Direct mass measurements of neutron-rich ${}^{86}$Kr projectile fragments and the persistence of neutron magic number $N$ = 32 in Sc isotopes

Abstract

In this paper, we present direct mass measurements of neutron-rich ${}^{86}$Kr projectile fragments conducted at the HIRFL-CSR facility in Lanzhou by employing the Isochronous Mass Spectrometry (IMS) method. The new mass excesses of ${}^{52-54}$Sc nuclides are determined to be -40492(82), -38928(114), -34654(540) keV, which show a significant increase of binding energy compared to the reported ones in the Atomic Mass Evaluation 2012 (AME12). In particular, ${}^{53}$Sc and ${}^{54}$Sc are more bound by 0.8 MeV and 1.0 MeV, respectively. The behavior of the two neutron separation energy with neutron numbers indicates a strong sub-shell closure at neutron number $N$ = 32 in Sc isotopes.

publised in Chinese Physics C Vol. 39, No. 10 (2015) 104001