Liquid Hole-Multipliers: A potential concept for large single-phase noble-liquid TPCs of rare events

A novel concept is proposed for large-volume single-phase noble-liquid TPC detectors for rare events. Both radiation-induced scintillation-light and ionization-charge are detected by Liquid Hole-Multipliers, LHM, immersed in the noble liquid. The latter may consist of cascaded Gas Electron Multipliers (GEM), Thick Gas Electron Multiplier (THGEM) electrodes or others, coated with CsI UV-photocathodes. Electrons, photo-induced on CsI by primary scintillation in the noble liquid, and event-correlated drifting ionization electrons are amplified in the cascaded elements primarily through electroluminescence, and possibly through additional moderate avalanche, occurring within the holes. The resulting charge-signals or light-pulses are recorded on anode pads or with photosensors, e.g. gaseous photomultipliers (GPM), respectively. Potential affordable solutions are proposed for multi-ton dark-matter detectors; open questions are formulated for validating this dream.