发表机构
Nanjing University; Institute of High Energy Physics, Chinese Academy of Sciences; China Center of Advanced Science and Technology（南京大学; 中国科学院高能物理研究所; 中国高等科学技术中心）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对低能中微子实验中宇宙成因$^{9}$Li/$^{8}$He本底估计难题，提出距离约束的J-MuCAT（DCJ-MuCAT）拟合方法，结合时间与距离信息，在探测器模拟中将统计不确定性较传统方法降低超40%，并验证了广泛适用性。
AI 中文摘要
宇宙成因$^{9}$Li和$^{8}$He同位素是低能中微子实验中重要的关联本底，因为它们的$\eta$延迟中子衰变特征可能模仿反贝塔衰变信号。在高缪子率下，基于距上次缪子时间的传统估计变得具有挑战性，而缪子相关的veto进一步减少了残余同位素统计量。我们将传统时间拟合扩展到事件级缪子分类联合时间（J-MuCAT）拟合，该拟合使用每个能量损失类别中距最近前驱缪子的时间。互补估计来自候选粒子到缪子径迹距离分布（TraDiTS）。缪子不相关成分由远距离区域确定并扣除。该估计随后用于约束J-MuCAT拟合，定义距离约束的J-MuCAT（DCJ-MuCAT）拟合。在连续宇宙成因本底veto的探测器级模拟中，DCJ-MuCAT相对于J-MuCAT将统计不确定性降低了超过40%，相对于TraDiTS降低了超过10%。拟合结果与模拟真值保持一致。适用性研究进一步表明在广泛的缪子率和同位素比例范围内性能良好。所提出的框架为大型中微子探测器中残余$^{9}$Li/$^{8}$He本底的估计提供了一种实用方法。
英文摘要
Cosmogenic $^{9}$Li and $^{8}$He isotopes constitute an important correlated background in low-energy neutrino experiments because their $β$-delayed neutron decay signatures can mimic inverse beta decay signals. Conventional estimates based on the time since the last muon become challenging at high muon rates, while muon-related vetoes further reduce the residual isotope statistics. We extend the conventional time fit to an event-level muon-categorized joint time (J-MuCAT) fit, which uses the time to the most recent preceding muon in each energy-loss category. A complementary estimate is obtained from the candidate-to-muon-track distance distribution (TraDiTS). The muon-uncorrelated component is determined from the far-distance region and subtracted. This estimate is then used to constrain the J-MuCAT fit, defining the distance-constrained J-MuCAT (DCJ-MuCAT) fit. In detector-level simulation with successive cosmogenic-background vetoes, DCJ-MuCAT reduces the statistical uncertainty by more than $40\%$ relative to J-MuCAT and by more than $10\%$ relative to the TraDiTS. The fitted results remain consistent with the simulation truth. Applicability studies further show good performance over a broad range of muon rates and isotope fractions. The proposed framework provides a practical approach for estimating residual $^{9}$Li/$^{8}$He backgrounds in large neutrino detectors.
Comments13 pages, 6 figures. Comments are welcome
