THE GAMMA-RAY BURST MONITOR FOR THE RUSSIAN MARS 1996 MISSION

We describe an innovative detector designed primarily for the study of cosmic gamma-ray bursts aboard interplanetary. spacecraft. The experi ment is a fully functional, low cost, low mass, low-power instrument, which, when combined with other similar instruments, has the capabilit y of localizing bursts to arcminute precision, The burst monitor is ba sed on a photomultiplier tube and a plastic/CsI(Tl) phoswich detector and records photons in the 20-150-keV energy range with time resolutio ns up to several milliseconds, In addition, it records photon energy s pectra, Events in the plastic scintillator are distinguished by a puls e shape discrimination circuit and are used to count electrons and pro tons, In a planetary orbiter or fly-by mission, this capability can be used to detect the presence of a magnetosphere. We describe in detail a version of this instrument which was built for the Russian Mars 199 6 mission.