Measurement of the T+T Neutron Spectrum Using the National Ignition Facility

Abstract

Neutron time-of-flight spectra from inertial confinement fusion experiments with tritium-filled targets have been measured at the National Ignition Facility. These spectra represent a significant improvement in energy resolution and statistics over previous measurements, and afford the first definitive observation of a peak resulting from sequential decay through the ground state of [superscript 5]He at low reaction energies E[subscript c.m.]≲100 keV. To describe the spectrum, we have developed an R-matrix model that accounts for interferences from fermion symmetry and intermediate states, and show these effects to be non-negligible. We also find the spectrum can be described by sequential decay through ℓ=1 states in [superscript 5]He, which differs from previous interpretations.