High Purity Germanium (HPGe) and BGO

Gammasphere's detectors use high purity germanium in order to increase a detector's probability of gamma ray interaction. The germanium used within each detector produces ten different signals known as the GeCenter, GeSide and 7 BGO signals, which are compacted by the analog pre-processing into four differential signals (GeCenter, GeSide, BGOSum & BGOPattern).

BGO (Bismuth Germanate) detectors surround each Ge Detector in Gammasphere to help with Compton scattering suppression. They form a hexagonal shape around the cylindrical Ge, with each of the BGO sides producing its own signal. Furthermore, there is a BGO "backplug" which goes behind the Ge piece and also has its own signal, meaning the DAQ accounts for seven BGO signals.