Measurements of the Neutron Magnetic Form Factor and the Two-Photon Exchange Contribution to the Electron-Neutron Elastic Scattering Cross Section 461 views

The Super BigBite Spectrometer (SBS) program in Experimental Hall A of Jefferson Lab is a series of high-precision, large Q-squared, electromagnetic form factor experiments. GMn and nTPE were the first two experiments of the SBS program and ran from October 2021 through February 2022. Both experiments detect neutron-tagged d(e,e'n) and proton-tagged d(e,e'p) quasi-elastic electrons scattering from a deuterium target. The GMn experiment is a measurement of the magnetic form factor of the neutron, GMn, via the ratio method over a Q-squared range of 3.5 to 13.5 (GeV/c)^(2). The nTPE experiment ran in-parallel with the GMn experiment and shared an overlapping kinematic point with GMn. nTPE extends the GMn experiment to assess the differences between Rosenbluth Slop and the single-photon exchange approximation. The nTPE experiment had two kinematic settings corresponding to different electron scatting angles at a fixed Q-squared values of 4.5 (GeV/c)^(2). Comparisons of nucleon form factor ratio measurements acquired through polarization transfer and LT separation reveal discrepancies as Q-squared increases. Two-photon exchange is strongly favored as the reason for this discrepancy. GMn has been extracted at two kinematic settings corresponding to Q-squared values of 3.0 and 4.5 (GeV/c)^(2). Additionally, I will present an assessment of the differences between Rosenbluth Separation and single-photon exchange measurements.

PHD (Doctor of Philosophy)

Electromagnetic form factors; Form Factors; EMFF; Super BigBite Spectrometer; SBS; Jefferson Lab; Thomas Jefferson National Accelerator Facility; JLab; Hall A; Experimental Hall A; GMn; gmn; nTPE; ntpe; form factors; magnetic form factor; neutron magnetic form factor; neutron electric form factor; GEn; magnetic form factor of the neutron; form factor ratio problem; form factor ratio puzzle; Rosenbluth Slope; Rosenbluth Separation; Rosenbluth Technique; LT Separation; Polarization transfer; Ratio Method; Durand Technique; Standard Model; physics; nucleon structure; nuclear physics; experimental nuclear physics; proton; neutron; electron; electron beam; electron scattering; electron-nucleon scattering; electron-proton scattering; electron-neutron scattering; single photon exchange; single-photon exchange; two photon exchange; two-photon exchange; the; TPE; GEM; GEM detector; GEM detectors; GEM R&D; GEMs; Gas Electron Multiplier; Gas electron multipliers; radiation; radiation detector; radiation detectors; quasi-elastic electron scattering; Electromagnetic Form Factor; form factor

English

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2024-05-02