$Q^2$-Evolution of the Spin Structure Function $g_1 (x, Q^2)$ of the Proton and the Deuteron

Inelastic scattering using polarized nucleon targets and polarized charged lepton beams allows the extraction of spin structure functions that provide information about the helicity structure of the nucleon. A program designed to study such processes at low and intermediate $Q^2$ for the proton and deuteron has been pursued by the CLAS Collaboration at Jefferson Lab since 1998. The latest inclusive data with high statistical precision were measured using polarized 6 GeV electrons incident on a 2.5\% r.l. polarized ammonia target. In the framework of pQCD, these results can be used to better constrain the polarization of quarks and gluons in the nucleon, as well as high-twist contributions. Some preliminary results will be shown, along with the expected impact on the NLO global fits and phenomenological models of valent spin structure.