Pairing rotations and separation energies

Recent experiments exhibit a strong regularity of the two-neutron (proton) binding energies in superconducting nuclei. Using BCS calculations by Soloviev and by Kisslinger and Sorensen for the rare earth and tin region, respectively, we show that the pairing rotational model accounts for this behaviour provided the deformation does not change appreciably when two neutrons or protons are added to the system. The model relates the degree of pairing to the ground state energies of neighbouring even-even nuclei and supplements the information coming from the odd-even effect.