Establishment of two-dimensional analysis method with resonance-absorption transmission utilizing pulsed neutrons

本研究的目的是利用脉冲中子的特性建立二维分析方法，重点研究共振吸收。首先介绍了京都大学研制的μPIC（Micro Projection Ion Chamber）探测器，作为探测器系统的准备。实验结果表明，μPIC的时间和空间分辨率（~1μs，~0.5mm），中子和γ射线的分离度（&lt;10 μ s）是适合于本研究<-6>的。利用该探测器系统，在日本PARC中心Noboru的束线上进行了脉冲中子共振吸收实验。作为样品，由于定量性的确认，在厚度的改变中使用具有共振吸收峰的Co、Ta、Mo等的单一材料。结果表明，用核数据计算的厚度与真实的厚度相比，误差约为7%。另一方面，还发现背景成分影响定量的准确性。模拟和实验结果表明，本底来源于实验室中的散射中子。建立了二维共振吸收分析方法的基本算法。然而，为了更精确地分析，需要改进探测器系统和测量方法。

The purpose of this study was the establishment of two-dimensional analysis method utilizing the characteristics of the pulsed neutron, focusing on the resonance absorption. Firstly, as the preparation of the proper detector system, the μPIC (Micro Projection Ion Chamber) detector developed in Kyoto University has been introduced. As the result of test experiments, it was found that μPIC was suitable for this study in viewpoint of time and spatial resolutions(～1μs, ～0.5mm), and neutron and gamma-ray separation (<10^<-6>). With this detector system, the resonance absorption experiments using pulsed neutrons were performed at beam line of the J-PARC Center NOBORU. As a sample, single materials of Co, Ta, Mo, and so on having the resonance absorption peak was used in changing of the thickness due to the confirmation of the quantitativity. As a result, the measured thickness derived with the nuclear data and no correction, it was found to be about 7% compared with the real thickness. On the other hand, it was also found that the background component affects the accuracy of quantification. As the results of the simulation and the experiment, the background is originated from the scattering neutron in the experimental room. The basic algorithm for the analysis could be established for two-dimensional resonance absorption analysis method. However, for the more precise analysis, the improvement of the detector system and the measurement method is necessary.