Primary Electron Detector Experiment for OGO-E

Abstract

A primary electron detector has been designed to measure the electron component in the primary cosmic radiation. The measurement will reveal the absolute flux and energy spectrum of electrons in the energy range of 0.5 to 10 gev. The experiment will also measure gamma rays above 500 Mev and protons between 20 and 100 gev. The detector system consists of five individual radiation counters that are further grouped into the following subsystems; a lead glass total absorption spectrometer crystal, a cesium iodideglass scintillator phoswich, and a cesium iodide-plastic scintillator phoswich. All detectors are viewed by RCA 7151-N multiplier phototubes. The outputs of the photomultipliers are fed directly into the electronics where they are properly separated, amplified, and where the necessary coincidence/anticoincidence logic requirements are met. Of special interest in the electronics systems are the logarithmic amplifiers and pulse splitting circuits used on the phoswich signals. A three-decade logarithmic amplifier was also used for the lead glass subsystem. Several configurations were studied before a final decision was made to use a straight-line approximation system. The pulse-splitting circuits were designed to separate the fast and slow component of an optically mixed signal. A splitting ratio of about 8:1 was maintained for the cesium iodide-plastic subsystem. Three nine-bit spacecraft telemetry words were used to read out all pulse height and operational information. The experiment was launched on an Orbiting Geophysical Observatory (OGO-E) in early 1968.