The Lane-Lynn theory of direct capture is subjected to a quantitative test in the radiative capture of thermal neutrons by ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$. Strong destructive interference effects are observed for the ground state transitions in ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$ as predicted by the theory. An outcome of these investigations is the demonstration of the physical significance of the interaction radius. The theory was applied to deduce a ($d, p$) spectroscopic factor of 0.060 ± 0.004 for the 6589 keV state of ${}_{}{}^{14}{}_{}{}^{}\mathrm{C}$. In addition, the ratio of the radiative capture cross section of ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ relative to ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ was measured as 0.388 ± 0.010.

NUCLEAR REACTIONS ${}_{}{}^{12,13}{}_{}{}^{}\mathrm{C}(n, \gamma )$ $E=\mathrm{thermal}$; measured ${\sigma }_{\gamma }$, $I_{\gamma }$. ${}_{}{}^{12,13}{}_{}{}^{}\mathrm{C}$ levels; verified Lane-Lynn theory of direct capture; deduced $S$.

• Received 30 April 1982

DOI:https://doi.org/10.1103/PhysRevC.26.2698