Magicity of the Ca-52 and Ca-54 isotopes and tensor contribution within a mean-field approach

作者：Grasso Marcella^*

来源：Physical Review C, 2014, 89(3): 034316.

DOI：10.1103/PhysRevC.89.034316

I investigate the magicity of the isotopes Ca-52 and Ca-54, which was recently confirmed by two experimental measurements, and relate it to like-particle and neutron-proton tensor effects within a mean-field description. By analyzing Ca isotopes, it is shown that the like-particle tensor contribution induces shell effects that render these nuclei more magic than would be predicted by neglecting it. In particular, such induced shell effects are stronger in the Ca-52 nucleus, and the single-particle gaps are increased in both isotopes due to the tensor force. By studying N = 32 and N = 34 isotones, neutron-proton tensor effects may be isolated and their role analyzed. It is shown that neutron-proton tensor effects lead to increasing N = 32 and N = 34 gaps, when going along isotonic chains, from Fe-58 to Ca-52 and from Fe-60 to Ca-54, respectively. Mean-field calculations are perfomed by employing one Skyrme parameter set, which was introduced in a previous work by fitting the tensor parameters together with the spin-orbit strength. The signs and values of the tensor strengths are thus checked within this specific application. The obtained results indicate that the employed parameter set, even if generated with a partial adjustment of the parameters of the force, leads to the correct shell behavior and provides, in particular, a description of the magicity of Ca-52 and Ca-54 within a pure mean-field picture with the effective two-body Skyrme interaction.

• 出版日期2014-3-21