Simulations of background sources in AMoRE-I experiment

Abstract

The first phase of the Advanced Mo-based Rare Process Experiment (AMoRE-I), an experimental search for neutrinoless double beta decay (0$\hat{I}½{\hat{I}}^2{\hat{I}}^2$) 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.