Neutron-proton interaction and backbending in Cr nuclei

The high-spin state properties of the neutron-proton (n-p) residual effective interaction are analysed in Cr nuclei, where the experiments have observed anomalous rotational alignment. The self-consistent microscopic Hartree-Fock-Bogoliubov equations have been solved by employing monopole and quadrupole pairing plus quadrupole-quadrupole interaction. We have studied the mechanism of backbending in yrast energies in terms of moment of inertia and angular frequencies, E2 transition probabilities and quadrupole moments as a function of the angular momentum states. It is shown that the self-consistent theory with variation after angular momentum projection describes well overall trends of experimental data with n-p residual interaction strength decreasing from 0.0795 in a N = Z nucleus to 0.0495 MeV b in a N = Z + 2 nucleus. However, the strong n-p residual interaction force is quite important in explaining the experimental data in N ≈ Z.