Scintillation and optical properties of xenon-doped liquid argon

Abstract

AbstractLiquid argon (LAr) is a common choice as detection medium in particle physics and rare-event searches. Challenges of LAr scintillation light detection include its short emission wavelength, long scintillation time and short attenuation length. The addition of small amounts of xenon to LAr is known to improve the scintillation and optical properties. We present a characterization campaign on xenon-doped liquid argon (XeDLAr) with target xenon concentrations ranging from 0 to 300 ppm by mass encompassing the measurement of the photoelectron yieldY, effective triplet lifetimeτ3and effective attenuation lengthλatt. The measurements were conducted in the Subterranean Cryogenic ARgon Facility,Scarf, a 1 t (XeD)LAr test stand in the shallow underground laboratory (UGL) of TU-Munich. These three scintillation and optical parameters were observed simultaneously with a single setup, theLegendLiquid Argon Monitoring Apparatus,Llama. The actual xenon concentrations in the liquid and gaseous phases were determined with the Impurity DEtector For Investigation of Xenon,Idefix, a mass spectrometer setup, and successful doping was confirmed. At the highest dopant concentration we find a doubling ofY, a tenfold reduction ofτ3to ∼90 ns and a tenfold increase ofλattto over 6 m.