X-ray sources me critical to studying electron acceleration and transport in solar flares. Strong thermal emission radiated from the preheated plasma before the flare impulsive phase often makes it difficult to detect low-energy X-ray sources that are produced by relatively low-energy nonthermal electrons. Knowledge of the distribution of these low-energy nonthermal electrons is particularly important in determining the total nonthermal electron energy in solar flares. We report on an 'early impulsive flare' in which impulsive hard X-ray emission was seen early in the flare before the soft X-ray emission had risen significantly, indicating limited plasma pre-heating. Early in the flare, RHESSI < 25 keV images show coronal sources that moved first downward and then upwards along the legs of a flare loop. In particular, the 3-6 keV source appeared as a single coronal source at the start of the flare, and then it involved into two coronal sources moving down along the two legs of the loop. After nearly reaching the two footpoints at the hard X-ray peak, the two sources moved back up to the looptop again. RHESSI images and light curves all indicate that nonthermal emission dominated at energies as low as 3-6 keV. We suggest that the evolution of both the spectral index and the low-energy cutoff of the injected electron distribution could result in the accelerated electrons reaching a lower altitude along the legs of the dense flare loop and hence result in the observed downward and upward motions of the nonthermal sources.

  2. Fluxes across a thermohaline interface

    NASA Astrophysics Data System (ADS)

    Fleury, M.; Lueck, R. G.

    1991-07-01

    Measurements of velocity and temperature microstructure and hydrography were made with a towed vehicle moving in and around a single interface in a double-diffusive staircase. The interface was traversed 222 times in a saw-tooth pattern over a track 35 km long. The salinity and potential temperature and density in the mixed layers adjacent to the interface were spatially uniform except for one 8 km long anomaly. The rate of dissipation of kinetic energy was uniformly low in the interface and in the mixed layers, except for one section 600 m long where a Kelvin-Helmholtz instability generated turbulence. For the non-turbulent section of the interface, the mean rate of dissipation was 30.2 × 10 -10 W kg -1 in the mixed layers and 9.5 × 10 -10 W kg -1 in the interface. The non-dimensional dissipation rate, ɛ/vN 2, was almost always less than 16 in the interface and therfore, there was no turblent buoyancy flux according to ROHRet al. (1988, Journal of Fluid Mechanics, 195, 77-111). The average double-diffusive flux of buoyancy by heat was 3.6 × 10 -10 W kg -1. Under certain assumptions the ratio of the flux of buoyancy by heat and salt can be estimated to be 0.53 ± 0.10, in good agreement with laboratory and theoretical estimates for salt fingers. The average Cox number was about 8 in the interface, consistent with the theories of STERN (1975, Ocean circulation physics, Academic Press) and KUNZE (1987, Journal of Marine Research, 45 533-556), but displayed an inverse dependence on the vertical temperature gradient which was not predicted. As a result, the flux of buoyancy, as well as the individual contributions by heat and salt, were independent of the local mean vertical temperature gradient and the buoyancy frequency. The length of the turbulent section of the interface was only 1.7% of the total length observed. However, the turbulence was intense—the mean rate of dissipation was 2.5 × 10 -8 W kg -1—and may have sufficiently enhanced the flux of heat to

  3. Neutron scattering measurements in {sup 197}Au from 850 keV to 2.0 MeV

    SciTech Connect

    O`Connor, M.; Chen, J.; Egan, J.J.

    1995-10-01

    Differential elastic and inelastic neutron scattering cross-sections for low lying levels in {sup 197}Au have been measured for incident neutron energies of 1.0 MeV, 1.5 MeV and 2.0 MeV. In addition, the total neutron cross sections in {sup 197}Au was measured from 850 keV to 1.5 MeV. For both experiments the UML 5.5 MV Van-de-Graaff accelerator with a Mobley post acceleration compression system, produced subnanosecond proton pulses which generated neutrons via the {sup 7}Li(p,n) {sup 7}Be reaction.

  4. A New Population of Compton-thick AGNs Identified Using the Spectral Curvature above 10 keV

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick active galactic nuclei (AGNs) in low-quality Swift/Burst Alert Telescope (BAT) X-ray data. Using NuSTAR, we observe nine high SC-selected AGNs. We find that high-sensitivity spectra show that the majority are Compton-thick (78% or 7/9) and the remaining two are nearly Compton-thick (N H ≃ (5-8) × 1023 cm-2 ). We find that the SC BAT and SC NuSTAR measurements are consistent, suggesting that this technique can be applied to future telescopes. We tested the SC method on well-known Compton-thick AGNs and found that it is much more effective than broadband ratios (e.g., 100% using SC versus 20% using 8-24 keV/3-8 keV). Our results suggest that using the >10 keV emission may be the only way to identify this population since only two sources show Compton-thick levels of excess in the Balmer decrement corrected [O iii] to observed X-ray emission ratio ({F}[{{O}{{III}}]}/{F}2{--10 {keV}}{obs}\\gt 1) and WISE colors do not identify most of them as AGNs. Based on this small sample, we find that a higher fraction of these AGNs are in the final merger stage (<10 kpc) than typical BAT AGNs. Additionally, these nine obscured AGNs have, on average, ≈4× higher accretion rates than other BAT-detected AGNs (< {λ }{Edd}> \\=\\0.068+/- 0.023 compared to < {λ }{Edd}> \\=\\0.016+/- 0.004). The robustness of SC at identifying Compton-thick AGNs implies that a higher fraction of nearby AGNs may be Compton-thick (≈22%) and the sum of black hole growth in Compton-thick AGNs (Eddington ratio times population percentage) is nearly as large as mildly obscured and unobscured AGNs.

  5. A New Population of Compton-thick AGNs Identified Using the Spectral Curvature above 10 keV

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

    We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick active galactic nuclei (AGNs) in low-quality Swift/Burst Alert Telescope (BAT) X-ray data. Using NuSTAR, we observe nine high SC-selected AGNs. We find that high-sensitivity spectra show that the majority are Compton-thick (78% or 7/9) and the remaining two are nearly Compton-thick (N H ≃ (5–8) × 1023 cm‑2 ). We find that the SC BAT and SC NuSTAR measurements are consistent, suggesting that this technique can be applied to future telescopes. We tested the SC method on well-known Compton-thick AGNs and found that it is much more effective than broadband ratios (e.g., 100% using SC versus 20% using 8–24 keV/3–8 keV). Our results suggest that using the >10 keV emission may be the only way to identify this population since only two sources show Compton-thick levels of excess in the Balmer decrement corrected [O iii] to observed X-ray emission ratio ({F}[{{O}{{III}}]}/{F}2{--10 {keV}}{obs}\\gt 1) and WISE colors do not identify most of them as AGNs. Based on this small sample, we find that a higher fraction of these AGNs are in the final merger stage (<10 kpc) than typical BAT AGNs. Additionally, these nine obscured AGNs have, on average, ≈4× higher accretion rates than other BAT-detected AGNs (< {λ }{Edd}> \\=\\0.068+/- 0.023 compared to < {λ }{Edd}> \\=\\0.016+/- 0.004). The robustness of SC at identifying Compton-thick AGNs implies that a higher fraction of nearby AGNs may be Compton-thick (≈22%) and the sum of black hole growth in Compton-thick AGNs (Eddington ratio times population percentage) is nearly as large as mildly obscured and unobscured AGNs.

  6. Energetic neutral atoms (E approximately 50 keV) from the ring current - IMP 7/8 and ISEE 1

    NASA Technical Reports Server (NTRS)

    Roelof, E. C.; Mitchell, D. G.; Williams, D. J.

    1985-01-01

    Energetic neutral atoms (ENA), emitted from the magnetosphere with energies of about 50 keV, have been measured with solid state detectors on the IMP 7/8 and ISEE 1 spacecraft; they are produced when singly charged trapped ions collide with the exosphere neutral hydrogen geocorona and the energetic ions are neutralized by charge exchange. ENA observations during the recovery phase of two moderate geomagnetic storms are analyzed: November 22-23, 1973, from IMP 8 at 33 earth radii and December 17, 1977, from ISEE 1 at 20 earth radii.

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

    NASA Astrophysics Data System (ADS)

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

    2016-07-01

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

  8. Infrared spectroscopy investigation of various plasma-deposited polymer films irradiated with 170 keV He + ions

    NASA Astrophysics Data System (ADS)

    Gelamo, R. V.; Trasferetti, B. C.; Durrant, S. F.; Davanzo, C. U.; Rouxinol, F. P.; Gadioli, G. Z.; Bica de Moraes, M. A.

    2006-08-01

    This work illustrates the advantages of using p-polarized radiation at an incidence angle of 70° in contrast to the conventional unpolarized beam at normal (or near-normal) incidence for the infrared spectroscopic study of polycarbosilane, polysilazane and polysiloxane thin films synthesized by plasma enhanced chemical vapor deposition (PECVD) and subsequently irradiated with 170 keV He+ ions at fluences from 1 × 1014 to 1 × 1016 cm-2. Several bands not seen using the conventional mode could be observed in the polarized mode.

  9. Backscattering of α-Quartz (0 6 10) for 14.4 keV Mössbauer Photons

    NASA Astrophysics Data System (ADS)

    Imai, Yasuhiko; Yoda, Yoshitaka; Zhang, Xiaowei; Kikuta, Seishi

    2007-01-01

    Backscattering of α-quartz (0 6 10) was investigated using 14.4 keV 57Fe Mössbauer photons from α-57Fe2O3 at nuclear resonant scattering beamline BL09XU, SPring-8. The α-quartz crystal was heated to around 353 K by an oven so that the Bragg angle of α-quartz 0 6 10 diffraction meats 90 degrees. Energy width of the reflection was measured by changing temperature of the oven. The measured bandwidth is 1.14(33) meV. Backscattering by a α-quartz crystal can be applied for high-energy-resolution monochromator or analyzer.

