[TorpX]

Years ago, I worked for a materials testing company. They trained us field techs to use a nuclear density guage; I forget who manufactured them. We were given all sorts of cautions and proceedures related to the radiation hazards. I think the radiation source was cesium. The theoretical stuff was interesting, but as it turned out I hardly ever touch one. I wonder about the precautions they must take with them now (this was before 9/11).