MICE Ionization-Cooling Demonstration

中微子工厂可能是未来的一个加速器设施，它可以从存储环中的µ子衰变中产生中微子束。来自中微子工厂的中微子光束将具有最高的强度，并且可以以前所未有的精度进行控制。由于这些原因，中微子工厂有可能发现中微子和反中微子振荡之间的可测量差异，这可能是理解宇宙物质-反物质不对称之谜的关键。这种现象被称为CP破坏，在夸克部分已经观察到，但在中微子部分从未见过。未来的中微子工厂将尽可能准确地确定中微子部分的CP破坏。此外，中微子工厂可以作为建造Muon对撞机之前的第一阶段，可以用来以最终的精度测量希格斯玻色子的性质，并有可能达到高达6TeV的能量，以便在最高能量前沿探索新的物理现象。中微子工厂和Muon对撞机都依赖于Muon的加速。为了能够创建Muon加速器设施，我们需要减小Muon束的大小，以便它可以加速。由于介子在其自身的静止坐标系中会在2微秒内衰变，因此在介子衰变之前缩小介子束相空间的唯一已知方法是使用电离冷却的概念，即介子在液体氢或氢化锂(LiH)等吸收体中损失能量，然后通过使用射频腔加速它们来恢复动量的纵向分量。国际上的Muon电离冷却实验(MICE)是电离冷却概念的工程演示。这项实验是在卢瑟福·阿普尔顿实验室进行的，在这个实验中，一束Muon将在一个Muon冷却单元中被冷却，该单元由三个吸收体和两个射频腔组成，位于两个聚焦线圈磁铁的磁场中。使用超导螺线管内的闪烁光纤跟踪器测量冷却通道前后的束流发射度，并使用飞行时间探测器、切伦科夫探测器和量热系统识别µ子，该系统由闪烁纤维铅预簇射探测器(称为KL)和完全活跃的闪烁探测器(称为电子Muon Ranger(EMR))组成。在这项建议中，我们的目标是在没有射频腔的情况下进行发射度降低的测量(MICE步骤IV)，并执行有射频腔的电离冷却的最终演示。这项提案是一项为期42个月的资金申请，从2016年10月到2020年4月，在此期间支持学术和学生的努力，并从2016年12月结束的过渡支持结束时起支持研究人员。

The Neutrino Factory is a possible future accelerator facility that creates beams of neutrinos from the decays of muons in a storage ring. The neutrino beams from a Neutrino Factory would have the highest intensity and can be controlled with unprecedented accuracy. For these reasons, the Neutrino Factory has the potential to discover measurable differences between neutrino and antineutrino oscillations, which could be the key to understanding the puzzle of the matter-antimatter asymmetry of the universe. This phenomenon, known as CP violation, has been observed in the quark sector but has never been seen in the neutrino sector. A future Neutrino Factory would determine CP violation in the neutrino sector with the best possible accuracy. Furthermore, a Neutrino factory could be used as a first stage before the construction of a Muon Collider, which could be used to measure the properties of the Higgs boson with the ultimate precision, and could potentially reach energies of up to 6 TeV, in order to explore new physics phenomena at the highest energy frontier.Both the Neutrino Factory and a Muon Collider rely on the acceleration of muons. To be able to create muon accelerator facilities, we require to reduce the size of the muon beam so that it may be accelerated. Since muons decay within 2 microseconds in their own rest frame, the only known way to reduce the phase space of the muon beam before the muons decay is to use the concept of ionisation cooling, in which the muons lose energy in an absorber such as liquid hydrogen or lithium hydride (LiH) and then recover the longitudinal component of the momentum by accelerating them using RF cavities. The international Muon Ionization Cooling Experiment (MICE) is an engineering demonstration of the concept of ionisation cooling. This experiment is being built at the Rutherford Appleton Laboratory, in which a beam of muons will be cooled in a muon cooling cell consisting of three absorbers and two RF cavities inside the field of two focus coil magnets. The emittance of the beam is measured before and after the cooling channel using a scintillating fibre tracker inside a superconducting solenoid, and the muons are identified using time-of-flight detectors, a Cherenkov detector and a calorimeter system consisting of a scintillating fibre-lead pre-shower detector (named the KL) and a totally active scintillating detector, called the Electron Muon Ranger (EMR). In this proposal we aim to perform measurements of emittance reduction, without RF cavities (MICE step IV) and perform the final demonstration of ionization cooling with RF cavities. This proposal is a bid for 42 months funding from October 2016 to April 2020, supporting academic and student effort over that period and research staff from the end of the bridging support that ends in December 2016.