Angular-momentum-projected yrast states in even xenon isotopes

Using the procedure of Ewart and de Takacsy to obtain expressions for the energy of angular momentum projected yrast states coming from coherent phonon intrinsic states, the energy expressions are then minimized with respect to the phonon structure coefficients and for each individual level the calculation is made self-consistent with an amended Bardeen-Cooper-Schrieffer number equation. The pairing plus quadrupole Hamiltonian is used and quite good results are obtained for the low spin yrast states of even xenon isotopes. The proton gap was found to vanish at J = 10 or 12