Construction of the MuPix HV-CMOS tracker and background suppression for Mu3e

Mu3e实验旨在通过寻找被禁止的Me+e-e+衰变来寻找带电的轻子味道违规。对中微子振荡的观察表明，轻子的味道并不是一个守恒量，然而，尽管之前的搜索从未在带电轻子中发现过。在标准模型中，这种衰变被抑制到不可观测的水平，然而，标准模型之外的许多模型预测的分枝比例要高得多。Mu3e探测器被设计为能够具有10-16的分支比灵敏度，这比SINDRUM目前的限制提高了四个数量级。利物浦大学将在实验的MuPix HV-CMOS跟踪器的建设中发挥主要作用。作为一名研究生，作为团队的活跃成员，将为MuPix跟踪器的组装和质量保证做出贡献。这项工作将与模拟研究一起进行，模拟研究将改进对主要背景过程之一的拒绝。具有内部光子转换的Michel衰变在探测器中具有相同的最终状态，但总能量低于Muon质量的3个电子。减少这一背景的关键方法是了解MuPix跟踪器的动量测量结果。我还将参加测试光束，以表征最终探测器的MuPix传感器。

The Mu3e experiment is designed to search for charged lepton flavour violation by looking for the forbidden mu e+e-e+ decay. The observations of neutrino oscillations have revealed that lepton flavour isn't a conserved quantity, however despite previous searches it has never been found in charged leptons. In the standard model this decay is suppressed to unobservable levels however many models beyond the standard model predict much higher branching fractions. The Mu3e detector is designed to be able to have a branching ratio sensitivity of <10-16, this is an improvement of four orders of magnitude over the current limit from SINDRUM.The University of Liverpool will play a major role in the construction of the MuPix HV-CMOS tracker for the experiment.As a research student the roles that will be undertaken as a active member of the team is contributing to the assembly and quality assurance of the MuPix tracker. This work will be done alongside simulations studies which will improve the rejection of one of the main background processes. Michel decays with an internal photon conversion have the same final state in the detector, but a total energy of the 3 electrons below the muon mass. The key way to reduce this background is by understanding the momentum measurements from the MuPix tracker. I will also take part in test beams to characterise the MuPix sensor for final detector.