MICE Ionization-Cooling Demonstration

中微子工厂是未来可能的加速器设施，它从储存环中的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可测量的差异，这可能是理解宇宙物质-反物质不对称性之谜的关键。这种现象被称为CP破坏，在夸克扇区中观察到，但在中微子扇区中从未见过。未来的中微子工厂将以尽可能高的精度确定中微子区的CP破坏。此外，中微子工厂可以作为建造μ子对撞机的第一阶段，μ子对撞机可以用于以最终精度测量希格斯玻色子的属性，并且可能达到高达6 TeV的能量，以探索最高能量前沿的新物理现象。中微子工厂和μ子对撞机都依赖于μ子的加速。为了能够建立μ子加速器设施，我们需要减小μ子束的尺寸，以便它可以被加速。由于μ子在其自身的静止坐标系中在2微秒内衰减，因此在μ子衰减之前减小μ子束的相空间的唯一已知方法是使用电离冷却的概念，其中μ子在吸收剂（例如液氢或氢化锂（LiH））中损失能量，然后通过使用RF腔加速它们来恢复动量的纵向分量。国际μ子电离冷却实验（MICE）是电离冷却概念的工程演示。该实验正在卢瑟福阿普尔顿实验室进行，其中一束μ子将在一个μ子冷却室中冷却，该冷却室由三个吸收器和两个聚焦线圈磁铁场内的两个RF腔组成。在冷却通道之前和之后使用超导螺线管内的蒸发光纤跟踪器测量束的发射度，并且使用飞行时间探测器、切伦科夫探测器和由蒸发光纤铅预簇射探测器（命名为KL）和完全主动蒸发探测器（称为电子μ子Ranger（EMR））组成的量热计系统来识别μ子。在本提案中，我们的目标是进行测量的发射度减少，没有RF腔（MICE步骤IV），并进行最后的演示与RF腔的电离冷却。该提案是从2016年10月到2020年4月的42个月资助的投标，支持学术和学生在此期间的努力，以及从2016年12月结束的桥接支持结束时的研究人员。

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.