Effect of the breakup on the fusion and elastic scattering of weakly bound projectiles on ${}^{64}\mathrm{Zn}$

We study the behavior of the fusion, breakup, reaction, and elastic scattering of different projectiles on ${}^{64}\mathrm{Zn}$, at near and above barrier energies. We present fusion and elastic scattering data with the tightly bound ${}^{16}\mathrm{O}$ and the stable weakly bound ${}^6\mathrm{Li}$, ${}^7\mathrm{Li}$, and ${}^9\mathrm{Be}$ projectiles. The data are analyzed by coupled channel calculations. The total fusion cross sections for these systems are not affected by the breakup process at energies above the barrier. The elastic (noncapture) breakup cross section is important at energies close to and above the Coulomb barrier and increases the reaction cross sections. In addition, we show that the breakup process at near and below barrier energies is responsible for the vanishing of the usual threshold anomaly of the optical potential and gives rise to a new type of anomaly.

Figure 1

(a) Typical biparametric energy vs. mass spectrum obtained for the ${}^9\mathrm{Be}+{}^{64}\mathrm{Zn}$ system at ${\theta }_{\mathrm{lab}}$ = 10° and 24 MeV and (b) projection of this spectrum on the mass axis.

Figure 2

Total fusion for the ${}^9\mathrm{Be}+{}^{64}\mathrm{Zn}$ system, as a function of 1/E${}_{c.m}$., obtained by the γ-ray and TOF methods.

Figure 3

Total fusion and reaction excitation functions for the ${}^{16}\mathrm{O}+{}^{64}\mathrm{Zn}$ system. The dashed and solid curves are results of $\text{CCFULL}$ calculations for the fusion without couplings and with coupling to the first two excited states of the target, respectively.

Figure 4

Reaction and total fusion excitation functions for the ${}^9\mathrm{Be}+{}^{64}\mathrm{Zn}$ system, and the estimated EBU cross sections (see text for details). The dashed and solid curves are results of $\text{CCFULL}$ calculations for fusion (TF) without couplings and with coupling of target excited states, respectively.

Figure 5

Same as Fig. 4, but for the ${}^6\mathrm{Li}+{}^{64}\mathrm{Zn}$ system.

Figure 6

Same as Fig. 4, but for the ${}^7\mathrm{Li}+{}^{64}\mathrm{Zn}$ system, without couplings.

Figure 7

Elastic scattering angular distribution fits by the use of the SPOP with two free parameters (solid curves) and without any fit parameter (dashed curves), for the ${}^9\mathrm{Be}+{}^{64}\mathrm{Zn}$ system. $\sigma /{\sigma }_{\mathrm{Ruth}.}$ is the ratio between the elastic and Rutherford differential cross sections.

Figure 8

Energy dependence of the normalization factors $N_R$ and $N_i$, for real and imaginary potentials, corresponding to the SPOP with two free parameters, for the ${}^9\mathrm{Be}+{}^{64}\mathrm{Zn}$ system. The solid horizontal lines are the values of these parameters, fixed for the global potential without any fit. The vertical arrow indicates the energy of the Coulomb barrier $V_B$.

Figure 9

Same as Fig. 7, but for the ${}^{16}\mathrm{O}+{}^{64}\mathrm{Zn}$ system. ${\sigma }_{\mathrm{el}.}/{\sigma }_{\mathrm{Ruth}.}$ is the ratio between the elastic and Rutherford differential cross sections.

Figure 10

Same as Fig. 8, but for the ${}^{16}\mathrm{O}+{}^{64}\mathrm{Zn}$ system.