A. Klein

Measurements of the Proton and Deuteron Spin Structure Functions g1 and g2

Measurements are reported of the proton and deuteron spin structure functions g1 at beam energies of 29.1, 16.2, and 9.7 GeV and g2 at a beam energy of 29.1 GeV. The integrals of g1 over x have been evaluated at fixed Q**2 = 3 (GeV/c)**2 using the full data set. The Q**2 dependence of the ratio g1/F1 was studied and found to be small for Q**2>1 (GeV/c)**2. Within experimental precision the g2 data are well-described by the Wandzura-Wilczek twist-2 contribution. Twist-3 matrix elements were extracted and compared to theoretical predictions. The asymmetry A2 was measured and found to be significantly smaller than the positivity limit for both proton and deuteron targets. A2 for the proton is found to be positive and inconsistent with zero. Measurements of g1 in the resonance region show strong variations with x and Q**2, consistent with resonant amplitudes extracted from unpolarized data. These data allow us to study the Q**2 dependence of the first moments of g1 below the scaling region.

Measurements of the Proton and Deuteron Spin Structure Function g2 and Asymmetry A2

We have measured proton and deuteron virtual photon-nucleon asymmetries A2p and A2d and structure functions g2p and g2d over the range 0.03<x<0.8 and 1.3<Q2<10 (GeV/c)2 by inelastically scattering polarized electrons off polarized ammonia targets. Results for A2 are significantly smaller than the positivity limit sqrt(R) for both targets. Within experimental precision, the g2 data are well-described by the twist-2 contribution g2WW. Twist-3 matrix elements have been extracted and are compared to theorectical predictions.

Measurements of R = σL/σT for 0.03 < x < 0.1 and Fit to World Data

Abstract Measurements were made at SLAC of the cross section for scattering 29 GeV electrons from carbon at a laboratory angle of 4.5°, corresponding to 0.03Measurements 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.

The CLAS drift chamber system

Abstract Experimental Hall B at Jefferson Laboratory houses the CEBAF Large Acceptance Spectrometer, the magnetic field of which is produced by a superconducting toroid. The six coils of this toroid divide the detector azimuthally into six sectors, each of which contains three large multi-layer drift chambers for tracking charged particles produced from a fixed target on the toroidal axis. Within the 18 drift chambers are a total of 35,148 individually instrumented hexagonal drift cells. The novel geometry of these chambers provides for good tracking resolution and efficiency, along with large acceptance. The design and construction challenges posed by these large-scale detectors are described, and detailed results are presented from in-beam measurements.

Energy loss of fast quarks in nuclei

We report an analysis of the nuclear dependence of the yield of Drell-Yan (DY) dimuons from the 800 GeV/c proton bombardment of

Probing the high momentum component of the deuteron at high Q2.

^2H

Proton Spin Structure in the Resonance Region

, C, Ca, Fe, and W targets. A light-cone formulation of the DY process is employed in the rest frame of the nucleus. In this frame, for

LARGE-SOLID-ANGLE STUDY OF PION ABSORPTION ON 3HE

x_2\ll x_1

Probing Quark-Gluon Interactions with Transverse Polarized Scattering

, DY production appears as bremsstrahlung of a virtual photon followed by decay into dileptons. We treat the two sources of nuclear suppression, energy loss and shadowing, in a consistent formulation. Shadowing, involving no free parameters, is calculated within the light-cone dipole formalism. Initial-state energy loss, the only unknown in the problem, is determined from a fit to the nuclear-dependence ratio versus

A LARGE ACCEPTANCE DETECTOR SYSTEM (LADS) FOR STUDIES OF PION ABSORPTION

x_1