The development of two-dimensional position-sensitive counter for high-energy X rays provided from synchrotron radiation facility

本研究为研制基于漂移室原理的10 - 100 keV高能X射线二维位置灵敏探测器作了基础研究。1）高压正比计数管在有限比例区的工作机理（a）对特征X射线引起的晕轮效应进行了详细的分析，并对晕轮效应引起的正比计数管响应进行了充分的解释。首次发现，在RLP中，晕事件的气体放大程度大于光峰事件。从实际的观点来看，这一事实是有帮助的，因为简单的脉冲高度选择能够排除已知会恶化位置分辨率的晕轮事件。结果发表在第（1）号文章中。(b)证实了在7-atm Ar+3中存在由初级电子云结构变化引起的雪崩模式突变 ...更多信息 0%CH_4。(the（3）在带电粒子加速器实验中检验了位置灵敏正比计数器（PSPC）的可行性。结果表明，PSPC的高能量（位置）分辨率使其能够用于PIXE分析痕量元素。(the在KEK光子工厂测试了PSPC对10-60 KeV高能光子束的性能。获得了较好的位置分辨率，20-keV X射线为122 μ m（fwhm），35-keV X射线为140 μ m。部分结果在第（3）篇文章中给出。2）X射线漂移探测器的制作（a）制作了一个灵敏面积为110 × 110 mm^2的X射线漂移探测器。漂移空间由25层漂移方向和4层反深度方向的场线组成。4层分别延伸4根阳极丝，其厚度分别为2、4、6和8 mm。(b)计算了电位分布，实现了6 mm厚层的足够平坦电位。发现阳极丝附近的电势分布对于有效地收集初级电子是重要的。(c)用5-7 MeV质子束对漂移计数器进行了测试实验。由于窗口材料，如Kapton膜，光束的精细准直是不可能的。束流展宽是带电粒子特有的现象，而X射线则不然。因此，我们希望在今年六月的准直光子束实验中，能得到更好的结果。少

In this research, we have made basic studies for the development of two-dimensional position-sensitive detector for high energy X rays of 10 - 100keV range, being based on the drift chamber principle. Our achievements are as follows :1) Operational mechanism of high-pressure proportional counter in the region of limited proportionality (RLP) (a) Detailed analysis was performed for the halo effect due to characteristic X rays, and the response of proportional counter caused by this effect was fully explained. It was first found that, in RLP,the degree of gas amplification for the halo events is greater than that for the photo-peak events. From the practical view-point, this fact helps since a simple pulse-height selection is able to exclude the halo events which is known to deteriorate position resolution. The results are published in the article No. (1). (b) It was confirmed that the sudden change of avalanche mode due to structural change of primary-electron cloud exists in 7-atm Ar+3 … More 0% CH_4. (the article No. (2)) (c) The feasibility of our position-sensitive proportional counter (PSPC) was examined in charged-particle accelerator experiment. The result showed that high-energy (position) resolving power of the PSPC enables to analyze trace elements to be studied in PIXE.(the article No. (4)) The performance of the PSPC for 10-60 KeV high-energy photon beams was tested in KEK Photon Factory. Fairly good position resolution of 122mum (fwhm) for 20-keV X rays and 140mum for 35-keV X rays were obtained. A part of the results is given in the article No. (3).2) Fabrication of drift detector for X rays (a) A drift detector for X rays with a large sensitive area of 110 x 110 mm^2 was made. The drift space consists of field wires of 25 layrs in drift direction and 4 laryers in counter-depth direction. 4 anode wires are extended for the 4 layrs, the thicknesses of which are 2,4,6 and 8 mm, respectively. (b) The potential distribution was calculated and the adequate flat potential for the 6-mm layr is realized. It was found that the distribution of the potential near the anode wire is important to efficiently collect primary electrons. (c) Test experiments of the drift counter were carried out by using 5-7 Mev proton beams. Owing to the window materials such as Kapton films, fine collimation of the beam was not possible. The beam broadening is peculiar aspect for the charged particles, but not the case for X rays. Thus, it is hoped that, in the well-collimated photon beam experiment scheduled in this June, much better result can be obtained. Less