Measurements of polarized photo-pion production on longitudinally   polarized HD and Implications for Convergence of the GDH Integral
  We report new measurements of inclusive pion production from frozen-spin HD for polarized photon beams covering the Delta(1232) resonance. These provide data simultaneously on both H and D with nearly complete angular distributions of the spin-difference cross sections entering the Gerasimov-Drell-Hearn (GDH) sum rule. Recent results from Mainz and Bonn exceed the GDH prediction for the proton by 22 microbarns, suggesting as yet unmeasured high-energy components. Our pi0 data reveal a different angular dependence than assumed in Mainz analyses and integrate to a value that is 18 microbarns lower, suggesting a more rapid convergence. Our results for deuterium are somewhat lower than published data, considerably more precise and generally lower than available calculations. 
LEGS Spin Collaboration: S. Hoblit, A.M. Sandorfi, K. Ardashev, C.   Bade, O. Bartalini, M. Blecher, A. Caracappa, A. D'Ange...