Collaborative Research: Muon Ionization Cooling Experiment

提高加速器能力的一个重要活动是研究和开发高光度的Muon对撞机。在考虑高能物理设施的下一步可能时，与电子和质子相比，µ子具有重要的性质。由于与电子相比，介子的辐射受到了很大的抑制，因此考虑在能量为TeV的范围内对介子进行相对紧凑的圆形对撞机是可行的。然而，像电子一样，Muon是一个点粒子，因此可以探索与质子相同的物理机制，能量大约高出十倍。因此，在过去的几年里，Muon对撞机吸引了越来越多的兴趣。由于介子是一种不稳定的粒子，因此需要对加速器物理和技术的许多新方面进行研究，然后才能有把握地说这样的设备将会工作。国际Muon电离冷却实验(简称MICE)是首次致力于观察Muon电离冷却的高能物理实验。这种冷却是迈向Muon对撞机的必要一步。冷却是一种过程，通过降低束流的发射度来减小束流大小，以便在较小口径的加速器和较少的聚焦磁铁中加速更多的µ子。这可能会使建造高强度的Muon加速器成为可能，例如用于中微子工厂或Muon对撞机，它有可能获得比电子-正电子对撞机更高的能量。为了寻找冷却µ子的方法，研究人员设计了小鼠实验，以测试一种名为电离冷却的技术的有效性。电离冷却发生时，通过一个吸收体，他们失去了动量通过电离能量损失。然后，它们在直线加速器中被重新加速，在那里它们的能量只在正向恢复。老鼠将使用单粒子束，大约每10纳秒不超过一个介子通过探测器。这项实验需要平衡能量损失带来的冷却和Muon多次散射产生的热量。Muon电离冷却实验将使用卢瑟福·阿普尔顿实验室(Ral)新建造的低能量Muon束对Muon电离冷却进行详细测量。该实验是一个单粒子实验，利用了许多高能物理实验中的探测器技术。为了表征和监测介子光束线，采用了新开发的闪烁光纤轮廓监测器和闪烁体划桨速率监测器。为了监测束流的纯度和标记单个µ子的到达时间，使用了双气凝胶切伦科夫系统，并将使用塑料闪烁体飞行时间系统。

An important activity toward advancing accelerator capability is research and development for a high luminosity muon collider. Muons have important properties compared to electrons and protons when considering a possible next step for a high energy physics facility. Since radiation by muons is much suppressed compared to electrons, it is feasible to consider a relatively compact circular collider in the TeV energy range for muons. However the muon, like the electron, is a point particle and therefore can explore the same physics regime as protons with approximately ten times higher energy. Accordingly the muon collider has attracted increasing interest over the past couple of years. Since the muon is an unstable particle there are many new facets of accelerator physics and technology that need to be examined before one can say with confidence that such a device will work. The International Muon Ionization Cooling Experiment (or MICE) is a high energy physics experiment dedicated to observing ionization cooling of muons for the first time. Such cooling is a necessary step toward a muon collider. Cooling is a process whereby the emittance of a beam is reduced in order to reduce the beam size, so that more muons can be accelerated in smaller aperture accelerators and with fewer focussing magnets. This might enable the construction of high intensity muon accelerators, for example for a Neutrino Factory or Muon Collider, which potentially can attain higher energies than electron-positron colliders. Researchers looking for a method of cooling muons designed the MICE experiment to test the effectiveness of a technique called ionization cooling. Ionization cooling takes place when muons are sent through an absorber in which they lose momentum via ionization energy loss. They are then reaccelerated in a linear accelerator where their energy is restored only in the forward direction. MICE will use a single particle beam, with not more than one muon passing through the detector about every 10 nanoseconds. The experiment needs to balance the cooling from energy loss with the heating from multiple scattering of the muons.The Muon Ionization Cooling Experiment will make detailed measurements of muon ionization cooling using a newly constructed low-energy muon beam at the Rutherford Appleton Laboratory (RAL). The experiment is a single particle experiment and utilizes many detector techniques from high energy physics experiments. To characterize and monitor the muon beamline, newly developed scinitillating fiber profile monitors and scintillator paddle rate monitors are employed. In order to monitor the purity of the beam and tag the arrival time of individual muons, a dual aerogel Cherenkov system is used, and a plastic scintillator time-of-flight system will be used.