A DEVELOPMENT OF X-RAY IMAGER AND POLARIMETER IN WIDE ENERGY RANGES BY GAS COUNTER WITH MICROCHANNEL PLATE

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We have developed a new type of gas proportional counter with the capability of fine position resolution and energy resolution by using a capillary plate, which is bi-product of a micro-channel plate. The capillary plate consists of a bundle of fine glass capillaries with electrodes on both the inlet and the outlet. The glass is lead glass and has higher resistivity, compared with the typical microchannel plates. The diameter and length of a capillary investigated are 100mum and 800mum, respectively. The diameter of the plate is effectively 20mm. The cappilary plate is installed in a vacuum tight gas chamber and is operated in gas by applying voltages between the inlet and the outlet. The fill gas was argon+5% methane at a pressure of latm.The characteristics of the capillary plate gas proportional counter (CGPC) were investifgated in using _<55>Fe 5.9keV X-rays. The resulting proportional counter was found to operate up to a gain of 10^4 without the onset of breakdown. The gas gain as the function of applied voltage and an analysis of Townsend ionization coefficient indicate that the electron multiplication of the CGPC is due to gas multiplication in each capillary. An energy resolution was 26% for 5.9keV X-rays at a gas gein of 7000. The escape peak in the energy of 2.9keV was clearly separated from the main peak. The gas gain of the CGPC was stable for long term operation over 10hours except during the first 15minutes after turning on the high voltages.An inportant point of the CGPC is that the gas multiplication occurs in each capillary and hence each part of the electron cloud entered in each capillary is identified in a very small domain. As an application of CGPC,we are available it to detect a X-ray in a capillary and a part of a electron cloud. We can envision development of a fine X-ray imaging detector and X-ray polarimeter from the results.