VELA-4 Satellite Energetic Particle Experiment

The Vela-4 satellite energetic-particle experiment consists of (a) a pair of diffused-junction semiconductor detectors for electrons in the energy range 30-600 keV, and (b) a garded, four-element, solar particle telescope for detecting protons from 0.5-100 MeV and alpha particles from 3.6-380 MeV, in 13 dfferentially-counted channels. Separation of protons from alpha particles is accomplished by an in-flight particle identifier. Two additional simplified telescopes are used to extend the angular coverage of the primary telescope, and a wide angle, high sensitivity scintillation detector is employed to monitor low intensity solar particle events. The design and operation of these instruments will be described.