Parity-Violating Electron Scattering

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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.