Performance of large area Micro Pixel Chamber

A novel gaseous two-dimensional imaging detector “Micro Pixel Chamber (μ-PIC)” has been developed. This detector is based on double sided printed circuit board (PCB). We have developed large area (10 cm×10 cm) μ-PICs with 65536 pixel anodes of 400 μm pitch on a 100 μm thick insulating substrate. Achieved energy resolution was 30% (FWHM) at 5.9 keV, and a gas gain of 7000 was obtained with argon ethane (8:2) gas mixture. This gain is high enough to detect minimum ionizing particles with such a small electrode pitch. Although several discharges occurred during 65 h continuous operation, the detectors have kept stable operation with high gain. The μ-PIC is a useful detector for many applications e.g. X-ray, gamma ray, and charged particle imaging. The micro electrode structure allows us to measure directions of primary electrons due to incident X-rays or gamma rays, which provide a strong method for X-ray polarimetry and gamma-ray imaging.