Shell evolution of N = 40 isotones towards 60Ca: First spectroscopy of 62Ti

Abstract Excited states in the N = 40 isotone 62Ti were populated via the 63V ( p , 2 p ) 62Ti reaction at ∼200 MeV/nucleon at the Radioactive Isotope Beam Factory and studied using γ-ray spectroscopy. The energies of the 2 1 + → 0 gs + and 4 1 + → 2 1 + transitions, observed here for the first time, indicate a deformed 62Ti ground state. These energies are increased compared to the neighboring 64Cr and 66Fe isotones, suggesting a small decrease of quadrupole collectivity. The present measurement is well reproduced by large-scale shell-model calculations based on effective interactions, while ab initio and beyond mean-field calculations do not yet reproduce our findings. The shell-model calculations for 62Ti show a dominant configuration with four neutrons excited across the N = 40 gap. Likewise, they indicate that the N = 40 island of inversion extends down to Z = 20 , disfavoring a possible doubly magic character of the elusive 60Ca.