A NOVEL COMPACT GE-BGO COMPTON-SUPPRESSION SPECTROMETER

A novel Compton-suppression spectrometer has been designed and its per formance has been tested experimentally. The device consists of a sing le BGO crystal with a cylindrical well that holds a Ge crystal without interfering material between the crystals. Both crystals are cooled t o an equilibrium temperature of 104 K which allows a proper performanc e of the Ge detector. The BGO crystal is read out by a single PM tube. Photodiodes have been applied to investigate the light yield and timi ng properties of BGO at low temperature. The light transport phenomena were well reproduced by computer simulations. The photopeak-to-total ratio amounts to 0.74 with an average suppression factor of 10.1 for a Cs-137 source and 0.60 and 6.4, respectively, for a Co-60 source. The se results are well reproduced by Monte Carlo codes simulating the gam ma-ray interactions, also taking into account some charge-collection i nefficiency.