First beta-decay studies of the neutron-rich isotopes 53–55Sc and 56–59V

Abstract The neutron-rich isotopes 53–55 Sc and 56–59 V have been produced at GANIL in interactions of a 64.5 MeV/u 65 Cu beam with a 9 Be target. They were separated by the doubly achromatic spectrometer LISE3. Beta-decay half-lives and subsequent low-energy γ-rays were observed for the first time. The present results are compared to QRPA model predictions. The quick drop of the half-life observed at N = 33 for 20 53 Ca 33 is weaker for 23 56 V 33 and absent for 21 54 Sc 33 , indicating a vanishing of the N = 32 subshell north to 52 Ca 32 . In an astrophysical context, these neutron-rich isotopes represent r-process progenitors which, after β-decay, would produce the correlated isotopic over-abundances of 54 Cr, 58 Fe, 64 Ni in certain refractory inclusions of meteorites.