Muon Science Laboratory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan.
Rep Prog Phys. 2012 Feb;75(2):026302. doi: 10.1088/0034-4885/75/2/026302. Epub 2012 Jan 27.
The Muon Science Establishment (MUSE) is one of the major experimental facilities, along with those for neutron, hadron and neutrino experiments, in J-PARC. It makes up a part of the Materials and Life Science Experiment Facility (MLF) that hosts a tandem neutron facility (JSNS) driven by a single proton beam. The facility consists of a superconducting solenoid (for pion confinement) with a modest-acceptance (about 45 mSr) injector of pions and muons obtained from a 20 mm thick edge-cooled stationary graphite target, delivering a 'surface muon' beam (μ(+)) and a 'decay muon' beam (μ(+)/μ(-)) for a wide variety of applications. It has recently been confirmed that the beamline has the world's highest muon intensity (∼10(6) μ(+)/s) at a proton beam power of 120 kW. The beamline is furnished with two experimental areas (D1 and D2) at the exit branches, where an apparatus for muon spin rotation/relaxation experiments (μSR) is currently installed at the D1 area while test experiments are conducted at the D2 area. In this paper, the current performance of the MUSE facility as a whole is reviewed. The facility is still in the early stage of development, including both beamlines and infrastructure for experiments, and plans for upgrading it are discussed together with perspectives for research works envisaged with unprecedented high-intensity muons.
缪子科学设施（MUSE）是日本质子加速器研究机构（J-PARC）中的主要实验设施之一，与中微子、中子和强子实验设施一起构成了材料与生命科学实验设施（MLF）的一部分。MLF 容纳了一个由单束质子驱动的串列中子设施（JSNS）。该设施由一个超导螺线管（用于介子约束）组成，具有适度的接收度（约 45 mSr），从中子源（20 毫米厚的边缘冷却固定石墨靶）中注入介子和缪子，提供用于各种应用的“表面缪子”束（μ(+)) 和“衰变缪子”束（μ(+)/μ(-))。最近证实，在 120kW 的质子束功率下，该束流线具有世界上最高的缪子强度（约 10(6) μ(+)/s）。该束流线在出口分支处配备了两个实验区（D1 和 D2），在 D1 区安装了用于缪子旋转/弛豫实验（μSR）的仪器，而在 D2 区则进行测试实验。本文综述了整个 MUSE 设施的当前性能。该设施仍处于发展的早期阶段，包括束流线和实验基础设施，同时还讨论了升级计划以及对利用前所未有的高强度缪子进行研究工作的展望。
