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 experiment is a fully functional, low cost, low mass, low-power instrument, which, when combined with other similar instruments, has the capability of localizing bursts to arcminute precision. The burst monitor is based on a photomultiplier tube and a plastic/CsI(Tl) phoswich detector and records photons in the 20-150-keV energy range with time resolutions up to several milliseconds. In addition, it records photon energy spectra. Events in the plastic scintillator are distinguished by a pulse shape discrimination circuit and are used to count electrons and protons. 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 1996 mission.