A5051892111- Astrophysical Phenomena and Observations
- Gamma-ray bursts and supernovae
- Astronomy and Astrophysical Research
- Particle Detector Development and Performance
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- Advanced X-ray Imaging Techniques
- Adaptive optics and wavefront sensing
- X-ray Spectroscopy and Fluorescence Analysis
- Nuclear Physics and Applications
- High-pressure geophysics and materials
- Advanced X-ray and CT Imaging
- Particle Accelerators and Free-Electron Lasers
- Radiation Detection and Scintillator Technologies
- Advanced Optical Sensing Technologies
- Astro and Planetary Science
- Particle physics theoretical and experimental studies
- Photocathodes and Microchannel Plates
- Solar and Space Plasma Dynamics
- Calibration and Measurement Techniques
- Spacecraft Design and Technology
- Medical Imaging Techniques and Applications
Los Alamos National Laboratory
2004-2024
Government of the United States of America
2023
The Open University
2007
University of Leicester
2007
University of California, Riverside
2007
Los Alamos National Security (United States)
2001-2006
Los Alamos Medical Center
2003
The University of Melbourne
1995-1996
Goddard Space Flight Center
1989
Max Planck Institute for Astrophysics
1986-1987
The XMM-OM instrument extends the spectral coverage of XMM-Newton observatory into ultraviolet and optical range. It provides imaging time-resolved data on targets simultaneously with observations in EPIC RGS. also has ability to track stars its field view, thus providing an improved post-facto aspect solution for spacecraft. An overview operation is given, together current information performance instrument.
view Abstract Citations (248) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Discovery of a Second Orbital Period from the X-Ray Source 4U 1820-30 in Globular Cluster NGC 6624 Stella, L. ; Priedhorsky, W. White, N. E. discovery coherent 685 s periodicity X-ray source 1820 -30, which is located globular cluster 6624, reported. modulation has peak-to-peak amplitude up to 3 percent and was independently detected three observations by EXOSAT...
When a large piece of space debris forced change flight plan for arecent U.S. Space Shuttle mission, the concept that we are trashing as well Earth finally attained broad public awareness. Almost million pieces have been generated by 35 years spaceflight, and now threaten long-term missions. The most economical solution to this problem is cause items reenter burn up in atmosphere. For safe handling objects, it desired do on precomputed trajectory. Due number, speed, spacial distribution...
We demonstrate that high-Z material can be detected and located in three dimensions using radiographs formed by cosmic-ray muons. Detection of hidden inside large volume ordinary cargo is an important timely task given the danger associated with illegal transport uranium heavier elements. Existing radiography techniques are inefficient for shielded material, often expensive involve radiation hazards, real perceived. recently demonstrated muons [K. N. Borozdin et al., Nature (London) 422, 277...
Over 120 million vehicles enter the United States each year. Many are capable of transporting hidden nuclear weapons or material. Currently deployed X-ray radiography systems limited because they cannot be used on occupied and energy dose too low to penetrate many cargos. We present a new technique that overcomes these limitations by obtaining tomographic images using multiple scattering cosmic radiation as it transits vehicle. When coupled with passive detection, muon interrogation could...
view Abstract Citations (81) References (4) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Prevalent Properties of Gamma-Ray Burst Variability Link, Bennett ; Epstein, Richard I. Priedhorsky, William C. With the aim isolating universal characteristics gamma-ray burst variability, we compare time histories for 20 bright bursts detected by and Transient Source Experiment (Fishman et al., 1992). Using an autocorrelation function method, find that durations...
We present a spectral analysis of XMM-Newton data ten dwarf novae, nine which were observed during quiescent state. The X-ray spectra indicate the presence hot, optically thin plasma with temperature distribution consistent simple, isobaric cooling flow. likely origin emission is in boundary layer settling onto white dwarf. Using flow model, we derive temperatures, accretion rates, rotational velocities, and elemental abundances emitting gas. discuss implications our findings for structure...
view Abstract Citations (121) References (32) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Evidence for an approximatily 300 day period in Cygnus X-1. Priedhorsky, W. C. ; Terrell, J. Holt, S. Results from 10 years of observation Cyg X-1 by the Vela 5B satellite are reported. Good evidence approximately is found, which confirmed independent data All-Sky Monitor instrument on Ariel 5. varies about 25 percent with a 294 + or -4 period. This modulation...
view Abstract Citations (90) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Long-term X-ray observations of CEN X-3, GX 301-2 (4U 1223-62), 304-1 1258-61) and 4U 1145-61. Priedhorsky, W. C. ; Terrell, J. Ten-day time resolution histories are presented from the 1969-1976 period, for sources Cen 301-2, 304-1, Three four examined show periods in excess one month, keeping with model which these neutron stars eccentric orbits around early type...
view Abstract Citations (69) References (32) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Extended-bandwidth X-ray observations of Cygnus X-1. Priedhorsky, W. ; Garmire, G. P. Rothschild, R. Boldt, E. Serlemitsos, Holt, S. An energy- and time-resolved observation Cyg X-1, sensitive from 0.15 to 20 keV, is reported which was performed investigate the spectrum time variability flux at low energies. Data in band 1.5 42 obtained two previous rocket flights,...
