Measurement of the Proton and Deuteron Spin Structure Function<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi mathvariant="italic">g</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>in the Resonance Region

We have measured the proton and deuteron spin structure functions ${g}_{1}^{p}$ and ${g}_{1}^{d}$ in the region of the nucleon resonances for ${W}^{2}&lt;5{\mathrm{GeV}}^{2}$ and ${Q}^{2}\ensuremath{\simeq}0.5$ and ${Q}^{2}\ensuremath{\simeq}1.2{\mathrm{GeV}}^{2}$ by inelastically scattering 9.7 GeV polarized electrons off polarized ${}^{15}{\mathrm{NH}}_{3}$ and ${}^{15}{\mathrm{ND}}_{3}$ targets. We observe significant structure in ${g}_{1}^{p}$ in the resonance region. We have used the present results, together with the deep-inelastic data at higher ${W}^{2}$, to extract $\ensuremath{\gamma}({Q}^{2})\ensuremath{\equiv}\ensuremath{\int}{1}^{}{g}_{1}({x,Q}^{2})\mathrm{dx}$. This is the first information on the low- ${Q}^{2}$ evolution of $\ensuremath{\gamma}$ toward the Gerasimov-Drell-Hearn limit at ${Q}^{2}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$.