(α,2α) cluster knockout reaction on9Beand12Cat 580 MeV

Cross-section measurements of the ${}^{9}\mathrm{Be}{,}^{12}\mathrm{C}(\ensuremath{\alpha},2\ensuremath{\alpha})$ reaction at 580 MeV bombarding energy are presented. The data are compared with distorted-wave impulse approximation calculations. The agreement between theory and experiment suggests a dominance of the quasifree knockout mechanism. The extracted $\ensuremath{\alpha}$-particle spectroscopic factors are in reasonable agreement with theory and proton-induced knockout reactions, unlike measurements for the $(\ensuremath{\alpha},2\ensuremath{\alpha})$ reaction at energies $l~140$ MeV, but still show significant angular dependence.