Hyper-K One-Year Pre-Construction Extension

超神冈实验是研究中微子振荡、核子衰变和天体物理中微子的下一代旗舰实验。该探测器是第三代地下水切伦科夫探测器。它将作为计划用于升级的J-PARC(日本质子加速器研究综合体)中微束的长基线中微子振荡实验的远探测器，以及一个能够观测质子衰变、大气中微子和来自天文学来源的中微子的探测器，使测量能够远远超过目前世界上最好的测量。拟议的活动解决了STFC路线图1中的核心科学问题：什么是基本粒子？(C1)，是否有统一的框架？(C3)物质反不对称性的起源是什么？(C7)当被推向极端时，物理定律是如何发挥作用的？(D1)。由于长基线中微子实验能够解决这些问题，它是中微子空间研究中心路线图的最优先事项。此外，该项目也与认识到其重要性的欧洲战略完全一致[2]：在欧洲的大力参与下，中微子振荡物理方面的快速进展为探索CP破坏和中微子部门的质量等级的长基线中微子方案建立了强有力的科学依据。欧洲核子研究中心应该制定一项中微子计划，为欧洲在未来的长期基线实验中扮演实质性的角色铺平道路。欧洲应该探索主要参与美国和日本领先的长基线中微子项目的可能性。

The Hyper-Kamiokande experiment is the next generation flagship experiment for thestudy of neutrino oscillations, nucleon decays, and astrophysical neutrinos. The detector is a third generationunderground water Cherenkov detector. It will serve as the far detector for a long baseline neutrino oscilla-tion experiment planned for the upgraded J-PARC (Japan Proton Accelerator Research Complex) neutrinobeam as well as a detector capable of observing proton decays, atmospheric neutrinos, and neutrinos fromastronomical origins enabling measurements that far exceed the current world best measurements.The proposed activities address the core scientific questions in STFC's roadmap 1 : What are the fun-damental particles? (C1), Is there a unified framework? (C3) What is the origin of the matter anti-matterasymmetry? (C7) How do the laws of physics work when driven to the extremes? (D1). Because the longbaseline neutrino experiment is capable of addressing these questions it is the highest priority of the neutrinoSTFC roadmap. Furthermore, this project is also perfectly aligned with the European Strategy which recog-nises it importance [2]: Rapid progress in neutrino oscillation physics, with significant European involvement,has established a strong scientific case for a long-baseline neutrino programme exploring CP violation andthe mass hierarchy in the neutrino sector. CERN should develop a neutrino programme to pave the way for asubstantial European role in future long-baseline experiments. Europe should explore the possibility of majorparticipation in leading long-baseline neutrino projects in the US and Japan.