Triple α resonances in the ⁶Li + ⁶Li → 3α reaction at low energy

The ⁶Li + ⁶Li → 3α reaction has been measured in a kinematically complete experiment at 3.1 MeV of beam energy. The reaction mainly proceeds via intermediate ⁸Be states. The interaction between any two of the three α particles provides events with one, two or three ⁸Be interfering levels, with strong enhancement in the α–α coincidence yield. Evidence of three ⁸Be levels within the same 3α event suggests that one α particle is exchanged between the other two. This is a condition for Efimov states to occur in nuclei, for which no observation exists yet. The hyperspherical formalism for the low-energy three-body problem has been applied to point out the 3α particle correlation.