A novel discrimination method for neutrinos and cosmogenic isotopes in liquid scintillator-based detectors

Cosmogenic isotopes, known for their diverse types and relatively long lifetimes, are frequently treated as significant backgrounds in neutrino experiments. Particularly in the correlation events of inverse beta decay (IBD) events of reactor neutrinos, addressing and removing \(^{9}\) ${}^9$ Li and \(^{8}\) ${}^8$ He background is necessary. Similarly, for elastic scattering (ES) events of solar neutrinos, isotopes such as \(^{12}\) ${}^{12}$ B and \(^{8}\) ${}^8$ Li have significant impacts. This study aims to identify an appropriate method for reducing the backgrounds in neutrino experiments.

In this paper, we conducted simulations of muon backgrounds in a liquid scintillator detector using Geant4 and explored the correlation between cosmogenic isotopes and muons. We introduced a novel method to distinguish cosmogenic isotopes from neutrino signals. Utilizing the relationship between the distance and time of spallation isotopes to muons and neutrons, we employed the TMVA (tools for multi-variable analysis) to distinguish neutrino signals from isotope backgrounds, achieving good performance.

Compared with the traditional veto method, the efficiency has been improved by 1% for correlated events and 18% for single-event signals at the same background level.

This study presents a novel method for discriminating cosmogenic isotopic backgrounds, achieving a higher signal-to-noise ratio compared to traditional approaches, and showing good potential applicability to similar analyses in the future.