Optical study of the features of the streamer images in RPC

Abstract Optical images of the streamer from a Resistive Plate Chamber (RPC) are observed using a transparent high-voltage electrode in the operation of streamer mode. The optical images are measured using CCD camera system in mixture Ar/C 4 H 10 with and without C 2 H 2 F 4 . Area of typical streamer image is approximately 12 mm 2 in both gas mixtures with its surrounding halo of 2– 4 mm in diameter. We also observed the quenching effect of C 4 H 10 and C 2 H 2 F 4 on the optical image in the chamber.