Quasielastic backscattering and barrier distributions for the ${}^{6,7}\text{Li}+{}^{64}\text{Zn}$ systems

Excitation functions of quasielastic scattering at backward angles were measured for the weakly bound ${}^6$Li and ${}^7$Li projectiles on a ${}^{64}$Zn target at energies around the Coulomb barrier. The corresponding barrier distributions were derived from the experimental cross sections. The experimental data were analyzed within the coupled-channel model using a double-folding potential as the bare potential. Inelastic excitations of the target, the ${}^7$Li first-excited state, and ${}^{6,7}$Li resonant state(s), corresponding to sequential breakup, were included in the calculations. The comparison between the data and coupled-channel predictions shows that the effects of channels not included in the calculations, such as direct breakup and transfers, are much larger for ${}^6$Li than for ${}^7$Li.

Figure 1

Typical $\Delta E$-$E_{\text{res}}$ spectrum for the ${}^6\text{Li}+{}^{64}\text{Zn}$ system measured at $E_{\text{lab}}=13$ MeV, ${\theta }_{\text{lab}}=170.2^{\circ }$.

Figure 2

Projection of events with $Z=3$ of Fig. 1 on the total-energy axis.

Figure 3

Two-dimensional $\Delta E$-$E$ spectrum for events with $Z=3$ from the ${}^7\text{Li}+{}^{64}\text{Zn}$ reaction at $E_{\text{lab}}=16$ MeV, ${\theta }_{\text{lab}}=170.2^{\circ }$.

Figure 4

(a) Ratio of measured backward-angle cross sections to Rutherford cross sections for elastic (filled squares), inelastic ${}^{64}$Zn($2_1^{+}$) (filled triangles), and quasielastic (filled circles) scattering for ${}^6\text{Li}+{}^{64}\text{Zn}$ system. (b) Barrier distributions derived from the elastic and quasielastic excitation functions.

Figure 5

(a) Ratio of measured backward-angle cross sections to Rutherford cross sections for elastic (filled squares), inelastic ${}^{64}$Zn($2_1^{+}$) (filled triangles), inelastic ${}^7$Li($1/2_1^{-}$) (empty circles), and quasielastic (filled circles) scattering and $1n$ transfer to the low-lying states of ${}^{65}$Zn (stars) for ${}^7\text{Li}+{}^{64}\text{Zn}$ system. (b) Barrier distributions derived from elastic and quasielastic excitation functions.

Figure 6

(a) Quasielastic backscattering excitation function and (b) quasielastic barrier distribution for ${}^6\text{Li}+{}^{64}\text{Zn}$ system. The lines are results of CC calculations (see text for details).

Figure 7

(a) Quasielastic backscattering excitation function and (b) quasielastic barrier distribution for ${}^7\text{Li}+{}^{64}\text{Zn}$ system. The lines are results of CC calculations (see text for details).

Figure 8

(a) Quasielastic backscattering excitation function and (b) quasielastic barrier distribution for ${}^6\text{Li}+{}^{64}\text{Zn}$ system. The lines represent the CC calculations using “experimental” deformation lengths for transitions in ${}^6$Li (see text for details).

Figure 9

(a) Excitation functions of elastic (filled squares) and inelastic ${}^{64}$Zn($2_1^{+}$) (filled triangles) backscattering and corresponding contributions to the QEL barrier distribution in panels (b) and (c), respectively, for ${}^6\text{Li}+{}^{64}\text{Zn}$ system. The lines represent the CC calculations using deformation lengths obtained from the Coulomb matrix elements (solid lines) and “experimental” deformation lengths (dashed lines) for transitions in ${}^6$Li (see text for details).

Figure 10

(a) Excitation functions of elastic (filled squares), inelastic ${}^{64}$Zn($2_1^{+}$) (filled triangles), and inelastic ${}^7$Li($1/2_1^{-}$) (empty circles) backscattering and the corresponding contributions to the QEL barrier distribution in panels (b), (c), and (d), respectively, for ${}^7\text{Li}+{}^{64}\text{Zn}$ system. The lines are results of CC calculations.