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一套精密的多元素分析技术，对超微量陨石样品进行仪器中子活化分析。二是为精确讨论宇宙尘的起源积累了化学数据.超微小陨石仪器中子活化分析快速处理方法的研究。对于直径小于100 μm的微小样品，用肉眼是看不到的.采用高纯度聚乙烯袋（3 × 3 mm）包裹微小样品，建立了中子活化分析的快速处理系统。研制了用于长半衰期核素中子活化分析的微小样品辐照容器.亲石元素如稀土元素的玻璃标准由标准岩石粉末（例如JB-1）制成。用高纯金属制成了亲铁元素（Au、Ir等）的合金标准，在10 ~ 100 μg范围内进行了均匀性检验。但是，与微陨石样品相比，合金标准样品的放射性活度偏高.利用INAA分析了南极Dome Fuji站生活水箱沉积物中的微陨石样品。对采自南极大和裸冰场的未熔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.