We plan to make definitive measurements of the deuteron spin structure function g(1)(d)/F(1)(d) the deep-inelastic kinematics accessible with a 6 GeV beam at JLab. The principal goal is to provide the low Q(2) anchor points for NLO pQCD plus higher twist fits to g(1)(d)/F(1)(d), which is particularly sensitive to Delta G(x) (the polarized gluon density of the nucleon) and the sum of up and down quark polarizations. By spanning a factor of typically two in the Q(2)-range at nine values of x, the new data will strongly constrain the higher twist contribution to the fits, with a corresponding reduction in the polarized PDF uncertainties. The proposed measurements, when combined with existing and planned world data at higher Q(2), will provide the theoretically cleanest determination of Delta G(x) in the moderate to high x region, and will provide a necessary complement to the low x program of RHIC-spin.The experiment will use both (6)LiD and ND(3) as a source of polarized deuterons, with approximately equal running times for both to constrain the nuclear effects in (6)LiD, the target used by the higher Q(2) experiments at SLAC and CERN. Both the target and low current (nA scale) 6 GeV electron beam will be longitudinally polarized. Electrons scattered at angles from about 18 degrees to 45 degrees will be detected. Additional measurements at lower Q(2) will be made using a 4.8 GeV beam energy.

Data for pion electroproduction from both hydrogen and deuterium targets factorization tests ill the kinematic region Q(2) > 1 GeV2, 0.15 < x < 0.45, W > 2 GeV M-x > 1.5 GeV, and 0.3 < z < 0.6, for both spin-averaged and spin-dependent. scattering The pi(+)/pi(-) ratio of polarized SIDIS is found to exhibit a surprisingly large P-t dependence.

The properties of a polarimeter designed for the measurement of the degree of polarization of longitudinally polarized electrons and of circularly polarized photons at energies 10-40 GeV, which can be used in various fixed target experiments at SLAC and Jefferson Laboratory, have been investigated.

We have made an empirical fit to the world data for the proton elastic electromagnetic form factors ${\mathit{G}}_{\mathit{E}\mathit{p}}$, ${\mathit{G}}_{\mathit{M}\mathit{p}}$ for 0${\mathit{Q}}^{2}$30 (GeV/c${)}^{2}$, and to the neutron electromagnetic form factors ${\mathit{G}}_{\mathit{E}\mathit{n}}$,${\mathit{G}}_{\mathit{M}\mathit{n}}$ in the range 0${\mathit{Q}}^{2}$10 (GeV/c${)}^{2}$.

We have constructed a dynamical model for the elementary γN→Nπ0 reactions, which allows us to reproduce also the γD→Dπ0 and γ3He→3Heπ0 reaction cross sections measured at threshold.

The cross sections for neutral pion photoproduction on three-body targets are computed near threshold. The direct and the charge exchange pion rescattering amplitudes are taken into account.

By computing the non-relativistic limits of the direct and the pion-nucleon rescattering amplitudes, we have obtained a good accounting for the available experimental data, both at threshold and in the Δ(1236) region. The effects of the Fermi motion were fully taken into account. At threshold the pion-nucleon rescattering diagram is very important, and we have studied the sensitivity of the results to the different ingredients of the calculation: the deuteron wave function, the pion propagator, the elementary operators, etc. In the Δ(1236) region the rescattering effects are small and the cross section is mainly sensitive to the direct term. Here the Fermi motion effects are important and the kinematical ambiguities in the elementary amplitudes are avoided in our treatment. The good overall agreement with the data gives us some confidence in the methods we are using in this series of papers which study the electromagnetic properties of the πNN system.

${\ensuremath{\pi}}^{\ensuremath{\circ}}$ photoproduction on deuterium has been measured in the region of 1 to 7 MeV above threshold, relative to the same reaction on hydrogen. The comparison of our results with available theoretical predictions shows the necessity to go beyond the impulse approximation.

We have measured the excitation function from threshold to 9 MeV above threshold for the reaction γ + d → π+ + n + n by counting positrons after the bremsstrahlung beam burst. The extracted cross section is compared with a calculation using the impulse approximation, and good agreement is found near threshold.