The experiments discussed in this thesis exploit parity violation in elastic electron proton scattering in order to measure properties of the nucleon. Both experiments make use of the high quality, highly polarized electron beam available at Thomas Jefferson National Accelerator Facility. Q_weak will measure the weak mixing angle, sin²θ_W, via a measurement of the weak charge of the proton, at a four-momentum transfer, Q² ~ 0.026 GeV²/c². The precision of this measurement gives Q_weak access to new physics at the scale of 2.3 TeV, making it a test of the standard model. The G⁰ experimental program provides the fully separated contributions of the strange quark to the charge and magnetization distributions of the nucleon at two different values of four-momentum transfer, Q² ~ 0.22 and 0.63 GeV²/c². The measurement of the strange quark content of the proton in the G⁰ experimental program and other parity-violating electron scattering experiments provides a measurement of the hadronic contribution to the asymmetry in Q_weak. In addition, G⁰ was able to measure the parity-conserving beam normal single spin asymmetries that provide a measurement of the imaginary part of two photon exchange. The measurement of this asymmetry is necessary to understand the systematic contribution to measurements of parity-violating asymmetries, but it is also an important physics result. Recent theoretical work has shown that higher order radiative effects, such as two photon exchange, may be able to explain discrepancies between experiments which measure the ratio of the electric and magnetic form factors of the proton. The measurement of the transverse or beam normal single spin asymmetries provides a benchmark for theories that estimate the size of radiative corrections that are important for precision electroweak scattering experiments such as those described in this thesis. The results of the measurement of the transverse asymmetries at backward angles in G⁰ are presented at the two values of Q² ~ 0.22 and 0.63 GeV²/c² for hydrogen. Results for deuterium, which can provide the first measurements of the beam normal single spin asymmetries on the neutron, are also presented. / Ph. D.

The experiment E06010 measured the target single spin asymmetry (SSA) in the semiinclusive deep inelastic (SIDIS) n↑(e,éπ¯)X reaction with a transversely polarized 3He target as an effective neutron target. This is the very first independent measurement of the neutron SSA, following the measurements at HERMES and COMPASS on the proton and the deuteron. The experiment acquired data in Hall A at Jefferson Laboratory with a continuous electron beam of energy 5.9 GeV, probing the valence quark region, with x = 0.13→0.41, at Q2 = 1.31→3.1 GeV2. The two contributing mechanisms to the measured asymmetry, viz, the Collins effect and the Sivers effect can be realized through the variation of the asymmetry as a function of the Collins and Sivers angles. The neutron Collins and Sivers moments, associated with the azimuthal angular modulations, are extracted from the measured asymmetry for the very first time and are presented in this thesis. The kinematics of this experiment is comparable to the HERMES proton measurement. However, the COMPASS measurements on deuteron and proton are in the low-x region. The results of this experiment are crucial as the first step toward the extraction of quark transversity and Sivers distribution functions in SIDIS. With the existing results on proton and deuteron, these new results on neutron will provide powerful constraints on the transversity and Sivers distributions of both the u and d-quarks in the valence region.

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