Department of Physics and Astronomy

Nuclear and Particle Physics Seminar

Monday, September 27

12:30pm-1:30pm

Stevenson Center, Room 6333

Volker Oberacker

Vanderbilt University

Structure of Exotic Nuclei Near the Neutron Dripline

The aim of nuclear structure theory is to study the quantum many-particle aspects of the strong interaction, at relatively low energy. The majority of nuclear phenomena are non-perturbative; therefore, all fundamental nuclear structure theories require supercomputer calculations.The nuclear chart shows less than 300 stable isotopes. However, with the new Radioactive Ion Beam Facilities, in particular RIA, thousands of nuclear isotopes are still to be explored; most of these are exotic neutron-rich systems. Our primary goal is to study the structure of nuclei near the "neutron dripline" where nuclei become unstable against spontaneous neutron emission. In contrast to stable isotopes, these exotic nuclei exhibit large pairing correlations which can no longer be described by a small residual interaction. Furthermore, the outermost nucleons are weakly bound (large spatial extent), and they are strongly coupled to the particle continuum. These features represent major challenges for the quantum many-body theories. Our group has developed a new mean field nuclear structure code using the "Hartree-Fock-Bogoliubov" (HFB) approximation; the wavefunctions of all nucleons are represented on a spatial 2-D lattice. Besides binding energies, we predict Fermi levels, particle densities (from which we can infer multipole deformations and mean square radii), and pairing densities (which determine the pairing gap, pairing energy, and pair transfer formfactors). I will show color graphics results of the nuclear mean field, proton/neutron densities and pairing densities predicted by our HFB code and discuss the groundstate properties of very neutron-rich sulfur and zirconium isotopes.