Two-neutron pairing enhancement factors

The Spin Spectrometer was used to separate Dy ground-band and two-quasiparticle populations in one- and two-neutron transfer reactions with Sn and Ni projectiles. Transfer probabilities ${\mathit{P}}_{1\mathit{n},2\mathrm{}\mathit{n}}$ and two-neutron enhancement factors F==${\mathit{P}}_{2\mathit{n}}$/${\mathit{P}}_{1\mathit{n}}^2$ were determined as a function of scattering angle. For the two-quasiparticle bands F≃7–20, but for the ground band F≃30–500, indicating large pairing effects in two-particle transfer to the ground band. The data also indicate larger enhancement factors in Sn than in Ni collisions.