A Compact Pair Polarimeter and Spectrometer

紧凑型旋光仪和光谱仪对

• 批准号: ST/P002935/1
• 负责人: Kenneth Livingston
• 金额: $ 31.12万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 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=ST%2FP002935%2F1
• 关键词: Compact; Pair; Polarimeter; Spectrometer

The measurement of polarisation ovservables in hadron physics can provide detailed information about the excited stated of baryons and mesons. A programme of such measurements has been running at the world's major photon beam facilities for several years and has already produced execellent, and well publicised, results. These experiments require highly polarised beams and targets with precisely known properties. In particular, for linearly polarised photon beams, the degree of polarisation needs to be known with as much precision as possible. Recent improvements in luminosity and data taking rates have meant that is often the limiting systematic error in an experiment. This proposal aims to solve the problem by developing a new polarimiter which will be capable of measuring the degree of linear polarisation to better that 2% systematic error, by measuring the asymmetry in the orientation of e+e- pairs produced as the photon passes through a thin converter foil. The design is a compact, modular system based on Halbach dipole cylinders (permanent magnets) and TimePix3 pixel detectors. It is low cost, with minimal readout infrastructure and can be configured for any of the current photon beam facilities (MAMI in Mainz, ELSA in Bonn and CLAS and GlueX in Jefferson Lab, Virginia).

强子物理学中偏振可观测量的测量可以提供有关重子和介子激发态的详细信息。此类测量计划已在世界主要光子束设施运行多年，并已产生了出色且广为人知的结果。这些实验需要高度偏振的光束和具有精确已知特性的目标。特别是，对于线偏振光子束，需要尽可能精确地了解偏振度。最近亮度和数据采集率的改进意味着这通常是实验中的限制系统误差。该提案旨在通过开发一种新的偏振器来解决这个问题，该偏振器能够通过测量光子穿过薄转换器箔时产生的 e+e- 对的方向不对称性来测量线性偏振度，系统误差优于 2%。该设计是一个紧凑的模块化系统，基于 Halbach 偶极圆柱体（永磁体）和 TimePix3 像素探测器。它成本低廉，具有最少的读出基础设施，并且可以针对任何当前的光子束设施（美因茨的 MAMI、波恩的 ELSA 以及弗吉尼亚州杰斐逊实验室的 CLAS 和 GlueX）进行配置。