The development of a new type of imaging X-ray detector with a capillary plate

A new type of optical imaging X-ray detector with a capillary plate was constructed. The instrument consists of a CGPC (Capillary Gas Proportional Counter), a focusing mirror system, and an image intensified CCD camera. Both the charge signal and the light signal from the CGPC were proportional to energy up to hard X-rays of 60 keV. The light output of the CGPC was approximately 250 times larger than that of a NaI(Tl) scintillator. The light yield of the CGPC at gas gain of 300 was 1.2 photons per electron for a gas mixture of xenon +5% methane at 1 atm. Using the optical imaging detector, an image of a track due to an /spl alpha/-particle was detected. Also the first evidence was obtained that the light emission was due to gas multiplication occurring in a thin capillary. Our goal is to use this new type of optical imaging detector as an X-ray polarimeter.