30TH INTERNATIONAL COSMIC RAY CONFERENCE Simulations of Hard X Ray and Gamma Ray Response in CsI(Tl) Scintillator De- tector RADOSLAV BUCIK 1, 2 , KAREL KUDELA 2 , DAVID SMITH 3 1 IEP SAS, Kosice, Slovakia 2 MPS, Katlenburg-Lindau, Germany 3 UC Santa Cruz, Santa Cruz, USA bucik@saske.sk Abstract: Results of the computations of the response of the scintillator detector to high energy pho- tons using the code GEANT-3 is presented. The dependence of efficiency on energy is obtained for a given geometry of the detector and for different angular distributions of incident flux. The estimates of the efficiency of the SONG instrument on CORONAS-F satellite are discussed. Introduction The SONG experiment on low altitude polar orbiting CORONAS-F satellite contained CsI(Tl) scintillator (20 cm diameter x 10 cm length) for the measurement of energetic neutral radiation from the Sun [1]. The crystal scintillator was viewed by three photomultipliers and was entirely surrounded by a 2-cm thick plastic anticoinci- dence shield against charged particles. It was viewed by three other photomultipliers. The scin- tillation crystal had no collimator and its axis was parallel to the longitudinal axis of the satellite which was directed towards the Sun. Energy losses in the CsI were pulse-height-discriminated into twelve differential channels from 30 keV to 200 MeV. The preliminary simulations were performed by GEANT 3.21[2], which traces all possible inter- actions of particles with the instrument, and relia- bly takes into account deposited energy in the instrument detector. Results One of the basic measures of the instrument re- sponse is the detector effective area. Two kinds of gamma sources were chosen for simulation stud- ies: an isotropic gamma source evenly distributed in the upper hemisphere and a parallel gamma beam. For each source configuration, the effective Figure 1: Effective area vs energy for CsI (upper panel) and CsI in plastic veto (lower panel) ICRC 2007 Proceedings - Pre-Conference Edition