The N=50 and Z=28 shell closure revisited ...

• Main Authors: Routray, T. R., Bano, P., Anguiano, M., Centelles, M., Viñas, X., Robledo, L. M.
• Format: Text
• Language: unknown
• Published: arXiv 2021
• Subjects: Nuclear Theory nucl-th; FOS Physical sciences; sami
• Online Access: https://dx.doi.org/10.48550/arxiv.2105.15006; https://arxiv.org/abs/2105.15006

Recent experiments performed in neutron-rich copper isotopes have revealed a crossing in the nucleus $^{75}$Cu between the $3/2^-$ and $5/2^-$ levels, which correspond to the ground-state and the first excited state in isotopes with mass number below $A =75$. Due to the strong single-particle character of these states, this scenario can be investigated through the analysis of the proton spectrum provided by mean-field models in nickel isotopes with neutron numbers between $N$=40 and $N$=50. In this work we show that the aforementioned crossing is mainly driven by the mean-field provided by the effective nucleon-nucleon and spin-orbit interactions. We also analyze the impact of the tensor interaction, and find that in some mean-field models it is essential to reproduce the crossing of the 2$p_{3/2}$ and 1$f_{5/2}$ proton single-particle levels, as in the case of the SAMi-T Skyrme force and the D1M Gogny interaction, whereas in other cases, as for example the SLy5 Skyrme force, a reasonable tensor force ... : 7 pages, 3 figures, 1 table ...