A Satellite-Borne High Resolution Ge(Li) Gamia-Ray Spectrometer System Part 2: Description of the Electronic, Data Handling and Auxiliary Sensor Systems

The first high-resolution gamma-ray spectrometer system employing Ge(Li) detectors has been designed and successfully flown on an earth-orbiting satellite. The complete scientific payload consists of two large-volume Ge(Li) spectrometers for the measurements of photons in the 40 keV - 2.8 MeV energy range with 4096-channel energy resolution and six auxiliary sensors for measuring the location, intensity and energy spectra of charged-particle backgrounds in earth orbit. To achieve and maintain an overall systems resolution of 3.5-4 keV in photon energy, a low-noise bias power supply and charge sensitive preamplifier-amplifier combination were designed for the germanium detectors. Amplified signals are analyzed in a 4096-channel analyzer of the linear-ramp type, with an integral and differential linearity of ± 0.2 percent and ± 1.0 percent, respectively. Individual pulse-height addresses are sampled at a rate of 1625 addresses/sec and time tagged together with absolute count-rate data by the experiment digital-data-handling system and then stored on magnetic tape recorders. A detailed description of the gamma-ray spectrometer electronic system including the method of collecting and analysis of flight data is given.