First demonstration of long-distance electron drift in liquid xenon with the Xenoscope time projection chamber

Xenoscope is a dual-phase xenon time projection chamber operated at the University of Zurich to investigate electron transport over distances relevant to the next-generation XLZD (XENON-LUX-ZEPLIN-DARWIN) observatory. We demonstrate electron drift over $2.6$ m in liquid xenon using cosmic-muon-induced ionization signals. External muon tagging provides a timing reference for charge produced at known depths, while the endpoint of the average electroluminescence waveform probes transport over the full drift length. We measure electron drift velocities of (1.320 ± 0.006) mm/$μ$s at (80.92 ± 0.36) V/cm and (1.436 ± 0.001) mm/$μ$s at (96.00 ± 0.42) V/cm. These results establish detectable charge transport over meter-scale distances and provide an experimental benchmark for the development of future large liquid-xenon time projection chambers.