Neutron spectrometry from thermal energies to GeV with single-moderator instruments

Abstract

A major challenge in neutron measurements is the development of an instrument able to simultaneously determine all energy components of the neutron field at a given point. Bonner spheres can actually determine the complete neutron spectrum at a point, but they require sequential exposures. This excludes any possibility to use Bonner spheres as a spectrometric beam monitor. NESCOFI@BTF project (2011–2013) developed two neutron spectrometers similar to the Bonner spheres, in terms of response energy interval and accuracy, but able to determine the neutron spectrum in only one exposure. These devices, called SP² and CYSP, embed multiple (seven to thirty-one) thermal neutron detectors within a single moderator. Whilst the SP² has spherical geometry and nearly isotropic response, the CYSP has cylindrical geometry and is a directional spectrometer. The prototypes were equipped with especially developed thermal neutron detectors. The resulting instruments may be used as real-time neutron spectrometers in neutron-producing facilities.