Alexander Klein

Measurements of Deuteron Photodisintegration up to 4.0 GeV

The first measurements of the differential cross section for the d(γ,p)n reaction up to 4.0 GeV were performed at the Continuous Electron Beam Accelerator Facility (CEBAF) at Thomas Jefferson Laboratory. We report the cross sections at the proton center-of-mass angles of 36°, 52°, 69°, and 89°. These results are in reasonable agreement with previous measurements at lower energy. The 89° and 69° data show constituent-counting-rule behavior up to 4.0 GeV photon energy. The 52° and 36° data disagree with the counting-rule behavior. The quantum chromodynamics (QCD) model of nuclear reactions involving reduced amplitudes disagrees with the present data.

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 0.03 1 (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.The ratio g1/F1 has been measured over the range 0.03<x<0.6 and 0.3<Q2<10 (GeV/c)2 using deep-inelastic scattering of polarized electrons from polarized protons and deuterons. We find g1/F1 to be consistent with no Q2-dependence at fixed x in the deep-inelastic region Q^2>1 (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.

MEASUREMENT OF THE PROTON AND DEUTERON SPIN STRUCTURE FUNCTION G1 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<5 GeV^2 and

Differential cross sections for the reactions {gamma}p{yields}p{eta} and {gamma}p{yields}p{eta}{sup '}

Q^2\simeq 0.5

Precision measurement of the proton spin structure function g1p

and

Precision measurement of the deuteron spin structure function g1d

Q^2\simeq 1.2

Measurement of Direct f(980) Photoproduction on the Proton

GeV^2 by inelastically scattering 9.7 GeV polarized electrons off polarized

Differential cross sections and spin density matrix elements for the reaction {gamma}p{yields}p{omega}

^{15}NH_3

Differential cross sections for the reactions pp and pp{sup '}

and

Differential cross sections and spin density matrix elements for the reaction pp

^{15}ND_3