论文部分内容阅读
在电子自旋共振(Electron spin resonance,ESR)-铀系化石测年中,需要考虑α、β和γ辐射对年剂量的贡献。由于α射线产生顺磁中心的效率明显低于相同能量的β和γ射线,所以在牙化石ESR-铀系测年的年剂量计算中需要对α辐射贡献的剂量率乘以一个校正参数(k值)。但不同学者通过实验测量给出的k值各不相同,本文通过对5颗来自重庆巫山龙骨坡遗址的动物牙化石测年样品的分析,探讨了k值变化及采用两种常用k值对化石样品年代计算结果的影响。结果显示,当k值从0增加到0.3时样品年龄随之递减,对于铀含量较低的样品,年龄变化范围不大(~2%),而对铀含量较高的样品年龄随k值有较大变化(~50%),其中k值从0.13增加到0.23的过程中,高铀含量样品的年龄减小了~20%;对铀含量相近的样品,230Th/234U比高的样品其年龄计算结果随k值的变化更大。
In electron spin resonance (ESR) - uranium series fossil dating, the contributions of α, β, and γ radiation to annual doses need to be considered. Since alpha rays produce paramagnetic centers with significantly lower efficiencies than beta and gamma rays of the same energy, the dose rate contribution to alpha radiation in the annual dose calculation of the ESR-uranium series dating of the dental fossil is multiplied by a correction parameter (k value). However, the k values obtained by different scholars through experimental measurements are different. Based on the analysis of five samples of animal dental fossils from the Longguobo site in Wushan, Chongqing, this paper discusses the changes of k value and the effects of two commonly used k values on fossil Effect of sample age calculation results. The results showed that the age of the sample decreases as the k value increases from 0 to 0.3, and the range of age does not vary much (~ 2%) for samples with lower uranium content, while for samples with higher uranium content (~ 50%). When the k value increased from 0.13 to 0.23, the age of samples with high uranium content decreased by ~ 20%. For samples with similar uranium content, the samples with 230Th / 234U ratio had the same age The calculation results vary more with the k value.