Analyzing powers and the role of multistep processes in the C12(Li7,t)O16 reaction

The analyzing powers $^{T}T_{10}\phantom{\rule{0.16em}{0ex}},^{T}T_{20}$, and $^{T}T_{30}$ for the $^{12}\mathrm{C}(^{7}\mathrm{Li},t$) reaction were measured and combined with new and previously determined angular distributions to probe the role of multistep processes through coupled channel Born approximation (CCBA) calculations employing new $\ensuremath{\alpha}$-particle spectroscopic amplitudes calculated with the phenomenological shell model in the unrestricted $psd$ space. Good descriptions of the cross-section angular distributions could be obtained except for the larger angles for the 6.05 MeV ${0}^{+}$ and 6.13 MeV ${3}^{\ensuremath{-}}$ states, while the analyzing powers were not generally described. The calculations presented demonstrate the sensitivity of the angular distributions of both the differential cross sections and the analyzing powers to various multistep routes. While the measured analyzing power $^{T}T_{30}$ is roughly zero for all states, the various CCBA calculations produced large and highly oscillatory values for this observable, showing that other multistep processes must be present beyond those taken into account in this work. Standard distorted wave Born approximation (DWBA) calculations were also carried out and these show considerable differences from the CCBA results but the description of the analyzing powers, while slightly improved, is still poor.