Precision measurement of the deuteron spin structure function g1dg^{d}_{1}

We report on a high-statistics measurement of the deuteron spin structure function g[sup d][sub 1] at a beam energy of 29 GeV in the kinematic range 0.029 < x < 0.8 and 1 < Q2 < 10 (GeV/c)2. The integral Gamma [sup d][sub 1] = (integral)[sup 1][sub 0]g[sup d][sub 1]dx evaluated at fixed Q2 = 3 (GeV/c)2 gives 0.042 ± 0.003(stat) ± 0.004(syst). Combining this result with our earlier measurement of g[sup p][sub 1], we find Gamma [sup p][sub 1]- Gamma [sup n][sub 1] = 0.163 ± 0.010(stat) ± 0.016(syst), which agrees with the prediction of the Bjorken sum rule with O( alpha [sup 3][sub s]) corrections, Gamma [sup p][sub 1]- Gamma [sup n][sub 1] = 0.171 ± 0.008. We find the quark contribution to the proton helicity to be Delta q = 0.30 ± 0.06

Measurements of R=sigma_L/sigma_T for 0.03<x<0.1 and Fit to World Data

Measurements were made at SLAC of the cross section for scattering 29 GeV electrons from carbon at a laboratory angle of 4.5 degrees, corresponding to 0.03<x<0.1 and 1.3<Q^2<2.7 GeV^2. Values of R=sigma_L/sigma_T were extracted in this kinematic range by comparing these data to cross sections measured at a higher beam energy by the NMC collaboration. The results are in reasonable agreement with pQCD calculations and with extrapolations of the R1990 parameterization of previous data. A new fit is made including these data and other recent results.Comment: 8 pages, 4 figures, late

Measurements of the Q2-Dependence of the Proton and Deuteron Spin Structure Functions g1p and g1d

The ratio g1/F1 has been measured over the range 0.031 (GeV/c)2. A trend is observed for g1/F1 to decrease at lower Q2. Fits to world data with and without a possible Q2-dependence in g1/F1 are in agreement with the Bjorken sum rule, but Delta_q is substantially less than the quark-parton model expectation

Precision measurement of the proton spin structure function g1pg^{p}_{1}

We have measured the ratio g[sup p][sub 1]/F[sup p][sub 1] over the range 0.029 < x < 0.8 and 1.3 < Q2 < 10 (GeV/c)2 using deep-inelastic scattering of polarized electrons from polarized ammonia. An evaluation of the integral (integral)g[sup p][sub 1](x,Q2)dx at fixed Q2 = 3 (GeV/c)2 yields 0.127 ± 0.004(stat) ± 0.010(syst), in agreement with previous experiments, but well below the Ellis-Jaffe sum rule prediction of 0.160 ± 0.006. In the quark-parton model, this implies Delta q = 0.27 ± 0.10

Precision measurement of the proton spin structure function g(p1)

We have measured the ratio (gi) /F(gi) over the range 0.029 ( x ( 0.8 and 1.3 (Q+/- ( 10 (GeV/c) using deep-inelastic scattering of polarized electrons from polarized ammonia. An evaluation of the integral fo g+/_ (x, Q2) dx at fixed Q2 = 3 (GeV/c)2 yields 0.127 +/- 0.004(stat) +/- 0.010(syst), in agreement with previous experiments, but well below the Ellis-Jaffe sum rule prediction of 0.160 +/- 0.006. In the quark-parton model, this implies Aq = 0.27 +/- 0.10.This work was supported by Department of Energy Contracts No. DE-AC05-84ER40150 (CEBAF), No. W-2795-Eng-48 (LLNL), No. DE-AC0376SF00515 (SLAC), No. DE-FG03-88ER40439 (Stanford), No. DE-FG05-88ER40390 and No. DEFG05-86ER4026 (Virginia), and No. DE-AC02-76ER00881 (Wisconsin); by National Science Foundation Grants No. 9114958 (American), No. 9307710 (Massachusetts), No. 9217979 (Michigan), No. 9104975 (ODU) and No. 9118137 (U. Penn.); by the Schweizersche Nationalfonds (Basel); by the Commonwealth of Virginia (Virginia); by the Centre NAtional de la Recherche Scientifique and the Commissariat a l'Energie Atomique (French groups); and by the Japanese Ministry of Education, Science and Culture (Tohoku)

Precision measurement of the deuteron spin structure function gd1

We report on a high-statistics measurement of'. the deuteron spin structure function g(di) at a beam energy of 29 GeV in the kinematic range 0.029 < x < 0.8 and 1 < Q2 < IO (GeV / c) (2) • The integral r(di) = f(1o) g(di) dx evaluated at fixed Q2 = 3 (GeV/c) 2 gives 0.042 ± 0.003(stat) ± 0.004(syst). Combining this result with our earlier measurement of g(di), we find r(pi) - r(nt) = 0.163 ± O.OIO(stat) ± 0.016(syst), which agrees with the prediction of the Bjorken sum rule with O(a(3x)) corrections, r(pi) - r(ni) = 0.171 ± 0.008. We find the quark contribution to the proton helicity to be liq = 0.30 ± 0.06.This work was supported by Department of Energy Contracts No. DE-AC05-84ER40150 (CEBAF), No. W-2795-Eng-48 (LLNL), No. DE-AC0376SF00515 (SLAC), No. DE-FG03-88ER40439 (Stanford), No. DE-FG05-88ER40390 and No. DEFG05-86ER4026 (Virginia), and No. DE-AC02-76ER00881 (Wisconsin); by National Science Foundation Grants No. 9114958 (American), No. 9307710 (Massachusetts), No. 9217979 (Michigan), No. 9104975 (ODU) and No. 9118137 (U. Penn.); by the Schweizersche Nationalfonds (Basel); by the Commonwealth of Virginia (Virginia); by the Centre NAtional de la Recherche Scientifique and the Commissariat a l'Energie Atomique (French groups); and by the Japanese Ministry of Education, Science and Culture (Tohoku)