A systematic investigation of the Coriolis antipairing effect in the rare earth region including projection onto exact particle number and angular momentum

The Coriolis antipairing effect is investigated for the rare earth nuclei. A new two-parameter expression for the pairing strength is introduced which is adjusted to the even-odd mass differences. Good agreement with the experimental results concerning the linear part of the moment of inertia as a function of the square of the angular velocity can be reached if projection onto exact particle number is taken into account. The latter causes an essential stabilization of the pair correlations. The critical angular velocity for the transition from the suprafluid to the normal state is defined and calculated. It is substantially increased by projection onto exact particle number whereas it remains almost unchanged by projection onto exact angular momentum. The critical angular velocity at which the neutron pairing vanishes is systematically larger than the angular velocity at which back-bending is observed. From this it is concluded that backbending cannot be caused by a collapse of pairing.