Neutron spectroscopy with a high-pressure nitrogen-filled spherical proportional counter

TL;DR

This paper demonstrates the use of a nitrogen-filled spherical proportional counter as an effective neutron spectrometer at pressures up to 1.8 bar, leveraging recent technological advances.

Contribution

It presents the first neutron measurements with this detector at high pressures, expanding its potential applications in various challenging environments.

Findings

Successful neutron measurements at 1.8 bar pressure

Enhanced detector capabilities for underground, industrial, and medical use

Validation of simulation techniques for high-pressure operation

Abstract

The spherical proportional counter is a large volume gaseous detector which finds application in several fields, including direct Dark Matter searches. When the detector is filled with nitrogen it becomes an effective neutron spectrometer thanks to the $^{14}$N(n,$\mathrm{\alpha}$)$^{11}$B and $^{14}$N(n,p)$^{14}$C reactions. Nitrogen, however, is a challenging operating gas for proportional counters and requires a high electric field strength to gas pressure ratio. Benefiting from the latest advances in spherical proportional counter instrumentation and simulation techniques, we report first neutron measurements at operating pressures of up to 1.8 bar. This achievement enhances the prospects of the spherical proportional counter to act as a neutron spectrometer appropriate for challenging environments, including underground laboratories, and industrial and medical settings.