Distributed detector radiation networks: Static and mobile sensor configurations

Distributed networks of robust, low-cost, radiation detectors offer the ability to track and locate materials across a number of applications. Individual sensors must be positioned to collectively optimise both the sensing and communication roles of the network and ruggedized to achieve consistent detection performance under a range of environmental conditions. Here we consider the interplay between the modelled optimisation of sensor location and required signal communication. The performance of a purely static sensor network was compared to configurations including mobile sensor units. A random sequential deposition method was applied to locate static sensors and simulations performed with a radiological source moving along both random and pre-defined trajectories. A variety of statistics were used to assess the performance of the network and compared to models where a proportion of sensors were allowed to travel along pre-defined paths. Statistics included the number of interactions, frequency and length of time between the source and deployed sensor coverage, the total area of coverage afforded by the sensors, the area encompassed by the travelling source and the number of sensors deployed. In addition initial experiments were conducted exploring aerial configurations, bandwidth and frequency step as a function of sensor separation. The ranging capabilities of the Atmel AT86RF233 chip were tested with bandwidths from 10 to 100 MHz and from frequencies of 500 kHZ to 4 MHz. These results may influence the choice of future static and mobile sensor configurations.