Projected background and sensitivity of AMoRE-II

TL;DR

AMoRE-II is a cryogenic experiment aiming to detect neutrinoless double beta decay in molybdenum-100, with detailed background simulations to achieve high sensitivity and cover the inverted mass hierarchy region.

Contribution

This paper provides a comprehensive Monte Carlo simulation of background sources and estimates the sensitivity of AMoRE-II for neutrinoless double beta decay detection.

Findings

Estimated background level meets the required 10^{-4} counts/(keV·kg·yr) in the ROI.

Projected half-life sensitivity reaches approximately 6 × 10^{26} years.

The experiment aims to explore the inverted mass hierarchy region of neutrino masses.

Abstract

AMoRE-II aims to search for neutrinoless double beta decay with an array of 423 Li$_2$$^{100}$MoO$_4$ crystals operating in the cryogenic system as the main phase of the Advanced Molybdenum-based Rare process Experiment (AMoRE). AMoRE has been planned to operate in three phases: AMoRE-pilot, AMoRE-I, and AMoRE-II. AMoRE-II is currently being installed at the Yemi Underground Laboratory, located approximately 1000 meters deep in Jeongseon, Korea. The goal of AMoRE-II is to reach up to $T^{0\nu\beta\beta}_{1/2}$ $\sim$ 6 $\times$ 10$^{26}$ years, corresponding to an effective Majorana mass of 15 - 29 meV, covering all the inverted mass hierarchy regions. To achieve this, the background level of the experimental configurations and possible background sources of gamma and beta events should be well understood. We have intensively performed Monte Carlo simulations using the GEANT4 toolkit in all the experimental configurations with potential sources. We report the estimated background level that meets the 10$^{-4}$counts/(keV$\cdot$kg$\cdot$yr) requirement for AMoRE-II in the region of interest (ROI) and show the projected half-life sensitivity based on the simulation study.