New element and isotope synthesis

During this report period most of the physics with OASIS was focused on the synthesis and study of new neutron-deficient nuclei in the rare-earth region. Several new beta-delayed proton emitters were discovered and their proton spectra, half lives, and, in some cases, their ground state spins were measured. The isotope separator uniquely determines the mass of a new isotope while Z-identification is achieved by measuring K/sub α,β/-x-rays in coincidence with beta-delayed protons. Information about the spin of the proton precursor is obtained by measuring gamma radiation from the daughter nucleus in coincidence with protons. In the same experiment the level scheme of the proton-emitting nucleus can be studied through positron-gamma and x-ray-gamma coincidences. One of the Ge detectors also measures positron endpoint energies which are directly related to electron capture Q-values. The most important information, however, is obtained from the proton spectrum itself. It is the result of a two step process -β+ decay followed by proton emission - and reflects β+-transition rates to excited states in the intermediate nucleus and the competition between proton and gamma decay of these states. By comparing calculations of this process using a constant β-strength function with the experimental proton spectrum, an experimental β-strength function is obtained which itself can be compared to calculations using, for instance, the gross theory of beta decay or the random phase approximation method