Physics Letters B (Oct 2022)

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,
  • J. Cardona,
  • K. Dietrich,
  • E. Dunling,
  • G. Gwinner,
  • Z. Hockenbery,
  • J.D. Holt,
  • C. Izzo,
  • A. Jacobs,
  • A. Javaji,
  • B. Kootte,
  • Y. Lan,
  • D. Lunney,
  • E.M. Lykiardopoulou,
  • T. Miyagi,
  • M. Mougeot,
  • I. Mukul,
  • T. Murböck,
  • W.S. Porter,
  • M. Reiter,
  • J. Ringuette,
  • J. Dilling,
  • A.A. Kwiatkowski

Journal volume & issue
Vol. 833
p. 137288


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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.