RUI: Studies of Nucleon Structure Using Electromagnetic Probes at Jefferson Lab

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It is now a well-established fact that nucleons, protons and neutrons, are made up of more elementary particles called quarks. The main physics program supported by this grant aims to study of the structure of the proton. More specifically, we scatter electrons from protons at Jefferson Laboratory to measure the electric and magnetic properties of the proton. Our group is involved in these efforts through the design of new experiments, the construction of advanced particle detectors, and the development of novel analysis and modeling software. We involve students by providing meaningful, substantive projects to both undergraduate and graduate students. Our group's long established program of experiments embody Jefferson Lab's primary mission: to elucidate the underlying structure of protons, neutrons, and mesons. We focus on experiments which will further our understanding of the quark spin structure of the proton in the non-perturbative regime. Jefferson Lab has recently completed an upgrade to electron beams of energy 12 GeV, and our group is now poised to take advantage of the increased physics reach. We continue to lead the efforts to extend the measurement of the proton electromagnetic form factor ratio to the highest momentum transfers possible at Jefferson Lab, and also investigate the possible modification of this form factor ratio within the nuclear medium. These experiments will provide severe tests of the available theoretical models of proton structure, and will serve as a strong impetus for the development of more advanced models based upon quantum chromodynamics (QCD).