Abstract
We report on the measurement of the first and states of and via in-beam -ray spectroscopy. The nuclei of interest were produced by reactions at incident energies of . The experiment was performed at the Radioactive Isotope Beam Factory, RIKEN, using the DALI -ray detector array and the novel MINOS device, a thick liquid hydrogen target combined with a vertex tracker. A low-energy plateau of and energies as a function of the neutron number was observed for and for even-even Cr and Fe isotopes, respectively. State-of-the-art shell model calculations with a modified Lenzi-Nowacki-Poves-Sieja (LNPS) interaction in the valence space reproduce the observations. Interpretation within the shell model shows an extension of the island of inversion at for more neutron-rich isotopes towards .
- Received 30 April 2015
DOI:https://doi.org/10.1103/PhysRevLett.115.192501
© 2015 American Physical Society