  10. A compact source of intense 1-100 keV monochromatic X-rays from low energy protons

    NASA Astrophysics Data System (ADS)

    Arduini, G.; Cicardi, C.; Milazzo, M.; Sangaletti, L.; Silari, M.

    1995-05-01

    The properties and possible applications of a very intense source of monochromatic X-rays, tunable in the 1-100 keV range, obtained by coupling a low energy (2-4 MeV) high current proton accelerator with an irradiation chamber provided with a multiple target system and collimator are discussed. The properties of the source are presented in terms of intensity, monochromaticity, polarizability and time structure. Fields where such a source can be employed are discussed, namely PIXE-induced XRF, X-ray photoemission spectroscopy, generation of soft X-rays, radiographic applications in archeometry and medical radiography with monoenergetic radiation.

  11. Spectral reflectance change and luminescence of selected salts during 2-10 KeV proton bombardment - Implications for Io

    NASA Technical Reports Server (NTRS)

    Nelson, R. M.; Nash, D. B.

    1979-01-01

    Radiation damage and luminescence caused by magnetospheric charged particles have been suggested by several investigators as mechanisms that are capable of explaining some of the peculiar spectral/albedo features of Io. In the present paper, this possibility is pursued by measuring the UV-visual spectral reflectance and luminescent efficiency of several proposed Io surface constituents during 2 to 10 keV proton irradiation at room and low temperatures. The luminescence efficiencies of pure samples, studied in the laboratory, suggest that charged-particle induced luminescence from Io's surface might be observable by spacecraft such as Voyager when viewing Io's dark side.

  12. 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

  13. One-dimensional x-ray imaging using a spherically bent mica crystal at 4.75 keV

    SciTech Connect

    Workman, J.; Evans, S.; Kyrala, G. A.

    2001-01-01

    One-dimensional x-ray imaging of static gold bars using a spherically bent mica crystal is presented for the first time at an x-ray energy of 4.75 keV. X rays are produced using 1-ns-square pulses on the TRIDENT laser facility driving the He-like resonance transition in solid titanium disks. Time-integrated images of square profile parallel gold bars are recorded on direct exposure film with a magnification of {approx}10. Rising edge measurements of the bars demonstrate resolutions of about 6--7 {mu}m over a 400 {mu}m field of view.

  14. Measurements of the total atomic differential cross section of elastic scattering of 59.54-keV photons

    NASA Astrophysics Data System (ADS)

    Casnati, E.; Baraldi, C.; Tartari, A.

    1990-09-01

    Accurate measurements, mostly to within 2%, of the total atomic cross section for the elastic scattering of 59.54-keV photons on atoms in the 13<=Z<=82 range were carried out at 60°, 90°, and 120° scattering angles. Very good agreement with other experimental data was observed, in particular, with those of Schumacher and Stoffregen [Z. Phys. A 283, 15 (1977)]. The comparison with the theoretical results given by Kissel and co-workers [Phys. Rev. A 22, 1979 (1980); Phys. Rep. 140, 75 (1986)] confirms the validity of their procedure within the value intervals explored.

  15. DWBA analysis of {sup 12}C(d,p){sup 13}C cross section data below 300 keV deuteron energy

    SciTech Connect

    Naqvi, A.A.; Ayer, Z.; Ludwig, E. ||

    1994-12-31

    {sup 12}C(d,p){sup 13}T differential cross section data at 200, 220, 250, 280 and 300 keV deuteron energies has been analyzed using finite range DWBA codes PTOLEMY and TWOFNR. It was observed that shape and magnitude of the cross section data at 300, 280 keV energies can be fitted well but the shape of 250, 220 and 200 keV data cannot be fitted. However 250, 220 and 200 keV data shape can be fitted by changing the optical model parameters at each energy. This indicates a very strong energy dependence of the optical model parameters data of the entrance channel over such a small energy range which is not observed in the presently available elastic scattering data of the entrance channel.

  16. Simulations of Microchannel Plate Sensitivity to <20 keV X-rays as a Function of Energy and Incident Angle

    SciTech Connect

    Kruschwitz, Craig; Wu, M.; Rochau, G. A.

    2013-06-13

    We present results of Monte Carlo simulations of microchannel plate (MCP) response to x-rays in the 250 eV to 20 keV energy range as a function of both x-ray energy and impact angle. The model is based on the model presented in Rochau et al. (2006). However, while the Rochau et al. (2006) model was two-dimensional, and their results only went to 5 keV, our results have been expanded to 20 keV, and our model has been incorporated into a three-dimensional Monte Carlo MCP model that we have developed over the past several years (Kruschwitz et al. 2011). X-ray penetration through multiple MCP pore walls is increasingly important above 5 keV. The effect of x-ray penetration through multiple pores on MCP performance was studied and is presented.

  17. The Galactic plane at faint X-ray fluxes - II. Stacked X-ray spectra of a sample of serendipitous XMM-Newton sources

    NASA Astrophysics Data System (ADS)

    Warwick, R. S.; Byckling, K.; Pérez-Ramírez, D.

    2014-03-01

    We have investigated the X-ray spectral properties of a sample of 138 X-ray sources detected serendipitously in XMM-Newton observations of the Galactic plane, at an intermediate to faint flux level. We divide our sample into five subgroups according to the spectral hardness of the sources, and stack (i.e. co-add) the individual source spectra within each subgroup. As expected these stacked spectra show a softening trend from the hardest to the softest subgroups, which is reflected in the inferred line-of-sight column density. The spectra of the three hardest subgroups are characterized by a hard continuum plus superimposed Fe-line emission in the 6-7 keV bandpass. The average equivalent width (EW) of the 6.7-keV He-like Fe Kα line is 170^{+35}_{-32} eV, whereas the 6.4-keV Fe K fluorescence line from neutral iron and the 6.9-keV H-like Fe Lyα line have EWs of 89^{+26}_{-25} and 81^{+30}_{-29} eV, respectively, i.e. roughly half that of the 6.7-keV line. The remaining subgroups exhibit soft thermal spectra. Virtually all of the spectrally soft X-ray sources can be associated with relatively nearby coronally active late-type stars, which are evident as bright near-infrared (NIR) objects within the X-ray error circles. On a similar basis only a minority of the spectrally hard X-ray sources have likely NIR identifications. The average continuum and Fe-line properties of the spectrally hard sources are consistent with those of magnetic cataclysmic variables but the direct identification of large numbers of such systems in Galactic X-ray surveys, probing intermediate to faint flux levels, remains challenging.

  18. Determination of the total electron scattering cross sections of the noble gases by a linear transmission technique in the intermediate energy range 0.3 keV to 2.0 keV

    NASA Astrophysics Data System (ADS)

    Goains, Christopher P.

    Total electron scattering cross sections for the noble gases He, Ne, Ar, Kr and Xe have been determined by the linear transmission technique in the intermediate energy range 0.3 keV to 2.0 keV with a random experimental error of +/-3.0%. The total electron scattering cross sections were compared to other total cross sections determined by the linear transmission technique and the Ramsauer technique previously reported in the literature. In general, the total electron scattering cross sections determined in the present agree with the previously-reported total electron scattering cross sections determined by other experimental groups using the linear transmission technique, especially with those that report relatively large random errors of +/-6. Deviations of up to 11% are, however, seen in the cross sections for He and deviations of up to 15% can be seen with experiments citing large corrections for small-angle elastically- and inelastically-scattered electrons. The total cross sections determined by the Ramsauer technique agree with the present ones to within 7% for Ne and Ar, but show deviations of up to nearly 20% for He, Kr and Xe at energies above 1000 eV.

  19. The counterpart/s of IGR J20159+3713/SWIFT J2015.9+3715: dissecting a complex region with emission from keV to TeV

    NASA Astrophysics Data System (ADS)

    Bassani, L.; Landi, R.; Malizia, A.; Stephen, J. B.; Bazzano, A.; Bird, A. J.; Ubertini, P.

    2014-01-01

    We report on the identification of a new soft gamma-ray source, namely IGR J20159+3713/SWIFT J2015.9+3715, first detected by INTEGRAL/IBIS and then confirmed by Swift/BAT. The source, which has an observed 20-100 keV flux in the range (0.7-1.4) × 10-11 erg cm-2 s-1, encloses a Fermi variable source (2FGL J2015.6+3709) and is spatially close to a TeV emitter (VER J2016+372). Thanks to X-ray follow-up observations performed with the X-ray telescope on board Swift, we have been able to identify the new IBIS/BAT detection with the combined emission of the blazar B2013+370 and the cataclysmic variable RX J2015.6+3711. Both objects show variability in X-rays, with the cataclysmic variable being the most variable of the two. At high energies (above 20 keV) the emission is likely dominated by B2013+370, but the contribution from RX J2015.6+3711 is not negligible, The blazar emits up to GeV frequencies where it is seen by Fermi, while the cataclysmic variable has a bremsstrahlung temperature which is too low to provide any contribution at these high energies. These findings also indicate that the INTEGRAL/Swift source is not associated with the TeV emission, which is most likely due to the supernova remnant (SNR)/pulsar wind nebula (PWN) CTB 87.

  20. Absolute flux scale for radioastronomy

    SciTech Connect

    Ivanov, V.P.; Stankevich, K.S.

