TY - JOUR T1 - Study of radon reduction in gases for rare event search experiments Y1 - 2018 A1 - K. Pushkin A1 - C. Akerlof A1 - D. Anbajagane A1 - J. Armstrong A1 - M. Arthurs A1 - Jacob Bringewatt A1 - T. Edberg A1 - C. Hall A1 - M. Lei A1 - R. Raymond A1 - M. Reh A1 - D. Saini A1 - A. Sander A1 - J. Schaefer A1 - D. Seymour A1 - N. Swanson A1 - Y. Wang A1 - W. Lorenzon AB -

The noble elements, argon and xenon, are frequently employed as the target and event detector for weakly interacting particles such as neutrinos and Dark Matter. For such rare processes, background radiation must be carefully minimized. Radon provides one of the most significant contaminants since it is an inevitable product of trace amounts of natural uranium. To design a purification system for reducing such contamination, the adsorption characteristics of radon in nitrogen, argon, and xenon carrier gases on various types of charcoals with different adsorbing properties and intrinsic radioactive purities have been studied in the temperature range of 190-295 K at flow rates of 0.5 and 2 standard liters per minute. Essential performance parameters for the various charcoals include the average breakthrough times (τ), dynamic adsorption coefficients (ka) and the number of theoretical stages (n). It is shown that the ka-values for radon in nitrogen, argon, and xenon increase as the temperature of the charcoal traps decreases, and that they are significantly larger in nitrogen and argon than in xenon gas due to adsorption saturation effects. It is found that, unlike in xenon, the dynamic adsorption coefficients for radon in nitrogen and argon strictly obey the Arrhenius law. The experimental results strongly indicate that nitric acid etched Saratech is the best candidate among all used charcoal brands. It allows reducing total radon concentration in the LZ liquid Xe detector to meet the ultimate goal in the search for Dark Matter.

UR - https://arxiv.org/abs/1805.11306 U5 - https://doi.org/10.1016/j.nima.2018.06.076 ER -