Reactions of ${}^7\mathrm{Li}{+}^7\mathrm{Li}$ at $E_{\mathrm{lab}}=34\mathrm{}\hspace{0.5em}\mathrm{MeV},$ which lead to charged particle decaying excited states of ${}^{10}\mathrm{Be},$ have been studied by use of a detection system sensitive to decay energies of a few hundred keV. The α-particle branching fractions in ${}^{10}{\overrightarrow{{\mathrm{Be}}^{*}}}^4\mathrm{He}{+}^6\mathrm{He}$ have been measured for excited states at $E_x=7.542\mathrm{}$ and $\sim 9.6\hspace{0.5em}\mathrm{MeV}.$ For the 7.542 MeV state an unusually large separation radius is required to explain the observed branching fraction of ${\Gamma }_{\alpha }/\Gamma =(3.5\mathrm{}\pm 1.2)\times {10}^{-3}.$ This result is interpreted in terms of the energy level structure of ${}^{10}\mathrm{Be}$ as related to analogous states in ${}^{12}\mathrm{C}$ and to the recent molecular orbital calculations. A new $J^{\pi }{=0\mathrm{}}^{-}$ state is observed in the decay ${}^{10}{\overrightarrow{{\mathrm{Be}}^{*}}}^7{\mathrm{Li}}^{*}\left(0.478\mathrm{}\hspace{0.5em}\mathrm{MeV}\right)+t.\mathrm{}$

• Received 4 October 2001

DOI:https://doi.org/10.1103/PhysRevC.65.034317