title: A novel fast-neutron detector concept for energy-selective imaging and imaging spectroscopy.
abstract: We present and discuss the operational principle of a new fast-neutron detector concept suitable for either energy-selective imaging or for imaging spectroscopy. The detector is comprised of a series of energy-selective stacks of converter foils immersed in a noble-gas based mixture, coupled to a position-sensitive charge readout. Each foil in the various stacks is made of two layers of different thicknesses, fastened together: a hydrogen-rich (plastic) layer for neutron-to-proton conversion, and a hydrogen-free coating to selectively stop/absorb the recoil protons below a certain energy cut-off. The neutron-induced recoil protons, that escape the converter foils, release ionization electrons in the gas gaps between consecutive foils. The electrons are then drifted towards and localized by a position-sensitive charge amplification and readout stage. Comparison of the images detected by stacks with different energy cut-offs allows energy-selective imaging. Neutron energy spectrometry is realized by analyzing the responses of a sufficient large number of stacks of different energy response and unfolding techniques. In this paper, we present the results of computer simulation studies and discuss the expected performance of the new detector concept. Potential applications in various fields are also briefly discussed, in particularly, the application of energy-selective fast-neutron imaging for nuclear safeguards application, with the aim of determining the plutonium content in Mixed Oxide (MOX) fuels.
authors.affiliation: Nuclear Energy and Safety Research Department, Paul Scherrer Institut, Villigen PSI 5234, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Cortesi
authors.affiliation: Ion and Neutron Radiation Department, Physikalisch-Technische Bundesanstalt, Braunschweig 38116, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Dangendorf
authors.affiliation: Mechanical Engineering Department, Swiss Federal Institute of Technology, Zurich 8092, Switzerland.
authors.forename: R
authors.initials: R
authors.lastname: Zboray
authors.affiliation: Nuclear Energy and Safety Research Department, Paul Scherrer Institut, Villigen PSI 5234, Switzerland.
authors.forename: H-M
authors.initials: HM
authors.lastname: Prasser