THE FIRST MOMENT OF G1 MEASURED WITH THE CLAS DETECTOR

Abstract

A large program of spin structure function measurements is underway in Jefferson Lab's Hall B. Of particular interest is the first moment of the spin structure function g1, which 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. One can then study the transition from hadronic to quark degrees of freedom over the whole range of Q2. We use polarized electrons incident on polarized NH3 and ND3 targets to study proton and deuteron spin observables in and above the resonance region. Using the Cebaf Large Acceptance Spectrometer (CLAS) and beam energies of 1.6, 2.4, 4.2 and 5.7 GeV, we are able to cover a wide kinematic range: 0.05 GeV2 < Q2 < 5.0 GeV2 and W < 3.2 GeV. We will describe the experiment and present the GDH and Bjorken integrals using the 1.6 and 5.7 GeV data.