Extension to the build project for the Mu3e MuPix Pixel Tracker

Mu3e实验将研究大量的μ子衰变。为此，该实验背后的团队正在建造一个探测器，以前所未有的精度测量这些衰变中产生的子粒子。该实验将寻找一种非常特殊的衰变类型，其中一个反介子衰变成两个正电子和一个电子。关键是，在这个过程中，反介子失去了变成正电子的“味道”。虽然夸克和中微子等其他粒子也会发生这种变化，但在带电的轻子（电子、μ子或τ子）身上从未观察到这种变化。如果粒子物理学中建立的标准模型（SM）是完整的故事，那么涉及违反带电轻子风味守恒的过程就不应该被观察到。然而，粒子物理学家希望解决物理学中的一些重大问题，比如为什么在我们的宇宙中物质占主导地位而不是反物质，需要超越标准模型的新模型。已经制定了大量这样的模型，但仍然缺乏确凿的证据来证实这些模型。到目前为止，之前的实验已经排除了每1000,000,000,000 （1E12）次衰变中包含带电轻子味破坏的μ子衰变发生一次以上的可能性。Mu3e实验的灵敏度将提高1万倍，可能会在这个已经令人印象深刻的结果上再加4个零；或者——更好的是——找到所寻找的余烬过程的证据，从而直接证明新物理学的存在。粒子物理学家试图回答的另一个关键问题是了解神秘暗物质的本质。暗物质的存在从天文观测中得到了强有力的证实，但它的性质仍然未知。Mu3e实验的独特能力可以非常精确地研究大量μ子的衰变产物，这也使建造和操作探测器的团队成员能够寻找假想的暗光子，这些暗光子在我们已知的物质粒子和一个隐藏的暗物质粒子世界之间提供了联系。

The Mu3e experiment will study a very large numbers of muon decays. For this the team behind the experiment is building adetector that can measure with unprecedented accuracy the daughter particles produced in these decays. The experimentwill look for a very specific type of decay in which an anti-muon decays to 2 positrons and an electron. Crucially, in this aprocess the anti-muon loses its "flavour" to become a positron. Although other particles such as quarks and neutrinos areknown to do this, such a change of flavour has never been observed for the charged leptons (electrons, muons or taus).If the well-established standard model (SM) of particle physics is the complete story, processes involving the violation ofthe conservation of charged lepton flavour should not be observed. However, particle physicists expect that to address somebig questions in physics, such as why in our universe matter dominates over antimatter, new models going beyond thestandard model are needed. A plethora of such model have been formulated but substantive evidence to corroborate anyof these remains absent.To date, previous experiments have excluded that muon decays involving charged lepton flavour violation occur more than oncein every 1,000,000,000,000 (1E12) decays. The Mu3e experiment will be more sensitive by a factor 10,000,potentially adding 4 zeros to this already impressive result; or - much better - finding evidence of the sought afterdecay process and with that, direct evidence of new physics.Another key question particle physicist are trying to answer is to understand the nature of the mysterious dark matter. Theexistence of dark matter is strongly established from astronomical observations, but its nature remains unknown. Theunique capabilities of the Mu3e experiment to study with great precision the decays product of a very large number ofmuons, also allows the members of the team that will build and operate the detector to search for hypothetical dark photons that provide a link between the matter particles we know and a hidden world of dark matter particles.