Study of High Intensity Stopping Muon Beams and Experimental Apparatuses for μィイD1+ィエD1 →eィイD1+ィエD1+γ Experiment

设计了一个实验来改进和鉴别一个轻子味数违反衰变过程，一个μ子衰变为一个正电子和一个光子。这个过程是被基本粒子的标准模型所严格禁止的，而这个过程的识别给了我们一个信号，让我们看到了粒子物理学的新世界，超越了标准模型。实验的概念基于两个创新的想法，用于测量能量的液体氙闪烁量热计，光子的位置和定时以及测量正电子动量的COBRA谱仪。为了使上述实验成为可能，已经进行了几个发展计划。首先，研制了一种新型光电倍增管，用于在-100℃低温下探测液体氙中的闪烁光子（波长175 nm）。一个小型的测试量热计与32光电倍增管的建立和使用，以确认预期的性能的液体氙量热计。第二，研制了一种直接制冷大量氙气的脉管制冷机，并与其他研究一起，于1999年5月向瑞士Paul Sherrer研究所提交了实验方案。1999年7月，该研究所接受了这一建议。目前，正在研究进一步的细节。

An experiment was designed to improve and identify a lepton flavor number violating decay process, a muon decay into a positron and a photon. The process is severely prohibited by the standard model of the elementary particle, and the identification of the process gives us a signal of the new world of the particle physics, beyond the standard model.The concept of the experiment is based on two innovative ideas, liquid xenon scintillation calorimeter for measuring energy, position and timing of photons and COBRA spectrometer for measuring momentum of positrons.Several development programs have been carried out to made the above experiment possible. Firstly, a new phtomultiplier tube was developed to detect the scintillation photons(wavelength of 175 nm) from liquid xenon at the low temperature of -100℃. A small test calorimeter with 32 photomultiplier tubes was built and used to confirm the expected performances of the liquid xenon calorimeter. Secondly, a pulse tube refrigerator was developed to directly liquefy the large amount of xenon gas.Together with other studies, and experimental proposal was written and submitted to Paul Sherrer Institute, Switzerland in May 1999. The proposal was accepted in July, 1999 by the Institute. Currently, further details are being studied.