PICsIT: a position sensitive detector for space applications

Pixellated Imaging CsI Telescope (PICsIT) is the high energy detector plane of Imager on Board INTEGRAL Satellite (IBIS), one of the main instruments on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite that will be launched in the year 2001. It consists of 4096 CsI(T1) individual detector elements and operates in the energy range from 120 to 10,000 keV. PICsIT is made up of 8 identical modules, each housing 512 scintillating crystals coupled to PIN photodiodes (PD). Each crystal, 30 mm long and with a cross-section of 8.55 x 8.55 mm(2), is wrapped with a white diffusing coating and then inserted into an aluminium crate. In order to have a compact design, two electronic boards, mounted directly below the crystal/PD assembly, host both the Analogue and it, Digital Front-End Electronics (FEE). The behaviour of the read-out FEE has a direct impact on the performance of the whole detector in terms of lower energy threshold, energy resolution and event time tagging. Due to the great number of channels to be handled, an Application Specific Integrated Circuit (ASIC), that manages signals coming from groups of 16 detecting units, has been designed. The first reduced model of a PICsIT module has been now constructed and is under intensive tests in order to evaluate the main qualification parameters of the detector. In this paper, after a description of the PICsIT hardware and assembly procedures, the main results on system functionality are presented. (C) 2002 Elsevier Science B.V. All rights reserved.