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.