J.D. Bierman, P. Chan, M.P. Kelly, J.F. Liang, A.A. Sonzogni and R. Vandenbosch
We have completed an experiment to obtain the fusion cross sections for the systems 40Ca + 46,48,50Ti at energies close to the Coulomb barrier. Description of the experimental technique as well as the motivation for the project can be found in the previous Annual Report.1
As an example of our results, we show in the figure below the cross sections and the corresponding barrier distributions for 40Ca + 48Ti. The full line is from a coupled channel calculation, while the dashed line is from an uncoupled one.
By analyzing the fusion excitation functions, we found that 40Ca + 50Ti has a larger enhancement in the sub-barrier fusion cross section than 40Ca + 48Ti, which in turn presents a larger enhancement than 40Ca + 46Ti.
We used a coupled channel model2 to separate inelastic and transfer contributions. We found that most of the enhancement for 46Ti could be explained by the inelastic coupling alone, while 50Ti required an important transfer contribution. A similar situation was observed when trying to fit the barrier distributions.
Fig. 3.4-1. The left panel shows the fusion excitation function for 40Ca + 48Ti as a function of the center of mass energy. The right panel shows the corresponding barrier distribution. The full line is from a coupled channel calculation while the dashed line is from an uncoupled one.