${}^7\mathrm{Li}(d,\alpha \alpha )n$ reaction and the $2^{+}$ isospin-mixed doublet in ${}^8\mathrm{Be}$

Coincidence spectra from the ${}^7\mathrm{Li}(d,\alpha \alpha )n$ reaction measured for incident energies from 3 to 6 MeV show strong direct contributions for the lower (16.6 MeV) state of the ${}^8\mathrm{Be}$ isospin mixed doublet as well as the interference of these states. We discuss how similar behavior of the mirror $\mathrm{}(d,p)\mathrm{}$ reaction at low energy could affect determination of the total ${}^7\mathrm{Li}{\mathrm{}(d,p)\mathrm{}}^8\mathrm{Li}$ cross section at 0.78 MeV, the quantity often used for normalization in the measurement of the astrophysically important ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ reaction.