Electron Spin Resonance Dating of Prehistoric Sites

在美国国家科学基金会的支持下，Henry Schwarcz博士将继续研究电子自旋共振（ESR）对史前考古和古人类遗址的年代测定。ESR测年可以提供几千年到200多万年的年代。它的原理是，在考古遗址发现的一些材料储存了它们所暴露的辐射量的物理记录。几乎在每一个考古遗址都能找到的牙釉质，显示出一种典型的ESR信号，这种信号随着辐射的暴露而增强，而在现代牙齿中则为零。可以通过实验确定牙釉质恢复部位的剂量率，以及牙釉质吸收产生观察到的ESR信号的等效剂量。这些数量的比例提供了牙齿的年龄，从而提供了占据该地点的时间。日期的精度为±5%至10%。麦克马斯特实验室是北美唯一开展ESR研究的实验室，并已成功地将该方法应用于欧洲、亚洲和非洲的许多地点。在NSF的支持下，研究将继续完善ESR技术本身。施瓦茨博士和他的同事还将分析并提供一系列重要的人类学标本的日期。

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.