Masses of Exotic Nuclei

Abstract

Masses of exotic nuclei play a key role in multiple physics applications ranging from nuclear structure studies and input to astrophysical modeling to tests of the electroweak standard model, quantum electrodynamics, and neutrino physics. The nowadays most prominent mass spectrometry techniques rely on the storage and cooling of charged particles in multi-reflection time-of-flight, Penning-trap, and storage ring devices and the measurement of the revolution frequency of the ion of interest to a reference ion. We provide a comprehensive overview of these measurement techniques as well as the status of the most important mass measurements on exotic nuclei and their applications in atomic and nuclear physics.We also review the various global mass models of interest for practical applications with a special emphasis on the two main widely developed approaches, i.e., the phenomenological macroscopic-microscopic and the semi-microscopic mean-field models. Both approaches can reach a root-mean-square deviation with respect to all the 2457 known masses better than typically 0.8 MeV. Such models need also to be tested with respect to their capacity to describe not only masses but also bulk structure properties like deformations, radii, as well as infinite nuclear-matter properties. While extrapolations by macroscopic-microscopic formulas remain unstable to different parametrization and to the incoherent link between the macroscopic part and the microscopic correction, mean-field models mainly suffer from uncertainties related to the type of adopted energy-density functional and the still large range of acceptable parameters. The different approaches typically lead to extrapolations toward experimentally unknown nuclei that can deviate by more than ∼5 MeV but also give rise to non-negligible variations of the pairing and shell effects.