Effect of energy variation on the dissipative evolution of the system in heavy-ion fusion reactions

In heavy-ion fusion reactions, the energy of the projectile couples with the intrinsic degrees of freedom of the target during the collision process and this leads to a dissipative phenomenon. Consequently, the dissipation in the system causes the angular momentum hindrance during the fusion process. In this work, we have focused on the dissipative behavior of the fusing nuclei and its dependency on the incident energy. The dissipative evolution of the system depends not only on the entrance channel mass asymmetry but also on the incident energy, which was not mentioned in earlier studies. Moreover, the dissipative behavior of the fusing nuclei is also compared with respect to the entrance channel parameters like mass asymmetry $\alpha$ and the Coulomb interaction term $Z_P{Z}_T$. The dissipation phenomenon decreases when the mass asymmetry increases and it increases when the Coulomb interaction term $Z_P{Z}_T$ increases.

Figure 1

Comparison of experimental charged-particle spectra (dots) with the statistical model (solid line) for asymmetric and symmetric reactions [7] (a) ${}^{16}\mathrm{O}+{}^{63}\mathrm{Cu}$ at 109 MeV and (b) ${}^{34}\mathrm{S}+{}^{45}\mathrm{Sc}$ at 140 MeV.

Figure 2

Comparison of exclusive experimental neutron spectra (dots) with the statistical model (solid line) for asymmetric reaction and symmetric reactions [13] (a) ${}^{12}\mathrm{C}+{}^{46}\mathrm{Ti}$ at 80 MeV and (b) ${}^{31}\mathrm{P}+{}^{27}\mathrm{Al}$ at 131 MeV.

Figure 3

Calculated evolution of the separation ($s$) as a function of time for asymmetric systems (a)–(c) and symmetric systems (d)–(f).

Figure 4

Variation of angular momentum ${\mathit{l}}_{\max }$ with respect to incident energy $E_{\mathrm{lab}}$ for asymmetric systems (a)–(c) and symmetric systems (d)–(f).

Figure 5

Variation of angular momentum difference $\mathrm{\Delta }{\mathit{l}}_{\max }$ with respect to mass asymmetry $\alpha$ for various target-projectile combinations, leading to the same compound nucleus ${}^{80}\mathrm{Sr}$ at different excitation energies.

Figure 6

Variation of angular momentum difference $\mathrm{\Delta }{\mathit{l}}_{\max }$ with respect to the charge product $Z_P{Z}_T$ for various target-projectile combinations, leading to the same compound nucleus ${}^{80}\mathrm{Sr}$ at different excitation energies.

Figure 7

Threshold energy $E_s$ vs $\zeta$ for several heavy-ion fusion systems, where the $Q$ values for the fusion are positive.