Australians scour desert for dangerous radioactive capsule smaller than a penny
Radiation detection is my specialty. This source is Cs-137, few hundred mCi. It's easy to detect within a few seconds at distances of a few tens of meters or more with professional detection equipment if there is direct line of sight.<p>If it was knocked off the road, though, the question will be if it fell into a crack or other such place because then the radiation is somewhat shielded and it would take much more measuring time to identify it.<p>I suspect if a few passes with vehicle-mounted detectors don't find it then some drones with detectors traveling along the sides of the road would be a good next step. If a critter moved it or ate it then it's probably gone forever. At a distance of 1 meter the dose rate from that source is already not extremely hazardous unless a person were exposed for an extended period of time (like a full day or two). Getting closer, like putting it directly against your torso, would mean serious health effects in a matter of minutes.