Simulations of background sources in AMoRE-I experiment

The first phase of the Advanced Mo-based Rare process Experiment (AMoRE-I), an experimental search for neutrinoless double beta decay (0νββ) of 100Mo in calcium molybdate (40Ca100MoO4) crystal using cryogenic detection techniques, is in preparation at the YangYang underground laboratory (Y2L) in Korea. A GEANT4 based Monte Carlo simulation was performed for the first-phase AMoRE detector and shield configuration. Background sources such as 238U, 232Th, 235U, and 210Pb from inside the crystals, surrounding materials, outer shielding walls of the Y2L cavity were simulated. The estimated background rate in the region of interest was estimated to be <1.5×10−3 counts/keV/kg/yr (ckky). The effects of random coincidences between backgrounds and two-neutrino double beta decays of 100Mo as a potential background source were estimated to be <2.3×10−4 ckky.