Study on the coupled readout MRPC and eco working gas by a cosmic test system

As a new type of gaseous detector, Multi-gap Resistive Plate Chamber (MRPC) has been widely used in high-energy physics experiments to identify the secondary particles produced in the collisions. In this paper we introduce a new version of MRPC with copper high voltage electrodes to solve the issues of complexity, pollution, noise uniformity and impedance matching, which are due to the graphite HV structure of the present counters. The analysis combined with simulation proved that the major part of charge can be induced through capacitive coupling between the corresponding high voltage and readout strips. Cosmic test on the coupled readout MRPC shows a 96% efficiency and 71 ps time resolution. The cosmic test system is also applied for the task to find eco working gas mixtures, since Freon and Sulfur Hexafluoride, as the most commonly used components for MRPCs, have high values of Global Warming Potential. The task becomes important and urgent in the context when EU has set targets for reducing selling and emission of fluorinated greenhouse gases. We report the results which verify the good detector operation in several Hydrofluoroolefins based ecological gas mixtures. The system can be used to test more eco gas mixtures in the future.