single-electron events and 0{\nu}{\beta}{\beta} events in CdZnTe: A Monte Carlo simulation study

TL;DR

This study introduces a novel topological signature called REF track for distinguishing neutrinoless double beta decay events from single-electron backgrounds in CdZnTe detectors, achieving high rejection and efficiency in simulations.

Contribution

It proposes the REF track as an accurate approximation of particle trajectories and develops energy deposition models to improve event discrimination in Monte Carlo simulations.

Findings

Achieved 93.8% single-electron background rejection.

Achieved 85.6% detection efficiency for 0νββ events.

Demonstrated the effectiveness of the REF track method in simulations.

Abstract

In neutrinoless double beta (0{\nu}{\beta}{\beta}) decay experiments, the diversity of topological signatures of different particles provides an important tool to distinguish double beta events from background events and reduce background rates. Aiming at suppressing the single-electron backgrounds which are most challenging, several groups have established Monte Carlo simulation packages to study the topological characteristics of single-electron events and 0{\nu}{\beta}{\beta} events and develop methods to differentiate them. In this paper, applying the knowledge of graph theory, a new topological signature called REF track (Refined Energy-Filtered track) is proposed and proven to be an accurate approximation of the real particle trajectory. Based on the analysis of the energy depositions along the REF track of single-electron events and 0{\nu}{\beta}{\beta} events, the REF energy deposition models for both events are proposed to indicate the significant differences between them. With these differences, this paper presents a new discrimination method, which, in the Monte Carlo simulation, achieved a single-electron rejection factor of 93.8+-0.3 (stat.)% as well as a 0{\nu}{\beta}{\beta} efficiency of 85.6+-0.4 (stat.)% with optimized parameters in CdZnTe.