Fast Neutron Spectroscopy with a High-pressure Nitrogen-filled Large Volume Spherical Proportional Counter

TL;DR

This paper introduces a fast neutron spectroscopy system using a nitrogen-filled spherical proportional counter, capable of operating at 1.5 bar, providing an alternative to 3He detectors for neutron detection.

Contribution

The paper demonstrates the development and successful operation of a nitrogen-based gaseous detector for fast neutron spectroscopy, offering a viable alternative to traditional 3He detectors.

Findings

Operated successfully up to 1.5 bar pressure

Able to estimate neutron energy via nitrogen reactions

Deployed in university and underground lab environments

Abstract

We present a fast neutron spectroscopy system based on a nitrogen-filled, large volume gaseous detector, the Spherical Proportional Counter. The system has been successfully operated up to gas pressure of 1.5 bar. Neutron energy is estimated through measurement of the 14N(n,a)11B and 14N(n,p)14C reaction products. These reactions have comparable cross sections and Q-values with the 3He(n,p)3H reaction making nitrogen a good alternative to 3He use for fast neutron detection. Two detectors were built at the University of Birmingham and are currently used for the measurement of fast and thermal neutrons in the University of Birmingham and the Boulby underground laboratory, respectively.