Abstract
Bubble formation in liquid xenon underneath a Thick Gaseous Electron Multiplier (THGEM) electrode immersed in liquid xenon was observed with a CCD camera. With voltage across the THGEM, the appearance of bubbles was correlated with that of electroluminescence signals induced by ionization electrons from alpha-particle tracks. This confirms recent indirect evidence that the observed photons are due to electroluminescence within a xenon vapor layer trapped under the electrode. The bubbles seem to emerge spontaneously due to heat flow from 300 K into the liquid, or in a controlled manner by locally boiling the liquid with resistive wires. Controlled bubble formation resulted in energy resolution of σ/E ≈ 7.5% for ∼ 6000 ionization electrons. The phenomenon could pave ways towards the conception of large-volume `local dual-phase' noble-liquid TPCs.
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Corrections were made to this article on 01 March 2016. The title and an author surname were corrected.