Construction of a Beam Test Prototype of the Hyper-K Water Cherenkov Detector to Control Systematic Errors for Leptonic CP Violation Measurements

为了达到Hyper-K实验的完全灵敏度，有必要将系统不确定度控制在2%或更小的水平。系统误差的主要来源是水切伦科夫探测器的建模、中微子-原子核相互作用的建模和中微子产生的建模。加拿大合作者提出了一个1千吨尺度的水切伦科夫探测器，即J-PARC E61 （NuPRISM）探测器，该探测器位于距离J-PARC中微子源1公里的地方，用于测量Hyper-K中微子-核相互作用的关键特征。为了使Hyper-K的系统误差达到2%，有必要将Hyper-K和E61都校准到1%的水平。在这里，我们提出了一个30吨的水切伦科夫实验，放置在费米实验室测试束设备（FTFB）中，粒子动量范围为100 MeV/c至1200 MeV/c。该实验将为Hyper-K和E61中部署的校准系统和光电传感器提供一个测试平台。在已知粒子类型、能量和轨迹的光束下，可以对探测器进行1%水平的校准测试，并根据需要对校准系统进行改进。此外，我们将为已经在FTBF中运行的强调强子生产实验做出贡献，该实验将测量强子相互作用过程，为Hyper-K计划提供精确的中微子通量计算所必需的。*** FTFB的试验光束计划将与日本、美国、英国、波兰和意大利进行国际合作。加拿大的贡献是开发、测试和制造光敏传感器。由加拿大合作开发的光电传感器是一个高分辨率多pmt（光电倍增管）模块，由19个直径为3英寸的快速pmt组成，安装在一个耐压容器中。pmt通过丙烯酸窗口查看检测器，容器中包含高压和读出电子电路。多pmt模块的第一个原型，包括丙烯酸穹顶、容器和电子设备，正在使用现有的2018财年RTI拨款，在2018/2019年进行组装和测试。在这里，我们建议完善多pmt的设计，以实现生产就绪的设计，并构建30个多pmt模块用于测试光束实验。***同时，这笔拨款将支持对着重强子产生实验的贡献，该实验将表征强子-核相互作用过程，这是精确计算中微子产生所必需的。强调是日本，美国和加拿大之间的国际合作，每个国家提供子探测器。气凝胶环成像切伦科夫探测器的设计由TRIUMF和温尼伯大学共同开发，并将在这笔拨款下建造。该探测器将提供向前方向的粒子识别，动量高达8 GeV/c。**

To achieve the full sensitivity of the Hyper-K experiment, it is necessary to control systematic uncertainties to the level of 2% or less. The primary sources of systematic error are on the modeling of the water Cherenkov detector, the modeling of the neutrino-nucleus interactions, and the modeling of neutrino production. Canadian collaborators have proposed a 1-kiloton scale water Cherenkov detector, the J-PARC E61 (NuPRISM) detector, located 1 km from the neutrino source at J-PARC to measure critical features of neutrino-nucleus interactions for Hyper-K. To achieve 2% systematic errors for Hyper-K, it is necessary to calibrate both Hyper-K and E61 to the level of 1%. Here, we propose a 30-ton water Cherenkov experiment to be placed in the Fermilab Test Beam Facility (FTFB) with particle momenta ranging from 100 MeV/c to 1200 MeV/c. This experiment will provide a test-bed for the calibration systems and photosensors that will be deployed in Hyper-K and E61. With a beam of known particle type, energy and trajectory, the calibration of the detector to the 1% level can be tested and improvements to the calibration systems can be made as necessary. Additionally, we will contribute to the EMPHATIC hadron production experiment already running in the FTBF, that will measure hadronic interaction processes that are necessary to provide the precise neutrino flux calculations necessary for the Hyper-K program.***The test beam program in the FTFB will be carried out as an international collaboration with Japan, the United States, the United Kingdom, Poland and Italy. The Canadian contribution is the development, testing and contruction of photosensors. The photosensor, developed by the Canadian collaboration, is a high resolution multi-PMT (photomultiplier tube) module that consists of 19 3 inch diameter fast PMTs in a pressure tolerant vessel. The PMTs view the detector through an acrylic window, and high voltage and readout electronics circuits are contained in the vessel. The first prototypes of the multi-PMT module, including the acrylic dome, vessel and electronics are being assembled and tested in 2018/2019 using an existing FY2018 RTI grant. Here, we propose to refine the design of the multi-PMT to achieve a production-ready design and build 30 of the multi-PMT modules for deployment in the test beam experiment.***In parallel, this grant will support the contribution to the EMPHATIC hadron production experiment that will characterize the hadron-nucleus interaction processes that are necessary to make precision calculations of neutrino production. EMPHATIC is an interantional collaboration between Japan, the United States and Canada, with each country providing sub-detectors. The design for an aerogel ring imaging Cherenkov detector has been developed by TRIUMF and University of Winnipeg and it will be built under this grant. This detector will provide particle identification in the forward direction for momenta up to 8 GeV/c.**