0ͦ¦ Discrimination of Single-Crystal Multielectrode Readout of High Purity Germanium Detector 76Ge

Experiments conducted to investigate the neutrinoless double-beta (0 nu beta beta) decay of Ge-76 using a high purity germanium (HPGe) detector heavily rely on background suppression technologies to enhance their sensitivities. Differentiating between single-electron (background) and double-electron (0 nu beta beta) events is challenging because of the minimal discrimination between their respective signal characteristics. In this article, a waveform-simulation method is established for a single-crystal multielectrode HPGe detector, and the position resolution of the double-sided crossed-strip multielectrode HPGe detector is investigated. At the same time, the lightGBM model is built to classify and train the simulated waveforms collected by each electrode of the multielectrode HPGe detector. The results reveal that the multielectrode HPGe detector demonstrates good position sensitivity in the direction of electrode distribution. The depth of particle interaction can be determined by the time difference between waveforms collected by the electrodes. Based on the lightGBM model, the recognition effect of the 0 nu beta beta double-electron events is 68.4%. The trained lightGBM model has been verified to exhibit a remarkable inhibitory effect on Ge-68 and Co-60 in the background. This can be attributed to the fact that the 0 nu beta beta signal event is not substantially inhibited and can therefore be inhibited by 3.33 and 2.66 times before and after the discrimination, respectively. The results show that the multielectrode HPGe detector can be feasibly applied to the 0 nu beta beta decay detection of Ge-76, which provides a reference for future event-by-event research on the 0 nu beta beta decay of Ge-76 in the China Jinping Underground Laboratory.