Two-body dissipation effect in nuclear fusion reactions

Abstract

Friction coefficients for the fusion reaction ${}^{16}$O+${}^{16}$O $\to$ ${}^{32}$S are extracted based on both the time-dependent Hartree-Fock and the time-dependent density matrix methods. The latter goes beyond the mean-field approximation by taking into account the effect of two-body correlations, but in practical simulations of fusion reactions we find that the total energy is not conserved. We analyze this problem and propose a solution that allows for a clear quantification of dissipative effects in the dynamics. Compared to mean-field simulations, friction coefficients in the density-matrix approach are enhanced by about $20\%$. An energy-dependence of the dissipative mechanism is also demonstrated, indicating that two-body collisions are more efficient at generating friction at low incident energies.

Comments: 9 pages, 6 figures