Superfluid-to-normal phase transition and extreme regularity of superdeformed bands

Abstract

We derive the exact semiclassical expression for the second inertial parameter B for the superfluid and normal phases. Interpolation between these limiting values shows that the function B(I) changes sign at the spin I c , which is critical for a rotational spectrum. The quantity B turns out to be a sensitive measure of the change in static pairing correlations. The superfluid-to-normal transition reveals itself in the specific variation of the ratio B/A versus spin I with the plateau characteristic of the normal phase. We find this dependence to be universal for normal deformed and superdeformed bands. The long plateau with a small value B/A ∼ A −8/3 explains the extreme regularity of superdeformed bands.