Using radiation from the ${\mathrm{F}}^{19}(p, \alpha \gamma )$ reaction at 874-kev proton energy, the cross section for the reaction ${\mathrm{C}}^{13}(\gamma , n)$ was found to be 94.1±10 microbarns. The neutrons emitted from a target enriched in ${\mathrm{C}}^{13}$ were detected by an arrangement of B${\mathrm{F}}_3$ counters embedded in wax to give a $4\pi$ geometry.

• Received 25 April 1960

DOI:https://doi.org/10.1103/PhysRev.119.1643