An Electronics System for Gamma-Ray Spectrometry in Satellite Applications

This paper describes the design techniques and performance of a prototype electronics subsystem for a ¿-ray spectrometer intended for spaceflight applications. The spectrometer uses a NaI(Tl) crystal for ¿ rays between 100 KeV and 8 MeV and a proportional counter for X rays between 1 KeV and 10 KeV. The 512-channel analog-to-digital converter is based on a design for Ge(Li) detectors and interfaces with a logic system providing serial readout of completely formatted spectral data. The instrument contains high-voltage power supplies for detector biasing and operates from 1.2 W of + 28 ±5 Vdc. Measurements show an electronic gain stability of ±0.09% for temperatures from -50°C to + 75°C and a differential linearity no worse than ±0.2% for the top 99% of the channels. Spectra resulting from 22Na and 55Fe are presented.