Isospin Impurity of the 6.88-MeV State inB10

The $\gamma$-ray yield for the reaction ${}_{}{}^9{}_{}{}^{}\mathrm{Be}(p, \gamma ){}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ has been measured over the range of bombarding energies 0.20-0.85 MeV and the radiative decay of the 6.88-MeV resonance level in ${}_{}{}^{10}{}_{}{}^{}\mathrm{B}$ studied. A large nonresonant contribution to the reaction cross section has been identified and compared with calculated cross sections based on an extranuclear direct-capture process. The previously measured high isospin impurity of the 6.88-MeV state is consequently significantly reduced; the amplitudes for the $T=0\mathrm{}$ and $T=1\mathrm{}$ parts of the wave function for this state are determined to be 0.92 and 0.39, respectively.