Muon Imaging 1: Detecting the Frequency and Location of Cosmic Ray Muon Events to Enable the Development of a Muon Based Imaging System
S.J. Stanley1, D. Rhodes2, P.M. Jenneson3, W.B. Gilboy3 and S.J.R. Simons4
1 Nexia Solutions, Hinton House, Risley, Warrington, UK, Email: email@example.com
2 Nexia Solutions, B170 Technology Centre, Sellafield, Seascale, Cumbria, UK.
3Dept. of Physics, University of Surrey, Guildford, Surrey,UK
4Dept. of Chemical Engineering, University College London, Torrington Place. London, UK.
In recent years the use of non-intrusive and non-invasive imaging techniques to safely interrogate non-nuclear (industrial) storage vessels or process units has seen a significant increase. The nature of material found within active ‘legacy waste’ storage vessels and other radiation shielded vessels coupled with the distinct lack of access makes representative sampling or visual inspection of the vessel extremely problematic and in some cases impossible. However, until recently, the radiation shielding which is commonplace on all nuclear sites has rendered existing remote non-intrusive imaging techniques useless. This is due to the limiting penetrative power of X-rays and gamma-rays as well as lack of access for other semi-invasive techniques such as electrical and acoustic imaging. Because of their superior penetrability naturally occurring cosmic ray muons offer an attractive means to peer through large shielded structures common place on most nuclear facilities. This paper describes research undertaken prior to the building of a prototype muon imaging system. In this work muon event positions have been experimentally determined along a scintillator bar which represents a first step to detecting muon trajectories which represents the basis of the proposed muon based imaging system. Also included are the first lead phantom shadow experiments which inhibit both a reasonable spatial accuracy. The measured muon attenuation corresponds well to previous muon attenuation measurements enabling an image facilitated phantom thickness measurement. Although the muon energies and trajectories at sea level are quite random, the experiments described here that over time these statistical uncertainties become predictive and reproducible.
Keywords: Imaging, muons, storage vessel, nuclear, cosmic ray, tomography, legacy waste.
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