A spectroscopic radiation imager for internet-based safeguards and monitoring

Monitoring nuclear material that is dangerously radioactive, remotely located, or difficult to access is a challenging task. The necessary research required to develop a system capable of remotely monitoring radioactive materials has been undertaken at Radiation Monitoring Devices, Inc. We report on a system utilizing a spectroscopic gamma-ray imager for real-time observation of sensitive nuclear materials over the Internet or dedicated networks, Research at RMD has produced a spectroscopic gamma-ray imager centered on a position-sensitive photomultiplier tube coupled to scintillation crystal and a coded aperture. A gamma-ray intensity pattern from the detector is stored and processed by a portable computer workstation and then mathematically corrected to yield the original radiation-source image. The pseudo-color, radiation-source image is overlaid on a co-registered video picture of the same area captured by a high-resolution charge-coupled device. The combined image is displayed as an accurate map of gamma-ray sources in the physical environment. Recent developments involve instrument control and data transmission through computer networks. Alarm triggers based on changes in the video image, the radiation image, the energy spectrum are under development. Work to remotely control alarm sensitivity and type, as well as the image update frequency, has also been examined.