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

开发利用共振核反应对岩石和矿物样品进行氢分析的方法

基本信息

批准号：
12304032
负责人：
FURUNO Kohei
金额：
$ 13.56万
依托单位：
University of Tsukuba
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12304032/
关键词：
NRA Microbeam Hydrogen analysis ERDA Hydrogen in rocks and Minerals 岩石・鉱物水濃度

项目摘要

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.

利用筑波大学串列加速器获得的16 ~ 25 MeV ^ F离子束和20 MeV质子束，开发了一种新的高能离子微探针，并改进了实验方法<19>。针对传统的二次西姆斯法难以测量熔体夹杂物中氢含量的问题，提出了一种新的测量方法。研究结果如下：1.成功研制了一台用于地球科学研究的高能离子探针.束斑的横向尺寸为30μm，这是足够小的，因为大多数熔体夹杂物大于30μm。NRA的氢分布深度分辨率为0.1μm，灵敏度低至50 wt. %，最大深度为4μm。用^1H（^<19>F，α γ）^<16>O反应测定H_20的相对总不确定度为15%。在ERDA中，样品厚度为0.2mm，深度分辨率为5μm，灵敏度低至10 wt.采用质子-质子符合法测定H_2O，相对总不确定度为15%.采用离子注入法制备了含氢标准样品，并利用^1H（^ F，α γ）^ O反应的α-γ角关联法标定了含氢标准样品中的氢浓度<19><16>，相对总不确定度为9.7%。开发了计算机程序，通过从NRA中获得的激发函数或质子-质子符合ERDA中的和能谱展开来提取最可能的氢分布。为了重新评价原子弹爆炸产生的中子通量，测量了广岛市一座桥花岗岩中的氢浓度。还测量了火山灰中熔融包裹体的氢含量。