    1986-07-01

    The authors propose and provide support for a new absolute flux scale for radio astronomy, which is not encumbered with the inadequacies of the previous scales. In constructing it the method of relative spectra was used (a powerful tool for choosing reference spectra). A review is given of previous flux scales. The authors compare the AIS scale with the scale they propose. Both scales are based on absolute measurements by the ''artificial moon'' method, and they are practically coincident in the range from 0.96 to 6 GHz. At frequencies above 6 GHz, 0.96 GHz, the AIS scale is overestimated because of incorrect extrapolation of the spectra of the primary and secondary standards. The major results which have emerged from this review of absolute scales in radio astronomy are summarized.

  1. Flux Quantization Without Cooper Pairs

    NASA Astrophysics Data System (ADS)

    Kadin, Alan

    2013-03-01

    It is universally accepted that the superconducting flux quantum h/2e requires the existence of a phase-coherent macroscopic wave function of Cooper pairs, each with charge 2e. On the contrary, we assert that flux quantization can be better understood in terms of single-electron quantum states, localized on the scale of the coherence length and organized into a real-space phase-antiphase structure. This packing configuration is consistent with the Pauli exclusion principle for single-electron states, maintains long-range phase coherence, and is compatible with much of the BCS formalism. This also accounts for h/2e in the Josephson effect, without Cooper pairs. Experimental evidence for this alternative picture may be found in deviations from h/2e in loops and devices much smaller than the coherence length. A similar phase-antiphase structure may also account for superfluids, without the need for boson condensation.

  2. Heisenberg groups and noncommutative fluxes

    SciTech Connect

    Freed, Daniel S. . E-mail: dafr@math.utexas.edu; Moore, Gregory W.; Segal, Graeme

    2007-01-15

    We develop a group-theoretical approach to the formulation of generalized abelian gauge theories, such as those appearing in string theory and M-theory. We explore several applications of this approach. First, we show that there is an uncertainty relation which obstructs simultaneous measurement of electric and magnetic flux when torsion fluxes are included. Next, we show how to define the Hilbert space of a self-dual field. The Hilbert space is Z{sub 2}-graded and we show that, in general, self-dual theories (including the RR fields of string theory) have fermionic sectors. We indicate how rational conformal field theories associated to the two-dimensional Gaussian model generalize to (4k+2)-dimensional conformal field theories. When our ideas are applied to the RR fields of string theory we learn that it is impossible to measure the K-theory class of a RR field. Only the reduction modulo torsion can be measured.

  3. SQUID With Integral Flux Concentrator

    NASA Technical Reports Server (NTRS)

    Peters, Palmer N.; Sisk, Robert C.

    1989-01-01

    In improved superconducting quantum interference device (SQUID), change in size and shape of superconducting ring improves coupling to external signal coil and eases coil-positioning tolerances. More rugged and easier to manufacture than conventional SQUID's with comparable electrical characteristics. Thin-film superconducting flux concentrator utilizes Meissner effect to deflect magnetic field of signal coil into central hole of SQUID. Used in magnetometers, ammeters, analog-to-digital converters, and related electronic applications in which high signal-to-noise ratios required.

  4. Recent Solar-Proton Fluxes

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.

    2005-01-01

    The event-integrated fluences of energetic solar protons up to 2004 at the Earth have been determined and compared to previous data. The current solar cycle has been very active, and very large fluxes of solar protons have been observed that have had serious effects in the solar system and will have produced many radionuclides in the surfaces of meteorites. Such huge events are not expected again until about 2008 or 2009.

  5. Structural Control of Metabolic Flux

    PubMed Central

    Sajitz-Hermstein, Max; Nikoloski, Zoran

    2013-01-01

    Organisms have to continuously adapt to changing environmental conditions or undergo developmental transitions. To meet the accompanying change in metabolic demands, the molecular mechanisms of adaptation involve concerted interactions which ultimately induce a modification of the metabolic state, which is characterized by reaction fluxes and metabolite concentrations. These state transitions are the effect of simultaneously manipulating fluxes through several reactions. While metabolic control analysis has provided a powerful framework for elucidating the principles governing this orchestrated action to understand metabolic control, its applications are restricted by the limited availability of kinetic information. Here, we introduce structural metabolic control as a framework to examine individual reactions' potential to control metabolic functions, such as biomass production, based on structural modeling. The capability to carry out a metabolic function is determined using flux balance analysis (FBA). We examine structural metabolic control on the example of the central carbon metabolism of Escherichia coli by the recently introduced framework of functional centrality (FC). This framework is based on the Shapley value from cooperative game theory and FBA, and we demonstrate its superior ability to assign “share of control” to individual reactions with respect to metabolic functions and environmental conditions. A comparative analysis of various scenarios illustrates the usefulness of FC and its relations to other structural approaches pertaining to metabolic control. We propose a Monte Carlo algorithm to estimate FCs for large networks, based on the enumeration of elementary flux modes. We further give detailed biological interpretation of FCs for production of lactate and ATP under various respiratory conditions. PMID:24367246

  6. Simulation of plasma current ramp-up with reduced magnetic flux consumption in JT-60SA

    NASA Astrophysics Data System (ADS)

    Wakatsuki, T.; Suzuki, T.; Hayashi, N.; Shiraishi, J.; Ide, S.; Takase, Y.

    2015-06-01

    Current ramp-up with reduced central solenoid (CS) flux consumption in JT-60SA has been investigated using an integrated modeling code suite (TOPICS) with a turbulent model (CDBM). The plasma current can be ramped-up from 0.6 MA to 2.1 MA with no additional CS flux consumption if the plasma current is overdriven by neutral-beam-driven and bootstrap current. A time duration required for the current ramp-up without CS flux consumption becomes as long as 150 s in the scenario we have examined. In order to achieve a current overdrive condition from 0.6 MA, the current drive by a lower energy neutral beam (85 keV) is effective. A higher energy neutral beam (500 keV) cannot be used in this early phase with a low central electron density (~2 × 1019 m-3) due to large shine through loss, while it can be effectively used in the later phase. Therefore, the main current driver should be switched from the lower energy neutral beam to the higher energy neutral beam during the current ramp-up phase. As a result of an intensive auxiliary heating, plasma beta (the ratio of the plasma pressure to the magnetic pressure) becomes high. Ideal MHD instabilities of such high beta plasmas have been investigated using a linear ideal MHD stability analysis code (MARG2D). External kink modes which might affect the core plasma can be stabilized during the current ramp-up if there is a perfectly conducting wall at the location of the stabilizing plate and the vacuum vessel of JT-60SA and the plasma has a broader pressure profile with the H-mode pedestal and the internal transport barrier.

  7. Profiles of the Ribbon: Systematic ENA Flux Features Within and Beyond the Central Ribbon

    NASA Astrophysics Data System (ADS)

    Funsten, H. O.; Demajistre, R.; Frisch, P. C.; Fuselier, S.; Janzen, P. H.; Livadiotis, G.; McComas, D. J.; Pittman, K. T.; Reisenfeld, D. B.; Schwadron, N.

    2014-12-01

    The ribbon of enhanced energetic neutral atom (ENA) flux is the most prominent feature of outer heliospheric ENA emission as observed by the Interstellar Boundary Explorer (IBEX). Here, we study the systematic variation of ENA flux in the ribbon and in its vicinity as a function of angle from the ribbon center at ecliptic (219°, 40°) as projected in the sky. We find that the ENA emission on the interior of the ribbon (between the ribbon and the ribbon center) is correlated with the emission brightness of the ribbon peak, whereas ENA emission on the exterior of the ribbon (between the ribbon and the antipode of the ribbon center) is not correlated with ribbon brightness. The ribbon flux falls to zero beyond a great circle in the sky at 90º from the ribbon center and is thus constrained to a hemisphere of emission that is centered on the ribbon center. These results are consistent with the "secondary" emission process of ribbon formation in the outer heliosheath [Heerikhuisen et al., 2010; McComas and Schwadron, 2013]. We additionally deconvolve the IBEX point spread function from analytical fits to the ribbon shape. We find that the ribbon peak is approximately 5% brighter than observations that do not consider the PSF. We also find a wide but consistent variation of ribbon widths, with the full width at half maximum ranging from 14º and 34º for 0.7-2.7 keV. At 4.3 keV the ribbon is consistently wider, with a 24º minimum ribbon width. We discuss the implications of the sharpness of the ribbon peak for observations of the Interstellar Mapping and Acceleration Probe (IMAP).

  8. Sediment flux and the Anthropocene.

    PubMed

    Syvitski, James P M; Kettner, Albert

    2011-03-13

    Data and computer simulations are reviewed to help better define the timing and magnitude of human influence on sediment flux--the Anthropocene epoch. Impacts on the Earth surface processes are not spatially or temporally homogeneous. Human influences on this sediment flux have a secondary effect on floodplain and delta-plain functions and sediment dispersal into the coastal ocean. Human impact on sediment production began 3000 years ago but accelerated more widely 1000 years ago. By the sixteenth century, societies were already engineering their environment. Early twentieth century mechanization has led to global signals of increased sediment flux in most large rivers. By the 1950s, this sediment disturbance signal reversed for many rivers owing to the proliferation of dams, and sediment load reduction below pristine conditions is the dominant signal today. A delta subsidence signal began in the 1930s and is now a dominant signal in terms of sea level for many coastal environments, overwhelming even the global warming imprint on sea level. Humans have engineered how most water and sediment are discharged into the coastal ocean. Hyperpycnal flow events have become more common for some rivers, and less common for other rivers. Bottom trawling is now widespread, suggesting that even continental shelves have received a significant but as yet quantified Anthropocene impact. The Anthropocene attains the level of a geological climate event, such as that seen in the transition between the Pleistocene and the Holocene.

