ESR Dating at Archaeological Sites in Europe and Africa

Bonnie Blackwell和Anne Skinner博士将进行一系列实验室实验，以改进电子自旋共振（ESR）技术，然后将其应用于各种领域。ESR提供了一种方法，以日期牙齿和适当类别的石制品之间的日期约。两万年前甚至可能有四百万年的历史。由于这两类文物在考古遗址中很常见，而且许多此类事件无法通过其他现有技术确定年代，因此ESR如果开发得当，可以提供一个重要的人类学工具。该技术依赖于这样一个事实，即埋藏的物体从土壤中吸收少量的铀，并且内部和外部的衰变副产物轰击会在样品中产生与时间相关的电子位移。ESR提供了一种方法来衡量这种情况发生的程度。当确定剂量率后，就可以计算年龄。许多史前人在将石制品制成工具之前先将其加热，因为加热引起的结构变化使材料更容易加工。幸运的是，热也将电子位移时钟设置为零，从而使热处理过的零件适合ESR分析。 虽然它在原则上是可行的，并产生了直观合理的数据，ESR并没有得到很好的发展，结果是可以理解的谨慎对待。铀的吸收率很难确定，已经提出了几种不同的模型。布莱克威尔和斯金纳的研究集中在技术发展上。他们应将牙釉质与牙本质、牙骨质和邻近沉积物进行比较，以了解铀的吸收情况。他们还应通过分析已用其他技术确定年代的地点的牙齿和岩屑进行校准测试。最后，他们将审查来自欧洲和南部非洲一系列重要遗址的材料并确定其年代。 因此，这项研究将有助于开发一种重要的测年技术，并产生数据，从而提高我们对人类出现的理解。

Drs. Bonnie Blackwell and Anne Skinner will conduct a series of laboratory experiments to improve the electron spin resonance (ESR) technique and then apply it in a variety of field contexts. ESR provides a method to date teeth and appropriate categories of stone artifacts which date between ca. 20,000 and possibly as much as 4,000,000 years old. Because both categories of artifacts are common in archaeological sites and because many such occurrences are not datable by other available techniques, ESR, if properly developed, can provide an important anthropological tool. The technique depends on the fact that buried objects absorb small amounts of uranium from the soil and the internal as well as external bombardment by disintegration byproducts creates time dependent displacement of electrons within the sample. ESR provides a method to measure the extent to which this has occurred. When the dose rate has been determined, it is then possible to calculate age. Many prehistoric peoples heated lithics before they fashioned them into tools because the structural changes caused by heating made the material easier to work. Luckily, heat also sets the electron displacement clock to zero thus making heat treated pieces amenable to ESR analysis. While it is feasible in principle and has produced intuitively reasonable dates, ESR is not well developed and the results are treated with understandable caution. Uranium uptake rates are hard to determine and several different models have been proposed. Blackwell and Skinner's research focuses on technique development. They shall compare tooth enamel with dentine and cementum and adjacent sediment to gain insight into uranium absorption. They shall also perform calibration tests through analysis of teeth and lithics from sites which have been securely dated by other techniques. Finally they shall examine and date materials from a series of important sites in both Europe and Southern Africa. The research therefore will both help to develop an important dating technique and yield data which will improve our understanding of the emergence of humans.