Summit of the N=40 island of inversion: Precision mass measurements and ab initio calculations of neutron-rich chromium isotopes
R. Silwal, C. Andreoiu, B. Ashrafkhani, J. Bergmann, T. Brunner, Jaime Cardona, K. Dietrich, E. Dunling, G. Gwinner, Z. Hockenbery, J. D. Holt, C. Izzo, Andrew Jacobs, A. Javaji, B. Kootte, Y. Lan, D. Lunney, E. M. Lykiardopoulou, T. Miyagi, M. Mougeot, Ish Mukul, T. Murböck, W. S. Porter, M. P. Reiter, Jon Ringuette, J. Dilling, A. A. Kwiatkowski
Abstract
Mass measurements continue to provide invaluable information for elucidating nuclear structure and scenarios of astrophysical interest. The transition region between the Z=20 and 28 proton shell closures is particularly interesting due to the onset and evolution of nuclear deformation as nuclei become more neutron-rich. This provides a critical testing ground for emerging ab-initio nuclear structure models. Here, we present high-precision mass measurements of neutron-rich chromium isotopes using the sensitive electrostatic Multiple-Reflection Time-Of-Flight Mass Spectrometer (MR-TOF-MS) at TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN) facility. Our high-precision mass measurements of 59,61−63Cr confirm previous results, and the improved precision in measurements of 64−65Cr refine the mass surface beyond N=40. With the ab initio in-medium similarity renormalization group, we examine the trends in collectivity in chromium isotopes and give a complete picture of the N=40 island of inversion from calcium to nickel.