加速器质谱测量^(129)Ⅰ方法的改进

An improved method for ^(129)Ⅰ-AMS measurement

在筑波大学的12UD串列加速器上开发了一套改进的129Ⅰ加速器质谱(AMS)测量方法,包括在120°磁铁后安装了一副自行设计制作有静电偏转板,有效改善了对127Ⅰ束流和129Ⅰ计数的测量;采用97MoO2分子导航束稳定加速器端电压,加速器的端电压能稳定在几天内不超过0.1%,结合二次剥离,取得了满意的测量效果。用该方法测得AgI试剂样品的本底水平为7.83×10-13。对129Ⅰ/127Ⅰ比值范围为(4.92~0.28)×10-10的一系列样品的测量不确定度在7%以下,准确度较前有所提高。

An improved 129I-AMS tor at the University of Tsukuba. measurement method has been developed on the 12UD tandem accelera.These improvements include making a deflector and installing it behind the 120° magnet to mend the measurement of ^127I current and ^129I count. With MoO2 molecular pilot beam to stabilize accelerator terminal voltage, the terminal voltage is kept stably within 0. 1% accuracy. Combining with second stripper, this method is proved to be effective. The level of background is 7.83 10-13 for AgI reagent sample. The uncertainty of the measurement is under 7 % for a series of samples which ^129I/127I ratio are between 4. 92×10^-10 and 0.28 10^-10.