BETA-DECAY HALF-LIVES OF VERY NEUTRON-RICH ISOTOPES OF ELEMENTS FROM TI TO NI

The unknown beta-decay half-lives of 22 isotopes far off stability (5 < T-z < 10) in the region from Ti to Ni were measured at GSI, Darmstad t. The nuclei were produced in a fragmentation reaction of 500 A.MeV K r-86-projectile impinging on a thick Be target. The isotopes of intere st mere separated and identified with the fragment separator, FRS, by a combination of B rho, Z, and ToF techniques. An additional range sep aration was performed by a selective implantation into granular detect ors. The spatial and time correlations of the implant with the consecu tively detected beta-particles were used to determine the unknown half -lives. For nuclei far off stability, beta-decay chains were measured and analyzed as well, leading to an even more reliable evaluation of t he lifetimes. The large discrepancies found between the measured and t he theoretical values emphasize that most recent theoretical work is n ot an improvement over calculations made almost a decade ago.