Luminescence quenching of the triplet excimer state by air traces in gaseous argon

Understand

While developing a liquid argon detector for dark matter searches we investigate the influence of air contamination on the VUV scintillation yield in gaseous argon at atmospheric pressure.

• We determine with a radioactive alpha-source the photon yield for various partial air pressures and different reflectors and wavelength shifters.
• We find for the fast scintillation component a time constant tau1= 11.3 +- 2.8 ns, independent of gas purity.
• However, the decay time of the slow component depends on gas purity and is a good indicator for the total VUV light yield.