Nuclear Physics Seminar

The High Intensity g-ray Source (HIgS) is a joint project between TUNL and the Duke Free Electron Laser Laboratory (DFELL). This facility utilizes intra-cavity back-scattering of the UV-FEL light in order to produce intense g-ray beams. An upgrade is presently underway which will allow for the production of g rays up to energies of about 160 MeV having total intensities in excess of 109 /sec. The primary component of the upgrade is a 1.2 GeV booster-injector. The booster injector will provide for efficient injection at any chosen operating energy of the storage ring from 300 MeV to 1.2 GeV. In addition, an upgrade of the present linear undulator to a helical system is underway. This new system has many advantages over the present one, including making switchable linear and circularly polarized beams available, an increase in power and a decrease in mirror-damaging radiation. The full system, including the booster injector, is expected to be ready for use by the end of 2006—although some mirror development is required before full energy operation can be achieved. TUNL researchers, in collaboration with outside theoretical and experimental colleagues, have proposed a broad-based research program in nuclear physics which is designed to exploit the unique flux, energy resolution and polarization of the HIGS beams. The program includes low-energy studies of nuclear reactions of importance in nuclear astrophysics as well as studies of nuclear structure using the technique of nuclear resonance fluorescence. Double polarization experiments include a study of the Gerasimov-Drell-Hearn Sum Rule for the deuteron and 3He and an extensive Compton scattering program designed to probe the internal structure of the proton and the neutron. Studies at pion-threshold designed to observe Isospin symmetry breaking effects are also being planned. A description of the anticipated facility following the present upgrades will be given in this talk, along with a summary of some rece