α反冲径迹定年——新兴热年代学技术  

Alpha-Recoil Track Dating

作　　者：董金泉[1] 袁万明[1] 高绍凯[1] 保增宽[1] 王世成[1] 

机构地区：[1]中国科学院高能物理研究所核分析重点实验室,北京100039

出　　处：《地球学报》2005年第B09期258-261,共4页Acta Geoscientica Sinica

基　　金：本文由国家自然科学基金项目（编号：10475093,10175076,40072068）;国家重点基础研究发展规划项目（编号：2001CB409804）;国家科技攻关项目（编号：2001BA609A-07-03）资助.

摘　　要：与裂变迹径定年类似，α反冲径迹定年（Alpha～Recoil Track）也是基于天然放射性元素所释放核粒子在固体中产生可蚀刻径迹的积累。铀钍及它们的子体核素进行α衰变时形成α反冲径迹，当发射一个α粒子时，重的剩余核反冲并造成30～40nm的辐射损失痕迹，经过蚀刻α反冲径迹可在干涉相差显微镜下观测。如果在样品形成以后全部迹径被保留下来，那么测定它们的总数就可以得到样品的年龄。α反冲径迹定年是一种刚刚开始研究的新型热年代学核分析技术，研究样品可以是单个小云母片（约0．5mm），定年范围10^2～10^6a，该方法对第四纪地质、地理、灾害及考古等领域有很大的应用潜力。Like fission-track dating, alpha-recoil track （ART） dating is based on the accumulation of unclear particles which are released by natural radioactivity and produce etchable tracks in solids. ARTs are formed during the alpha-decay of uranium and thorium as well as their daughter nuclei. When emitting an alpha-particle, the heavy remaining nucleus recoils 30- 40nm, leaving behind a trail of radiation damage. Through etching, the ART tracks become visible under the interference phase-contrast microscope. Under the presupposition that all tracks are preserved since the formation of a sample, their total number should be a measure of the sample＇ s age. The technique is applicable to tiny （0.5 mm） single mica flakes in the age-range of 102 - 106 years. Alpha-recoil dating has a great application potential in such fields as geology, geography and disaster of Quaternary and archaeology.

关 键 词：α反冲径迹 热年代学 定年 黑云母 金云母 核分析技术 径迹 反冲 天然放射性元素 相差显微镜 

分 类 号：P597.3[天文地球—地球化学] X51[天文地球—地质学]