Pulse Shape Discrimination of Bulk and Very Bulk Events within HPGe Detectors

Abstract

The CDEX (China Dark matter Experiment) now deploys ~10 kg pPCGe (p-type Point Contact Germanium) detectors in CJPL (China Jinping Underground Laboratory). It aims to detect rare events such as dark matter and 0vbb (neutrinoless double beta decay). The discrimination of bulk and very bulk events are essential for improvements of the analysis threshold of dark matter. Very bulk events are generated near the p+ point surface of pPCGe, which are usually from radioactive materials of electronic devices. Due to different locations of charge collection, bulk and very bulk events have different pulse shape. This paper will present two linear PSD (Pulse Shape Discrimination) methods: CCM (Charge Comparison Method) and Fisher's LDA (Linear Discriminant Analysis), to realize the discrimination of bulk and very bulk events. The results show that FOMs (Figure of Merit) are 1.38 $\pm$ 0.33 and 1.62 $\pm$ 0.18 by CCM and Fisher's LDA respectively.

arXiv comment3 pages, 7 figures, 2020 IEEE Real Time Conference

References in corpus (7)

• Dark Matter Candidates from Particle Physics and Methods of Detection
• Dark matter direct-detection experiments
• The GERDA experiment for the search of 0νββ decay in ^{76}Ge
• Light Neutralinos and WIMP direct searches
• Limits on Light Weakly Interacting Massive Particles from the First 102.8 kg $\times$ day Data of the CDEX-10 Experiment
• Prototype of Pulse Digitizer and Readout Electronics for CDEX-10 in CJPL
• Performance of Linear Classification Algorithms on alpha/gamma Discrimination for LaBr3:Ce Scintillation Detectors with Various Pulse Digitizer Properties