Small laboratory sources
Samples of small laboratory sources marketed by an U.S. company to test the functioning of Geiger counters. A quantity of radionuclide, of required activity, is placed in a 3 mm deep hollow plastic disc, filled with epoxy glue that holds the radioactivity. The activity of the three sources of the figure (of alpha, beta and gamma) is about the microcurie (millionths of a curie), activities comparable to those of human body natural activity, that’s to say very low.