$R$-Matrix Analysis of Particle Spectra from the T(t,2n)$\alpha$ Reaction at Low Energies

The particle spectra from the low-energy T(t,2n)$\alpha$ reaction are of interest to several research areas, including fusion energy and the neutron-neutron scattering length. We present an $R$-Matrix model for the final states of this reaction, considering sequential neutron emission via $l=0$ and 1 $n+\alpha$ intermediate states as well as emission of a correlated $l=0$ $n+n$ (di-neutron) pair. The amplitudes for these processes are constructed to be antisymmetric under neutron exchange. The two-body $n+\alpha$ channel is highly constrained by existing experimental data. Substantial effects in the neutron and $\alpha$-particle energy spectra are found to result from antisymmetrization as well as from the interference between different decay channels. Results for fits to the available experimental data will be presented.