The Proton Spin Structure Function g2 at Low Q2 and Applications of Polarized 3He

Since the Stern-Gerlach experiment in 1922, spin has had major implications on practically almost all areas of modern physics. Quantum chromodynamics (QCD) is the fundamental theory that describes strong interaction in terms of quark and gluon degrees of freedom. While QCD has been well tested in the high-energy regime, it is still unsolved in the low-energy, non-perturbative regime. With developments in polarized beam and polarized target technologies, spin offers a unique tool to probe the internal structure of nucleons and non-perturbative QCD dynamics. The polarization techniques developed for these fundamental nuclear physics study also bring new impulses to the idea of polarized fusion, in which spin-polarized deuterium and tritium (D-T) fuel in a tokamak reactor would provide a boost to the fusion rate.

This thesis consists of three topics based on spin physics. The first topic is the Jefferson Lab (JLab) Hall A E08-027 (g2p) experiment performed with the polarized electron beam scattering off a polarized ammonia target to obtain the proton spin-dependent structure function g2 in the low momentum transfer region (0.02 < Q2 < 0.2 GeV2). The measured data will provide a benchmark test of Chiral Perturbation Theory calculations in the non-perturbative region by extracting the generalized longitudinal-transverse polarizability, and help test the Burkhardt-Cottingham Sum Rule at low Q2. This thesis will discuss the physics motivation, data analysis, and preliminary results from the E08-027 experiment in Chapters 2-5. The second topic is focused on the JLab polarized 3He target, which is essential for the neutron spin structure study. Progress on the upgrade of this target for the JLab 12 GeV program will be presented in Chapter 6. The final topic is an application of such polarization techniques in thermonuclear fusion. A direct test of spin-polarized fusion was proposed for the DIII-D tokamak in San Diego using the isospin mirror reaction D-3He. Preliminary results on the polarized 3He performance in inertial confinement fusion (ICF) polymer pellets will be presented in Chapter 7.