  9. Strengths of the resonances at 436, 479, 639, 661, and 1279 keV in the 22Ne(p ,γ ) 23Na reaction

    NASA Astrophysics Data System (ADS)

    Depalo, Rosanna; Cavanna, Francesca; Ferraro, Federico; Slemer, Alessandra; Al-Abdullah, Tariq; Akhmadaliev, Shavkat; Anders, Michael; Bemmerer, Daniel; Elekes, Zoltán; Mattei, Giovanni; Reinicke, Stefan; Schmidt, Konrad; Scian, Carlo; Wagner, Louis

    2015-10-01

    The 22Ne(p ,γ )23Na reaction is included in the neon-sodium cycle of hydrogen burning. A number of narrow resonances in the Gamow window dominate the thermonuclear reaction rate. Several resonance strengths are only poorly known. As a result, the 22Ne(p ,γ )23Na thermonuclear reaction rate is the most uncertain rate of the cycle. Here, a new experimental study of the strengths of the resonances at 436, 479, 639, 661, and 1279 keV proton beam energy is reported. The data have been obtained using a tantalum target implanted with 22Ne. The strengths ω γ of the resonances at 436, 639, and 661 keV have been determined with a relative approach, using the 479- and 1279-keV resonances for normalization. Subsequently, the ratio of resonance strengths of the 479- and 1279-keV resonances were determined, improving the precision of these two standards. The new data are consistent with, but more precise than, the literature with the exception of the resonance at 661 keV, which is found to be less intense by one order of magnitude. In addition, improved branching ratios have been determined for the gamma decay of the resonances at 436, 479, and 639 keV.

  10. 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.

  11. Electron events from the scattering with solar neutrinos in the search of keV scale sterile neutrino dark matter

    NASA Astrophysics Data System (ADS)

    Liao, Wei; Wu, Xiao-Hong; Zhou, Hang

    2014-05-01

    In a previous work, we showed that it is possible to detect keV scale sterile neutrino dark matter νs in a β decay experiment using radioactive sources such as T3 or Ru106. The signals of this dark matter candidate are monoenergetic electrons produced in the neutrino capture process νs+ N'→N+e-. These electrons have energy greater than the maximum energy of the electrons produced in the associated decay process N'→N+e-+ν ¯e. Hence, signal electron events are well beyond the end point of the β decay spectrum and are not polluted by the β decay process. Another possible background, which is a potential threat to the detection of νs dark matter, is the electron event produced by the scattering of solar neutrinos with electrons in target matter. In this article, we study in detail this possible background and discuss its implications for the detection of keV scale sterile neutrino dark matter. In particular, bound state features of electrons in Ru atoms are considered with care in the scattering process when the kinetic energy of the final electron is the same order of magnitude of the binding energy.

  12. The Physical Nature of the Sharp Spectral Feature at 7 keV Detected in 1H0707-495

    NASA Technical Reports Server (NTRS)

    Brandt, Niel

    2005-01-01

    XMM-Newton acquired data on the accepted target, 1H0707-495, on 2002 October 13 during revolution 0521. The observation was successful, with only about 5% data loss due to background flaring. We compared the data from this observation with earlier data taken on this Narrow-Line Seyfert 1 about two years before, performing interpretation studies in the context of the partial-covering model. Our second longer observation once again displays a sharp (< 200 eV) spectral drop above 7 keV. However, in comparison to the first observation, the edge depth and energy have changed significantly. In addition to changes in the edge parameters, the high-energy spectrum appears steeper. The changes in the high-energy spectrum can be adequately explained in terms of a partial-covering absorber out-flowing from the central region. The low-energy spectrum also shows significant long-term spectral variability, including (1) a substantial increase in the disk temperature, (2) detection of an approx. 0.9 keV emission feature, and (3) the presence of ionized absorption that was detected during the ASCA mission. The large increase in disk temperature, and the more modest rise in luminosity, can be understood if we consider a slim-disk model for 1H0707-495. In addition, the higher disk luminosity could be the driving force behind the outflow and the re-appearance of an ionized medium during the second XMM-Newton observation.

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

    NASA Astrophysics Data System (ADS)

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

    2012-07-01

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

  14. Electric Fields Associated with Deep Injections of 10s to 100s keV Electrons in the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Califf, S.; Li, X.; Jaynes, A. N.; Zhao, H.; Malaspina, D.

    2015-12-01

    Recent observations by HOPE and MagEIS onboard the Van Allen Probes show frequent penetration of 10s to 100s keV electrons through the slot region and into the inner belt, resulting in an abundant electron population below L=3. The conventional picture is that the source populations of these 10s to 100s keV electrons originate in the plasma sheet and are injected (along with plasma sheet ions) into the inner magnetosphere either through enhancements in the large-scale convection electric field and/or through earthward propagating dipolarization fronts associated with substorms. In such cases the inward radial limit of the injections should coincide with the plasmapause. However, these electron injections often extend inside the plasmasphere, are observed far earthward of the typically accepted "flow-braking" region for dipolarization fronts, and occur at much lower L shells than injections of ions with similar energies. We investigate the electric fields associated with these deep electron injections using data from the Van Allen Probes and THEMIS in order to shed light on the underlying mechanisms that allow them to penetrate so far into the inner magnetosphere.

  15. Measurement of the Erc .m .=259 keV resonance in the 14N(p ,γ )15O reaction

    NASA Astrophysics Data System (ADS)

    Daigle, S.; Kelly, K. J.; Champagne, A. E.; Buckner, M. Q.; Iliadis, C.; Howard, C.

    2016-08-01

    The 14N(p ,γ )15O reaction regulates the power generated by the CN cycle and thus impacts the structure and evolution of every star at some point in its life. The lowest positive-energy resonance in this reaction is located at Erc .m .=259 keV, too high in energy to strongly influence quiescent stellar burning. However, the strength of this resonance is used as a cross-section normalization for lower-energy measurements of this reaction. We report on new measurements of the energy, strength, and γ -ray branching ratios for the 259-keV resonance, using different detection and data-analysis schemes. We have also reevaluated previous results, where possible. Our new recommended strength of ω γ =12.6 (3 ) meV is in agreement with the previous value of 13.1(6) meV, but is more precise and thus provides a more reliable normalization for low-energy (p ,γ ) measurements.

  16. New production mechanism for keV sterile neutrino Dark Matter by decays of frozen-in scalars

    SciTech Connect

    Merle, Alexander; Niro, Viviana; Schmidt, Daniel E-mail: niro@ecm.ub.edu

    2014-03-01

    We propose a new production mechanism for keV sterile neutrino Dark Matter. In our setting, we assume the existence of a scalar singlet particle which never entered thermal equilibrium in the early Universe, since it only couples to the Standard Model fields by a really small Higgs portal interaction. For suitable values of this coupling, the scalar can undergo the so-called freeze-in process, and in this way be efficiently produced in the early Universe. These scalars can then decay into keV sterile neutrinos and produce the correct Dark Matter abundance. While similar settings in which the scalar does enter thermal equilibrium and then freezes out have been studied previously, the mechanism proposed here is new and represents a versatile extension of the known case. We perform a detailed numerical calculation of the DM production using a set of coupled Boltzmann equations, and we illustrate the successful regions in the parameter space. Our production mechanism notably can even work in models where active-sterile mixing is completely absent.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

  18. 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.

  19. Energetic particle characteristics of magnetotail flux ropes

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    During the recent ISEE-3 Geotail Mission three events have been identified from the magnetometer data which are consistent with a spacecraft crossing of a magnetotail flux rope. Energetic electron and proton observations obtained by the Max-Planck-Institut/University of Maryland sensor system during two of the possible flux rope events are presented. During one event remote sensing of the flux rope with energetic protons reveals that the flux rope is crossed by the spacecraft from south to north. This allows determination of the bandedness of the magnetic field twist and of the flux rope velocity relative to the spacecraft. A minimal flux rope radius of 3 earth radii is derived. Energetic proton intensity is highest just inside of the flux rope and decreases towards the core. Energetic electrons are streaming tailward near the outer boundary, indicating openness of the field lines, and are isotropic through the inner part of the flux rope.

  20. Vertical transport and sources in flux models

    SciTech Connect

    Canavan, G.H.

    1997-01-01

    Vertical transport in flux models in examined and shown to reproduce expected limits for densities and fluxes. Disparities with catalog distributions are derived and inverted to find the sources required to rectify them.

  1. Inverse Compton X-Ray Emission from TeV Blazar Mrk 421 During a Historical Low-flux State Observed with NuSTAR

    NASA Astrophysics Data System (ADS)

    Kataoka, Jun; Stawarz, Łukasz

    2016-08-01

    We report on the detection of excess hard X-ray emission from the TeV BL Lac object Mrk 421 during the historical low-flux state of the source in 2013 January. Nuclear Spectroscopic Telescope Array observations were conducted four times between MJD 56294 and MJD 56312 with a total exposure of 80.9 ks. The source flux in the 3-40 keV range was nearly constant, except for MJD 56307 when the average flux level increased by a factor of three. Throughout the exposure, the X-ray spectra of Mrk 421 were well represented by a steep power-law model with a photon index of Γ ≃ 3.1, although a significant excess was noted above 20 keV in the MJD 56302 data when the source was in its faintest state. Moreover, Mrk 421 was detected at more than the 4σ level in the 40-79 keV count maps for both MJD 56307 and MJD 56302 but not during the remaining two observations. The detected excess hard X-ray emission connects smoothly with the extrapolation of the high-energy γ-ray continuum of the blazar constrained by Fermi-LAT during source quiescence. These findings indicate that while the overall X-ray spectrum of Mrk 421 is dominated by the highest-energy tail of the synchrotron continuum, the variable excess hard X-ray emission above 20 keV (on the timescale of a week) is related to the inverse Compton emission component. We discuss the resulting constraints on the variability and spectral properties of the low-energy segment of the electron energy distribution in the source.

