The development of gas-sealed type position-sensitive counter utilizing peculiar electron-avalanche mode

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In this research, we have made basic studies for the development of gas-sealed type position-sensitive counter utilizing peculiar electron-avalanche mode. Our achievements are as follows :(1) Operational mechanism and performance of high-preessure 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 pulseheight 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) The feasibility of our position-sensitive proportional counter (PSPC) was examined in charged-particle accelerator experiment. The result showed that high-ene … More rgy (position) resolving power of the PSPC enables to analyze trace elements to be studied in PIXE.(the article No.(2)) (c) It was confimed that the sudden change of avalanche mode due to strutural change of primary-electron cloud exists in 7-atm Ar+30% CH_4. (the article No.(3)) (d) The performance of the PSPC for 10-60 KeV high-energy photon beams was tested in KEK Photon Factory. Fairly good position resolitions of 122mum (fwhm) for 20-keVX rays and 140mum for 35-keVX rays were obtained. A part of the results is given in the article No.(4). (e) Recently, high-resolution X-ray measurement using crystal spectrometer equipped with our PSPC was made by bombarding several targets with 6-MeV proton beams. The results reveled anomalous peak structures which clearly show many-body effect of atomic system. The elaborate analysis is being proceeded to publish paper as soon as possible.(2) Further improvement In this research project, we have completed to construct a newly improved PSPC,gas purification system to remove oxygen and water, and a gas mixing system to vary counting gases and mixing ratio. The gas systems are combined with oil-free turbo molecular pump. For Ar gas, relatively good performance was obtained when the gas is sealed in the PSPC.For Xe gas, however, it is needed to improve gas system especially the performance of the gas-purification system. Less