Evidence for strong n–α correlations in the t+t reaction proved by the neutron energy distribution of muon catalyzed t–t fusion

We conducted a neutron measurement associated with muon catalyzed t–t fusion reactions, t+t+μ−→α+n+n+μ−+Q (11.33 MeV), in a solid T2 target formed by a high-purity tritium gas (98.9%) with a deuterium component of less than 100 ppm. The observed fusion neutrons showed a continuous energy distribution with a shoulder at 6 MeV and the maximum energy at 9 MeV. This feature is inconsistent with the reaction Q-value and three-particle decay with no particle correlations at the exit channel. The obtained neutron-energy distribution was well reproduced by a simple model with two neutron-energy components. The result suggests strong n–α correlations in the three-particle decay at the exit channel of the t+t reactions which proceed at an extremely low energy through ttμ mesomolecule formation.