Date Awarded


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Doctor of Philosophy (Ph.D.)




The scattering of polarized electrons from a polarized proton target provides a means for studying the internal spin structure of the proton. The CLAS (CEBAF Large Acceptance Spectrometer) EG1b experiment in Hall-B at Jefferson Laboratory measured double-spin inclusive and exclusive electron-nucleon scattering asymmetries using longitudinally polarized frozen NH3 and ND3 targets and a longitudinally polarized electron beam at 4 different energies (1.6, 2.5, 4.2, 5.6 GeV). Extraction of the virtual photon asymmetry Ap1 (for 0.05 GeV2 < Q2 < 5.0 GeV2) provides precision measurements of the polarized proton spin-structure function gp1 in and above the resonance region. Linear regression of data between the varying energies yields new constraints on the virtual photon asymmetry Ap2 (and thus the structure function gp2 ) in the resonance region (for 0.3 GeV2 < Q2 < 1.0 GeV2). Measurements of these structure functions and their moments allows testing of perturbative Quantum Chromodynamics (pQCD) models and evaluation of moments of the structure functions in the Operator Product Expansion. Testing of Chiral Perturbation Theory (chiPT) at Q2 < 0.2 GeV 2 is enabled by the new data. Other applications of polarized structure functions include measurement of foward-spin polarizability, evaluation of high-order corrections in 1H hyperfine splitting, and testing of quark-hadron duality.



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