Searching for charged lepton flavour violation with the Mu3e experiment - Scintillating Tile Detector

Mu 3e第一阶段实验的主要目标是寻找带电荷轻子味破坏衰变gamma -> e e e，在90%置信水平（CL）下BR（gamma → e e e）< 5 × 10−15，与现有的界限相比，相应地提高了200倍。为了达到Mu 3e第一阶段的灵敏度目标，必须在大约一年的数据采集时间内观察到每秒10^8 μ子的衰变。这就要求有很好的背景抑制能力。为了有效地区分信号事件与随机符合和具有内部转换的辐射衰变产生的背景，使用高分辨率跟踪和顶点以及非常精确的定时。定时信息由Mu 3e定时系统提供，该系统由位于实验中心部分的目标区域周围的薄闪烁光纤探测器（FID）和放置在递归站内的两个闪烁瓦片探测器（TID）组成;两者的闪烁光由硅光电倍增管（SiPM）读出，并使用海德堡HD-KIP开发的所谓MuTrig芯片进行检测。该项目涉及TID的生产、调试、维护和操作，以及用于TID和FID前端读出的MuTrig芯片的制造和验证。

The main goal of the Mu3e Phase I experiment is the search for the charged lepton flavour violating decay gamma -> e e e with a sensitivity of BR(gamma → e e e) < 5 × 10−15 at 90% confidence level (CL), corresponding to a factor 200 improvement compared to the existing bound. In order to reach the Mu3e Phase I sensitivity goal, of order 10^8 muon decays per second have to be observed for about one year of data taking time. This requires an excellent background rejection capability. To effectively distinguish signal events from background arising from random coincidences and radiative decays with internal conversion, high-resolution tracking and vertexing as well as very precise timing are used. The timing information is provided by the Mu3e timing system, consisting of a thin scintillating fiber detector (FID) located around the target region in the central part of the experiment, and two scintillating tile detectors (TID) placed inside the recurl stations; the scintillation light of both is detected by Silicon-Photomultipliers (SiPMs) readout with the so-called MuTrig chip developed at HD-KIP in Heidelberg. This project concerns the production, commissioning, maintenance and operation of the TID as well as the fabrication and validation of the MuTrig chip for the front-end readout of both TID and FID.