Bulk and Surface Event Identification in p-type Germanium Detectors

TL;DR

This paper introduces an improved method for distinguishing surface events from bulk signals in p-type germanium detectors, enhancing the accuracy of low-energy event identification crucial for dark matter and neutrino research.

Contribution

The paper presents a novel ratio-based calibration method that improves surface event identification without relying on spectral shape assumptions.

Findings

The ratio method yields results consistent with the spectral shape method.

Reanalysis of CDEX-1 and TEXONO data validates the new approach.

Enhanced discrimination of surface events improves detector performance.

Abstract

The p-type point-contact germanium detectors have been adopted for light dark matter WIMP searches and the studies of low energy neutrino physics. These detectors exhibit anomalous behavior to events located at the surface layer. The previous spectral shape method to identify these surface events from the bulk signals relies on spectral shape assumptions and the use of external calibration sources. We report an improved method in separating them by taking the ratios among different categories of in situ event samples as calibration sources. Data from CDEX-1 and TEXONO experiments are re-examined using the ratio method. Results are shown to be consistent with the spectral shape method.