核分析新技术:Alpha反冲径迹热年代学

A new method of nuclear analysis:Alpha-recoil track thermochronology.

矿物中U、Th及其子核进行α衰变释放出α粒子时,剩余重核受到反冲而产生辐射损伤。在适当条件下经化学蚀刻,这些辐射损伤成为在光学显微镜下可观测的核径迹。通过建立适当的蚀刻模型和定年模型,计算径迹面密度和体密度,并测量U、Th含量,便可得到年龄。Alpha反冲径迹年代学的特点是可以确定较年轻的时代(百万年至数百年),故在资源环境、地理、考古等领域具有广泛的应用前景。

When U, Th and their daughter nuclei emit α particles after α decays, heavy residual nuclei are recoiled, leaving behind a trail of radiation damage in the mineral. The trail of radiation damage is called the nuclear track and can be observed under optical microscope through chemical etching under appropriate conditions. Based on the etching and dating models established, we can obtain both the alpha-recoil track （ART） areal densities and volume densities, as well as the concentrations of U and Th, and then the age of the mineral can be calculated. Alpha-recoil track thennochronology is dominantly used in dating younger samples （10^6-10^2 a） and can be widely used in areas of resource environment, geology, archeology and so on.