Influence of Pairing Correlations on the Probability and Dynamics of Tunneling Through the Barrier in Fission and Fusion of Complex Nuclei

摘要

An analytically solvable model is used to study the potential barrier penetrability in the case when the gap parameter delta is treated as a dynamical variable governed by the least action principle. It is found that, as compared to the standard (BCS) approach, the dynamical treatment of pairing results in a considerably weakened dependence of the fission barrier penetrability on the intensity of pairing correlations in the initial state ( delta /sub 0/), on the barrier height, and on the energy of the initial state. On this basis, a more adequate explanation is proposed for typical order-of-magnitude values of the empirical hidrance factors for groun-state spontaneous fission of odd nuclei. It is also shown that a large enhancement of superfluidity in tunneling - the inherent effect of the dynamical treatment of pairing - strongly facilitates deeply subbarier fusion of complex nuclei. Finally, an analysis is given for the probability of spontaneous fission from K-isomeric quasiparticle (q-p) states in even-even heavy nuclei. The relative change of the partial spontaneous fission half-life in going from the ground-state to a high-spin q-p isomeric state, T*/sub sf//T/sub sf/, is found to be strongly dependent on whether or not there takes place the dynamically induced enhancement of superfluidity in tunneling. Measurements of T*/sub sf//T/sub sf/ provide thus a unique possibility of verifying theoretical predictions about the strong, inverse-square delta dependence of the effective inertia associated with large-scale subbarrier rearrangements of nuclei. 49 refs.; 7 figs. (Atomindex citation 19:021291)