Spin Structure Functions of the Deuteron Measured with CLAS in and above the Resonance Region

Abstract

Spin structure functions of the nucleon in the region of large x and small to moderate Q2 continue to be of high current interest. The first moment of the spin structure function g1, γ1, goes through a rapid transition from the photon point (Q2=0), where it is constrained by the Gerasimov-Drell-Hearn sum rule, to the deep inelastic limit where it is sensitive to the nucleon spin fraction carried by quarks. The interesting behavior in the transition region is dominated by baryon resonance excitations. We concluded an experiment to measure these observables for deuterium as part of the ''EG1'' run group in Jefferson Lab's Hall B. We used a highly polarized electron beam with energies from 1.6 GeV to 5.7 GeV and a cryogenic polarized ND3 target together with the CEBAF Large Acceptance Spectrometer (CLAS) to accumulate over 11 billion events. In this thesis, we present results for the spin structure function g$d\atop{1}$ (x,Q2), as well as its first moment, γ$d\atop{1}$(Q2) in and above the resonance region over a Q2 range from 0.05 to 5 Gev2, based on the data taken with beam energies of 1.6 and 5.7 GeV. We also extract the behavior of A$d\atop{1}$(x) at large x. Our data are consistent with the Hyperfine-perturbed quark model calculation which predicts that A$d\atop{1}$ (x → 1) → 1. We also see evidence for duality in g$d\atop{1}$ (x, Q2) at Q2 > GeV2.