中国极化电子离子对撞机(EicC)物理及探测器设计研究

Physics and detector design of polarized Electron Ion Collider in China(EicC)

核子(质子和中子的总称)大约占宇宙中可见物质总质量的99%.作为构成宇宙可见物质中的最主要成分,核子也是研究强相互作用,尤其是禁闭区非微扰QCD的重要实验室.电子离子对撞机(Electron Ion Collider, EIC),被称作当代卢瑟福散射实验,是人类认识物质世界深层次结构,特别是核子与原子核结构的理想工具.中国极化电子离子对撞机项目设想在已开建的HIAF高能离子束的基础上升级建造中国电子-离子对撞机(EIC in China,EicC),为我国核物理与粒子物理以及相关科学领域提供大型综合实验平台.本文综述了EicC在核子内不同味道海夸克的一维自旋味道结构、横动量依赖部分子分布函数、广义部分子分布函数测量的理论和模拟研究,展示了EicC在以上测量中可达到的预期精度,以及与现有测量精度的对比.另外,本文也综述了EicC在质子质量起源、重味强子谱、核介质效应及π介子的内部结构等重要物理问题中的潜在贡献,以及EicC探测器概念设计.EicC装置将有力地促进人们对核子自旋和质量的起源、夸克胶子禁闭机制等基本问题的理解.

The innermost exploration regime of visible matter involves the nucleon structure. High-energy electron-nucleon scattering, regarded as a modern "Rutherford" experiment, is an ideal platform to conduct investigations of the nucleon structure, which improves our understanding of matter and aids the common interests of nuclear and particle physicists.Electron Ion Colliders(EICs) are super electron microscopes that can take clear images of the inner structure of a nucleon;hence, they are effective tools for gaining insights into the fundamental constituents of matter, e.g., structures of a nucleon and nuclei. An Electron Ion Collider in China(EicC) project is proposed for the heavy ion analytical facility.This project will provide a large integrated experimental platform to propel the development of nuclear and particle physics and other relevant fields in China. The energy of an EicC is confined in the region where the contributions of seaquarks are dominant. However, this region is well suited for the study of the origin of the nucleon mass and its 3 D structure. Additionally, it can fill the gap between the energy regions of current electron scattering experiments and future EIC(for instance, in the US). In this study, we review the rich physics highlights of EicC, including the precise measurements of 1 D and 3 D sea-quark structures, such as TMDs and GPDs. Comparisons of the projected EicC precision with current data are presented. Moreover, this work reviews the significance of EicC for the study of the origin of proton mass, nuclear medium effects, π-structure functions, and the first conceptual design of an EicC detector. The EicC facility will promote our understanding of many fundamental questions including the origin of proton spin and mass and mechanism of quark-gluon confinement.