Physical and Economic Limitations for Distributed Nuclear Sensing

Remote sensing technologies make possible the detection of activities and communications from great distances. However, many objects and activities cannot be monitored at a distance. To obtain global situational awareness of the associated processes, one must deploy networks of and the cost of the individual sensors, drive the cost of coverage per square kilometer. We examine some of the fundamental and practical limits to these costs. There are limits on the miniaturization of certain sensors, and it will be expensive to cover large areas to detect, for example, nuclear sources. These costs can be minimized by deploying smaller sensors in greater numbers, by more discriminating sensors, and by exploring alternative signatures. In some cases, considerable improvement in sensitivity for moving sources can be obtained by following up a tentative detection with a fixed detector with a mobile, more discriminating detector.