The High-Energy Celestial X-ray Experiment, a Goddard Space Flight Center effort headed by K. H. Frost, measured the spectrum of X-ray sources in the energy range of 0.01 - 1 MeV and searched for temporal variations in the intensity and spectrum of point sources. In addition, it measured the diffuse component of celestial X-rays over a scanned strip of the sky and set limits on the intensity and isotropy of the 0.511 MeV positron annihilation radiation.
The Soft X-ray Background Radiation experiment of W. L. Kraushaar (U. Wisconsin) studied the galactic latitude dependence of the X-ray background radiation using proportional counters with as narrow a collimation as practical in the region 0.150 - 45 keV. Energy resolution relied largely on selective window transmission rather than pulse height measurement. Viewing was parallel and anti-parallel to the wheel spin direction, so that two single paths across the sky, galactic pole to galactic pole, were carefully surveyed with high statistical accuracy approximately every 6 months.
The Graphite Crystal X-ray Spectrometer, a Columbia University experiment headed by H. L. Kestenbaum, was used to measure continuum profiles over the 2 - 8 keV band with high spectral resolution. During satellite day, solar spectra were obtained. Stellar X-ray sources were observed during satellite night. The spectrometer made use of the wheel rotation to obtain a complete Bragg spectrum every 10 seconds. X-rays transmitted by the slat collimators struck the large graphite crystal panels. Those X-rays which satisfied the Bragg condition for reflection from graphite were reflected into the central bank of detectors. The detectors were double-sided proportional counters with 0.025 mm beryllium windows on each side and contained an argon-xenon gas mixture chosen for its high efficiency over the 2 - 8 keV range. The Graphite Crystal X-ray polarimeter experiment, also out of Columbia University, operated in a similar fashion reflecting X-rays off of a graphite crystal panel into a small proportional counter. The panels reflected preferentially those X-rays polarized perpendicular to the plane defined by the incident and reflected rays.
HEASARC Home | Observatories | Archive | Calibration | Software | Tools | Students/Teachers/Public
Last modified: Wednesday, 08-Oct-2003 18:57:19 EDT
The HEASARC is hiring! - Applications are now being accepted for a scientist with significant experience and interest in the technical aspects of astrophysics research, to work in the HEASARC at NASA Goddard Space Flight Center (GSFC) in Greenbelt, MD. Refer to the AAS Job register for full details.