6+ isomers in neutron-rich Sn-isotopes beyond N=82 and effective interaction
Abstract
Recent observation of the 6+ seniority isomers and measurements of the B(E2) values in the 134-138Sn isotopes lying close to the neutron drip line have raised some questions about the validity of the currently used effective interactions in the neutron-rich region. Simpson et al. [Phys. Rev. Lett. 113, 132502 (2014)] had to modify the diagonal and non-diagonal f7/22 two body matrix elements of the "Vlk" interaction by 150 keV in their shell model calculations in order to explain the data of 136Sn. In contrast, we are able to explain the observed energy levels and the B(E2) values after marginal reduction of the same set of matrix elements by 25 keV in the "RCDB" (Renormalized CD-Bonn) interaction. The observed mismatch in reproducing the data of 136Sn is due to the seniority mixing. Further, we do not find it necessary to consider the core excitations, and the "RCDB" interaction seems better suited to explain the data beyond N=82 magic number.