An empirical formula for the impact excitation coefficient of xenon-filled scintillation counters

Liquid Noble gases for Dark Matter searches: a synoptic survey

“…14 C is found in liquid argon, mostly close to the chamber walls and has an estimated contribution of less than 50 mHz. 60 Co and 40 K contamination is found in the surrounding materials (the total energy spectrum measured and simulated is shown above 100 keV, but these last two contaminations are not quantitatively given).…”

“…for proportional scintillation on gas pressure is still open to debate. Some authors have found this dependence [60], others have not and attributed this behaviour to the different UV spectral response of the detectors used [39], i.e. light production and detection efficiency.…”

“…Two main background components were found by the authors in the WARP prototype [59]: 1) contaminants present in the materials surrounding liquid argon, dewar etc. from 238 U chain ( 222 Rn was present in the liquid argon used for the bath), 232 Th chain, 60 Co and 40 K; 2) contaminants in the liquid argon target -mainly 222 Rn, 39 Ar and 85 Kr. After filling the chamber with new argon the total decay rate of 222 Rn is around 1-2 Hz and is quoted to be a few tens of events/day four weeks after the filling (considering the 222 Rn half-life).…”

“…The WARP authors declare daily calibrations "for long-term stability and linearity of the response" and the γ-ray sources used in ref. [59] were: 57 Co, 60 Co, 137 Cs placed outside the stainless steel chamber. As mentioned at the beginning of Sect.…”

“…ZEPLIN-II only reports one gamma source (they also mention a 60 Co source but they do not give any plots) writing at the end that the average photoelectron yield for the PMTs was 1.10±0.04 phe/keV with the electric drift field set to zero, and 0.55±0.02 phe/keV with the electric field at 1 kV/cm (the operating value) [50].…”