Exotic Molecular States in ${}^{12}\mathrm{Be}$

The breakup of ${}^{12}\mathrm{Be}$ into ${}^6\mathrm{He}{+}^6\mathrm{He}$ and ${}^4\mathrm{He}{+}^8\mathrm{He}$ has been studied using a 378 MeV ${}^{12}\mathrm{Be}$ beam inelastically excited by ${}^{12}\mathrm{C}$ and $({\mathrm{CH}}_2{)}_n$ targets. The measurements indicate that breakup occurs from rotational states in the 10 to 25 MeV excitation energy interval, with spins in the range of $4ħ$ to $8ħ$. The inferred moment of inertia is consistent with the cluster decay of an exotic molecular structure in ${}^{12}\mathrm{Be}$, which may be associated with an $\alpha -4n-\alpha$ cluster configuration.