Dynamical effects in the heavy ion fusion reactions of the compound nucleusSr*80via charged particle evaporation

Abstract

The alpha-particle spectra and the proton spectra at different laboratory angles from the fusion reactions $^{16}\mathrm{O}+^{64}\mathrm{Zn}$ at $95\phantom{\rule{0.3em}{0ex}}\mathrm{Mev}$ and $^{32}\mathrm{S}+^{48}\mathrm{Ti}$ at $125\phantom{\rule{0.3em}{0ex}}\mathrm{MeV}$ were measured. Both systems have zero channel spin and lead to the compound nucleus $^{80}{\mathrm{Sr}}^{*}$ with the same value of ${l}_{\mathrm{max}}=43\ensuremath{\hbar}$. The observed spectra from the asymmetric reaction $^{16}\mathrm{O}+^{64}\mathrm{Zn}$ reaction can be reproduced with the statistical model calculations using rotating liquid drop model values of moment of inertia and transmission coefficients for spherical nuclei. However, the charged particle spectra in case of the symmetric $^{32}\mathrm{S}+^{48}\mathrm{Ti}$ reaction are not in agreement with the predictions of the statistical model. In order to explain the experimental spectra for the $^{32}\mathrm{S}+^{48}\mathrm{Ti}$ reaction, the analysis was done using the dynamical model of Feldmeier et al. [Rep. Prog. Phys. 50, 915 (1987)]. This analysis shows that the effective ${l}_{\mathrm{max}}$ value for fusion to take place in the case of the symmetric system is lowered to $30\ensuremath{\hbar}$. The statistical model calculations for the dynamical model predicted the ${l}_{\mathrm{max}}$ value reproduced the observed spectra reasonably well indicating entrance channel effects on the decay of the compound nucleus.