  2. Inverse Compton X-Ray Emission from TeV Blazar Mrk 421 During a Historical Low-flux State Observed with NuSTAR

    NASA Astrophysics Data System (ADS)

    Kataoka, Jun; Stawarz, Łukasz

    2016-08-01

    We report on the detection of excess hard X-ray emission from the TeV BL Lac object Mrk 421 during the historical low-flux state of the source in 2013 January. Nuclear Spectroscopic Telescope Array observations were conducted four times between MJD 56294 and MJD 56312 with a total exposure of 80.9 ks. The source flux in the 3–40 keV range was nearly constant, except for MJD 56307 when the average flux level increased by a factor of three. Throughout the exposure, the X-ray spectra of Mrk 421 were well represented by a steep power-law model with a photon index of Γ ≃ 3.1, although a significant excess was noted above 20 keV in the MJD 56302 data when the source was in its faintest state. Moreover, Mrk 421 was detected at more than the 4σ level in the 40–79 keV count maps for both MJD 56307 and MJD 56302 but not during the remaining two observations. The detected excess hard X-ray emission connects smoothly with the extrapolation of the high-energy γ-ray continuum of the blazar constrained by Fermi-LAT during source quiescence. These findings indicate that while the overall X-ray spectrum of Mrk 421 is dominated by the highest-energy tail of the synchrotron continuum, the variable excess hard X-ray emission above 20 keV (on the timescale of a week) is related to the inverse Compton emission component. We discuss the resulting constraints on the variability and spectral properties of the low-energy segment of the electron energy distribution in the source.

  3. CRTF Real-Time Aperture Flux system

    SciTech Connect

    Davis, D.B.

    1980-01-01

    The Real-Time Aperture Flux system (TRAF) is a test measurement system designed to determine the input power/unit area (flux density) during solar experiments conducted at the Central Receiver Test Facility, Sandia National Laboratories, Albuquerque, New Mexico. The RTAF is capable of using both thermal sensors and photon sensors to determine the flux densities in the RTAF measuring plane. These data are manipulated in various ways to derive input power and flux density distribution to solar experiments.

  4. Flux balance analysis accounting for metabolite dilution.

    PubMed

    Benyamini, Tomer; Folger, Ori; Ruppin, Eytan; Shlomi, Tomer

    2010-01-01

    Flux balance analysis is a common method for predicting steady-state flux distributions within metabolic networks, accounting for the growth demand for the synthesis of a predefined set of essential biomass precursors. Ignoring the growth demand for the synthesis of intermediate metabolites required for balancing their dilution leads flux balance analysis to false predictions in some cases. Here, we present metabolite dilution flux balance analysis, which addresses this problem, resulting in improved metabolic phenotype predictions. PMID:20398381

  5. High-flux solar photon processes

    SciTech Connect

    Lorents, D.C.; Narang, S.; Huestis, D.C.; Mooney, J.L.; Mill, T.; Song, H.K.; Ventura, S.

    1992-06-01

    This study was commissioned by the National Renewable Energy Laboratory (NREL) for the purpose of identifying high-flux photoprocesses that would lead to beneficial national and commercial applications. The specific focus on high-flux photoprocesses is based on the recent development by NREL of solar concentrator technology capable of delivering record flux levels. We examined photolytic and photocatalytic chemical processes as well as photothermal processes in the search for processes where concentrated solar flux would offer a unique advantage. 37 refs.

  6. Force sensor using changes in magnetic flux

    NASA Technical Reports Server (NTRS)

    Pickens, Herman L. (Inventor); Richard, James A. (Inventor)

    2012-01-01

    A force sensor includes a magnetostrictive material and a magnetic field generator positioned in proximity thereto. A magnetic field is induced in and surrounding the magnetostrictive material such that lines of magnetic flux pass through the magnetostrictive material. A sensor positioned in the vicinity of the magnetostrictive material measures changes in one of flux angle and flux density when the magnetostrictive material experiences an applied force that is aligned with the lines of magnetic flux.

  7. Flux balance analysis accounting for metabolite dilution.

    PubMed

    Benyamini, Tomer; Folger, Ori; Ruppin, Eytan; Shlomi, Tomer

    2010-01-01

    Flux balance analysis is a common method for predicting steady-state flux distributions within metabolic networks, accounting for the growth demand for the synthesis of a predefined set of essential biomass precursors. Ignoring the growth demand for the synthesis of intermediate metabolites required for balancing their dilution leads flux balance analysis to false predictions in some cases. Here, we present metabolite dilution flux balance analysis, which addresses this problem, resulting in improved metabolic phenotype predictions.

  8. What are Up, Down and Net Fluxes?

    Atmospheric Science Data Center

    2014-12-08

    ... is of particular interest. Hence the term "Up" and "Down" for characterizing the direction of flow of radiative fluxes at a ... level. Moreover, by counting in or out these "Up" and "Down" energy fluxes, one can define a "Net" flux that is ultimately ...

  9. Apparatus for measuring a flux of neutrons

    DOEpatents

    Stringer, James L.

    1977-01-01

    A flux of neutrons is measured by disposing a detector in the flux and applying electronic correlation techniques to discriminate between the electrical signals generated by the neutron detector and the unwanted interfering electrical signals generated by the incidence of a neutron flux upon the cables connecting the detector to the electronic measuring equipment at a remote location.

  10. Latent Heat in Soil Heat Flux Measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, the...

  11. Measurements with the high flux lead slowing-down spectrometer at LANL

    NASA Astrophysics Data System (ADS)

    Danon, Y.; Romano, C.; Thompson, J.; Watson, T.; Haight, R. C.; Wender, S. A.; Vieira, D. J.; Bond, E.; Wilhelmy, J. B.; O'Donnell, J. M.; Michaudon, A.; Bredeweg, T. A.; Schurman, T.; Rochman, D.; Granier, T.; Ethvignot, T.; Taieb, J.; Becker, J. A.

    2007-08-01

    A Lead Slowing-Down Spectrometer (LSDS) was recently installed at LANL [D. Rochman, R.C. Haight, J.M. O'Donnell, A. Michaudon, S.A. Wender, D.J. Vieira, E.M. Bond, T.A. Bredeweg, A. Kronenberg, J.B. Wilhelmy, T. Ethvignot, T. Granier, M. Petit, Y. Danon, Characteristics of a lead slowing-down spectrometer coupled to the LANSCE accelerator, Nucl. Instr. and Meth. A 550 (2005) 397]. The LSDS is comprised of a cube of pure lead 1.2 m on the side, with a spallation pulsed neutron source in its center. The LSDS is driven by 800 MeV protons with a time-averaged current of up to 1 μA, pulse widths of 0.05-0.25 μs and a repetition rate of 20-40 Hz. Spallation neutrons are created by directing the proton beam into an air-cooled tungsten target in the center of the lead cube. The neutrons slow down by scattering interactions with the lead and thus enable measurements of neutron-induced reaction rates as a function of the slowing-down time, which correlates to neutron energy. The advantage of an LSDS as a neutron spectrometer is that the neutron flux is 3-4 orders of magnitude higher than a standard time-of-flight experiment at the equivalent flight path, 5.6 m. The effective energy range is 0.1 eV to 100 keV with a typical energy resolution of 30% from 1 eV to 10 keV. The average neutron flux between 1 and 10 keV is about 1.7 × 109 n/cm2/s/μA. This high flux makes the LSDS an important tool for neutron-induced cross section measurements of ultra-small samples (nanograms) or of samples with very low cross sections. The LSDS at LANL was initially built in order to measure the fission cross section of the short-lived metastable isotope of U-235, however it can also be used to measure (n, α) and (n, p) reactions. Fission cross section measurements were made with samples of 235U, 236U, 238U and 239Pu. The smallest sample measured was 10 ng of 239Pu. Measurement of (n, α) cross section with 760 ng of Li-6 was also demonstrated. Possible future cross section measurements

  12. Variation in the calibrated response of LiF, Al2O3, and silicon dosimeters when used for in-phantom measurements of source photons with energies between 30 KeV AND 300 KeV.

    PubMed

    Poudel, Sashi; Currier, Blake; Medich, David C

    2015-04-01

    The MCNP5 radiation transport code was used to quantify changes in the absorbed dose conversion factor for LiF, Al2O3, and silicon-based electronic dosimeters calibrated in-air using standard techniques and summarily used to measure absorbed dose to water when placed in a water phantom. A mono-energetic photon source was modeled at energies between 30 keV and 300 keV for a point-source placed at the center of a water phantom, a point-source placed at the surface of the phantom, and for a 10-cm radial field geometry. Dosimetric calculations were obtained for water, LiF, Al2O3, and silicon at depths of 0.2 cm and 10 cm from the source. These results were achieved using the MCNP5 *FMESH photon energy-fluence tally, which was coupled with the appropriate DE/DF card for each dosimetric material studied to convert energy-fluence into the absorbed dose. The dosimeter's absorbed dose conversion factor was calculated as a ratio of the absorbed dose to water to that of the dosimeter measured at a specified phantom depth. The dosimeter's calibration value also was obtained. Based on these results, the absorbed dose conversion factor for a LiF dosimeter was found to deviate from its calibration value by up to 9%, an Al2O3 dosimeter by 43%, and a silicon dosimeter by 61%. These data therefore can be used to obtain LiF, Al2O3, and silicon dosimeter correction factors for mono-energetic and poly-energetic sources at measurement depths up to 10 cm under the irradiation geometries investigated herein.

