Search

Hall D at Jefferson Laboratory is building its new GlueX spectrometer to study QCD gluonic excitations. The hermetic detector includes a scintillating fiber-lead barrel calorimeter where the photodetectors must operate in a high magnetic field. The silicon photomultiplier (SiPM) array manufactured by Hamamatsu Corporation was chosen for the photodetector of the BCAL. We report on the measurement of neutron radiation hardness of SiPMs at Jefferson Lab.

Understanding the structure of baryons in terms of the fundamental interaction of the constituent quarks and gluons is one of the challenges in strong interaction physics. This interaction is governed by Quantum Chromodynamics (QCD). However, solutions of this theory in the non‐perturbative domain of the interaction are extremely difficult to achieve. In inelastic electron scattering, very little is known about exclusive hadron production purely contributed to a lack of knowledge. The γN interaction is recognized for being a powerful method for investigating hadrons and the mysteries that still exist within the strong interaction. From reactions with the nucleon, the strong interaction can be tested through the amplitudes of the N and Δ resonances. More specifically, if an electromagnetic interaction is well known then the intermediate resonance states may be evaluated through pion photoproduction. To gain more detailed insight into this interaction, we look to probe the baryon structure of Δ and the meso...

High quality polarized electron beams at Jefferson Lab make possible precision measurements of hadronic properties in the regime of strongly interacting QCD. We will describe a few programs at Jefferson Lab that are making measurements that link the basic static properties of hadrons to their quark sub-structure. For example, parity-violating electron proton elastic scattering probes the spatial distribution of strange quarks in the nucleon. The nucleon-Delta transition form factors give us information about the deformation of nucleons and Deltas. Finally, new high statistics measurements of photons scattering off proton and deuteron targets are used to set upper limits on the production of exotic baryons with strangeness S=+1. These examples will be used to illustrate the capabilities and focus of the experimental program at JLab., Contribution to XI International Conference on Hadron Spectroscopy, 4 figures

Generalized parton distributions provide a unifying framework for the interpretation of exclusive reactions at high $Q^2$. The most promising reaction for the investigation of these distributions is the hard production of photons using Deeply Virtual Compton Scattering (DVCS). This reaction can be accessed experimentally by determining the production asymmetry using polarized electrons on a proton target. Pioneering experiments with CLAS and HERMES have produced the first measurements of this asymmetry. We will review the current experimental program to study DVCS at Jefferson Lab. Recent high statistics data taken with CLAS at 5.75 GeV allows us to determine this asymmetry at low -$t$ in the valence region ($x_{B}$=0.1-0.5) up to a $Q^2$ of 4 GeV$^2/c^2$., 5 pages, 3 figures, Conference on the Intersections of Particle and Nuclear Physics, New York City, May 19-24, 2003