| The Space Physics Group and the Space Science and Engineering Center of the University of Wisconsin have designed and built a novel instrument, the Diffuse X-ray Spectrometer (DXS), for the spectroscopic study of the diffuse X-ray background. Each of the two identical units consists of a one foot by two foot curved lead stearate crystal panel and a position-sensing proportional counter. The crystal panels reflect X-ray photons into the proportional counters according Bragg's law. The instrument, sensitive to X-ray photons between 42 Å and 83 Å with Δλ (FWHM) ∼2.5 Å observed the X-ray background for about 40,000 seconds on Space Shuttle flight STS 54 in January 1993. This thesis presents the formulation of the detector response functions from pre- and post-flight calibration data and the data reduction methods used for the in-flight spectral data. The resulting estimates of the wavelength scale accuracy (0.3 Å), the flat-field response (corrected to better than 3%), the absolute flux calibrations (∼10%), and the detailed agreement of the spectral shape of the instrument response to three mono-energetic input sources are also discussed. Several plasma emission models are compared to the observed spectra, none of which fit satisfactorily. These results constrain current theories concerning the origin and nature of the diffuse X-ray background. |
