Collaborative Research: Apparatus for Normalization and Systematic Control of the MOLLER Experiment

合作研究：莫勒实验标准化和系统控制装置

• 批准号: 2012232
• 负责人: Chandika Annasiwatta
• 金额: $ 14.45万
• 依托单位: Muskingum College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-03-01 至 2024-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2012232&HistoricalAwards=false
• 关键词: Collaborative; Research; Apparatus; Normalization; Systematic

A central goal of nuclear and particle physics is to obtain a complete understanding of the fundamental constituents of matter and the forces through which they interact. The Standard Model (SM) of particle physics has proven remarkably successful at describing the interactions of the known fundamental particles for the past 50 years. However, the SM is known to be incomplete, and there are compelling reasons to expect that the SM will eventually fail to describe some observed properties of matter. To address the question of whether there is new physics beyond the Standard Model, a precision measurement of the weak charge of the electron will be performed in a collaborative experiment at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia. The electron’s weak charge is the weak force analog of the common electric charge of the electron, and it is precisely predicted in the SM. Any deviation of the measurement from this prediction would be evidence for undiscovered phenomena that represent new physics beyond our current understanding. The experiment is named MOLLER and it comprises a range of hardware design and construction activities as well as software development which will provide excellent training for students and young scientists. The experience of working in a collaborative modern science enterprise with state of the art technology provides a strong basis for a variety of careers.The funds provided by this project will support construction of essential apparatus for the MOLLER experiment (Measurement of a Lepton-Lepton Electroweak Reaction) at Jefferson Lab. MOLLER will measure the electron’s neutral weak charge by making a precision measurement of the parity-violating asymmetry in the elastic scattering of polarized electrons on unpolarized electrons at very low momentum transfer. This will result in a determination of the weak mixing angle at low energy with a precision comparable to the best determinations from high energy colliders, providing excellent sensitivity to physics scenarios that extend beyond the Standard Model. The MOLLER experiment consists of three major subsystems: 1) the beam/target/spectrometer to prepare the scattered Møller electrons to be observed, 2) apparatus to measure the raw parity-violating asymmetry to the needed statistical precision, and 3) apparatus for Normalization and Systematic Control to achieve sub-ppb and sub-% level systematic uncertainty and normalization control goals. The collaborative project described in this proposal will develop subsystem #3; namely the design, construction, and testing of the MOLLER Normalization and Systematic Control apparatus. The work will be done over the period December 2020 – November 2024. This includes the tracking system, background detectors, auxiliary asymmetry measurement detectors, and certain aspects of beam monitoring/control and beam polarimetry.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

核物理和粒子物理学的一个中心目标是全面了解物质的基本组成及其相互作用的作用力。在过去的50年里，粒子物理的标准模型(SM)在描述已知基本粒子之间的相互作用方面已被证明是非常成功的。然而，人们知道SM是不完整的，而且有令人信服的理由期待SM最终无法描述物质的一些观察到的属性。为了解决在标准模型之外是否存在新的物理问题，将在弗吉尼亚州纽波特纽斯的托马斯·杰斐逊国家加速器设施进行一项合作实验，对电子的弱电荷进行精确测量。电子的弱电荷是电子的普通电荷的弱力模拟，它在SM中得到了精确的预测。测量结果与这一预测的任何偏差都将是尚未发现的现象的证据，这些现象代表了超出我们目前理解的新物理。该实验被命名为穆勒，它包括一系列硬件设计和建造活动以及软件开发，这将为学生和年轻科学家提供极好的培训。在拥有最先进技术的协作现代科学企业工作的经验为各种职业提供了坚实的基础。该项目提供的资金将支持在杰斐逊实验室建造穆勒实验(利普顿-利普顿电弱反应的测量)的基本仪器。穆勒将通过精确测量极化电子与非极化电子在极低动量转移下的弹性散射中违反宇称的不对称性，来测量电子的中性弱电荷。这将导致在低能量下确定弱混合角，其精度可与高能对撞机的最佳测定相媲美，从而对超出标准模型的物理场景提供极好的敏感性。穆勒实验由三个主要的子系统组成：1)束流/靶/能谱仪，用于准备要观测的散射的穆勒电子；2)装置，用于测量原始的宇称破坏不对称性，达到所需的统计精度；3)归一化和系统控制装置，以实现亚ppb和亚%级别的系统不确定度和归一化控制目标。本建议书中描述的合作项目将开发子系统#3；即设计、建造和测试穆勒标准化和系统控制装置。这项工作将在2020年12月至2024年11月期间完成。这包括跟踪系统、背景探测器、辅助不对称测量探测器，以及光束监测/控制和光束偏振测量的某些方面。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。