An application of microstrip gas proportional counter for a X-ray polarimeter

An application of a microstrip gas proportional counter to a X-ray polarimeter was investigated. Primary electron clouds produced by photoelectric absorption extend to the direction of electric vector of incident polarized X-ray and the direction of electron clouds to the microstrip plate (MS plate) affects the rise time of signal from MSGC. By using a test counter which mounted a MS plate, the characteristics of the rise time distributions of pulses from MSGC were investigated. The difference of the rise times between X-rays of /sup 55/Fe and /sup 241/Am sources was 71 nsec in Xe+methane (10%) with 0.4 atm. It reflects the difference of length of the trajectory between 5.9 keV X-rays and 29.8 keV photoelectrons ejected by photoabsorption. The detection of the rise time due to MSGC is available to a X-ray polarimeter.