A pulsed-beam time-of-flight technique has been used to study neutrons and $\gamma$ rays from the proton bombardment of ${\mathrm{Be}}^9$ in the energy range from 2.3 to 5.4 Mev. Excitation curves for the ground-state neutron group from the ${\mathrm{Be}}^9(p, n){\mathrm{B}}^9$ reaction have been measured at 0° and 90°. These curves show the well-known resonances at 2.56 and 4.6 Mev and, in addition, show a broad maximum near 3.5 Mev. The $\gamma$-ray excitation curve also indicates maxima at 2.56, 3.5, and 4.5 Mev. The 3.5- and 4.6-Mev resonances are tentatively assigned to $p$- and $d$-wave states having ($J=2^{+}$, $T=1\mathrm{}$) and ($J=3^{-}$, $T=1\mathrm{}$), respectively. The previously observed maximum near 4.9 Mev appears to be the result of the effect of the 3.5-Mev resonance on the $n_1$ group immediately above its threshold. The cross section for the production of continuum neutrons is appreciable for proton energies above about 3 Mev. A large fraction of these neutrons appear to result from the neutron decay of the 2.43-Mev ${\mathrm{Be}}^9$ level following the inelastic excitation of this level.

• Received 12 February 1959

DOI:https://doi.org/10.1103/PhysRev.115.144