GAMMASPHERE-correction technique for detector charge trapping

GAMMASPHERE uses 110 very large germanium detectors. Such detectors exhibit charge trapping effects on energy resolution initially due to a native electron trap that is present in virtually all germanium. Furthermore, radiation damage is a serious problem in GAMMASPHERE experiments, producing hole traps that degrade resolution and eventually require annealing to restore the original performance. The technique discussed here uses the current pulse shape from a detector to develop a parameter related to the radius of the largest interaction in the “track” of a gamma ray in the detector. Since the charge trapping loss in a signal can be related to the distance carriers travel, the “radius” parameter can be used by software to apply a trap correction to the signal