The cross section for the capture of protons by ${\mathrm{C}}^{13}$ at 129 kilovolts is $\sigma =5\mathrm{}\pm 1\times {10}^{-33\mathrm{}} {\mathrm{cm}}^2.$ This measurement was made possible through the use of a scintillation counter that had an over-all detection efficiency of 8.7 percent, and a pulsed ion source that had a peak proton current capability of one milliampere. A rough analysis of the radiation shows that 80 percent is due to the transition to the ground state of ${\mathrm{N}}^{14}$, while the exact nature of the remaining 20 percent was not determined.

• Received 27 September 1951

DOI:https://doi.org/10.1103/PhysRev.85.51