An Electron & Proton Spectrometer Detector System for an OGO-E Satellite Experiment

Abstract

A detector system for use with a magnetic electron spectrometer and a proton telescope is described. The experiment will be included on the Orbiting Geophysical Observatory "E" (OGO-E) satellite. Electron measurements cover the range from 60 keV to 2.7 MeV in seven differential energy channels. Each channel consists of an electron-plus-background detector and a background detector. A method of handling information from both detectors with the same amplifier system is discussed. This scheme is used to ensure that the proper background subtraction is made in spite of electronic drifts. Coincidence and anticoincidence logic is used for routing the electron-plus-background and background signals to their respective scalers. The four-element proton telescope uses solid state detectors directly in line with the collimator. The telescope lies within the pole pieces of the electron spectrometer magnet. Seven proton channels are provided covering the range from 200 keV to 50 MeV. In addition, three alpha channels from 6 MeV to 130 MeV are obtained. Pulse height selection of the pulses from each detector plus coincidence and anticoincidence between these pulses will resolve the double valued energy loss in the detectors and determine the energy channels. The alpha particles are differentiated from protons only through their greater dE/dx. A tunnel diode differential discriminator is discussed. This discriminator makes its logical decisions at the trailing edge of the input pulse. In this way pulses of varying widths cannot cause false decisions. Two charge sensitive preamplifiers have been developed for this work.