  13. Distributions of nonsupersymmetric flux vacua

    NASA Astrophysics Data System (ADS)

    Denef, Frederik; Douglas, Michael R.

    2005-03-01

    We continue the study of the distribution of nonsupersymmetric flux vacua in IIb string theory compactified on Calabi-Yau manifolds, as in hep-th/0404116. We show that the basic structure of this problem is that of finding eigenvectors of the matrix of second derivatives of the superpotential, and that many features of the results are determined by features of the generic ensemble of such matrices, the CI ensemble of Altland and Zirnbauer originating in mesoscopic physics. We study some simple examples in detail, exhibiting various factors which can favor low or high scale supersymmetry breaking.

  14. Methane Fluxes from Subtropical Wetlands

    NASA Astrophysics Data System (ADS)

    DeLucia, N.; Gomez-Casanovas, N.; Bernacchi, C.

    2013-12-01

    It is well documented that green house gas concentrations have risen at unequivocal rates since the industrial revolution but the disparity between anthropogenic sources and natural sources is uncertain. Wetlands are one example of a natural ecosystem that can be a substantial source or sink for methane (CH4) depending on climate conditions. Due to strict anaerobic conditions required for CH4-generating microorganisms, natural wetlands are one of the main sources for biogenic CH4. Although wetlands occupy less than 5% of total land surface area, they contribute approximately 20% of total CH4 emissions to the atmosphere. The processes regulating CH4 emissions are sensitive to land use and management practices of areas surrounding wetlands. Variation in adjacent vegetation or grazing intensity by livestock can, for example, alter CH4 fluxes from wetland soils by altering nutrient balance, carbon inputs and hydrology. Therefore, understanding how these changes will affect wetland source strength is essential to understand the impact of wetland management practices on the global climate system. In this study we quantify wetland methane fluxes from subtropical wetlands on a working cattle ranch in central Florida near Okeechobee Lake (27o10'52.04'N, 81o21'8.56'W). To determine differences in CH4 fluxes associated with land use and management, a replicated (n = 4) full factorial experiment was designed for wetlands where the surrounding vegetation was (1) grazed or un-grazed and (2) composed of native vegetation or improved pasture. Net exchange of CH4 and CO2 between the land surface and the atmosphere were sampled with a LICOR Li-7700 open path CH4 analyzer and Li-7500A open path CO2/H20 analyzer mounted in a 1-m3 static gas-exchange chamber. Our results showed and verified that CH4 emissions from subtropical wetlands were larger when high soil moisture was coupled with high temperatures. The presence of cattle only amplified these results. These results help quantify

  15. Flux emergence event underneath a filament

    NASA Astrophysics Data System (ADS)

    Palacios, J.; Cerrato, Y.; Cid, C.; Guerrero, A.; Saiz, E.

    2015-10-01

    Flux emergence phenomena are relevant at different temporal and spatial scales. We have studied a flux emergence region underneath a filament. This filament elevated itself smoothly, and the associated CME reached the Earth. In this study we investigate the size and the amount of flux in the emergence event. The flux emergence site appeared just beneath a filament. The emergence acquired a size of 24 Mm in half a day. The unsigned magnetic flux density from LOS-magnetograms was around 1 kG at its maximum. The transverse field as well as the filament eruption were also analysed.

  16. Electron acceleration associated with the magnetic flux pileup regions in the near-Earth plasma sheet: A multicase study

    NASA Astrophysics Data System (ADS)

    Tang, C. L.; Zhou, M.; Yao, Z. H.; Shi, F.

    2016-05-01

    Using the Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations, we study electron acceleration (<30 keV) in the magnetic flux pileup regions (FPRs) in the near-Earth plasma sheet (X ~ -10 RE). We present three cases of FRPs associated with dipolarization fronts and substorm dipolarization. Based on the characteristics of the magnetic field, we defined the magnetic field enhancement region (MFER) as the magnetic field with significant ramp that is usually observed near the dipolarization front boundary layer. On the other side, the increased magnetic field without a significant ramp is the rest of a FPR. Our results show that betatron acceleration dominates for 10-30 keV electrons inside the MFER, whereas Fermi acceleration dominates for 10-30 keV electrons inside the rest of the FPR. Betatron acceleration is caused by the enhancement of the local magnetic field, whereas Fermi acceleration is related to the shrinking length of magnetic field line. These accelerated electrons inside the FPRs in the near-Earth tail play a potentially important role in the evolution of the Earth's electron radiation belt and substorms.

  17. Laser-Driven Magnetic-Flux Compression: Theory and Experiments

    NASA Astrophysics Data System (ADS)

    Chang, Po-Yu

    Laser-Driven Flux Compression (LDFC) is a technique used to compress the magnetic field in Inertial Confinement Fusion (ICF) targets driven by a laser. The compressed field in the ICF target is beneficial to the target performance. Embedding a magnetic field in a conventional ICF target reduces the heat loss if the central hot spot becomes magnetized. Higher hot spot temperatures lower the requirements on the implosion velocities, leading to larger shell masses and therefore higher energy gains. For a typical hot spot density of ˜ 10 g/cc, and temperature of ˜ 5 keV, a magnetic field B > 10 MG is required to magnetize the hot spot. Such a strong magnetic field is difficult to be externally generated. Instead of providing the strong magnetic field directly, a seed magnetic field much lower than the required field was provided and compressed by the imploding shell. The field needs to be compressed faster than its diffusion due to the finite resistivity of the fill gas and the shell. This requires the gas in the target being ionized by the shock so that the flux is frozen in the gas region and compressed by the imploding shell. In this thesis, theoretical models, numerical calculations, and basic experiments of flux compression in ICF targets are investigated. A measurable Lawson criterion, developed as a metric to assess the performance of an ICF target, is used to evaluate the benefits of suppressing the heat conductivity. A simple model is used to describe the process of field compression by shock waves during the shell implosion. The magnetohydrodynamics codes, LILAC-MHD and LILAC-MHD-SP, are used to simulate the field compression and the target performance. The Magneto-Inertial-Fusion-Electrical-Discharge-System (MIFEDS), the device providing the seed magnetic field, is described in detail. LDFC experiments using the OMEGA laser at the Laboratory for Laser Energetics are presented. The results include the first demonstration of ˜ 550-fold amplification of a 50

  18. Flux Sampling Errors for Aircraft and Towers

    NASA Technical Reports Server (NTRS)

    Mahrt, Larry

    1998-01-01

    Various errors and influences leading to differences between tower- and aircraft-measured fluxes are surveyed. This survey is motivated by reports in the literature that aircraft fluxes are sometimes smaller than tower-measured fluxes. Both tower and aircraft flux errors are larger with surface heterogeneity due to several independent effects. Surface heterogeneity may cause tower flux errors to increase with decreasing wind speed. Techniques to assess flux sampling error are reviewed. Such error estimates suffer various degrees of inapplicability in real geophysical time series due to nonstationarity of tower time series (or inhomogeneity of aircraft data). A new measure for nonstationarity is developed that eliminates assumptions on the form of the nonstationarity inherent in previous methods. When this nonstationarity measure becomes large, the surface energy imbalance increases sharply. Finally, strategies for obtaining adequate flux sampling using repeated aircraft passes and grid patterns are outlined.

  19. Automated Heat-Flux-Calibration Facility

    NASA Technical Reports Server (NTRS)

    Liebert, Curt H.; Weikle, Donald H.

    1989-01-01

    Computer control speeds operation of equipment and processing of measurements. New heat-flux-calibration facility developed at Lewis Research Center. Used for fast-transient heat-transfer testing, durability testing, and calibration of heat-flux gauges. Calibrations performed at constant or transient heat fluxes ranging from 1 to 6 MW/m2 and at temperatures ranging from 80 K to melting temperatures of most materials. Facility developed because there is need to build and calibrate very-small heat-flux gauges for Space Shuttle main engine (SSME).Includes lamp head attached to side of service module, an argon-gas-recirculation module, reflector, heat exchanger, and high-speed positioning system. This type of automated heat-flux calibration facility installed in industrial plants for onsite calibration of heat-flux gauges measuring fluxes of heat in advanced gas-turbine and rocket engines.

  20. Monitoring the Crab Nebula with LOFT

    NASA Technical Reports Server (NTRS)

    Wilson-Hodge, Colleen A.

    2012-01-01

    From 2008-2010, the Crab Nebula was found to decline by 7% in the 15-50 keV band, consistently in Fermi GBM, INTEGRAL IBIS, SPI, and JEMX, RXTE PCA, and Swift BAT. From 2001-2010, the 15-50 keV flux from the Crab Nebula typically varied by about 3.5% per year. Analysis of RXTE PCA data suggests possible spectral variations correlated with the flux variations. I will present estimates of the LOFT sensitivity to these variations. Prior to 2001 and since 2010, the observed flux variations have been much smaller. Monitoring the Crab with the LOFT WFM and LAD will provide precise measurements of flux variations in the Crab Nebula if it undergoes a similarly active episode.

  1. Atmospheric discharges and particle fluxes

    NASA Astrophysics Data System (ADS)

    Chilingarian, A.; Chilingaryan, S.; Reymers, A.

