Determining Limits of Detection for Different Detector Geometries through Monte Carlo based Simulations

The threat from nuclear terrorism represents a complex challenge for global governments. Although currentsystems for detecting threats from illicit materials exist, each have inherent limitations. However, it is crucialthat a system can detect when material is being transported with malicious intent and where the potentialdamage caused by the distribution of such material is likely to require extensive cleanup operations. Onemonitoring approach comprises the use of a network(s) of distributed detectors in an attempt to detectanomalous events. Quantifying the limits of detection for these small-volume and portable systems is achallenging, but vital, task. Existing work in designing a threat reduction system has not shown a goodunderstanding of what the system is capable of detecting. To rectify this issue, work has been undertakento create a numerical simulation capable of modelling a moving detector and stationary source with a givendistance of closest approach. The algorithm is then able to estimate limits on parameters where the sourcestops being detectable, by cycling through variables and completing numerous pseudo-experiments at eachvalue. Such an approach will allow any proposed network to ascribe an estimate of the threats that itwill be sensitive to. Supplementary work was completed to empirically verify the simulated results. Thesereal-world tests provided confidence that the simulations approximate the physics modelled.