An Energetic Particle Detector for a Synchronous Satellite

The Energetic Particle Detector (EP) on the DSP satellites consists of four units designed to measure the electron, proton and alpha particle populations at synchronous altitude. The Lo E and Hi E units are sensitive to electrons in the 30-300 keV and 0.2-2 MeV energy ranges respectively; the Lo P and Hi P units to protons between 100-500 keV and 0.5-150 MeV respectively. Five Lo E sensors are arranged at angles of 0°, ± 30°, and ± 60° with respect to the spacecraft equator in order to measure the three-dimensional angular distribution of the low energy electrons as the satellite spins. All detectors are silicon semiconductors with well collimated fields of view. The Hi P unit is a telescope of three detector elements which can also measure alpha particles in the energy range 1.2 to 600 MeV upon command.