Research on the origin of micrometeorite by extremely accurate instrumental neutron activation analysis

本研究的第一个目的是建立超小陨石样品中多元素的仪器中子活化分析(INAA)准确分析技术。第二是为精确讨论宇宙尘埃的起源积累化学数据。超小陨石样品的仪器中子活化分析快速处理方法的研究我们用颈眼看不到直径小于100μm的微小样品。利用装有微量样品的高纯聚乙烯袋(3x3 Mm)，建立了INAA的快速搬运系统。并研制了一种新型的长半衰期中子活化分析微量样品辐照容器。稀土元素等亲石元素的玻璃标准由标准岩粉(如JB-1)制成。用高纯金属制成了亲铁元素(Au、Ir等)的合金标准，检查了这些标准在10~100μg范围内的均匀性。但与微陨石样品的放射性活度相比，合金标准样品的放射性活度偏高。对从南极富士穹顶站生活水箱中的沉积物中收集的微陨石样品进行了INAA.4分析。对从南极大和裸露冰场采集的未熔融微陨石样品进行了初步分析。

The first purpose of this research is establishment of accurate analytical technique for multi-elements by instrumental neutron activation analysis (INAA) for multi-elements in ultra-small micrometeorite sample. The second is accumulate of chemical data for precise discussion of the origin of cosmic dust.1. Development of the rapid handling method of instrumental neutron activation analysis for ultra-small micrometeorite sample. We cannot see tiny sample such diameter as less than 100 μm with the necked eye. By using the high purity polyethylene bag (3x3 mm) which enclosed tiny samples, a rapid handling system of INAA is established. New irradiation container of tiny sample for INAA using long half life nuclides was also developed.2. Glass standards for lithophile elements such as rare earth elements were made from standard rock power (e.g. JB-1). An alloy standard for siderophile elements (Au, Ir etc) was made from high purity metals.Homogeneities for 10 to 100 μg range of these standards were checked. However, radio activity of alloy standard was too high compared with the radio activities for micrometeorite samples.3. Micrometeorite samples collected from sediments in the water tank for living at the Dome Fuji station, Antarctica were analyzed by INAA.4. Preliminary analyses were performed to unmelted micrometeorite samples collected from Yamato bare ice field, Antarctica.