Elastic scattering and fusion cross sections for ${}^7\mathrm{Be}$,${}^7\mathrm{Li}+{}^{27}\mathrm{Al}$ systems

Quasi-elastic-scattering and transfer reaction cross-section measurements were made for the ${}^7\mathrm{Be}+{}^{27}\mathrm{Al}$ system at $E_{\mathrm{lab}}=17$, 19, and 21 MeV in the angular range ${\theta }_{c.m.}={12}^{°}-{43}^{°}$. An optical model (OM) analysis of the quasi-elastic scattering data was carried out. The fusion cross sections were derived at these energies by subtraction of the integrated transfer cross sections from the reaction cross sections obtained from the fits to quasi-elastic-scattering data. These fusion cross sections were found to be consistent with those obtained from the coupled-channels calculations. Elastic scattering and fusion cross sections were measured for the ${}^7\mathrm{Li}+{}^{27}\mathrm{Al}$ system at $E_{\mathrm{lab}}=10$, 13, 16, 19, and 24 MeV. For elastic scattering the angular coverages were in the ${\theta }_{\mathrm{lab}}={12}^{°}-{72}^{°}$ range and for fusion the α-evaporation spectra from the compound nucleus were measured in the angular range ${\theta }_{\mathrm{lab}}={52}^{°}-{132}^{°}$ (142° at 10 MeV). The elastic-scattering angular distributions were subjected to OM analysis. The α-evaporation spectra were reproduced with the statistical model calculations, and the fusion cross sections were extracted from them. The fusion cross sections were also extracted by subtraction of the integrated inelastic-scattering cross sections from the reaction cross sections obtained from the OM fits to the elastic-scattering data, and these fusion data were found to be consistent. The CCDEF calculations describe these data quite well. A comparison of the fusion data for the ${}^7\mathrm{Be}+{}^{27}\mathrm{Al}$ and ${}^7\mathrm{Li}+{}^{27}\mathrm{Al}$ systems shows a similar and consistent behavior.

Figure 1

Schematic diagram of the HIRA RIB facility at IUAC.

Figure 2

Experimental setup for measuring elastic, transfer, and fusion cross sections for the ${}^7\mathrm{Be}+{}^{27}\mathrm{Al}$ system.

Figure 3

1D elastic scattering spectrum for ${}^7\mathrm{Be}+{}^{27}\mathrm{Al}$ system, with target and blank for the same incident flux at $E_{\mathrm{lab}}=21$ MeV and ${\theta }_{\mathrm{lab}}={27}^{°}$.

Figure 4

Angular distributions for quasi-elastic scattering of ${}^7\mathrm{Be}$ from ${}^{27}\mathrm{Al}$ at $E_{\mathrm{lab}}=17$, 19, and 21 MeV. The solid curves are OM fits obtained with the SNOOPY code [34].

Figure 5

Fusion cross sections (solid squares) obtained from the analysis of quasi-elastic-scattering data and from the coupled-channels calculations by use of CCDEF [38] (continuous curve). The triangular point at $E_{c.m.}=19.05$ MeV is for the ${}^7\mathrm{Li}+{}^{27}\mathrm{Al}$ system (taken from Ref. 7).

Figure 6

Angular distributions for elastic scattering of ${}^7\mathrm{Li}$ from ${}^{27}\mathrm{Al}$ at $E_{\mathrm{lab}}=10$, 13, 16, 19, and 24 MeV. The solid curves are OM fits obtained with the SNOOPY code [34].

Figure 7

α-energy spectra from ${}^7\mathrm{Li}+{}^{27}\mathrm{Al}$ $\to {}^{34}{S}^{*}$ CN at various angles corresponding to various lab energies.

Figure 8

Comparison of experimental fusion cross sections with CCDEF calculations for the ${}^7\mathrm{Li}+{}^{27}\mathrm{Al}$ system.

Figure 9

Reduced fusion excitation functions for ${}^7\mathrm{Be}$, ${}^9\mathrm{Be}$, ${}^7\mathrm{Li}+{}^{27}\mathrm{Al}$ systems with reduced energy scale.

Figure 10

Reduced fusion excitation functions for systems consisting of different projectiles on the same target.