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# Towards a Precision Measurement of Parity-Violating e-p Elastic Scattering at Low Momentum Transfer

 dc.contributor.supervisor Martin, Jeffrey (Physics and Astronomy) en_US dc.contributor.author Pan, Jie dc.date.accessioned 2012-07-27T17:16:05Z dc.date.available 2012-07-27T17:16:05Z dc.date.issued 2012-07-27 dc.identifier.uri http://hdl.handle.net/1993/8124 dc.description.abstract The goal of the Q-weak experiment is to make a measurement of the proton's weak charge ($Q^p_W = 1-4\sin^2\theta_W$) to an accuracy of ~4%. This would represent a ~0.3% determination of the weak mixing angle ($\sin^2\theta_W$) at low energy. The measurement may be used for a precision test of the Standard Model (SM) prediction on the running of $\sin^2\theta_W$ with energy scale. The Q-weak experiment operates at Thomas Jefferson National Accelerator Facility (Jefferson Lab). The experiment determines the proton's weak charge by measuring the parity violating asymmetry in elastic electron-proton scattering at low momentum transfer $Q^2 = 0.026 (GeV/c)^2$ and forward angles (~8 degree). The anticipated size of the asymmetry, based on the SM, is about 230 parts per billion (ppb). With the proposed accuracy, the experiment may probe new physics beyond Standard Model at the TeV scale. This thesis focuses on my contributions to the experiment, including track reconstruction for momentum transfer determination of the scattering process, and the focal plane scanner, a detector I designed and built to measure the flux profile of scattered electrons on the focal plane of the Q-weak spectrometer to assist in the extrapolation of low beam current tracking results to high beam current. Preliminary results from the commissioning and the first run period of the Q-weak experiment are reported and discussed. en_US dc.subject Electroweak en_US dc.subject Standard Model en_US dc.subject Weak Charge en_US dc.subject Weak Mixing Angle en_US dc.subject Track Reconstruction en_US dc.subject Momentum Transfer en_US dc.subject e-p Scattering en_US dc.subject Parity Violation en_US dc.subject Scanner Detector en_US dc.subject Flux Profile Image en_US dc.subject Parity Violating Asymmetry en_US dc.subject Cerenkov en_US dc.title Towards a Precision Measurement of Parity-Violating e-p Elastic Scattering at Low Momentum Transfer en_US dc.degree.discipline Physics and Astronomy en_US dc.contributor.examiningcommittee Birchall, James (Physics and Astronomy) Goltz, Douglas (Chemistry) Page, Shelley (Physics and Astronomy) Hornidge, David (Physics, Mount Allison University) en_US dc.degree.level Doctor of Philosophy (Ph.D.) en_US dc.description.note October 2012 en_US
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