Simulations of background sources in AMoRE-I experiment

TL;DR

This paper presents a detailed Monte Carlo simulation of background sources for the AMoRE-I experiment, estimating background rates and potential interference in the search for neutrinoless double beta decay of $^{100}$Mo.

Contribution

It provides the first comprehensive background estimation for the AMoRE-I detector using GEANT4 simulations, including various radioactive sources and their impact.

Findings

Estimated background rate in the region of interest is below 1.5 x 10^{-3} counts/keV/kg/yr.

Potential background from random coincidences with two-neutrino double beta decay is below 2.3 x 10^{-4} ckky.

Simulation results inform the detector design and background mitigation strategies.

Abstract

The first phase of the Advanced Mo-based Rare Process Experiment (AMoRE-I), an experimental search for neutrinoless double beta decay (0$\nu\beta\beta$) of $^{100}$Mo in calcium molybdate (CMO) crystal using cryogenic techniques, is in preparation at the YangYang underground laboratory (Y2L) in South Korea. A GEANT4 based Monte Carlo simulation was performed for background estimation in the first-phase the AMoRE-I detector and shield configuration. Background sources such as $^{238}$U, $^{232}$Th, $^{40}$K, $^{235}$U, and $^{210}$Pb were simulated from inside the crystals, surrounding materials, outer shielding walls of the Y2L cavity. The estimated background rate in the region of interest was found to be $< 1.5 \times 10^{-3}$ counts/keV/kg/yr (ckky). The effects of random coincidences between background and two-neutrino double beta decay of $^{100}$Mo were estimated as a potential background source and its estimated rate was $< 2.3 \times 10^{-4}$ ckky.