Hyper-K One-Year Pre-Construction Extension

超级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。它将作为为升级后的J-PARC（日本质子加速器研究中心）中微子束计划进行的长基线中微子振荡实验的远端探测器，以及能够观察质子衰变、大气中微子和来自天文起源的中微子的探测器，使测量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？物质反物质不对称的起源是什么？物理定律在极端情况下是如何起作用的？(D1)。因为长基线中微子实验能够解决这些问题，所以它是中微子stfc路线图的最高优先级。此外，该项目也与欧洲战略完全一致，该战略认识到它的重要性：中微子振荡物理学的快速发展，在欧洲的大力参与下，为探索中微子部门CP违和和质量层次的长基线中微子计划建立了强有力的科学依据。欧洲核子研究中心应该制定一个中微子计划，为欧洲在未来的长基线实验中发挥重要作用铺平道路。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.