A simple, efficient, safe to use but also affordable fast neutron spectroscopy system is of paramount importance for many scientific and industrial communities. 3He based detectors provide a solution that fulfils most of the requirements but its high demand in combination with its scarcity created a worldwide shortage and efforts are focused on finding an alternative solution. A number of detectors are proposed for this task, such as BF3 proportional counters, plastic scintillators, and recoil detectors, all having disadvantages that make their adoption challenging. We propose the N2SPHERE system that utilises a spherical proportional counter filled with nitrogen-based gas mixtures to exploit the 14N(n,α)B11 and 14N(n,p)C14 reactions for the detection of fast neutrons. 3He and N2 have comparable Q-values and absorption cross sections for fast neutron capture, offering similar detection capabilities. For the demonstration of this method, a N2SPHERE is operated in the Boulby Underground Laboratory aiming to the measurement of neutron fluxes, as neutrons constitute an important background to rare event searches.
|Secondary track (number)||9|