K. Terao

A prototype detector for directional measurement of the cosmogenic neutron flux

This paper describes a novel directional neutron detector. 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 source and angular reconstruction studies using a collimated neutron source. The best performance is obtained with a 12.5% CF4 { 87.5% He gas mixture. At low energies the target for fast neutrons transitions is primarily helium, while at higher energies, the uorine contributes as a target. The reconstruction eciency is both energy and target dependent. For neutrons with energies less than 20 MeV, the reconstruction eciency is 40% for uorine recoils and 60% for helium recoils.