Identification of Bulk and Surface Event in Point Contact Germanium Detector at Sub-keV Energy Region

Germanium detector is one of the principal detection technologies in the study of dark matter physics, neutrino physics, etc. Among different configurations of germanium detector, point contact configuration is an apt in the study of the low-energy neutrino and low-mass WIMPs. There are two types of point contact configuration, i.e., n-type point contact detectors and p-type point contact detectors, in which p-type point contact germanium detectors possess an inactive layer of few mm thickness and give rise to anomalous surface events. These events are not able to give the correct information about the interaction due to partial charge collection. In order to interpret the accurate result, we have to remove these anomalous surface events from the bulk events, whereas n-type point contacts germanium detectors are free from these anomalous events. Here, we present two different methods to discriminate these events that arise from the surface layer of the p-type point contact germanium detectors.