    2015-07-01

    Fluxes of the electrons, gamma rays, and neutrons observed by particle detectors located on the Earth's surface during thunderstorms originate so-called Thunderstorm Ground Enhancements (TGEs). The relativistic runaway electron avalanches giving rise to TGEs originate in the thundercloud's lower dipole between the main negatively charged region in the middle of the thundercloud and transient lower positively charged region. Acceleration of electrons in the upper dipole between main negative and main positive charge regions leads to initiation of the terrestrial gamma flashes (TGFs) intensive researched during the last two decades by orbiting gamma ray observatories. TGFs are exceptionally intense, submillisecond bursts of electromagnetic radiation directed to the open space from the thunderstorm atmosphere. Unlike visible lightning, TGF beams do not create a hot plasma channel and optical flash; hence, in the literature they got name "dark lightning." We investigate the TGEs development in 1 min and 1 s time series of particle detector count rates. Synchronized time series of the near-surface electric field and lightning occurrences allows interconnecting two atmospheric phenomena. Registration of the Extensive Air Showers allows approaching problems of relation of the lightning occurrences and particle fluxes.

  2. Cosmic Ray Neutron Flux Measurements

    NASA Astrophysics Data System (ADS)

    Dayananda, Mathes

    2009-11-01

    Cosmic rays are high-energetic particles originating from outer space that bombard the upper atmosphere of the Earth. Almost 90% of cosmic ray particles consist of protons, electrons and heavy ions. When these particles hit the Earth's atmosphere, cascade of secondary particles are formed. The most abundant particles reach to the surface of the Earth are muons, electrons and neutrons. In recent years many research groups are looking into potential applications of the effects of cosmic ray radiation at the surface of the Earth [1, 2]. At Georgia State University we are working on a long-term measurement of cosmic ray flux distribution. This study includes the simultaneous measurement of cosmic ray muons, neutrons and gamma particles at the Earth surface in downtown Atlanta. The initial effort is focusing on the correlation studies of the cosmic ray particle flux distribution and the atmospheric weather conditions. In this presentation, I will talk about the development of a cosmic ray detector using liquid scintillator and the preliminary results. [4pt] [1] K.Borozdin, G.Hogan, C.Morris, W.Priedhorsky, A.Saunders, L.Shultz, M.Teasdale, ``Radiographic imaging with cosmic-ray muons'', Nature, Vol.422, p.277, Mar.2003[0pt] [2] Svensmark Henrik, Physical Review 81, 3, (1998)

  3. Constrained Allocation Flux Balance Analysis.

    PubMed

    Mori, Matteo; Hwa, Terence; Martin, Olivier C; De Martino, Andrea; Marinari, Enzo

    2016-06-01

    New experimental results on bacterial growth inspire a novel top-down approach to study cell metabolism, combining mass balance and proteomic constraints to extend and complement Flux Balance Analysis. We introduce here Constrained Allocation Flux Balance Analysis, CAFBA, in which the biosynthetic costs associated to growth are accounted for in an effective way through a single additional genome-wide constraint. Its roots lie in the experimentally observed pattern of proteome allocation for metabolic functions, allowing to bridge regulation and metabolism in a transparent way under the principle of growth-rate maximization. We provide a simple method to solve CAFBA efficiently and propose an "ensemble averaging" procedure to account for unknown protein costs. Applying this approach to modeling E. coli metabolism, we find that, as the growth rate increases, CAFBA solutions cross over from respiratory, growth-yield maximizing states (preferred at slow growth) to fermentative states with carbon overflow (preferred at fast growth). In addition, CAFBA allows for quantitatively accurate predictions on the rate of acetate excretion and growth yield based on only 3 parameters determined by empirical growth laws.

  4. Constrained Allocation Flux Balance Analysis.

    PubMed

    Mori, Matteo; Hwa, Terence; Martin, Olivier C; De Martino, Andrea; Marinari, Enzo

    2016-06-01

    New experimental results on bacterial growth inspire a novel top-down approach to study cell metabolism, combining mass balance and proteomic constraints to extend and complement Flux Balance Analysis. We introduce here Constrained Allocation Flux Balance Analysis, CAFBA, in which the biosynthetic costs associated to growth are accounted for in an effective way through a single additional genome-wide constraint. Its roots lie in the experimentally observed pattern of proteome allocation for metabolic functions, allowing to bridge regulation and metabolism in a transparent way under the principle of growth-rate maximization. We provide a simple method to solve CAFBA efficiently and propose an "ensemble averaging" procedure to account for unknown protein costs. Applying this approach to modeling E. coli metabolism, we find that, as the growth rate increases, CAFBA solutions cross over from respiratory, growth-yield maximizing states (preferred at slow growth) to fermentative states with carbon overflow (preferred at fast growth). In addition, CAFBA allows for quantitatively accurate predictions on the rate of acetate excretion and growth yield based on only 3 parameters determined by empirical growth laws. PMID:27355325

  5. Flux focusing eddy current probe

    NASA Technical Reports Server (NTRS)

    Simpson, John W. (Inventor); Clendenin, C. Gerald (Inventor); Fulton, James P. (Inventor); Wincheski, Russell A. (Inventor); Todhunter, Ronald G. (Inventor); Namkung, Min (Inventor); Nath, Shridhar C. (Inventor)

    1997-01-01

    A flux-focusing electromagnetic sensor which uses a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. The unique feature of the device is the ferrous shield isolating a high-turn pick-up coil from an excitation coil. The use of the magnetic shield is shown to produce a null voltage output across the receiving coil in the presence of an unflawed sample. A redistribution of the current flow in the sample caused by the presence of flaws, however, eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal. The maximum sensor output is obtained when positioned symmetrically above the crack. Hence, by obtaining the position of the maximum sensor output, it is possible to track the fault and locate the area surrounding its tip. The accuracy of tip location is enhanced by two unique features of the sensor; a very high signal-to-noise ratio of the probe's output which results in an extremely smooth signal peak across the fault, and a rapidly decaying sensor output outside a small area surrounding the crack tip which enables the region for searching to be clearly defined. Under low frequency operation, material thinning due to corrosion damage causes an incomplete shielding of the pick-up coil. The low frequency output voltage of the probe is therefore a direct indicator of the thickness of the test sample.

  6. Constrained Allocation Flux Balance Analysis

    PubMed Central

    Mori, Matteo; Hwa, Terence; Martin, Olivier C.

    2016-01-01

    New experimental results on bacterial growth inspire a novel top-down approach to study cell metabolism, combining mass balance and proteomic constraints to extend and complement Flux Balance Analysis. We introduce here Constrained Allocation Flux Balance Analysis, CAFBA, in which the biosynthetic costs associated to growth are accounted for in an effective way through a single additional genome-wide constraint. Its roots lie in the experimentally observed pattern of proteome allocation for metabolic functions, allowing to bridge regulation and metabolism in a transparent way under the principle of growth-rate maximization. We provide a simple method to solve CAFBA efficiently and propose an “ensemble averaging” procedure to account for unknown protein costs. Applying this approach to modeling E. coli metabolism, we find that, as the growth rate increases, CAFBA solutions cross over from respiratory, growth-yield maximizing states (preferred at slow growth) to fermentative states with carbon overflow (preferred at fast growth). In addition, CAFBA allows for quantitatively accurate predictions on the rate of acetate excretion and growth yield based on only 3 parameters determined by empirical growth laws. PMID:27355325

  7. Neutron flux enhancement at LASREF

    SciTech Connect

    Sommer, W.F.; Ferguson, P.D.; Wechsler, M.S.

    1991-01-01

    The accelerator at the Los Alamos Meson Physics Facility produces a 1-mA beam of protons at an energy of 800 MeV. Since 1985, the Los Alamos Spallation Radiation Effects Facility (LASREF) has made use of the neutron flux that is generated as the incident protons interact with the nuclei in targets and a copper beam stop. A variety of basic and applied experiments in radiation damage and radiation effects have been completed. Recent studies indicate that the flux at LASREF can be increased by at least a factor of ten from the present level of about 5 E+17 m{sup {minus}2}s{sup {minus}1}. This requires changing the beam-stop material from Cu to W and optimizing the geometry of the beam-target interaction region. These studies are motivated by the need for a large volume, high energy, and high intensity neutron source in the development of materials for advanced energy concepts such as fusion reactors. 18 refs., 7 figs., 2 tabs.

  8. Braiding fluxes in Pauli Hamiltonian

    SciTech Connect

    Kenneth, O. Avron, J.E.

    2014-10-15

    Aharonov and Casher showed that Pauli Hamiltonians in two dimensions have gapless zero modes. We study the adiabatic evolution of these modes under the slow motion of N fluxons with fluxes Φ{sub a}∈R. The positions, r{sub a}∈R{sup 2}, of the fluxons are viewed as controls. We are interested in the holonomies associated with closed paths in the space of controls. The holonomies can sometimes be abelian, but in general are not. They can sometimes be topological, but in general are not. We analyse some of the special cases and some of the general ones. Our most interesting results concern the cases where holonomy turns out to be topological which is the case when all the fluxons are subcritical, Φ{sub a}<1, and the number of zero modes is D=N−1. If N≥3 it is also non-abelian. In the special case that the fluxons carry identical fluxes the resulting anyons satisfy the Burau representations of the braid group.

