Geant4-GATE simulation of a large plastic scintillator for muon radiography

P Aguiar,E Casarejos,J.A Vilan,A Iglesias

doi:10.1109/animma.2013.6728082

Abstract

Envisaging the possibility of using large area plastic scintillator slabs as robust detectors for high spatial resolution muon radiography, and prior to prototype development, we study expected basic performance by Monte Carlo simulation. We present preliminary results for a scalable square footprint detector unit of ~1 m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , defining a representative simulation model volume of 50 cm × 50 cm, with reflective surfaces and light readout by direct coupling of 4 small PMTs (in a square arrangement) at one face of the scintillator slab. Light detection efficiency is calculated for several light collection configurations, considering different values of surface roughness, reflectivity, optical coupling index and scintillator thickness. Values maximizing photon detection have been identified. The light response function (LRF) of photodetectors for the proposed configuration has been determined. An average spatial resolution of the order of 1 cm is expected to be achieved using statistical methods for interaction point determination (based on MC a priory information and maximum-likelihood estimation).

Highlights

M UON Radiography has been used for passive inspection of large- volume objects in a number of applications in volcanology, civil engineering, vessel industry and security
Prior to any prototype development, we study the expected basic performance by Monte Carlo simulation with GATE (Geant4 Application for Emission Tomography: a simulation toolkit for PET and SPECT)
The aim of this study is to evaluate the feasibility of the proposed detector module for cosmic muon detection in terms of intrinsic spatial resolution, and its dependence on main detector parameters, as a basic input for a first estimation of muon tracking system performance depending on the number of detection planes and their relative distances

Summary

Introduction

M UON Radiography has been used (since 1955 [1]) for passive inspection of large- volume objects in a number of applications in volcanology, civil engineering, vessel industry and security. Segmented scintillator strips may attain good results, depending on the number of detection planes and their segmentation size Their spatial resolution is limited by mechanical segmentation and the need of a high number of photo-detectors (readout channels). Several muon detection systems using 3–5 cm section strip-segmented plastic scintillators, are been developed for geophysical applications [9], cargo inspection [10] or concreted nuclear waste inspection [11], giving 0.1 rad angular resolution, 5 cm or 1 cm voxel size tomographic images respectively. Prior to any prototype development, we study the expected basic performance by Monte Carlo simulation with GATE (Geant Application for Emission Tomography: a simulation toolkit for PET and SPECT) This tool has been shown to produce reliable MC simulation results including optical transport, and enables integration of low-level results into complex detection structures for future system R&D [12]. A “gammacameralike” light readout scheme is considered, where an uniformly (sparse) distributed arrangement of small PMTs is coupled to the scintillator face

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