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

点击翻译按钮获取中文摘要

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.