A measurement of the ($n, t$) cross sections for ${\mathrm{Be}}^9$, ${\mathrm{B}}^{10}$, and ${\mathrm{B}}^{11}$ is described. The tritium yield was determined by absolute counting of the beta activity. Neutron fluxes were measured by standard techniques. The following values were obtained for the ($n, t$) cross sections at the indicated neutron energies: ${\mathrm{Be}}^9$ at 14.1 Mev, 18±1.5 mb; ${\mathrm{B}}^{10}$ at 4 Mev, 95±10 mb; ${\mathrm{B}}^{10}$ at 5.6 Mev, 230±25 mb; ${\mathrm{B}}^{10}$ at 9.6 Mev, 125±15 mb; ${\mathrm{B}}^{10}$ at 14.1 Mev, 85±6 mb; ${\mathrm{B}}^{10}$ for fission spectrum, 30±2 mb; ${\mathrm{B}}^{11}$ at 14.1 Mev, 15±5 mb.

• Received 24 July 1958

DOI:https://doi.org/10.1103/PhysRev.112.1264