Oak Ridge National Laboratory

Physics Division

Physics Division Seminars

Physics Division Seminars bring us speakers on a variety of physics related subjects. Usually these are held in the Building 6008 large Conference Room, at 3:00 pm on the chosen day, but times and locations may vary. For more information, contact our seminar chairman,

Alfredo Galindo-Uribarri
Tel (Office): (865) 574-6124  (FAX): (865) 574-1268

Thu., July 14, 2005, at 3:00 p.m. (refreshments at 2:40 p.m.)

Puzzling over intricacies of the low-energy, few-nucleon interaction

Tom Clegg, University of North Carolina, Chapel Hill, NC
Building 6008 Conference Room

The interaction between two, three, or four nucleons has occupied the attention of nuclear physicists for decades. These studies are characterized by measurements of impressive accuracy, and by an evolving complexity of theoretical interpretation. New measurements at low energies, often involving spin-polarized beams and targets, have proven critical in developing today's detailed understanding. A historical review of such measurements will illustrate advances both in experimental and theoretical techniques. Recent results show satisfying agreement between most measurements and few-body calculations based on the known nucleon-nucleon (N-N) interaction. However, a striking example remains for bombarding energies below 10 MeV of 40% disagreement between experiment and theory for the vector analyzing powers in low-energy N-d and N-3He scattering. Recent work implies this may arise from a two-pion-exchange, three-body interaction which has not yet been included completely in theoretical calculations.