The instrumentation in Hall A at the Thomas Jefferson National Accelerator Facility was designed to study electro-and photo-induced reactions at very high luminosity and good momentum and angular resolution for at least one of the reaction products. The central components of Hall A are two identical high resolution spectrometers, which allow the vertical drift chambers in the focal plane to provide a momentum resolution of better than 2 x 10(-4). A variety of Cherenkov counters, scintillators and lead-glass calorimeters provide excellent particle identification. The facility has been operated successfully at a luminosity well in excess of 10(38) CM-2 s(-1). The research program is aimed at a variety of subjects, including nucleon structure functions, nucleon form factors and properties of the nuclear medium. (C) 2003 Elsevier B.V. All rights reserved

We present data on the inclusive scattering of polarized electrons from a polarized 3He target at energies from 0.862 to 5.06 GeV, obtained at a scattering angle of 15.5 degrees. Our data include measurements from the quasielastic peak, through the nucleon resonance region, and beyond, and were used to determine the virtual photon cross-section difference sigma(1/2)-sigma(3/2). We extract the extended Gerasimov-Drell-Hearn integral for the neutron in the range of four-momentum transfer squared Q2 of 0.1-0.9 GeV2.

We have measured the cross section for quasielastic 1p-shell proton knockout in the 16O(e,e(')p) reaction at omega = 0.439 GeV and Q2 = 0.8 (GeV/c)(2) for missing momentum P(miss)

We have measured the spin structure functions g(1) and g(2) of 3He in a double-spin experiment by inclusively scattering polarized electrons at energies ranging from 0.862 to 5.058 GeV off a polarized 3He target at a 15.5 degrees scattering angle. Excitation energies covered the resonance and the onset of the deep inelastic regions. We have determined for the first time the Q2 evolution of Gamma(1)(Q2)= integral (1)(0)g(1)(x,Q2)dx, Gamma(2)(Q2)= integral (1)(0)g(2)(x,Q2)dx, and d(2)(Q2)= integral (1)(0)x(2)[2g(1)(x,Q2)+3g(2)(x,Q2)]dx for the neutron in the range 0.1< or =Q2< or =0.9 GeV2 with good precision. Gamma(1)(Q2) displays a smooth variation from high to low Q2. The Burkhardt-Cottingham sum rule holds within uncertainties and d(2) is nonzero over the measured range.

We report measurements of cross sections for the reaction 1 H(e,eЈK ϩ )Y , for both the ⌳ and ⌺ 0 hyperon states, at an invariant mass of Wϭ1.84 GeV and four-momentum transfers 0.5ϽQ 2 Ͻ2 (GeV/c) 2 . Data were taken for three values of virtual photon polarization ⑀, allowing the decomposition of the cross sections into longitudinal and transverse components. The ⌳ data are a revised analysis of prior work, whereas the ⌺ 0 results have not been previously reported.

The generalized forward spin polarizabilities gamma(0) and delta(LT) of the neutron have been extracted for the first time in a Q2 range from 0.1 to 0.9 GeV2. Since gamma(0) is sensitive to nucleon resonances and delta(LT) is insensitive to the Delta resonance, it is expected that the pair of forward spin polarizabilities should provide benchmark tests of the current understanding of the chiral dynamics of QCD. The new results on delta(LT) show significant disagreement with chiral perturbation theory calculations, while the data for gamma(0) at low Q2 are in good agreement with a next-to-leading-order relativistic baryon chiral perturbation theory calculation. The data show good agreement with the phenomenological MAID model.

The D(e,e'p) coincidence cross section was measured at angles out of the plane, at an excitation energy of approximately 18 MeV and a momentum transfer of 0.33 fm _1 . This is the first reported measurement of the longitudinal-transverse and transverse-transverse interference terms of the electrodisintegration cross section of the deuteron. The longitudinal plus transverse cross section is also reported. The results are in good agreement with a theoretical calculation carried out with use of the Paris potential.PACS numbers: 25.30.Fj, 25.10,+s, 27.10.+h With the advent of high-duty-cycle electron accelerators, new types of experiments, such as coincidence experiments 1,2 and polarization experiments, 3,4 have become possible. These experiments have the potential to become very powerful tools for probing nuclear structure and the nuclear force.The deuteron, as a two-nucleon system, is of great importance in the investigation of the TV-TV interaction, and thus providing a surer foundation for the study of heavier nuclei. Of special interest in the case of the deuteron is the study of interaction effects such as mesonic-exchange currents (MEC's) and the influence of nuclear isobar configurations (IC's). 5 ' 6 Relativistic effects are also of interest in the reaction. 7 Although the importance of an out-of-plane measurement inThe expression for the cross section includes two interference terms involving the longitudinal-transverse (<) and the transverse-transverse (OTT) cross sections in addition to the longitudinal (a L ) and transverse (a T ) components. These interference terms are not present in inclusive electron-scattering experiments, where no outgoing nucleons are detected. The interference terms are expected to give new information about the TV-TV interaction. The transverse-transverse term, in particular, is sensitive to the existence of MEC's and IC's. According to Eq. (l), an out-of-plane measurement of the coincidence cross section enables the interference terms to be separated from other components.We measured the D(e,e'p) coincidence cross section in reaction planes at 0=45°, 90°, and 135°, and at excitation energies of approximately 18 MeV. A deuterat-coincidence experiments was mentioned some time ago, 6 no experiments have actually been made, because such experiments are difficult to perform with pulsed electron accelerators. The pulse stretcher 8 constructed at Tohoku University made it possible to perform such coincidence experiments. The out-of-plane coincidence experiment for the D(e,e'p) reaction is one of the first such experiments using the high-duty electron beam.In the (e.e'p) coincidence experiment, the direction of the emitted proton momentum p is determined by two angles: 0 P , the polar angle between p and the momentum transfer q, and 0, the azimuthal angle between the scattering plane and the reaction plane. The situation is shown in Fig. 1. The coincidence cross section in the laboratory frame is given by (1) FIG. 1. Geometry of the coincidence D(e,e'p) experiment in the laborato...

In the above-named study of the neutral kaon photoproduction, the cross sections given in Figs. 10 and 11 were wrong due to trivial mistakes, mainly in estimating the number of beam photons. The normalization factors for the cross sections are found to be larger by a factor of approximately 3.9 compared to the previous one, though it depends on the K 0 momentum. The corrected spectra are shown in Fig. 11 (numberings are the same as the original ones). As a result, the r K 1 Kγ value obtained by fitting the K 0 spectra in the lower photon energy region (0.9 E γ < 1.0 GeV) should be replaced by the new value of r K 1 Kγ = −1.405 for the Saclay-Lyon A (SLA) model. The phenomenological parameters are also changed: a 0 = 0.3532, a 1 = −0.2152, a 2 = −0.0359, and e 0 = −0.0866 with χ 2 /n.d.f. = 0.80.By these corrections, the experimental cross sections are larger than those calculated by the Kaon-MAID model in the momentum region of P K 0 < 0.4 GeV/c both in the lower and higher photon beam energies. However, the K 0 spectral shapes in the laboratory system are essentially the same as those of the previous ones and the discussion does not change. In Fig. 12, the K 0 angular distributions for the SLA and PH models calculated with the new parameters are shown together with those for the Kaon-MAID model. It suggests a much enhanced backward K 0 distribution in the c.m. system because the SLA and PH1 models are preferred to reproduce the new results with larger cross sections.