Parity-Violating Electron Scattering

亚原子物理学的一个中心目标是全面了解物质的基本“构建块”，以及它们如何相互作用。自近50年前提出以来，核物理和粒子物理的“标准模型”取得了显著的成功，使我们能够描述大量的物理现象。然而，我们知道它是不完整的，有令人信服的理由认为标准模型最终会崩溃，无法描述物质的某些特性。使用电子加速器的精密测量为检验粒子物理学的标准模型和寻找新的物理学提供了机会。位于弗吉尼亚州纽波特纽斯的托马斯·杰斐逊国家加速器设施（杰斐逊实验室）是目前世界领先的实验室，可以通过电子散射实验对标准模型进行精确测试。该项目将支持在托马斯·杰斐逊国家加速器设施（杰斐逊实验室）的大型合作实验（MOLLER）中精确确定电子的弱电荷。粒子物理标准模型的电弱部分的基本参数电弱混合角在标准模型中以能量尺度“运行”，并且将测量值与预测运行进行比较，可以灵敏地搜索标准模型之外的物理。PI将在MOLLER实验的轨道重建探测器和软件的开发中发挥主导作用，并且还负责测量电子和光产生的介子的背景的探测系统。该小组还将通过在PREx-II和CREx实验中使用违反宇称的电子散射来测量208Pb和48Ca两种核素的中子分布半径。该项目将训练本科生、研究生和博士后掌握精确核物理技术和分析大型复杂数据集。该奖项反映了美国国家科学基金会的法定使命，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。

A central goal of subatomic physics is to gain a comprehensive understanding of the basic "building blocks" of matter, and how they interact with each other. Since its formulation nearly five decades ago, the “Standard Model” of nuclear and particle physics has been remarkably successful and allows us to describe a vast range of physical phenomena. It is known, however, to be incomplete, and there are compelling reasons to expect that the Standard Model will eventually break down and fail to describe some properties of matter.Precision measurements using electron accelerators present an opportunity to test the Standard Model of particle physics and to search for new physics. The Thomas Jefferson National Accelerator Facility (Jefferson Lab) in Newport News, Virginia is currently the world's leading laboratory enabling precision tests of the Standard Model through electron scattering experiments.This project will support an effort to precisely determine the weak charge of the electron in a large collaborative experiment, known as MOLLER, at the Thomas Jefferson National Accelerator Facility (Jefferson Lab). The electroweak mixing angle, a fundamental parameter of the electroweak sector of the standard model of particle physics 'runs' with energy scale in the standard model, and comparison of the measured value with the predicted running allows a sensitive search for physics beyond the standard model.The PI will take a leading role in the development of the track reconstruction detectors and software for the MOLLER experiment, and is also responsible for a detection system to measure the background from electro- and photo-produced pions. The group will also contribute to measurements of the radius of the neutron distribution in two nuclides, 208Pb and 48Ca, through the use of parity-violating electron scattering in the PREx-II and CREx experiments. The project will serve to train undergraduate, graduate and postdoctoral students in the techniques of precision nuclear physics and in the analysis of large and complex data sets.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.