From the pulse-height spectrum from a ${\mathrm{BF}}_3$ proportional counter exposed to water-moderated ${}_{}{}^{252}{}_{}{}^{}\mathrm{Cf}$ neutrons, the thermal cross section for the reaction ${}_{}{}^{10}{}_{}{}^{}\mathrm{He}$ is determined to be 7±2 mb.

• Received 5 June 1987

DOI:https://doi.org/10.1103/PhysRevC.36.1194