The development of a method bf hydrogen analysis for rock and mineral samples using resonant nuclear reactions

利用筑波大学的串联加速器获得的16 ~ 25 MeV ^<19>的F离子束和20 MeV的质子束，进行了新型高能离子探针的研制和实验方法的改进。本文针对熔融包裹体中氢浓度的测量，采用SIMS等常规方法测量较为困难。结果如下：1。研制成功了用于地球科学研究的高能离子微探针。梁斑横向尺寸为30μm，由于熔体夹杂物的尺寸大多大于30μm，因此梁斑横向尺寸较小。在NRA中，最深深度为距样品表面4μm；氢气分布深度分辨率为0.1μm；灵敏度低至50 wt. ppm H_20通过^1H(^<19>F, α γ)^<16>O反应；相对总体不确定性为15%。在ERDA中，样品厚度为0.2 mm；深度分辨率为5μm；采用质子-质子重合法，灵敏度低至10 wt. ppm H_2O；相对总体不确定性为15%。采用离子注入法制备了一种含氢标准样品，用α-γ角相关法在^1H(^<19>F, α γ)^<16>O反应中对其氢浓度进行了标定，相对总体不确定度为9.7%。开发了计算机程序，通过展开NRA中获得的激发函数或质子-质子重合erda中的和能谱来提取最可能的氢分布。为了重新评估原子弹发射的中子通量，对广岛一座桥的花岗岩中的氢浓度进行了测量。还测量了一些火山灰中熔体包裹体中的氢。

The development of a new high-energy ion microprobe and improvements of experimental methods were carried out using the beams of 16〜25 MeV ^<19>F ions and 20 MeV protons obtained from the tandem accelerator in the University of Tsukuba. It is aimed at the measurement of hydrogen concentration in melt inclusions, which was rather difficult with such a conventional method as SIMS. The results are as follows.1. A high-energy ion microprobe dedicated to the investigation of earth science was successfully constructed.2. The lateral size of beam spot is 30μm, which is sufficiently small since the majority of melt inclusions are larger than 30μm. In NRA the deepest depth is 4μm from the sample surface ; the depth resolution of hydrogen distribution is 0.1μm ; the sensitivity is as low as 50 wt. ppm H_20 by ^1H(^<19>F, α γ)^<16>O reaction ; and the relative overall uncertainty is 15%. In ERDA, the thickness of samples is 0.2 mm ; the depth resolution is 5μm ; the sensitivity is as low as 10 wt. ppm H_2O by employing proton-proton coincidence method ; and the relative overall uncertainty is 15%.3. A hydrogen bearing standard sample was prepared by ion implantation, and its hydrogen concentration was calibrated by α-γ angular correlation in the ^1H(^<19>F, α γ)^<16>O reaction with a relative overall uncertainty of 9.7%.4. Computer programs were developed to extract most likely hydrogen distributions by unfolding from excitation functions obtained in NRA or sum-energy spectra in proton-proton coincidence ERDA.5. The hydrogen concentration in the granite of a bridge in Hiroshima city was measured for the reevaluation of neutron flux emitted from the atomic bomb. Hydrogen in melt inclusions confined in some volcanic ashes was also measured.