We propose a new technique for remote sensing: photon-counting laser mapping. Microchannel plate detectors with crossed delay-line (MCP/CDL) readout combine high position accuracy and subnanosecond photon timing, at event rates of 106 detected photons per second more. A mapping system would an MCP/CDL detector fast-pulse, high-repetition-rate illuminator. The map solid targets exceptional in-range cross-range resolution. resulting images be intrinsically three dimensional, without resorting...
We present XMM-Newton RGS observations of the soft X-ray spectrum NGC 4051, and explore their implications for inner accretion disk ionized outflow in active galactic nucleus. fit excess with a relativistically broadened O VIII recombination spectrum, including entire line series continuum. This plus an underlying power law continuum provides much better to than single temperature or blackbody law. The emission profiles, computed Kerr metric around maximally rotating black hole, reveal...
view Abstract Citations (111) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Bimodal Quasi-oscillatory and Spectral Behavior in Scorpius X-1 Priedhorsky, W. ; Hasinger, G. Lewin, H. Middleditch, J. Parmar, A. Stella, L. White, N. Exosat observations of Sco obtained using the Xe and/or Ar detectors for a total about 80,000 s during four runs on August 24-27, 1985 are reported analyzed. Two modes quasi-periodic oscillations (QPOs) corresponding...
We have made a series of snap-shot observations 37 polars using XMM-Newton. found that 16 these systems were in low, or much reduced, accretion state. Of those, 6 not detected X-rays. This suggests any survey polars, around half will be low tested if there was bias towards certain orbital periods: this is the case. 10 which at but significant rates X-rays, 8 showed variability their X-ray light curves. implies non-uniform still takes place during epochs. The bolometric luminosity ~10^30 ergs...
view Abstract Citations (87) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Long-term observations of X-ray sources : the Aquila-Serpens-Scutum. Priedhorsky, W. C. ; Terrell, J. (1969-1976) galactic in Aquila-Serpens-Scutum region are presented. Data were obtained by 3-12 keV detector on Vela 5B satellite. The time histories nine derived from sky maps this confused region: Scutum X-1, 4U 1823 - 00, 1915 05, Aquila Serpens 1907 + 09, A1850...
The first measurements of high-energy x-ray emission ($h\ensuremath{\nu}\ensuremath{\sim}30\ensuremath{-}300$ keV) by high-$Z$ microballoon targets irradiated at $5\ifmmode\times\else\texttimes\fi{}{10}^{14}<\ensuremath{\phi}<2\ifmmode\times\else\texttimes\fi{}{10}^{16}$ W/${\mathrm{cm}}^{2}$ 10.6-\ensuremath{\mu}m laser light are reported. An exponential spectrum with a slope $k{T}_{H}\ensuremath{\sim}250$ keV provides the best fit to spectrometer data ${\ensuremath{\phi}}_{l}={10}^{16}$...
view Abstract Citations (87) References (37) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Discovery of Rapid Quasi-periodic Oscillations in Scorpius X-1 Middleditch, J. ; Priedhorsky, W. C. The X-ray flux from Sco can vary quasi-periodically. Fourier analysis 5-20 keV data taken while the source was quiescent shows a power density peak at 6 Hz, with 2 Hz FWHM, and which corresponds to 5 percent (rms amplitude). No observed when more active, but rather...
view Abstract Citations (76) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Discovery of a 176 day period in 4U 1820-30. Priedhorsky, W. ; Terrell, J. Long-term X-ray observations the burster 1820-30 (in NGC 6624) reveal significant 176.4 + or - 1.3 period. These data were obtained by 3-12 keV detector on Vela 5 B satellite during years 1969-1976. The flux varies factor 2 over cycle; light curve, which has sawtooth shape with fast rise and...
We present the results of a study variability X-ray sources in central 30´of nearby Andromeda Galaxy (M 31) based on XMM-Newton Performance Verification observations. Two observations this field, with total exposure time about 50 ks, were performed June and December 2000. found 116 brighter than limiting luminosity 61035 erg s-1 (0.3-12 keV, kpc). For ~60 brightest sources, we searched for periodic non-periodic variability; at least 15% these appear to be variable scale several months....
We present the results of a study based on an XMM-Newton Performance Verification observation central 30´of nearby spiral galaxy M 31. In 34-ks European Photon Imaging Camera (EPIC) exposure, we detect 116 sources down to limiting luminosity #1 10#2 erg s-1 (0.3-12 keV, kpc). The distribution detected with flattens at luminosities below ~2.5 1037 . make use hardness ratios for in order distinguish between classes objects such as super-soft and intrinsically hard or highly absorbed sources....