Development of the oscillation system for a micro-are monochromatic X-ray diffractometer.

微观结构的不均匀性，如微畴和从主晶体中分离出来的晶体，对于研究岩石形成和合成矿物晶体中记录的生长和/或冷却过程具有重要意义。这些现象通常通过光学显微镜和/或电子探针显微分析来检验。到目前为止，通过x射线衍射研究的样品数量非常有限，因为样品（30μm厚度）被安装在1.4mm厚的侧面（薄片）上。建立了微针孔衍射系统，利用单色x射线束测量微畴的衍射。在0.7A^^°范围内，微针孔的有效直径为2.0μm，散度为24μrad。在之前的实验中，我们很难在旋转轴上设置样本位置。因此，已经准备了安装在样品旋转台上的x级，用于设置样品。x级通过实验前确定的校准曲线控制样品设置在微光束上的位置。但是，控制x级的方案并没有给出令人满意的结果，目前方案的改进正在进行中。为了验证该系统的性能，制备了两种薄片进行衍射实验：一种是从日本北海道岩井岩中橄榄石主体晶体中分离出的铬尖晶石晶体薄片，另一种是翡翠、辉长石和辉长石等变质岩的薄片。在平面成像板上成功地记录了几种矿物的振荡照片。对衍射数据的分析正在进行中。

Studies on textural inhomogeneity like micro-domains and crystallites segregated from the host crystals are important for investigation of growing and/or cooling process recorded in the rock-forming and synthetic mineral crystals. The phenomena are usually examined by optical microscopy and/or electron-probe micro-analysis. Very limited number of such samples have been investigated so far by X-ray diffraction, because the samples (30μm in thickness) are mounted on sides 1.4mm thick (thin sections). The diffraction system with the micro-pinhole and been developed to measure diffraction from micro-domains with the monochromatic X-ray beam. The effective deameter of a micro-pinhole is 2.0μm for 0.7A^^° with a divergence 24μrad.In the previous experiment, we had difficulty with setting the sample position on the axis of rotation. Therefore an x-stage installed on a rotating stage of the sample has been prepared for setting the sample. The x-stage was controlled as the position of the sample setting on the micro-beam with a calibration curve determined before the experiments. However, the program to control the x-stage did not give the satisfying results, the improvement of the program is now in progress.To check the performance of the system, two kinds of thin sections were prepared for the diffraction experiments : one is a thin section of Cr-spinel crystals segregated from olivine host crystal in dunite from Iwanai-dake, Hokkaido, Japan and the other thin sections of the metamorphic rocks including jadeite, omphacite and riebeckite. The oscillation photographs of several kinds of mineral were successfully recorded on a flat imaging plate. The analysis of the diffraction data is now in progress.