AI 中文总结
本文介绍了CROSS实验的探测器建造与本底模拟，该实验利用含4.9 kg $^{100}$Mo的闪烁低温量热计，可在1年或2年数据采集内达到对$^{100}$Mo 0ν2β衰变的世界领先或有竞争力灵敏度。
AI 中文摘要
CROSS实验利用包含4.9 kg $^{100}$Mo的闪烁低温量热计阵列，在西班牙坎弗兰地下实验室的低本底环境中，自2025年11月中旬起开展针对$^{100}$Mo的无中微子双β（0ν2β）衰变的搜寻工作。本文介绍了CROSS探测器的建造情况，以及基于Geant4的蒙特卡罗模拟对感兴趣区预期本底的描述。模拟预测，在$^{100}$Mo的Q值（3034 keV）为中心的100 keV宽区间内，本底水平为3.2(5)×10⁻³ cnts/keV/kg/yr。考虑到μ子 veto 截断导致的18%死时间及设施典型的90%运行占空比，该本底水平可在1年的数据采集时间内达到对$^{100}$Mo 0ν2β衰变的世界领先灵敏度（半衰期下限$T_{1/2}$~4×10²⁴年）。若因建造材料不可预测的放射性污染和/或探测器性能导致本底水平保守地恶化3倍（10倍），CROSS阵列运行2年仍可达到对$^{100}$Mo 0ν2β衰变的最佳（有竞争力）灵敏度。
英文摘要
The CROSS experiment to search for neutrinoless double-beta ($0\nu2β$) decay in $^{100}$Mo with the help of an array of scintillating cryogenic calorimeters, containing 4.9 kg of $^{100}$Mo, has been ongoing in a low-background setup at the Canfranc underground laboratory (Spain) since mid-November 2025. In this paper, we present the construction of the CROSS detector and the description of Geant4-based Monte Carlo simulations of expected background in the region of interest. The simulations predict the background index in a 100-keV-wide interval centered at the $Q$-value of $^{100}$Mo (3034 keV) on the level of 3.2(5) $\times$ 10$^{-3}$ cnts/keV/kg/yr. Taking into account an 18% deadtime induced by the muon veto cut and a typical 90% duty cycle of the facility, such background level would allow to reach the world-leading sensitivity to $^{100}$Mo $0\nu2β$ decay (lim $T_{1/2} \sim 4 \times 10^{24}$ yr) in 1 year of data taking. Considering conservatively a factor 3 (10) worse background index due to unpredictable radioactive contamination of construction materials and/or detector performance, a 2-yr-long operation of the CROSS array would be still compatible with the best (competitive) sensitivity to $0\nu2β$ decay in $^{100}$Mo.
Comments16 pages, 14 figures and 1 table; prepared for submission to EPJC
