182Hf的AMS测量技术研究

为实现对¹⁸²Hf岩石样品的AMS精确测量，基于HI-13串列加速器对测量技术和方法等进行了系统的改进，主要包括：¹⁸²Hf空白样品的制备、偏置束流的同时监测技术、加速器系统稳定性检验、交替测量方案的实施、¹⁸²W扣除方法的改进、模拟样品测量检验、岩石样品测量检验及测量结果可信度检验等。实验结果表明，对于1×10^-10(¹⁸²Hf/¹⁸⁰Hf)水平的模拟样品，测量结果的相对不确定度约为12%，基本达到岩石样品的测量要求。岩石样品的测量不确定度较大，主要原因是岩石样品中W的含量较高。

AMS Measurement Technology for 182Hf

In order to improve the accuracy of AMS measurement for ¹⁸²Hf/¹⁸⁰Hf, a series of improvement and innovations of measurement technique and method were taken, such as chemical synthesis of ¹⁸²Hf free samples, technique of monitoring off-axis current simultaneously, testing the stability of accelerator system, performing the alternate measurement, modified deduction method of ¹⁸²W, testing the measurement method with simulated samples and real rock samples, and testing the reliability of measurement results. The experimental results show that the relative uncertainty is about 12% for the simulated samples to the order of 1×10^-10(¹⁸²Hf/¹⁸⁰Hf), which satisfies the requirement of measurements for real rock samples. The reason of big uncertainty with the rock sample mainly lies in the high content of W in the rock sample.