Nuclear structure of 37, 38Si investigated by decay spectroscopy of 37, 38Al

Abstract

We present a study on the beta decays of the neutron-rich isotopes 37Al and 38Al, produced by projectile fragmentation of a 48Ca beam with an energy E = 345 A MeV at the RIKEN Nishina Center. The half-lives of 37Al and 38Al have been measured to 11.5(4)ms and 9.0(7)ms, respectively, using the CAITEN implantation and decay detector setup. The level schemes for 37Si and 38Si were deduced by employing gamma-gamma coincidence spectroscopy following the event-by-event identification of the implanted nuclei. Comparison to large scale nuclear shell model calculations allowed for a tentative assignment of spin and parity of the populated states. The data indicate that the classical shell gap at magic neutron number N = 28 between the f7/2 and p3/2 orbits gets reduced by 0.3 MeV in this region leading to low-energy states with intruder configuration in 37Si.