Precision measurements of g1 of the proton and of the deuteron with 6 GeV electrons

The inclusive polarized structure functions of the proton and deuteron, g(1)(p) and g(1)(d) , were measured with high statistical precision using polarized 6 GeV electrons incident on a polarized ammonia target in Hall B at Jefferson Laboratory. Electrons scattered at laboratory angles between 18 and 45 degrees were detected using the CEBAF Large Acceptance Spectrometer (CLAS). For the usual deep inelastic region kinematics, Q(2) > 1 GeV2 and the final-state invariant mass W > 2 GeV, the ratio of polarized to unpolarized structure functions g(1)/F-1 is found to be nearly independent of Q(2) at fixed x. Significant resonant structure is apparent at values of W up to 2.3 GeV. In the framework of perturbative quantum chromodynamics, the high-W results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions.