Development of detectors for CP violating rare decays

CP破坏稀有衰变探测器的开发

基本信息

批准号：
11440079
负责人：
YAMANAKA Taku
金额：
$ 5.82万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11440079/
关键词：
CP violation photon detector neutral kaons rare decays

项目摘要

We are planning a new experiment to measure the CP violating parameter in the standard model, η, by measuring the branching ratio of K_L→π^0vv^^-. The major background to this decay is K_L→π^0π^0 where we miss 2 out of 4 photons. In order to suppress this background, we will cover the decay region by a hermetic photon veto counters made of lead/scintillator sandwich.Here is a summary of what we have done.1. We found that the detection inefficiency of lead/scintillator sandwich would be smaller if the layers were aligned at angle (60 degrees) instead of aligning them in parallel (0 degrees) to the beam line. Also, the detection efficiency increases if the scintillator layers are extended to coverthe surface of exposed lead sheets.2. We are planning to read out the light from scintillator planes by using optical fibers with a wave length shifter, embeded in grooves. We studied the position dependence of the scintillator light collected in the fiber. We found that the light output is determined by the solid angle of the fiber, reflection/diffusion at the grooves, and the light loss at the surface reflections. The measured results were reproduced by simple model calculations.3. We have optimized cuts for the experiment to keep a high sensitivity while suppressing background events from K_L→π^0π^0.4. We have measured the flux and the energy spectrum of kaons and neutrons produced by 150GeV proton beam.5. Based on above studies, we are now preparing a proposal for the new experiment to be submitted in April.

我们正在计划一个新的实验，以测量标准模型η中违反参数的CP，通过测量K_L→π^0vv ^^ - 的分支比。这种衰减的主要背景是k_l→π^0π^0，我们错过了4张照片中的2个。为了抑制这种背景，我们将通过由铅/闪光灯夹心制成的密封光子否决柜台覆盖衰减区域。这里是我们所做的事情的总结。1。我们发现，如果将层以角度对齐（60度）对齐，而不是平行对齐（0度）与光束线对齐，则铅/闪烁夹三明治的效率低效率将较小。同样，如果将闪烁体的层扩展到覆盖裸露铅片的表面2。我们正计划通过使用带有波长换档器的光纤嵌入凹槽中的光纤来读取闪烁光平面的光。我们研究了收集在纤维中的闪烁体光的位置依赖性。我们已经测量了光输出取决于纤维的实体角度，凹槽处的反射/扩散以及表面反射处的光损失。测得的结果通过简单的模型计算复制3。我们对实验进行了优化的切割，以保持高灵敏度，同时抑制K_L→π^0π^0.4的背景事件。我们已经测量了由150GEV质子束产生的Kaons和中子的通量和能量光谱。5。基于上述研究，我们现在正在为4月提交的新实验做准备。