Investigations in Intermediate Energy Spin Physics

North Carolina Agricultural & Technical State University, Greensboro NC

Investigators

Abstract

The NC A&T State University Nuclear Physics group is contributing to three major experiments at Jefferson Laboratory: 1) The SANE experiment, E07-003; 2) experiment E-07-011, ?A High Precision Measurement of the Deuteron Spin-Structure Function g1d/F1d?; and 3) the experiment E05-101, ?Initial State Helicity Correlation in Wide Angle Compton Scattering? RCS. All three experiments explore the spin structure functions of proton and deuterium. The SANE experiment measures inclusive spin asymmetries on the proton at large x, where valence quarks dominate and hence a relatively clean region to study the spin structure of the nucleon. The measured spin observables are fundamental for understanding QCD in that region. QCD is the quantum field theory that describes the properties of the strong interactions between quarks and between protons and neutrons in the framework of the quantum theory. The RCS experiment will measure, the initial state helicity correlation asymmetry in real Compton scattering to a statistical accuracy of 0.1. Compton Scattering is when gamma ray photons of a certain energy will bounce off electrons as they pass through matter, and see their energy decrease. The measurement will significantly increase our confidence in the application of the generalized parton distributions (GPD) approach to reactions induced by real photons. The GPD's extend the well-known Feynman parton distribution and electromagnetic form factors of the nucleon to new kinematic dimensions. In the forward limit, these distributions reduce to the Feynman parton distributions. On the other hand, the first moment of GPD's give the electromagnetic form factors. In general, the GPD's contain much richer structural information of the nucleon than conventional observables. All three experiments will be conducted in Hall C, and will use the same experimental setup. The NC A&T group has built and is in charge of the Lucite Hodoscope, a major component of the experimental setup. The group is also building the quartz hodoscope for the SuperHMS spectrometer needed for the Hall C 12 GeV upgrade in Hall C. North Carolina A&T State University is a historically black university (HBCU). The proposed research program will provide our students with unique research opportunities in experimental nuclear physics, and therefore will have a strong impact on their training and education. The program will allow them to work in a state-of-the-art facility and interact with scientists from other nationally recognized universities. In this respect this proposal can be very effective in attracting African Americans and other underrepresented groups to advanced degrees in physics and engineering and therefore will contribute to greater diversity in the field of nuclear physics.