Clusters in the photodisintegration of 9 Be

The ground-state cross sections and angular distributions of ${}^{9}\mathrm{Be}(\ensuremath{\gamma},p),{}^{9}\mathrm{Be}(\ensuremath{\gamma},t),{}^{9}\mathrm{Be}(\ensuremath{\gamma}{,}^{3}\mathrm{He}),$ and ${}^{9}\mathrm{Be}(\ensuremath{\gamma},d)$ are reported, together with the cross section for the ${}^{9}\mathrm{Be}(\ensuremath{\gamma},d)$ reaction to the first excited state. Qualitative discussions of these cross sections are made on the basis of a simple model which assumes free clusters in ${}^{9}\mathrm{Be}.$ This is similar to the two-cluster model used for ${}^{6}\mathrm{Li}$ and ${}^{7}\mathrm{Li}$ for which theoretical calculations have been made. Predictions on the basis of this model indicate the importance of clustering in the photodisintegration of ${}^{9}\mathrm{Be},{}^{6}\mathrm{Li},$ and ${}^{7}\mathrm{Li}.$ The observed angular distributions are consistent with contributions due to $E1$ and $E2$ transitions.