Giant resonances in ${}^{116}\mathrm{Sn}$ from 240 MeV ${}^6\mathrm{Li}$ scattering

Giant resonances in ${}^{116}\mathrm{Sn}$ were measured by inelastic scattering of ${}^6\mathrm{Li}$ ions at $E_{{}^6\mathrm{Li}}=240$ MeV over the angle range $0^{°}\text{−}{6}^{°}$. Isoscalar $E0\text{−}E3$ strength distributions were obtained with a double folding model analysis. A total of ${106}_{-11}^{+27}\%$ of the $E$0 EWSR was found in the excitation energy range from 8 MeV to 30 MeV with a centroid ($m_1/m_0)$ energy $15.{39}_{-0.20}^{+0.35}$ MeV in agreement with results obtained with $\alpha$ inelastic scattering.

Figure 1

Sample excitation spectra taken for average center of mass angles $1.1^{°}$ and $5.9^{°}$ for 240 MeV ${}^6\mathrm{Li}$ ions scattered from ${}^{116}\mathrm{Sn}$. The gray curves represent different continuum choices used in the analysis.

Figure 2

Angular distributions of the differential cross sections for 240 MeV ${}^6\mathrm{Li}$ inelastic scattering from ${}^{116}\mathrm{Sn}$ for 100% of the respective EWSR for $L=0\text{−}4$ over the excitation energy range $8\text{−}40$ MeV in 2 MeV intervals. The cross sections decrease as the excitation energy increases.

Figure 3

Angular distributions of the differential cross section for 240 MeV ${}^6\mathrm{Li}$ inelastic scattering from ${}^{116}\mathrm{Sn}$ for $L=0\text{−}4$ for 100% of the EWSR at $E_x=15.0$ MeV.

Figure 4

Angular distributions of the cross section for inelastic scattering of 240 MeV ${}^6\mathrm{Li}$ from ${}^{116}\mathrm{Sn}$ for portions of the giant resonance peak and the continuum along with DWBA fits. The data are summed over 1.6 MeV wide excitation energy bins centered at $E_x=12.62,22.20,30.17$ MeV. The angular distributions for the giant resonance peak are on the left and those for the continuum are on the right. The thin black lines through the data show the fits. The $E0$ contribution is shown by the thick black line, with contributions from other multipoles labeled in the figure.

Figure 5

Isoscalar $E0\text{−}E3$ EWSR Strength distributions (a: $E0$, b: $E1$, c: $E2$, d: $E3$) for ${}^{116}\mathrm{Sn}$ obtained from analysis of ${}^6\mathrm{Li}$ inelastic scattering (black). Those obtained with $\alpha$ inelastic scattering [18] are shown in gray. Error bars represent the uncertainty due to the fitting of the angular distributions and different choices of the continuum as described in the text.

Figure 6

Comparison of the strength distribution for $E0\text{−}E3$ transitions (a: $E0$, b: $E1$, c: $E2$, d: $E3$) extracted from ${}^6\mathrm{Li}$ inelastic scattering using the deformed potential model (black) with those obtained from $\alpha$ inelastic scattering [37] using a folding potential (gray).