Instrument Description

It consists of four independent and collimated NaI(Tl)/CsI(Na) scintillation detectors and it is sorrounded by four anticoincidence (AC) CsI(Na) shields, called Lateral Shields (LSs), forming a square well around it and composing the GRBM experiment (fig. ); on the top, just above the entrance window of the PDS detectors,there is a fifth shield, called Top Shield (TS).