Developmental Research of mass spectrometric system for laser probe dating of mineral

设计并搭建了新型的高灵敏度低本底惰性气体分析质谱仪及其配套系统，并进行了测试分析。该系统已在日本京都举行的第29届国际地质大会上发表。该质谱系统具有三个收集器，可以同时分析三种氩同位素，与现有的单收集器系统相比，具有极高的同位素分析精度，对年轻火山岩的定年具有强大的作用。不幸的是，MS中的离子枪在最后的研究年中碰巧出现了一些问题，使得现在无法准确地分析自然样品。我们要求亚由美工业株式会社对离子枪进行改进和改造。我们直到项目期限结束才完成完善的系统，但不认为这个项目不成功，因为我们在麻烦之前已经掌握了这个质谱系统的基本能力。我们相信这是世界上第一台用于惰性气体分析的三重收集器系统的质谱仪。研究了用现有质谱仪分析天然岩石和矿物中氩元素的基本问题，并将已建立的分析技术应用于地质材料。研究结果已在多篇文献中发表。我们还开发了用于极少量材料或细晶单晶Ar-Ar定年的激光探针氩提取系统。这使得从几微克的材料中检测出氩气成为可能，并且在逐步加热的过程中，将材料的温度控制在+-1 C之间，相对精度在500到1500 C之间。这也适用于单晶激光探测Ar-Ar定年和寄主岩石热史的研究。它的精确度可能是世界上最好的。

We have designed and constructed new mass spectrometer and the associated system with ultra high sensitivity and low background for noble gas analysis, and then proceeded the test analysis. This system has been presented at 29th Internatinal Geological Congress in Kyoto. This mass spectrometric system having three collectors has made it possible to analyze simultaneously three argon isotopes and has extremely high precision for the isotopic analysis in comparison with the present system with single collector, being powerful for dating young volcanic rocks. Unfortunately, the ion gun in MS Happened to have some troubles in middle of the final research year, making it imposible to analyze exactly natural samples now. We have required the improvement of ion gun and the rebuilding by Ayumi Industry Co., Ltd. We were not able to complete the perfect system until end of the term of project but do not think this project unsuccessful because we have already catched the basic ability of this mass spectrometric system before the trouble. We believe this is the first mass spectrometer with triple collector system for noble gas analysis in the world.We have sexamined the basic problem of argon analysis of natural rocks and minerals using the present mass spectrometer and applied the established analytical technique to geological materials. The lots of results have been published in many literatures. We have also developed laser probe argon extraction system for very small aount of materials or fine grained single crystal for Ar-Ar dating. This has made it possible to detect argon from the materials of few micro gram and control temperatures of the materials with a relative accurracy of +-1ﾟC between 500 and 1500ﾟC in the stepwise heating. This is also applicable to laser probe Ar-Ar dating of single crystal and examination of thermal history of the host rock. Its precision is probably the best in the world.