Direct and direct-fusion reaction approach to continuum spectra of nuclear reactions

The multistep direct reaction approach to nuclear reactions leading to the continuum is extended so as to include also partial fusion taking place in channels reached via direct reactions. How to calculate cross sections of particles emitted from such reactions is briefly discussed, showing particularly that these can be evaluated by utilizing the same ingredients as those used in the usual direct reaction calculations. As an example, we consider the breakup-fusion reaction (i.e. breakup followed by fusion of one of the broken-up pair with the target nucleus) and apply it to analyze spectra of protons emitted from α-induced reactions. It is shown that many features of the observed spectra can be accounted for by this mechanism. (author)