Differences of nuclear binding energies tracked along isotopic or isotonic chains are among the main observables upon which the early intuition of nuclear (shell) structure has been built. Still today, nucleon separation energies and the discontinuities they exhibit across the nuclear “magic” numbers are referred to as “empirical” single-particle energies or shell gaps. As such, they are used to qualify the goodness of the associated shell closures, or to quantify their evolution. With the unprecedented expansion of ion-trap mass spectrometry at radioactive-ion-beam facilities, these observables have been determined with high precision over a wide range of isotopes and have contributed to the global discussion on the rise and fall of shell closures accross the nuclear chart.
In this talk, following an introduction on the link between empirical single-particle energies and the inferred nuclear shell structure, I will present the major experimental techniques which are currently at the forefront. I will subsequently discuss a few results in regions which have received particular interest in recent years. Finally, I will present the current challenges to move the experimental horizon even further and mention a few directions of interest.
This ESNT-DPhN seminar is an open lecture given in the framework of the ESNT workshop “Effective yet elusive: exploring single-particles”, discussing the link between the non-observable ESPE and the nuclear observables and the theoretical insights into nuclear shell evolution through ESPEs.
The workshop is organized from 17 till 21st November at CEA Saclay Orme les Merisiers b703. See https://esnt.cea.fr
IJCLab