The differential cross sections for the ${\mathrm{F}}^{19}(d, \alpha ){\mathrm{O}}^{17}$ reaction which leave ${\mathrm{O}}^{17}$ in its ground and lowest four excited states have been measured using silicon surface-barrier detectors. Thin Teflon targets (370 to 720 μg/${\mathrm{cm}}^2$) were bombarded with 9.2-MeV deuterons and alpha spectra were obtained at 46 laboratory angles between 10 and 172.5°. The five angular distributions exhibited forward and backward peaking, an over-all oscillatory structure, and minima whose magnitudes differ significantly from zero. The angular distributions are analyzed in terms of an expression which is the sum of an isotropic term and one which arises from the simultaneous action of two-nucleon pickup and heavy-particle stripping (HPS) mechanisms. Good fits are obtained for the ${\alpha }_0$, ${\alpha }_2$, and ${\alpha }_4$ distributions, but only the gross features of the ${\alpha }_1$ and ${\alpha }_3$ distributions could be fitted. A discussion regarding the identification of either the pickup or the knockout mechanism as the dominant forward-angle direct-interaction process for ($d, \alpha$) reactions in light nuclei is presented. It is concluded that the experimental angular distributions are fitted equally well irrespective of which one is assumed to act along with HPS. An interpretation of the differential cross sections is made which is based on the speculation that direct-interaction and statistical compound-nucleus (SCN) processes contribute incoherently. A method for the decomposition of the cross section is proposed in which the SCN contribution is assumed to be isotropic. The integrated SCN component of the cross sections is shown to be closely proportional to $2I+1$.

• Received 16 November 1964

DOI:https://doi.org/10.1103/PhysRev.138.B51