Phase transition in the ground state rotational band of sd shell nuclei

A similar anomaly at high angular momentum states as the "back bending" effect in rare earth nuclei is found in the sd shell. It can be quantitatively understood by a phase transition due to the Coriolis Antipairing (CAP) effect. The phase transition is calculated by performing a Hartree-Fock-Bogoliubov (HB) calculation with angular momentum projection approximately before variation (PHB). This method determines for each angular momentum the amount of pairing independently. Results obtained utilizing reaction matrix elements derived from the Hamada-Johnston potential agree in 22Ne and 24Ne surprisingly well with the experimental data.