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“构件”，以及它们如何相互作用。自近50年前形成以来，核物理和粒子物理的“标准模型”取得了巨大的成功，使我们能够描述广泛的物理现象。然而，众所周知，它是不完整的，有令人信服的理由期待标准模型最终会崩溃，无法描述物质的某些性质。使用电子加速器进行精确测量为检验粒子物理的标准模型和寻找新的物理提供了机会。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)目前是世界领先的实验室，能够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)的大型合作实验中精确确定电子弱电荷的努力。电弱混合角是粒子物理标准模型中电弱部分的一个基本参数，它与标准模型中的能量尺度一起运行，并将测量值与预测运行进行比较，从而允许对标准模型之外的物理进行灵敏的搜索。PI将在莫勒实验的径迹重建探测器和软件的开发中发挥主导作用，并负责一个探测系统，以测量来自电子和光生电子的背景。该小组还将通过在Prex-II和CRIX实验中使用违反宇称的电子散射，为测量两种核素-208Pb和48Ca中的中子分布半径做出贡献。该项目将用于培训本科生、研究生和博士后在精密核物理技术以及大型和复杂数据集的分析方面。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。

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.