Speaker
Description
Pre-breakdown high-voltage phenomena (HVPs)—notably electroluminescence (EL) and micro-discharges—limit the stability and background performance of liquid xenon time-projection chambers (LXe TPCs) in neutrinoless double-beta decay ($0\nu\beta\beta$) and Dark Matter searches. We present results from a 10 kg LXe high-voltage testbed at Stanford, designed to characterize these HVPs and evaluate mitigation strategies relevant to multi-ton detectors.
Using a plane-to-plane geometry with polished $15~\mathrm{cm}^2$ electrodes at fields up to $90~\mathrm{kV/cm}$, we systematically compare the effectiveness of thin metallic (Pt, Ni) and insulating ($\mathrm{MgF_2}$, Parylene-C) coatings against bare stainless steel in suppressing EL and micro-discharge activity. The intensity and rate of pre-breakdown events are quantified for each surface.
Our findings provide direct empirical guidance for electrode surface engineering in future noble-liquid rare-event searches, identifying promising coatings and conditions that suppress spurious signals and enable stable, long-term operation at the highest electric fields.