Performances of detector elements for PICsIT: the high-energy detector plane of the IBIS instrument on board the INTEGRAL satellite

IBIS is an instrument designed to produce images of the gamma-ray sky in the 15 keV to 10 MeV energy range with few arcminute resolution over a wide field of view. This will be obtained by deconvolving the shadowgram projected by a coded mask onto two pixelated detectors layers. One, ISGRI is made of 16384 CdTe elements operating in the low energy range, the other, PICsIT is made with 4096 CsI scintillating crystals coupled to PIN Photodiodes and it operates in the high energy range. Theoretical performances of the overall increments have been described in a dedicated session at SPIE in August 1996. Now, after a short description of the detector assembly and test procedures, the performances of a significant number of the PICsIT detector units are reported.