Total and partial capture cross sections in reactions with deformed nuclei at energies near and below the Coulomb barrie
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CLEI Theory
Total and Partial Capture Cross Sections in Reactions with Deformed Nuclei at Energies near and Below the Coulomb Barrier R. A. Kuzyakin* , V. V. Sargsyan, G. G. Adamian, and N. V. Antonenko Joint Institute for Nuclear Research, Dubna, Moscow oblast, 141980 Russia Received May 10, 2012; in final form, July 30, 2012
Abstract—Within the quantum diffusion approach, the capture of a projectile nucleus by a target nucleus is studied at bombarding energies above and below the Coulomb barrier. The effects of deformation of interacting nuclei and neutron transfer between them on the total and partial capture cross sections and the mean angular momentum of the captured system are studied. The results obtained for the 16 O + 112 Cd, 152 Sm, and 184 W; 19 F + 175 Lu; 28 Si + 94,100 Mo and 154 Sm; 40 Ca + 96 Zr; 48 Ca + 90 Zr; and 64 Ni + 58,64 Ni, 92,96 Zr, and 100 Mo reactions are in good agreement with available experimental data. DOI: 10.1134/S1063778813060094
1. INTRODUCTION In recent years, much attention has been given to experimentally and theoretically studying fusion and capture processes at near-barrier and subbarrier energies [1–13]. So far, investigation of fusion (capture) was focused primarily on measuring and calculating the excitation function—that is, the capture (fusion) cross section as a function of the energy of colliding nuclei. The capture (fusion) cross section is an integrated property of the angular-momentum distribution of partial capture (fusion) cross section. Since similar capture (fusion) cross sections can be obtained with different angular-momentum distributions, the angular-momentum distribution is more sensitive to basic ingredients of the model than the capture (fusion) cross section [14]. By way of example, we indicate that, in many reactions, capture (fusion) cross sections are described well, but mean angular momenta are not reproduced [15]. Therefore, a description of experimental angular-momentum distributions of partial fusion (capture) cross sections or their moments is a good test of the viability of fusion (capture) models. It is noteworthy that investigation of partial cross sections is of importance for better understanding the survival of a compound nucleus in the formation of evaporation residues, especially at high angular momenta, in which case a significant part of the excitation energy goes over to the rotation of the nucleus involved. Processes involving the fusion and capture of nuclei are affected not only by quantum effects but also *
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by the deformation of interacting nuclei and by neutron transfer between them [1, 16]. As for a nuclear deformation, experiments confirmed its effect on fusion and capture processes, and this effect consists in the following: if the target nucleus is prolate in the ground state, then the Coulomb barrier at its end is lower than that at its side, this leading to an increase in the probability for fusion and capture at subbarrier energies in relation to what we have for spherical nuclei. The effect of neut
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