Triple alpha resonances in the Li-6 + Li-6 -> 3 alpha reaction at low energy

The Li-6 + Li-6 -> 3 alpha reaction has been measured in a kinematically complete experiment at 3.1 MeV of beam energy. The reaction mainly proceeds via intermediate Be-8 states. The interaction between any two of the three a particles provides events with one, two or three Be-8 interfering levels, with strong enhancement in the a-a coincidence yield. Evidence of three Be-8 levels within the same 3a event suggests that one a 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 3 alpha particle correlation. (C) 2015 The Authors. Published by Elsevier B.V.