Studying the impact of humidity on the performance of THGEMs

In this study, we investigate the impact of humidity on the performance of a THGEM operated with an Ar-CO₂ gas mixture. The water content is introduced in a range of 0-4000 ppmV. It is observed that the presence of increased humidity does not degrade any of the studied performance criteria. On the contrary, our measurements suggest an improvement in discharge stability with increasing humidity levels at the highest gains and fields. No significant difference is observed at the lower gains, indicating that humidity helps to avoid spurious discharges related to electrode defects or charging-up of the insulating layers. We conclude that adding a small amount of water to the gas mixture may be beneficial for the stable operation of an MPGD.