A Proton Spectrometer for Nasa´s Apollo Applications Program

A high counting rate particle detector is described to measure trapped protons from 18.5 MeV to 400 MeV and electrons from approximately 1.2 MeV to 10 MeV. The instrument is a directional dE/dx - E telescope composed of solid state and scintillation counters with an acceptance angle of 450 and an energy independent geometric factor of approximately .4 cm2 sterad. The dE/dx detectors are fully depleted silicon surface barrier detectors of 500 micron thickness and 3 cm2 area. The energy detector is a sodium activated cesium iodide crystal of 100 MeV thickness for protons. A plastic scintillator is used as an anticoincidence shield. The detector design, electronics system, and calibration data for protons are presented in this paper.