利用混合切伦科夫-闪烁探测器寻找类轴子粒子
Axion-Like Particle Search with a Hybrid Cherenkov-Scintillation Detector
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中文总结 AI 辅助
本研究基于CCM实验，利用混合切伦科夫-闪烁探测器构建似然比分类器搜寻类轴子粒子，在10⁻³ MeV至10 MeV质量区间未发现显著超出，且灵敏度优于此前CCM120实验。
中文摘要 AI 辅助
本分析首次在束流dump设施中，利用混合切伦科夫-闪烁探测器开展类轴子粒子（ALPs）的概念验证型搜寻工作。该研究基于洛斯阿拉莫斯国家实验室的相干CAPTAIN-米尔斯（CCM）实验，这是一台10吨级液氩光收集探测器。CCM200探测器配备200个光电倍增管（PMTs），提供约50%的光阴极覆盖率；为实现光学甄别，80%的PMTs涂覆有波长转换材料，剩余20%未涂覆。该配置结合纳秒级时间分辨率，可探测瞬时切伦科夫辐射，同时高效探测液氩闪烁光。本分析构建了四个可观测量，利用ALP诱导电磁相互作用预期的切伦科夫发射与事例拓扑结构，将这些可观测量组合为似然比分类器，可有效压制稳态本底。在10⁻³ MeV < m_a < 10 MeV范围内，未观测到超出预期本底的统计显著 excess。不过，混合切伦科夫-闪烁探测带来的改进本底压制，使本分析虽曝光量较少，仍超越了此前CCM120搜寻的灵敏度，证明了混合切伦科夫-闪烁探测器的物理潜力。
英文摘要
This analysis presents the first proof-of-concept search for axion-like particles (ALPs) using a hybrid Cherenkov-scintillation detector at a beam-dump facility. The work is based on the Coherent CAPTAIN-Mills (CCM) experiment, a 10-ton liquid argon light collection detector located at Los Alamos National Laboratory. The CCM200 detector is instrumented with 200 photomultiplier tubes (PMTs), providing approximately 50% photocathode coverage. To enable optical discrimination, 80% of the PMTs are coated with a wavelength-shifting material while the remaining 20% are left uncoated. This configuration, combined with nanosecond-scale timing resolution, provides sensitivity to prompt Cherenkov radiation while maintaining efficient detection of liquid argon scintillation light [1, 2]. This analysis constructs four observables that exploit the Cherenkov emission and event topology expected from ALP-induced electromagnetic interactions. These observables are combined into a likelihood-ratio classifier that provides powerful rejection of steady-state backgrounds. No statistically significant excess above the expected background prediction is observed for $10^{-3}~\mathrm{MeV} < m_a < 10~\mathrm{MeV}$. Nevertheless, the improved background rejection enabled by hybrid Cherenkov-scintillation detection allows this analysis to surpass the sensitivity of the previous CCM120 search [3] despite less exposure and demonstrate the physics potential for hybrid Cherenkov-scintillation detectors.
