Detection of photoabsorption point with capillary imaging gas proportional counter

We have successfully detected the images of photoelectron tracks of 2.7and 5.9-keV X-rays utilizing a capillary imaging gas proportional counter (CIGC). The images of the photoelectron tracks were extracted by systematic analysis based on clustering of the tracks, eliminating the spurious noise cluster due to an image-intensified charge-coupled device camera. The characteristics of the images were investigated in terms of the relationship between the light yield and the area of the cluster. The extent of cluster spreading was approximately 1.3 mm on average for 2.7-keV photoelectrons. The light yield of the clusters for 5.9-keV X-rays was distributed at 74% full-width at half-maximum around a peak that is approximately two times larger than that for 2.7-keV photoelectrons. The area of the clusters for 5.9-keV X-rays was approximately 1.5 times larger than that for 2.7-keV photoelectrons. The results imply that the photoabsorption point is detectable for X-rays above 10 keV.