Demonstrating a directional detector based on neon for characterizing high energy neutrons

Abstract

MITPC is a gas-based time projection chamber used for detecting fast, MeV-scale neutrons. The standard version of the detector relies on a mixture of 600 torr gas composed of 87.5% ⁴He and 12.5% CF₄ for precisely measuring the energy and direction of neutron-induced nuclear recoils. We describe studies performed with a prototype detector investigating the use of Ne, as a replacement for ⁴He, in the gas mixture. Our discussion focuses on the advantages of Ne as the fast neutron target for high energy neutron events (lesssim100 MeV) and a demonstration that the mixture will be effective for this event class. We find that the achievable gain and transverse diffusion of drifting electrons in the Ne mixture are acceptable and that the detector uptime lost due to voltage breakdowns in the amplification plane is negligible, compared to ~ 20% with the ⁴He mixture.