Radiative Capture of Protons byBe9

Abstract

The gamma rays from the capture in ${\mathrm{Be}}^9$ of protons of energy between 0.27 and 1.2 Mev have been studied using large scintillation crystals. Excitation functions of the gamma rays leading to the 0-, 0.72-, 1.74-, 2.15-, 3.58-, and 5.16-Mev states of ${\mathrm{B}}^{10}$ were computed from the measured gamma-ray spectra. In addition to the resonances previously known to exist at 0.33-, 0.99-, and 1.086-Mev proton energy [corresponding to ($1^{-}$) 6.88-, ($2^{-}$) 7.48-, and ($0^{+}$) 7.56-Mev states in ${\mathrm{B}}^{10}$], evidence was found only for the $p$-wave resonance near 1 Mev [($2^{+}$) 7.5-Mev state in ${\mathrm{B}}^{10}$] postulated by Mozer and by Dearnaly and for the influence of higher lying states. This work leaves unexplained the large isotopic-spin impurity of the 6.88-Mev level. Appreciable nonresonant capture was found for the transitions to the 0-, 0.72-, 3.58-, and 5.16-Mev states, which is probably not $s$-wave for the latter two transitions. Accurate energy measurements and coincidence work showed that the 5.16-Mev level of ${\mathrm{B}}^{10}$ is populated in preference to the 5.11-Mev level, contradicting earlier work of Clegg. Also, experimental evidence has been found which appears to be in contradiction to the $0^{+}$ spin assignment for the 7.56-Mev level of ${\mathrm{B}}^{10}$ and raises doubts about the $2^{+}$ spin assignment of the 5.16-Mev level.