Neutron Fluence Spectrometry Using Disk Activation

Abstract

A simple and robust detector for spectrometry of environmental neutrons has been developed. The technique is based on neutron activation, i.e. the activation of a series of different metal disks followed by gamma-ray spectrometry of the activated disks and subsequent neutron spectrum unfolding. It is a technique similar to the foil activation but now applied to low neutron fluence rates. The detector has been tested in quasi mono-energetic neutron fields where the obtained spectra showed good agreement with spectra measured using a Bonner sphere spectrometer. The detector has also been tested by means of an AmBe source and, again, a good agreement with the assumed spectrum was achieved. Low-level and ultra-low level gamma spectrometry allowed for the measurements of very low neutron fluences with detection limits for fast neutrons in the order of 10 s-1 cm-2.JRC.D.5-Neutron physic