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Counting the Gamma Rays

Dr. Ronald L. Bishop, Curator of Mexican and Central American Archaeology takes small samples from some of the ceramic objects in this exhibition. Photo by the Penn Museum.

Dr. Ronald L. Bishop, Curator of Mexican and Central American Archaeology takes small samples from some of the ceramic objects in this exhibition. Photo by the Penn Museum.

Dr. Ronald L. Bishop, Curator of Mexican and Central American Archaeology, together with M. James Blackman, Senior Research Chemist, and Erin L. Sears, Research Collaborator (all in the Department of Anthropology, National Museum of Natural History, Smithsonian Institution), took small samples from some of the ceramic objects in this exhibition in order to try to identify the clay source from which they were made.

The samples were subjected to a bombardment of neutrons in a nuclear reactor, transforming the nuclei of certain elements into unstable radioactive isotopes, which give off gamma rays of characteristic energy as they decay.