Towards a large-area RPWELL detector: design optimization and performance

We present a new design and assembly procedure of a large-area gas-avalanche Resistive-Plate WELL (RPWELL) detector. A $50\times 50\mathrm{c}{\mathrm{m}}^2$ prototype was tested in $80\mathrm{G}\mathrm{e}\mathrm{V}\mathrm{/}\mathrm{c}$ muon beam at CERN-SPS, presenting improved performances compared to previous ones: MIP detection efficiency over 96% with 3% uniformity across the entire detector area, a charge gain of $\approx 7.5\times {10}^3$ with a uniformity of 22%, and discharge probability below ${10}^{-6}$ with a few single hotspots attributed to production imperfections. These results pave the way towards further up-scaling detectors of this kind.