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: 2013085
• 负责人: Nilanga Liyanage
• 金额: $ 123.51万
• 依托单位: University of Virginia Main Campus
• 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 2025-02-28
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2013085&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.

核物理和粒子物理的一个中心目标是完全理解物质的基本成分以及它们相互作用的力。 在过去的50年里，粒子物理学的标准模型（SM）在描述已知基本粒子的相互作用方面已经证明是非常成功的。 然而，已知SM是不完整的，并且有令人信服的理由预期SM最终将无法描述物质的一些观察到的性质。 为了解决标准模型之外是否存在新物理的问题，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的合作实验中对电子的弱电荷进行精确测量。 电子的弱电荷是电子的公共电荷的弱力模拟，并且它在SM中被精确地预测。 测量结果与这一预测的任何偏差都将成为未发现现象的证据，这些现象代表了超出我们目前理解的新物理学。 该实验被命名为MOLLER，它包括一系列硬件设计和建设活动以及软件开发，这将为学生和年轻科学家提供良好的培训。在一家拥有最先进技术的现代科学合作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杰斐逊实验室MOLLER实验（轻子-轻子电弱反应测量）的基本设备的建设。莫勒将通过精确测量极化电子在非常低的动量转移下对非极化电子的弹性散射中的宇称违反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确定结果相媲美，为超出标准模型的物理场景提供出色的灵敏度。 MOLLER实验由三个主要的子系统组成：1）束/目标/光谱仪，用于准备要观察的散射Møller电子，2）测量原始宇称违反不对称性所需的统计精度的装置，以及3）归一化和系统控制装置，以实现亚ppb和亚%水平的系统不确定性和归一化控制目标。 本建议书中描述的合作项目将开发子系统#3;即MOLLER标准化和系统控制装置的设计、建造和测试。 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束流监测/控制和束流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知识价值和更广泛的影响审查标准进行评估，被认为值得支持。