  9. 500-nm-Resolution 10 keV X-Ray Imaging Transmission Microscope with Tantalum Phase Zone Plates

    NASA Astrophysics Data System (ADS)

    Kagoshima, Yasushi; Ibuki, Takashi; Takai, Kengo; Yokoyama, Yoshiyuki; Miyamoto, Naoki; Tsusaka, Yoshiyuki; Matsui, Junji

    2000-05-01

    An imaging transmission hard X-ray microscope has been constructed at the Hyogo-BL (BL24XU) of SPring-8. It makes use of X-ray phase zone plates (PZP’s) made of tantalum as its condenser and objective lenses. The objective PZP has an outermost zone width of 250 nm, which corresponds to the theoretically expected spatial resolution of 300 nm. An experiment was performed at the photon energy of 10 keV to check the performance of the microscope. Since a 250 nm line-and-space pattern was clearly resolved, we concluded that the microscope attained a spatial resolution limit better than 500 nm. A few samples were also examined and the feasibility of the microscope was successfully demonstrated.

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

    NASA Astrophysics Data System (ADS)

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

    2008-01-01

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

  11. Angular dependence of L X-rays emission for Ag by 10 keV electron-impact

    NASA Astrophysics Data System (ADS)

    Wang, Xing; Xu, Zhongfeng; Zhang, Ying; Ma, Chao; Zhu, Chengwei

    2016-08-01

    The characteristic X-ray intensities of Ag-Lα, Lβ1, Lβ2 and Lγ1 are measured in electron-impact ionization at energy of 10 keV. The emission angle in this work ranges from 0° to 20° at interval of 5°. The angular dependence of L X-ray intensity ratios has been investigated for Lα / Lβ1, Lβ2 / Lβ1 and Lγ1 / Lβ1. It is found from the experimental results that the emissions of Lβ1, Lβ2 and Lγ1 X-rays are spatially isotropic, while the Lα X-rays exhibit anisotropic emission. Consequently, the alignment behavior of vacancy states is discussed with thorough analysis of vacancy transfer process.

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

    NASA Astrophysics Data System (ADS)

    Gafton, E. V.; Bulai, G.; Caltun, O. F.; Cervera, S.; Macé, S.; Trassinelli, M.; Steydli, S.; Vernhet, D.

    2016-08-01

    The effects of 90 keV neon beam irradiation on the structure and magnetic properties of zinc ferrite thin films have been investigated through several methods, namely, X-ray diffraction technique, Vibrating Sample and SQUID magnetometers. Beforehand, the pristine have also been characterized using profilometry and microscopy techniques. In particular single-phase formation of the thin films deposited on monocrystalline Si (111) substrate by pulsed laser deposition technique was confirmed. Crystal lattice, coercivity, saturation magnetization have been studied for the first time, as a function of ion penetration depth and irradiation fluence. The chemical composition and the crystallinity of the films are not affected with the ion impact acting as a mechanical stress relief. On the contrary, both magnetization and coercivity are sensitive to Neq+ ion irradiation and exhibit different behaviours depending on the ion fluence range.

  13. Nuclear resonant forward scattering of synchrotron radiation from 121 Sb at 37.13 keV.

    SciTech Connect

    Wille, H. C.; Shvydko, Y. V.; Alp, E. E.; Ruter, H. D.; Leupold, O.; Sergueev, I.; Ruffer, R.; Barla, A.; Sanchez, J. P.; X-Ray Science Division; European Synchrotron Radiation Facility; Univ. of Hamburg; Hamburder Synchrotronstrahlungslabor

    2006-02-22

    We report on the observation of nuclear resonant forward scattering of synchrotron radiation from {sup 121}Sb nuclei. A temperature stabilized {alpha}Al{sub 2}O{sub 3} crystal Bragg backscattering high-resolution monochromator with a relative energy resolution of 2 x 10{sup -7} was introduced. As first spectroscopic applications the hyperfine parameters in Sb{sub 2}O{sub 3}, USb and DySb were determined. The energy of the nuclear transition in {sup 121}Sb was measured to be 37.1298(2)keV, 40 times more precisely than reported before. The results open the field of nuclear resonance spectroscopy on antimony compounds taking advantage of the outstanding features of 3rd-generation synchrotron sources. Nuclear resonance scattering on Sb compounds at these sources allows element-specific dynamical studies on thermoelectric materials as well as studies on magnetism in micro- and nanometer dimensional systems like spintronic devices.

  14. Instrumentation for measurement of in-flight annihilations of 130 keV antiprotons on thin target foils

    NASA Astrophysics Data System (ADS)

    Todoroki, K.; Barna, D.; Hayano, R. S.; Aghai-Khozani, H.; Sótér, A.; Corradini, M.; Leali, M.; Lodi-Rizzini, E.; Mascagna, V.; Venturelli, L.; Prest, V.; Vallazza, L.; De Salvador, D.; Hori, M.

    2016-11-01

    We describe the instrumentation for an experiment to measure the cross sections of antiprotons with kinetic energies of 130±10 keV annihilating on carbon, palladium, and platinum target foils of sub-100 nm thicknesses. A 120 ns long pulsed beam containing 105 -106 antiprotons was allowed to traverse the foils, and the signal annihilations that resulted from this were isolated using a time-of-flight method. Backgrounds arose from Rutherford scattering of the antiprotons off the target foils, their annihilations in the target chamber walls, and π → μ → e decay of the charged pions that emerged from the annihilations. Some antiprotons slowed down and annihilated in the contamination on the target surfaces. This reduced the signal-to-background ratio of the measurement.

  15. Conditions for acceleration of energetic ions greater than 30 keV associated with the earth's bow shock

    NASA Technical Reports Server (NTRS)

    Scholer, M.; Hovestadt, D.; Ipavich, F. M.; Gloeckler, G.

    1980-01-01

    A statistical analysis of particles (greater than 30 keV/charge) upstream of the earth's bow shock is conducted and shows that the rate of occurrence of upstream particle events is relative to the angle between the magnetic field and the shock normal at the shock intersection point as well as relative to the angle between the magnetic field and the radial direction (i.e., the sun-earth line). In addition, the occurrence rate of upstream particle events relative to the bow shock connection time of a field line convected with the solar wind is presented for a model bow shock. A linear dependence of the diffusion coefficient on energy per charge is apparent with the value of the mean free path of a 30-keV proton found to be about 4 earth radii, and the free escape boundary to be at about 30 earth radii in front of the bow shock.

  16. 12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments

    SciTech Connect

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

    2008-04-22

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

  17. Phenomenological treatments of cross-sections for proton and hydrogen impact below 1 keV on molecular nitrogen

    NASA Technical Reports Server (NTRS)

    Porter, H. S.; Green, A. E. S.; Szydlik, P. P.

    1975-01-01

    An analytic independent-particle model is used to construct static potentials to describe the interaction of hydrogen-like ions with atoms and molecules. Parameters of the ion-atom potential are determined from ab initio total energy minimization procedure. The elastic scattering of He(+) from Ne and Ar is investigated as a test case and comparison is made with experiment. The model is then used in conjunction with low energy H(+)-N2 experimental data to construct differential and total cross-sections for the scattering of protons and hydrogen in the energy range of 10 eV to 1 keV from molecular nitrogen. Analytic forms are used to parametrize these cross-sections to facilitate their use in the calculation of energy deposition by protons and hydrogen atoms in atmospheric gases.

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

    SciTech Connect

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

    2007-12-10

    The authors measured the absolute response of image plate (Fuji BAS SR2040) for electrons at energies between 100 keV to 4 MeV using an electron spectrometer. The electron source was produced from a short pulse laser irradiated on the solid density targets. This paper presents the calibration results of image plate Photon Stimulated Luminescence PSL per electrons at this energy range. The Monte Carlo radiation transport code MCNPX results are also presented for three representative incident angles onto the image plates and corresponding electron energies depositions at these angles. These provide a complete set of tools that allows extraction of the absolute calibration to other spectrometer setting at this electron energy range.

  19. Enhanced room temperature oxidation in silicon and porous silicon under 10 keV x-ray irradiation

    SciTech Connect

    Ryckman, Judson D.; Reed, Robert A.; Weller, Robert A.; Fleetwood, D. M.; Weiss, S. M.

    2010-12-01

    We report the observation of enhanced oxidation on silicon and porous silicon samples exposed in air ambient to high-dose-rate 10 keV x-ray radiation at room temperature. The evolution of the radiation-induced oxide growth is monitored by ellipsometry and interferometric reflectance spectroscopy. Fourier transform infrared (FTIR) spectroscopy shows the emergence of Si-O-Si stretching modes and corresponding suppression of SiH{sub x} and Si-Si modes in the porous silicon samples. The radiation response depends strongly on initial native oxide thickness and Si-H surface species. The enhanced oxidation mechanism is attributed to photoinduced oxidation processes wherein energetic photons are used to dissociate molecular oxygen and promote the formation of more reactive oxygen species.

  20. A high-resolution time-of-flight energy analyzer for femtosecond electron pulses at 30 keV

    NASA Astrophysics Data System (ADS)

    Gliserin, Alexander; Walbran, Matthew; Baum, Peter

    2016-03-01

    We report a time-of-flight spectrometer for electron pulses at up to 30 keV, which is a suitable energy for atomic-resolution femtosecond investigations via time-resolved electron diffraction, microscopy, and energy loss spectroscopy. For realistic femtosecond beams without apertures, the instrument's energy resolution is ˜0.5 eV (full width at half maximum) or 2 × 10-5 at a throughput of 50%-90%. We demonstrate the analyzer's versatility by three first applications, namely, femtosecond electron pulse metrology via optical streaking, in situ drift correction in laser-microwave synchronization for electron pulse compression, and time-resolved electron energy loss spectroscopy of aluminum, showing the instrument's capability of tracking plasmonic loss peak positions with few-meV accuracy.