Q-DEFORMED PAIRING VIBRATIONS

Boson creation operators constructed from linear combinations of q-deformed zero-coupled nucleon pair operators acting on the nucleus (A,0) are used to derive pp random phase approximation equations. The solutions of these equations are the pairing vibrations in (A2) nuclei. For the 01+ and 02+ states of the nucleus Pb208, the variations of relative energies and transfer cross sections for populating these states via (t,p) reaction, with deformation parameter have been analyzed. For =0.405 the experimental excitation energy of 4.87 MeV and the ratio (02+)/(01+)=0.45 are well reproduced. The critical value of pairing interaction strength, for which phase transition takes place, is seen to be lower for deformed zero-coupled nucleon pair condensate with real, supporting our earlier conclusion that the real deformation simulates the two-body residual interaction. For purely imaginary a stronger pairing interaction is required to bring about the phase transition. The effect of imaginary deformation is akin to that of an antipairing type repulsive interaction. Using deformed zero-coupled quasiparticle pairs, a deformed version of quasiboson approximation for 0+ states in superconducting nuclei is developed. For the test model of 20 particles in two shells, the results of q-deformed boson and quasiboson approximations have been compared with exact results. It is found that the deformation effectively takes into account the anharmonicities and may be taken as a quantitative measure of the correlations not being accounted for in a certain approximate treatment. © 1994 The American Physical Society.