Multinucleon transfer in ${}^{58}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ and ${}^{60}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ in a stochastic mean-field approach

The multinucleon exchange mechanism in ${}^{58}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ and ${}^{60}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ collisions is analyzed in the framework of the stochastic mean-field approach. The results of calculations are compared with the time-dependent random-phase approximation (TDRPA) calculations and the recent data of ${}^{58}\mathrm{Ni}+{}^{60}\mathrm{Ni}$. A good description of the data and a relatively good agreement with the TDRPA calculations are found.

Figure 1

Density profile of the ${}^{58}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ at the center of mass energy $E_{\mathrm{c}.\mathrm{m}.}=135.6\mathrm{MeV}$ and the impact parameter $b=5.2\mathrm{fm}$ in the side configuration, at times 300 (a), 750 (b), and $1250\mathrm{fm}/c$ (c).

Figure 2

Neutron (solid lines) and proton (dotted lines) diffusion coefficients at the center of mass energy $E_{\mathrm{c}.\mathrm{m}.}=135.6\mathrm{MeV}$ and the impact parameter $b=5.2\mathrm{fm}$ in ${}^{60}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ collisions (a) and in ${}^{58}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ collisions in the side configuration (b).

Figure 3

One-sided mean-drift path at the center of mass energy $E_{\mathrm{c}.\mathrm{m}.}=135.6\mathrm{MeV}$ and the impact parameter $b=5.2\mathrm{fm}$ in ${}^{60}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ collisions (a) and in ${}^{58}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ collisions in the side and the tip configurations (solid and dashed lines) (b).

Figure 4

Covariances in the collision of ${}^{60}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ (a) and in the collision of ${}^{58}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ in the side geometry (b) at the center of mass energy $E_{\mathrm{c}.\mathrm{m}.}=135.6\mathrm{MeV}$ and the impact parameter $b=5.2\mathrm{fm}$, or equivalently initial orbital angular momentum $\ell =73\hslash$.

Figure 5

Dispersion ${\sigma }_{MR}$ per unit mass as function of the impact parameter. In (a), SMF and DRPA calculations in ${}^{60}\mathrm{Ni}+{}^{60}\mathrm{Ni}$ collisions are indicated by solid line and dash line with dots, respectively. In (b), SMF calculations in side and tip configurations (solid and dash lines) are compared with data.

Figure 6

Solid and dashed lines are the yields obtained from the SMF calculations, which are averaged over the tip and side configurations. For SMF1 and SMF2, the upper limit of the initial angular momentum is taken as ${\ell }_m=96\hslash$ and ${\ell }_m=90\hslash$, respectively. The experimental yield is indicated by the dotted line.