Scientific characterization of the PICsIT detector of the IBIS telescope

INTEGRAL is the forthcoming European Space Agency's (ESA) satellite mission for gamma-ray astronomy, which will be launched in 2002. IBIS is the imaging telescope onboard INTEGRAL and will produce images of the gamma-ray sky in the region between 15 keV and 10 MeV by means of a two-layer position sensitive detection plane coupled with a coded aperture mask. The detection plane of IBIS comprises two detectors: ISGRI, operative in the 15 keV - 1 MeV range, and PICsIT, 150 keV - 10 MeV. The PICsIT instrument, which is the high energy plane of the IBIS imager, comprises 8 individual modules of 512 detection elements. The modules are arranged in a 4 x 2 pattern, while the pixels are in a 16 x 32 array within each module. Detailed simulation programs of PICsIT qualification and flight model have been set up in order to provide a complete scientific characterization of the detector in terms of spectral and imaging performances. These simulation programs have also been used to reproduce the on-ground calibration results, and will be the basis for the production of the response matrix.