Self-consistent calculation of charge radii of Pb isotopes

Charge radii of lead isotopes are calculated with the HF plus BCS method, using Skyrme forces (SkM*, SIII and SGII) for the mean field. When these forces are combined with a seniority pairing force, all of them fail to reproduce the experiment. Neither higher-order corrections, nor ground-state correlations due to the collective modes can resolve the discrepancy. However, by introducing a density-dependent pairing force quenched inside the nucleus, one can explain the odd-even staggering as well as the large kink of charge radii at 208Pb when plotted versus A.