9410906 Schwarcz With National Science Foundation support, Dr. Henry Schwarcz will continue research on electron spin resonance (ESR) dating of prehistoric archaeological and hominid sites. ESR dating can provide dates over the range from a few thousand to more than two million years. It is based on the principle that some materials found at archaeological sites store a physical record of the amount of radiation to which they have been exposed. Tooth enamel, which is found at virtually every archaeological site, displays a characteristic ESR signal which increases in intensity with exposure to radiation, and which has zero intensity in modern teeth. One can experimentally determine the dose rate at the site where the enamel was recovered, and the equivalent dose that was absorbed by the enamel to produce the observed ESR signal. The ratio of these quantities provides the age of the tooth, and thus the time of occupation of the site. The precision of the dates is +- 5 to 10 %. The McMaster Laboratory is the only one in North America carrying out ESR research and has successfully applied the method to many sites in Europe, Asia and Africa. With NSF support research will continue to refine the ESR technique itself. Dr. Schwarcz and his colleagues will also analyze and provide dates for a range of significant anthropological specimens.
