Thermal Neutron Capture Cross Section of Carbon-13

The thermal neutron capture cross section of ${\mathrm{C}}^{13}$ has been determined from the amount of ${\mathrm{C}}^{14}$ formed in pile-irradiated samples of graphite, barium carbonate, and carbon dioxide. Because of the impurity reaction, ${\mathrm{N}}^{14}(n, p){\mathrm{C}}^{14}$, of comparatively high cross section, the results were consistent only when samples were used which were enriched in ${\mathrm{C}}^{13}$.