Speaker
Description
Exotic neutron-rich nuclei around N=40 exhibit rapid structural changes with proton and neutron number. While 68Ni40 shows signatures of a doubly magic nucleus, excitation energies and transition strengths suggest a rapid development of collectivity in the ground state of neutron-rich 26Fe and 24Cr isotopes towards N=40. Accurate masses in this region of the nuclear chart are essential to elaborate nuclear structure in what is now called the second “island of inversion”. The masses of neutron-rich chromium isotopes were too imprecisely known to address the shape of the mass surface towards 64Cr, where a maximal quadrupole deformation is thought to be reached. Although chromium was not considered to be a well-produced “ISOL” element, successful laser-ionization developments combined with high-sensitivity mass spectrometry enabled the mass measurements of 52-63Cr during two ISOLDE experimental campaigns in October 2014 and April 2016, using the Penning-trap mass spectrometer ISOLTRAP. These measurements greatly refine our knowledge of the mass surface in this region, indicating a progressive onset of collectivity towards N=40. The results of the measurement campaigns will be presented and compared to theoretical predictions.
