Experimental Nuclear Physics

Grant O'Rielly

Several research projects in nuclear physics are currently underway at UMass Dartmouth.

One project involves a series of measurements to investigate pion photoproduction near threshold from the proton and (eventually) the neutron. This process is one of the few low-energy phenomena for which exact quantum chromodynamics (QCD) based calculations can be made. Comparison between the theoretical calculations and these new results will form an important test of our understanding of the underlying dynamics of the nucleon system. This project is a collaborative effort involving researchers from the US and Sweden, and will be undertaken using the MAX-lab facility at Lund University in Lund, Sweden beginning in 2004. In addition to involvment with the data acquisition and analysis for these experiments, the UMD group will be responsible for the design , construction and testing of an active scintillator target to the used for the later measurements. This target development project is well suited for undergraduate participation on campus.

Two additional projects will study pion photoproduction at higher energies. These measurements will study the excited states of the proton by investigating the energy and angular distribution of the decay products (mostly pions), and compare the results with the predictions of various QCD theories. One of these experiments will measure pion photoproduction from a polarized proton target, and will be performed using the CEBAF Large Acceptance Spectrometer (CLAS) located at Jefferson Laboratory in Newport News Virginia. The other project will study the production of neutral pions. These events are much harder to detect and analyze, however since there are fewer reaction processes which produce background, the interpretation of the data is more straight forward. These measurements will be performed at the MAMI facility in Mainz, Germany using the Crystal Ball Spectrometer to detect the neutral pions.