Measurement of proton, deuteron, triton, and a particle emission after nuclear muon capture on Al, Si, and Ti with the AlCap experiment
Measurement of proton, deuteron, triton, and a particle emission after nuclear muon capture on Al, Si, and Ti with the AlCap experiment
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使用 AlCap 实验测量 Al、Si 和 Ti 上的核 μ 子捕获后的质子、氘核、氚核和粒子发射
DOI：
10.1103/physrevc.105.035501
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发表时间：
2022
影响因子：
3.1
通讯作者：
Edmonds A
中科院分区：
文献类型：
--
作者：
Edmonds A
背景：核μ子俘获后的重带电粒子是μ子-电子转换实验Mu 2 e和COMET的重要核物理背景，它们将以前所未有的灵敏度寻找带电轻子味违反。目的：AlCap实验旨在测量质子、氘核、氚核和μ子-电子转换实验相关低能范围内μ子核俘获停止在Al、Si和Ti中后发射的粒子的产额和能谱。方法：在分层硅探测器包中识别单个带电粒子类型，并从观察到的能谱中展开它们的初始能量分布。结果：每μ子俘获的质子产额为Yp（Al）=26.64（28 stat.）（77syst.）在3.5-20.0 MeV能量范围内，λ = 10 ×10 - 3;在4.0-20.0 MeV能量范围内，λ = 10 ×10 - 3。论文给出了所有观测到的核的产额和能谱的详细信息。结论：候选μ子停止靶Al和Ti的产额大约是过去用于估计该背景的Si的一半。在这些实验中，减少的背景允许更少的屏蔽和更好的能量分辨率。预计本文提供的全面信息将刺激现代理论计算的罕见过程中的μ子捕获带电粒子发射，并告知未来的μ子到电子转换实验的设计。
Background:Heavy charged particles after nuclear muon capture are an important nuclear physics background to the muon-to-electron conversion experiments Mu2e and COMET, which will search for charged lepton flavor violation at an unprecedented level of sensitivity.Purpose:The AlCap experiment aimed to measure the yield and energy spectra of protons, deuterons, tritons, andparticles emitted after the nuclear capture of muons stopped in Al, Si, and Ti in the low-energy range relevant for the muon-to-electron conversion experiments.Methods:Individual charged particle types were identified in layered silicon detector packages and their initial energy distributions were unfolded from the observed energy spectra.Results:The proton yields per muon capture were determined as Yp(Al)=26.64(28stat.)(77syst.)×10−3 andin the energy range 3.5–20.0 MeV, and asin the energy range 4.0–20.0 MeV. Detailed information on yields and energy spectra for all observed nuclei are presented in the paper.Conclusions:The yields in the candidate muon stopping targets, Al and Ti, are approximately half of that in Si, which was used in the past to estimate this background. The reduced background allows for less shielding and a better energy resolution in these experiments. It is anticipated that the comprehensive information presented in this paper will stimulate modern theoretical calculations of the rare process of muon capture with charged particle emission and inform the design of future muon-to-electron conversion experiments.