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

TL;DR

This paper explores replacing helium with neon in a gas-based neutron detector to improve high-energy neutron detection efficiency and operational stability.

Contribution

The study demonstrates that neon can effectively replace helium in the detector mixture, offering comparable gain and diffusion with reduced voltage breakdowns.

Findings

Neon mixture maintains acceptable gain and electron diffusion.

Neon mixture significantly reduces voltage breakdowns.

Detector uptime loss is negligible with neon compared to helium.

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% $^4$He and 12.5% CF$_4$ 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 $^4$He, in the gas mixture. Our discussion focuses on the advantages of Ne as the fast neutron target for high energy neutron events ($\lesssim$100 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 $\sim$ 20% with the $^4$He mixture.