SSCT for the observation of cosmic gamma rays in the GeV region

A scintillating fiber sampling calorimeter telescope (SSCT (SF)) is proposed which is to be operated on board a satellite for the observation of cosmic gamma rays ranging from 200 MeV to 200 GeV. The idea of SSCT (SF) is based on the experience in developing a Si(Li)/Pb sampling calorimeter telescope (SSCT (Si)); SSCT(SF) replaces the Si detectors in SSCT(Si) by scintillating fibers. Some key parameters of SSCT(Si) are: the active area is 2,500 cm2, effective area 1,500 cm2, the median angular reoslution 1.6 degree at 1 GeV, 0.34 degree at 10 GeV, 0.21 degree at 30 GeV, and the r.m.s energy resolution is 20, 17 and 18% at 1, 10 and 100 GeV, respectively. If a thicker calorimeter is used, 17%/√E(GeV) is possible. SSCT(SF) is now under development. From a preliminary test, we expect that the angular resolution of SSCT(SF) is, at worst, almost the same as SSCT(Si), and the energy resolution could be better than 30% at 1 GeV. Probably almost the same energy resolution is obtainable. An effective area of one order of magnitude larger than the EGRET can be attained with a low cost