Exploring the limits of existence of proton-rich nuclei in the <math><mrow><mi>Z</mi><mo>=</mo><mn>70</mn><mo>–</mo><mn>82</mn></mrow></math> region

International audienceα-, β-, and proton-decay energies have been combined with TITAN mass values for Yb150–157 to expand and refine the mass surface in the proton-rich Z=70–82 region. The calculations were performed using the Atomic Mass Evaluation (AME) algorithm, resulting in 11 new ground-state masses and uncertainty reductions of nine others. The new information allows the determination of the two-proton drip line for elements between Ir and Pb and provides indications of possible new candidates for two-proton emission. In addition, we examined binding energies in this region for Thomas-Ehrman shifts, so far only visible for light nuclides

Summit of the N=40 Island of Inversion: precision mass measurements and ab initio calculations of neutron-rich chromium isotopes

International audienceMass 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 $^{59, 61-63}$Cr confirm previous results, and the improved precision in measurements of $^{64-65}$Cr 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

Improved high-precision mass measurements of mid-shell neon isotopes

International audienceNew mass values measured with the TITAN MR-TOF-MS are reported for the short-lived isotopes 24−26Ne, produced at TRIUMF's ISAC facility using a uranium carbide target and cold FEBIAD ion source. A least-squares adjustment within the framework of the Atomic Mass Evaluation was performed and the improved precision of the new mass values is highlighted. The improved mass accuracy in this N=14 mid-shell region can also point to the refinement in values of the charge radii. By reducing the mass uncertainty of isotopes, their contribution of the mass shift uncertainty in laser spectroscopy can be negated. The work is part of developments for reaching the N=20 Island of Inversion, where high molecular contamination hinders mass measurements of the neon isotopes