Precise measurement of gas parameters in a realistic RPC configuration: the currently used R134a gas and a potential alternative eco-gas

In this work, we present a comprehensive method to measure the gas parameters, such as the effective Townsend coefficient and electron drift velocity in homogeneous high electric fields (up to 100 kV/cm}) at atmospheric pressure and room temperature. A pulsed laser facility with micro-meter spatial accuracy and picosecond pulse duration is used to ignite primary ionizations at specific positions in the gas gap of a Resistive Plate Chamber (RPC) detector prototype. The gas parameters are determined solely by the RPC signals. The main component of the current standard gas for RPC is Tetrafluoroethane (R134a) which has a high Global Warming Potential. Therefore, using Tetrafluoropropene (HFO-1234ze) is under research as an eco-friendly substance. We measure the parameters of these two types of working gases.It is the first direct measurement of the gas parameters of timing RPCs under working conditions. By comparison with existing data from other investigation points, we observe a dependence of gas parameters on the pressure.