Evolution of the N=28 shell closure: a test bench for nuclear forces

摘要

The evolution of the N=28 shell closure is investigated far from stability.Using the latest results obtained from various experimental techniques, wediscuss the main properties of the N=28 isotones, as well as those of the N=27and N=29 isotones. Experimental results are confronted to various theoreticalpredictions. These studies pinpoint the effects of several terms of thenucleon-nucleon interaction, such as the central, the spin-orbit, the tensorand the three-body force components, to account for the modification of theN=28 shell gap and spin-orbit splittings. Analogies between the evolution ofthe N=28 shell closure and other magic numbers originating from the spin-orbitinteraction are proposed (N=14,50, 82 and 90). More generally, questionsrelated to the evolution of nuclear forces towards the drip-line, in bubblenuclei, and for nuclei involved in the r-process nucleosynthesis are proposedand discussed.