Research with Heavy Ions and Radioactive Beams

This program is devoted to studies of nuclear structure, nuclear astrophysics, fundamental modes of nuclear excitation, andreactions between complex nuclei. Emphasis is placed on experimental programs at ORNL's Holifield Radioactive Ion Beam Facility(HRIBF). The nuclear structure program extends studies of nuclear properties to nuclei not previously accessible where newphenomena may be observed. Examples include studies of N~Z nuclei in the vicinity of 100Sn, detailed exploration of shell structurenear 78Ni and beyond 132Sn, and investigations of proton emitters near the proton drip line. The goal of the nuclear astrophysicsprogram is determination of quantitative details of the origin of the elements and the energy generation in novae, X-ray bursts,supernovae, red giant stars, and our sun, as well as the inner workings of stars and their evolution. With HRIBF beams, reactionson radioactive nuclei crucial to understanding stellar explosions will be measured directly and indirectly. Reaction studiesexplore characteristics of resonances, particle transfer, fusion and fission in reactions induced by radioactive ion beams,including investigations of the effects of neutron excess (or deficit). A program of study of giant multipole resonances focuses onstudies of strength distributions in unstable nuclei. Staff members supported by this program are key players in development ofnext-generation gamma-ray detector systems for nuclear physics studies, and in the development of the Majorana double beta decayexperiment. Measurements of neutron-induced reactions at the ORELA pulsed white neutron source help determine the origin of theheavy elements synthesized in red giant stars, and decipher the anomalous isotopic abundances found in meteorites.