[en] The article presents the results of studies of the characteristics of lead tungstate crystals (PbWO₄). Measurements of light transmission and light output from the passage of cosmic muons were carried out. The average light transmittance of crystals in the transverse direction is 62.82, 68.38 and 75.68% at wavelengths λ = 360, 420 and 620 nm, and the light output is ~16 pe/MeV. A prototype of electromagnetic calorimeter was designed and built from crystals arranged in 4 × 4 matrix which has been tested by cosmic muons. The results obtained confirm conclusions of other groups in the Electron-Ion Collider collaboration that quality of the crystals produced by CRYTUR meets requirements for the electromagnetic calorimeter, and that they can serve as basis for its construction

[en] We investigated simultaneously the 12C(e,e'p) and 12C(e,e'pp) reactions at Q2 = 2 [GeV/c]2, x_B = 1.2, and in an (e,e'p) missing-momentum range from 300 to 600 MeV/c. At these kinematics, with a missing-momentum greater than the Fermi momentum of nucleons in a nucleus and far from the delta excitation, short-range nucleon-nucleon correlations are predicted to dominate the reaction. For (9.5 +/- 2)% of the 12C(e,e'p) events, a recoiling partner proton was observed back-to-back to the 12C(e,e'p) missing momentum vector, an experimental signature of correlations

[en] An experiment is proposed to measure the cross sections for Real Compton Scattering from the proton in the energy range 3-6 GeV and over a wide angular range; and to measure the longitudinal and transverse components of the polarization transfer to the recoil proton at a single kinematic point. Together; these measurements will test models of the reaction mechanism and determine new structure functions of the proton that are related to the same nonforward parton densities that determine the elastic electron scattering form factors and the parton densities. The experiment utilizes an untagged bremsstrahlung photon beam and the standard Hall A cryogenic targets. The scattered photon is detected in a photon spectrometer; currently under construction. The coincident recoil proton is detected in one of the Hall A magnetic spectrometers and its polarization components are measured in the existing Focal Plane Polarimeter. This proposal extends and supercedes E97-108 which was approved by PAC13

[en] Cross-section values for Compton scattering on the proton were measured at 25 kinematic settings over the range s = 5-11 and -t = 2-7 GeV2 with statistical accuracy of a few percent. The scaling power for the s-dependence of the cross section at fixed center of mass angle was found to be 8.0 +/- 0.2, strongly inconsistent with the prediction of perturbative QCD. The observed cross section values are in fair agreement with the calculations using the handbag mechanism, in which the external photons couple to a single quark

[en] High precision measurements of the proton elastic form factor ratio have been made at four-momentum transfers, Q², between 0.2 and 0.5 GeV². The new data, while consistent with previous results, clearly show a ratio less than unity and significant differences from the central values of several recent phenomenological fits. By combining the new form-factor ratio data with an existing cross-section measurement, one finds that in this Q² range the deviation from unity is primarily due to GEp being smaller than the dipole parameterization

[en] 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 2x10^-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 10³⁸ 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