The absolute total ($4\pi$) neutron yield from ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(\alpha , n)$ has been measured for alpha energies from 1.7 to 10.5 MeV by extension of earlier measurements. In addition to previously reported states in ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, resonance peaks are observed corresponding to $E_{\mathrm{ex}}$ of 15.3 and 17.0 MeV. The widths for resonances at $E_{\alpha }=1.92, 2.25, \mathrm{and} 2.58$ MeV are 0.2, 0.4, and 0.3 MeV, respectively. Near $E_{\alpha }=10\mathrm{}$ MeV, reactions leading to states in ${}_{}{}^{12}{}_{}{}^{}C$ apparently account for <30% of the observed cross section.

• Received 6 November 1964

DOI:https://doi.org/10.1103/PhysRev.137.B1508