Measurement of cosmic-ray muon spallation products in a xenon-loaded liquid scintillator with KamLAND

TL;DR

This study measures the production of radioisotopes from cosmic-ray muons in a xenon-loaded liquid scintillator, providing data crucial for background reduction in rare event physics experiments.

Contribution

It introduces new muon reconstruction and spallation identification methods, and compares measured yields with simulation predictions.

Findings

Measured xenon spallation product yields are consistent with FLUKA and Geant4 simulations.

Developed high-efficiency muon detection techniques for background characterization.

Provided data to improve background modeling in rare event searches.

Abstract

Cosmic-ray muons produce various radioisotopes when passing through material. These spallation products can be backgrounds for rare event searches such as in solar neutrino, double-beta decay, and dark matter search experiments. The KamLAND-Zen experiment searches for neutrinoless double-beta decay in 745kg of xenon dissolved in liquid scintillator. The experiment includes dead-time-free electronics with a high efficiency for detecting muon-induced neutrons. The production yields of different radioisotopes are measured with a combination of delayed coincidence techniques, newly developed muon reconstruction and xenon spallation identification methods. The observed xenon spallation products are consistent with results from the FLUKA and Geant4 simulation codes.