We report the performance of a VUV-sensitive MWPC with a pad cathode covered by a solid CsI photon converter. Cherenkov photons produced by relativistic 1 2 C ions in a MgF 2 radiator have been detected with 95% single photo electron efficiency. In the HADES design a resulting figure of merit N 0 > 66 promises proper operation of the RICH as a fast hadron blind trigger device. In addition, we have investigated the scintillation properties of several fluoro-carbon radiator gases in the VUV wavelength region. A significant emission around λ 170 nm is found for CF 4 .