Terrestrial and Cosmic Background Radiation Effect on a Dual-Particle Imaging System

Year
2012
Author(s)
Shaun D. Clarke - Department of Nuclear Engineering & Radiological Sciences, University of Michigan
Marek Flaska - Department of Nuclear Engineering & Radiological Sciences, University of Michigan
Sara A. Pozzi - Department of Nuclear Engineering & Radiological Sciences, University of Michigan
Michael C. Hamel - Department of Nuclear Engineering & Radiological Sciences, University of Michigan
Marc F. Becchetti - Department of Nuclear Engineering & Radiological Sciences, University of Michigan
John K. Polack - Department of Nuclear Engineering & Radiological Sciences, University of Michigan
Kiyotaka Ide - Department of Nuclear Engineering & Radiological Sciences, University of Michigan
Abstract
Radiation imaging systems detect the location of potential threat objects by calculating the direction of incoming particles using correlations inside the system. As a consequence, background radiation can greatly affect the system response by causing accidentals or giving a misleading source location. An approach to accurately model background radiation on an event-by-event basis is therefore needed to rigorously design an imaging system. In this work we focus on a particular system capable of imaging photons and fast neutrons. The dual-particle imaging system is the combination of a traditional Compton camera and a neutron-scatter camera that utilizes liquid organic scintillators and NaI detectors. Event-by-event particle simulation is needed to model a realistic detector response as well as realistic correlations of events that are used to image a source. To achieve correct event-by-event simulation, MCNPX-PoliMi, a modified version of the MCNPX code was used. For the simulation of neutron and photon background, well characterized methods obtained from literature and collaborators were implemented. A Comptoncamera experiment was carried out to verify the activity of the photon background to lead us to a final background simulation with the full-scale dual-particle imaging system. This simulation methodology will be further verified by an outdoor measurement campaign in the near future. Keywords: radiation imaging, photon, neutron, detection, terrestrial background, cosmic background, liquid scintillators