Neutron activation and prompt gamma intensity in Ar/CO2-filled neutron detectors at the European Spallation Source

Monte Carlo simulations using MCNP6.1 were performed to study the effect of neutron activation in Ar/CO 2 neutron detector counting gas. A general MCNP model was built and validated with simple analytical calculations. Simulations and calculations agree that only the 40Ar activation can have a considerable effect. It was shown that neither the prompt gamma intensity from the 40Ar neutron capture nor the produced 41Ar activity have an impact in terms of gamma dose rate around the detector and background level.