A development of X-ray polarimeter using microstrip gas proportional counter

An application of a microstrip gas proportional counter to an X-ray polarimeter was investigated. Primary electron clouds produced by photoelectric absorption extend to the direction of the electric vector of incident polarized X-rays. Then the length of the electron clouds projected to the microstrip plate (MS plate) affects to the rise time of signal from the microstrip gas proportional counter (MSGC). By a prototype counter mounting a MS plate, the characteristics of the rise time distributions of the pulse from MSGC were investigated as a function of the pressure, the energy, the gas gain, and the reduced field. When the prototype counter was irradiated with polarized X-rays which have parallel or perpendicular electric vector to MS plate, the difference of 24 ns between the peak channels of the rise time distributions was observed for two cases. The results indicate that the detection of the rise time could be used as an X-ray polarimeter technique.