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Liquid argon (LAr) is widely employed as a scintillator in rare-event searches. Its optical and scintillation properties, as well as the impact of impurities, are being studied extensively by many groups world-wide. LAr scintillation light exhibits a main emission wavelength of 128 nm, which makes propagation and detection challenging because of short attenuation lengths and low quantum efficiencies of photo sensors in the VUV spectral range.
Previously, we have determined the attenuation length of purified liquid argon for its own scintillation light to be larger than 110 cm at a wavelength of 128 nm [1, 2]. Already in 1982 Kubota et al. [3] investigated the impact of xenon doping of LAr. Recently, we have studied the emission spectrum and time distribution dependent on the xenon concentration [4].
Here, we present our latest study of xenon-doped LAr with focus on the primary photon yield, the effective triplet lifetime and attenuation length, with xenon concentrations ranging from 3 ppm to 300 ppm. The scintillation and optical properties were measured simultaneously with the LLAMA [5] instrument operated inside SCARF, a 1 ton LAr test stand, and the xenon concentrations using IDEFIX, a dedicated mass spectrometer setup.
[1] A. Neumeier et al. “Attenuation of Vacuum Ultraviolet Light in Liquid Argon”. In: Eur. Phys. J. C72.10 (Oct. 2012).
[2] A. Neumeier et al. “Attenuation of Vacuum Ultraviolet Light in Pure and Xenon-Doped Liquid Argon — An Approach to an Assignment of the near-Infrared Emission from the Mixture”. In: EPL 111.1 (July 2015).
[3] Shinzou Kubota et al. “Liquid and Solid Argon, Krypton and Xenon Scintillators”. In: Nucl. Inst. Meth. Phys. Res. 196.1 (May 1982).
[4] A. Neumeier et al. “Intense Vacuum Ultraviolet and Infrared Scintillation of Liquid Ar-Xe Mixtures”. In: EPL 109.1 (Jan. 2015).
[5] Mario Schwarz et al. “Liquid Argon Instrumentation and Monitoring in LEGEND-200”. In: ANIMMA 2021 (July 2021)
