Atomic mass measurements and nuclear spectroscopy at TRISTAN and nuclidic mass measurements at LAMPF: Progress report for the period February 1, 1985-August 31, 1987

The Clark University research program is concerned with experimental determination of the nuclear structure of isotopes far from the line of β stability and their masses. This work is accomplished, primarily, by use of the TRISTAN on-line mass separator located at the High Flux Beam Reactor, Brookhaven National Laboratory, where investigations of short-lived fission products have been actively pursued since 1980. In 1985 mass measurements of light isotopes produced by fragmentation reactions on heavy targets were initiated using the TOFI (Time-of-flight Isochronous) Spectrometer at the LAMPF accelerator, Los Alamos National Laboratory. Together, the two facilities are capable of providing complementary information, potentially of great value in understanding the sum total effect of all nuclear interactions in a given nucleus, which gives rise to the property known as the mass. The thrust of the spectroscopic studies at TRISTAN has been to develop a database for neutron-rich, far-from-stability nuclides in order to provide a new testing ground for nuclear models. In particular, we have been active in pursuing microscopic and phenomenological understanding of nuclear structure in regions of shape transition near shell and subshell closures. Recent efforts have been concentrated on exploiting some very new ideas based on the pervasive influence of the proton-neutron interaction that offer the possibility of achieving a unified interpretation of nuclear structure and its evolution, of the interrelationships of different nuclear shapes and modes of excitation, and of the nuclear mass