Effect of electrode coat's surface resistivity of Resistive Plate Chamber on the space dispersion of induced charge

Abstract

Resistive Plate Chamber (RPC) is a parallel plate gaseous detector built using electrodes of high volume resistivity. Operation and performance of the RPCs crucially depends upon the conductive coating on the outer side of the electrodes. Therefore, it is imperative to study in detail the effect of the surface resistivity of the electrodes' coating on RPC characteristics and performance. In this report, the effects of surface resistivity of conductive coating on the spatial dispersion of the induced charge by the three fabricated prototype RPCs with surface resistivities of 1 MΩ/ □, 100 kΩ/ □, 40 kΩ/ □ were studied experimentally. A double-Gaussian function was used to fit the dispersion of the induced charge of the RPC. It is shown that the Gaussian distribution with the narrower width is due to the spread of the avalanche charge in the gas gap of the RPC and that of larger width is due to diffusion of charge as it passes through the resistive coat film. Effect of resistivity on other RPC detector parameters such as efficiency, noise rate and strip-multiplicity is also reported.