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The spin structure functions g_1 for the proton and the deuteron have beenmeasured over a wide kinematic range in x and Q2 using 1.6 and 5.7 GeVlongitudinally polarized electrons incident upon polarized NH_3 and ND_3targets at Jefferson Lab. Scattered electrons were detected in the CEBAF LargeAcceptance Spectrometer, for 0.05 < Q^2 < 5 GeV^2 and W < 3 GeV. The firstmoments of g_1 for the proton and deuteron are presented -- both have anegative slope at low Q^2, as predicted by the extended Gerasimov-Drell-Hearnsum rule. The first result for the generalized forward spin polarizability ofthe proton gamma_0^p is also reported. This quantity shows strong Q^2dependence at low Q^2, while Q^6\gamma_0^p seems to flatten out at the highestQ^2 accessed by our experiment. Although the first moments of g_1 areconsistent with Chiral Perturbation Theory (ChPT) calculations up toapproximately Q^2 = 0.06 GeV^2, a significant discrepancy is observed betweenthe \gamma_0^p data and ChPT for gamma_0^p, even at the lowest Q2.

Moments of the Spin Structure Functions g_1^p and g_1^d for 0.05 < Q^2 < 3.0 GeV^2