Determination of Natural Radioactivities, Especially Cosmic-Ray-Produced Radioactivities in Meteorites.

这项工作由两部分组成。首先，用伽马射线计数器测定宇宙射线在球粒陨石中产生的放射性；其次，用质谱仪测定陨石中的长寿命放射性核素。这两项工作都是从设备的改进开始的，因为要测量的天然放射性核素的数量非常少。目前有必要提高设备的灵敏度和分辨率（关于质谱仪改进的报告：下一页报告1）。各项工作的具体内容如下：(1)。球粒陨石中宇宙射线产生的放射性核素的测定(1)-1。宇宙射线在日本陨落或发现的球粒陨石中产生了^<26>的Al和^<53>的Mn：方法和结果的细节见报告No.3.(1)-2。宇宙射线产生稳定的稀有气体：为了比较上述数据，测定了日本球粒陨石中的稀有气体（报告2）。青森球粒陨石：宇宙射线产生的放射性核素在青森球粒陨石中被重新测定。结果将包括在第4号报告中。(1)-4。球粒陨石国分二：测量了五个球粒陨石标本的放射性。由此得出结论，该球粒陨石的原体大于500kg，当它撞击地球大气层时，损失超过90%。这些数据将很快公布（第5号报告）。(2)原始en辉石球粒陨石^<87>Rb-^<87>Sr关系：研究了两个E3，清镇（观测）和Yamato-6901（发现），一个E5， Yilmia（发现）和一个E6， Kailpur（观测）的Rb-Sr体系，发现这些原始球粒陨石的年龄不为4.6xlO^9年（报告6和7v）。

The work was composed of 2 parts. First, using gamma-ray counter, cosmic ray produced radioactivities in chondrites, and second, using mass spectrometer, long lived radioactive nuclides in meteorites, were determined.Both works were starting from the improvement of the equipments, because natural radioactive nuclides which should be measure, exist extremely small amounts. It is necessary to improve sensitivities and resolutions of devices for the present purpose(report on improvement of mass spectrometer: report No.1 in next page). Details of each work are as follows:(1). Determination of Cosmic Ray Produced Radioactive Nuclides in Chondrite(1)-1. Cosmic Ray Produced ^<26>Al and ^<53>Mn in Chondrites which fell or found in Japan: Details of methods and results were described in reports No.3.(1)-2. Cosmic Ray Produced Stable Rare Gases: For comparison of the above data, rare gases in Japanese chondrites were determined(report No.2).(1)-3. Chondrite Aomori: Cosmic ray produced radioactive nuclides in the chondrite Aomori were redetermined. Results will be included in report No.4.(1)-4. Chondrite Kokubunji: Radioactivities of five specimens of the chondrites were measured. As a results, it is concluded that the original body of the chondrite was larger than 500kg, and when it collide earth's atmosphere, it lost more than 90%. This data will be published soon(report No.5).(2) ^<87>Rb-^<87>Sr Relation in Primitive Enstatite Chondrites: Rb-Sr systems of two E3, Qingzhen(observed fall) and Yamato-6901(find), one E5, Yilmia (find) and one E6, Kailpur(observed fall) were investigated and found that those primitive chondrites did not have age of 4.6xlO^9 years(report No.6 and 7v.