This award supports cooperative reseach in nuclear physics to be conducted by Cyrus Baktash of Oak Ridge National Laboratory (ORNL) and G. Garcia-Bermudez of the TANDAR accelerator of the Atomic Energy Commission in Buenos Aires, Argentina. They will study the evolution of nuclear shape and collectivity at high spins around nuclear mass A = 80 and 180. In the mass A = 80 region, the focus will be on high spin band structures in isotopes of strontium and their neighboring transitional nuclei. In the A = 180 region they will concentrate on the odd-Z (atomic number) and particularly odd-odd (protons-neutrons) nuclei. These data, obtained by probing the high spin structure of nuclei in two widely separated regions, will provide an important test of current theoretical models. In recent years, the ORNL spectroscopy group has concentrated on the study of the evolution of nuclear collectivity and shape with spin and exitation energy. The group in Argentina has been in the forefront of the spectroscopy of odd-odd nuclei in the two regions, A = 80 and A = 180. In this program, the complementary resources at the two laboratories will be utilized. The availability of beam time at TANDAR is beneficial to the study of band structures while the extension of these bands to high spin will be accomplished at ORNL. Theoretical interpretation of the data will be carried out by both groups.
