Energy spectra of ${\mathrm{He}}^6$ particles emitted in the nuclear reaction ${\mathrm{Li}}^7$ (${\mathrm{Li}}^7$,${\mathrm{He}}^6$) ${\mathrm{Be}}^8$ were measured using a two-parameter $E-\frac{\mathrm{dE}}{\mathrm{dx}}$ data-taking system which incorporated a general-purpose computer. Incident ${\mathrm{Li}}^7$ ions had an energy of 3.0 MeV. The energy spectra showed peaks corresponding to the ground state and first (2.9 MeV) excited state of ${\mathrm{Be}}^8$ and an anomalous yield between these states. This yield is simply explained as resulting from the two-step reaction ${\mathrm{Li}}^7({\mathrm{Li}}^7, \alpha ){\mathrm{Be}}^{10*}\left({\mathrm{He}}^6\right)\alpha$. No evidence for direct three-body breakup is found. ${\mathrm{He}}^6$ angular distributions do not exhibit strong structure; the ground-state group shows slight anisotropy.

• Received 7 August 1964

DOI:https://doi.org/10.1103/PhysRev.136.B1687