IBIS/PICsIT in-flight performances

PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy detector of the IBIS telescope on-board the INTEGRAL satellite. PICsIT operates in the gamma - ray energy range between 175 keV and 10 MeV, with a typical energy resolution of 10% at 1 MeV, and an angular resolution of 12 arcmin within a similar to 100 square degree field of view, with the possibility to locate intense point sources in the MeV region at the few arcmin level. PICsIT is based upon a modular array of 4096 independent CsI(Tl) pixels, similar to 0.70 cm(2) in cross-section and 3 cm thick. In this work, the PICsIT on - board data handling and science operative modes are described. This work presents the in - flight performances in terms of background count spectra, sensitivity limit, and imaging capabilities.