CHARACTERIZATION OF AN IN-HOUSE DEVELOPED MULTI-CYLINDRICAL MODERATOR NEUTRON SPECTROMETER.

Abstract

This article describes the characterization of an in-house developed multi-cylindrical moderator neutron spectrometer, which consists of a cylindrical 3He proportional counter and cylindrical moderator shells of different sizes. The response matrix of the spectrometer was calculated by Monte Carlo simulations for neutron energies from 1 × 10-8 to 10 MeV and verified with measurements in 0.144 MeV, 1.2 MeV and 241AmBe neutron standard fields. Influence of scattered neutrons was properly eliminated from the measured response using the shadow cone technique. The calculated and measured responses were in good agreement in most cases. Differences were <10% for all moderated counter configurations, while larger deviations were observed for the bare counter configuration. The performance of the neutron spectrometer in terms of spectrum unfolding was verified in the 241AmBe neutron standard field, showing reliable neutron spectrum and fluence rate in the energy range up to 10 MeV as investigated in this work.