论文标题
MU2E实验 - 寻找违反充电的Lepton风味
The Mu2e Experiment -- Searching for Charged Lepton Flavor Violation
论文作者
论文摘要
MU2E实验将搜索一个标准模型，违反了在铝核存在下，MUON转化为电子中的中性溶液速率。观察这种充电的Lepton侵犯过程将是新物理学的明确迹象。 MU2E将通过四个数量级来改善对该过程的搜索。这需要世界上最高强度的亮束，这是一个能够有效地重建105 MeV/c转换电子信号的探测器系统，并最大程度地降低对背景事件的敏感性。脉冲8 GEV质子束撞击目标，产生腐烂成臂线的乳头。脉搏外的光束必须抑制至$ <10^{ - 10} $，以减少与光束相关的背景。 MUON光束从运输系统的生产目标引导到铝制停止目标。转换电子将停止目标留下，并在螺线管磁场内传播到跟踪器和电磁热量计。跟踪器是一个在1个atm处装满AR/CO $ _2 $的稻草管面板系统，该系统在1个atm上跟踪螺线管B场内的粒子，并用$ \ sim100 $ kev/$ c $分辨率测量其MONSA，以解决磁衰减背景中的信号事件。 CSI量热仪提供$ e /p $，用于用$σ_e /e /e \ sim {} 10 \％$和$σ_T<500〜 \ rm {ps} $播种轨道重建算法。此外，一种新型的宇宙射线否决，效率超过99.99 \％的效率将预期的背景事件数量提高到三年内不到一年。为了使实验归一化，停止目标监测器通过使用高纯晶也和灯笼溴化物闪光灯的系统来测量入射在停止目标上的MUON的捕获光子的速率。
The Mu2e experiment will search for a Standard Model violating rate of neutrinoless conversion of a muon into an electron in the presence of an aluminum nucleus. Observation of this charged lepton flavor violating process would be an unambiguous sign of new physics. Mu2e will improve upon previous searches for this process by four orders of magnitude. This requires the world's highest-intensity muon beam, a detector system capable of efficiently reconstructing the 105 MeV/c conversion electron signal, and minimizing sensitivity to background events. A pulsed 8 GeV proton beam strikes a target, producing pions that decay into muons. Beam outside the pulse must be suppressed to $< 10^{-10}$ to reduce beam-related backgrounds. The muon beam is guided from the production target along the transport system and onto the aluminum stopping target. Conversion electrons leave the stopping target and propagate inside a solenoidal magnetic field to the tracker and electromagnetic calorimeter. The tracker is a system of straw tube panels filled with Ar/CO$_2$ at 1 atm that tracks particles inside of a solenoidal B-field and measures their momenta with $\sim100$ keV/$c$ resolution to resolve signal events from decay-in-orbit backgrounds. The CsI calorimeter provides $E/p$ and is used to seed the track reconstruction algorithm with $σ_E /E \sim{}10\%$ and $σ_t<500~\rm{ps}$. Additionally, a novel cosmic ray veto with greater than 99.99\% efficiency brings the expected number of background events to fewer than one over three years of running. To normalize the experiment, the stopping target monitor measures the rate of capture photons from muons incident on the stopping target by using a system of high-purity germanium and lanthanum bromide scintillators.
