Investigation of the type of quadrupole pairing force in superdeformed nuclei

The variations of moments of inertia of superdeformed (SD) bands 194Hg(1) and 192Hg(1) with angular momentum (rotational frequency) are investigated using the particle-number conserving (PNC) method for treating the cranked shell model. Calculations show that if both the monopole and Y20 quadrupole pairing forces are taken into account, the observed ω variation of the moments of inertia of 194Hg(1) and 192Hg(1) can be reproduced very well both in the low-ω and high-ω ranges, in particular the J(2) downturn of 194Hg(1) and the flattening in J(2) of 192Hg(1) at ℎω≥0.40 MeV. On the contrast, the calculated J(2)'s with the Y2+-1 or Y2+-2 quadrupole pairing forces are in disagreement with the experiments. The microscopic mechanism of the ω variation of J(2) is clearly exhibited in the PNC calculation (the contributions to J(2) from various major shells and individual cranked Nilsson orbitals, the occupancy of each cranked Nilsson orbital etc). The ω variation of moment of inertia is the result of the competition among the shell effect (single particle motion in a deformed potential), pairing correlation, Pauli blocking effect and Coriolis (anti-pairing) interaction