New neutron-deficient isotopes from Kr 78 fragmentation

Abstract

In an experiment with the RIKEN projectile fragment separator called BigRIPS at the RIKEN Nishina Center, the fragmentation of a Kr78 beam allowed the observation of new neutron-deficient isotopes at the proton drip line. Clean identification spectra could be produced and Se63,Kr67, and Kr68 were identified for the first time. In addition, Ge59 was also observed. Three of these isotopes, Ge59,Se63, and Kr67, are potential candidates for ground-state two-proton radioactivity. In addition, the isotopes Ge58,Se62, and Kr66 were also sought but without success. The present experiment also allowed the determination of production cross sections for some of the most exotic isotopes. These measurements confirm the trend already observed that the empirical parametrization of fragmentation cross sections, EPAX, significantly overestimates experimental cross sections in this mass region.