Mascarenhas S, Baffa Filho O, Ikeya M
Am J Phys Anthropol. 1982 Dec;59(4):413-7. doi: 10.1002/ajpa.1330590411.
Electron spin resonance (ESR) signals from bone increase with exposure to radiation. This permits the dating of ancient bone from its exposure to natural radiation over the centuries. The ESR technique was used for dating human bones from Brazilian shell mounds. The results were compared with 14C dates on charcoal found near the bone. The natural radiation dose rate of the bones was about 0.01 Gy/year (1 rad/year), similar to that found in Japanese shell-mounds. Ages of the bone samples dated ranged from 2000-5000 years BP.
骨骼的电子自旋共振（ESR）信号会随着辐射暴露而增强。这使得我们能够根据古骨骼数百年来所受的自然辐射来测定其年代。ESR技术被用于测定巴西贝丘中人类骨骼的年代。研究结果与在骨骼附近发现的木炭的碳-14年代测定结果进行了比较。这些骨骼的自然辐射剂量率约为0.01戈瑞/年（1拉德/年），与在日本贝丘中发现的剂量率相似。所测定的骨骼样本年代范围为公元前2000年至5000年。
