Measurement of the proton spin structure function g1(x;Q2) for Q2 from 0.15-GeV2 to 1.6-GeV2 with CLAS

<p> Double-polarization asymmetries for inclusive ep scattering were measured at Jefferson Lab using 2.6 and 4.3 GeV longitudinally polarized electrons incident on a longitudinally polarized NH3 target in the CLAS detector. The polarized structure function g1(x,Q2) was extracted throughout the nucleon resonance region and into the deep inelastic regime, for Q2=0.15&ndash;1.64&thinsp;&hairsp;&hairsp;GeV2. The contributions to the first moment &Gamma;1(Q2)=&int;g1(x,Q2)&thinsp;dx were determined up to Q2=1.2&thinsp;&hairsp;&hairsp;GeV2. Using a parametrization for g1 in the unmeasured low x regions, the complete first moment was estimated over this Q2 region. A rapid change in &Gamma;1 is observed for Q2&lt;1&thinsp;&hairsp;&hairsp;GeV2, with a sign change near Q2=0.3&thinsp;&hairsp;&hairsp;GeV2, indicating dominant contributions from the resonance region. At Q2=1.2&thinsp;&hairsp;&hairsp;GeV2 our data are below the perturbative QCD evolved scaling value.</p>