A Prototype Detector for Directional Measurement of the Cosmogenic Neutron Flux

TL;DR

This paper introduces a new directional neutron detector prototype using a low pressure time projection chamber with helium and CF4 gases, capable of reconstructing energy and angular distributions of fast neutron recoils, with promising calibration and efficiency results.

Contribution

The paper presents a novel detector prototype that combines helium and CF4 gases for directional fast neutron detection and demonstrates its calibration and efficiency performance.

Findings

Energy calibration achieved with alpha source

Angular reconstruction validated with collimated neutron source

Reconstruction efficiency varies with energy and target material

Abstract

This paper describes a novel directional neutron detector prototype. The low pressure time projection chamber uses a mix of helium and CF4 gases. The detector reconstructs the energy and angular distribution of fast neutron recoils. This paper reports results of energy calibration using an alpha source and angular reconstruction studies using a collimated neutron source. The best performance is obtained with a 12.5% CF4 gas mixture. At low energies the target for fast neutrons transitions is primarily helium, while at higher energies, the fluorine contributes as a target. The reconstruction efficiency is both energy and target dependent. For neutrons with energies less than 20 MeV, the reconstruction efficiency is ~40% for fluorine recoils and ~60% for helium recoils.