A long-run study of aging in glass timing RPCs with analysis of the deposited material

In this study, aimed at timing RPCs operating in avalanche mode, we irradiated 0.3 mm gas gaps for 790 days of continuous operation at 300 Hz/cm2, corresponding to an accumulated charge of more than 20 mC/cm2. No evidence of any systematic long-term increase of dark current was found, but a visual inspection confirmed the existence of a bluish deposit over the glass electrodes. The identification of the deposit components was made by liquid extraction with organic solvents and subsequent analysis by gas chromatography with mass spectroscopy detection. The identified species are oligomers of tetrafluoroethylene.