Using X-rays as an irradiation source for direct ESR dating of fossil teeth

In this paper we have tested the potential application of X-rays as an irradiation source in Electron Spin Resonance dating of tooth enamel. A range of modern and fossil samples were used to assess the feasibility of dose estimations using this alternative irradiator. The use of a known laboratory additive dose allows the calculation of an absorption equivalent coefficient between gamma-rays and X-rays. The results show that equivalent doses obtained with gamma-rays on fossil powder enamel was frequently less than the doses obtained on fragments using only X-rays. This agrees with other studies that gamma irradiation can lead to age underestimation problems, and also indicates that X-ray sources could be more suitable for ESR dating. Here, we show that testing penetration attenuation for each individual irradiation source is required to accurately estimate the maximum enamel thickness and produce reliable protocols. We conclude that X-rays are an alternative irradiation source for ESR dating protocols, however, limitations remain in particular with alpha efficiency.