<title>SIXA: Silicon X-Ray Array</title>

Abstract

The Spectrum-X-Gamma satellite is scheduled for launch in 1995-96. Mission objectives include broad and narrow band imaging spectroscopy over a wide range of energies from the EUV through hard X-rays with an emphasis on studying galactic and extragalactic X-ray sources. Timing and moderate resolution spectroscopy can be performed with the solid state spectrometer SIXA (Silicon X-Ray Array), placed on the focal plane of the SODART telescope with total effective area of 1150 cm<SUP>2</SUP> at 6 keV (for f equals 8 m telescope). The detector consists of 19 circular Si(Li) pixels, each with an active diameter of 9.2 mm and thickness of 3 mm. A radiative cooler will be used to bring the detector to the proper operating temperature (110 - 120 K). The energy range 0.5 - 20 keV is divided into 1024 channels of 20 eV size. Photon can be recorded with 30 microsecond(s) time resolution and 160 - 200 eV (1 - 7 keV) energy resolution. Potential observing programs (for e.g. time-resolved Iron K<SUB>alpha</SUB> line spectroscopy) include stellar coronae, cataclysmic variables and X-ray binaries; accretion discs and coronae of neutron stars and black hole candidates; supernova remnants, active galactic nuclei and clusters of galaxies.