Measurement of deep exclusive meson-production in electron scattering off a neutron using CLAS12 at Jefferson Lab

杰斐逊实验室使用 CLAS12 测量中子电子散射中的深层排他介子产生

• 批准号: 2126391
• 金额: --
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2126391
• 关键词: Measurement; deep; exclusive; meson; production

The project is the study of nucleon structure through the experimental measurement of meson electro-production from the neutron. The experiment, run by the CLAS collaboration, will take place in Hall B of Jefferson Lab, USA, in 2019. It will use the lab's 10.6 GeV polarised electron beam, the CLAS12 detectors and a fixed deuterium target.Deep exclusive meson-production is a process in which a high energy electron scatters from the partons (at the energies available in this experiment they are valence quarks) inside the nucleon, and a high-momentum meson is produced as a result. Analysis of the cross-sections and asymmetries due to different polarisation states of the beam or target carry information about spatial and momentum distributions of the partons in the nucleon. Specifically, deeply virtual meson production yields information on Generalised Parton Distributions (GPDs), which correlate longitudinal parton momentum to their transverse position. As such, determination of GPDs enables 3D, tomographic imaging of the nucleon. GPDs also carry information on the composition of nucleon spin (unknown, beyond the fraction contributed by the intrinsic spin of quarks). The GPDs have recently also been linked to pressure distributions within the nucleon, opening an entirely new way of studying nucleon structure.The project will most likely focus on the analysis of beam-spin asymmetry in the deeply virtual production of neutral pions from the neutron. The production of a negative pion from the neutron is also under consideration (with the recoiling nucleon being a proton in this case). The student project will involve data-taking at Jefferson Lab, calibration of the Central Neutron Detector and analysis of the data for the extraction of the observable(s). The aim is a publication towards the end of the thesis project. ClassificationsType of activityAssign % relevance (in multiples of 5) to the activities listed, totalling 100%:- Exploitation and experiment %100- Investment in new instrumentation, facilities or techniques- Operation & maintenance of facilities- TheoryStudent classificationPlease select one of the following options to indicate the overall classification of the student:- Astronomy- Nuclear Physics. X- Particle Astrophysics

该项目是通过实验测量中子电生介子来研究核子结构。该实验由CLAS合作组织负责，将于2019年在美国杰斐逊实验室的B厅进行。它将使用实验室的10.6 GeV极化电子束、CLAS 12探测器和一个固定的氘靶。深排介子产生是一个高能电子从核子内部的部分子（在这个实验中可用的能量下，它们是价夸克）散射的过程，结果产生一个高动量介子。由于束或靶的不同偏振态，对截面和不对称性的分析携带了关于核子中部分子的空间和动量分布的信息。具体来说，深虚介子生产产生的广义部分子分布（GPD），纵向部分子动量与它们的横向位置相关的信息。因此，GPD的确定使得能够对核子进行3D断层成像。GPD还携带关于核子自旋组成的信息（未知，超出夸克的内禀自旋所贡献的部分）。GPD最近也与核子内的压力分布联系起来，为研究核子结构开辟了一条全新的途径。该项目很可能将重点放在分析中子深度虚拟产生中性π介子过程中的束自旋不对称性。从中子产生负π介子也在考虑之中（在这种情况下反冲的核子是质子）。学生的项目将涉及在杰斐逊实验室的数据采集，中央中子探测器的校准和数据的分析，以提取可观察到的（S）。目标是在论文项目结束时出版。分类活动类型分配百分比相关性（5的倍数）到所列的活动，总计100%：-开发和实验%100-投资于新仪器，设施或技术-设施的操作和维护-理论学生分类请选择以下选项之一，以表明学生的整体分类：-天文学-核物理学。X粒子天体物理学