Relation between pairing correlations and two-particle space correlations

We study the spatial correlations between two particles (or two holes) around a closed shell core in terms of the probability distribution expressed as a function of the c.m. coordinate $R$ of the two particles and of their relative coordinate $r$. We find that the mixing of configurations induced by the pairing force leads to a probability distribution centered in regions corresponding to larger values of $R$ and smaller values of $r$, as compared to the case of a pure ${\mathrm{}\left(j\right)\mathrm{}}_0^2$ configuration. This tendency to a "surface clustering" is mainly due to the interference of the contributions coming from levels with different parity. However, even with the inclusion of a large number of configurations, the size of the localized "cluster" is much larger than that of a free dinucleon system.