Radon reduction in gases for rare event search experiments

Radon-222 provides one of the most significant contaminants for rare-event search experiments. It is an inevitable product of trace amounts of natural uranium that is continuously supplied from detector components. Adsorption characteristics of radon in nitrogen, argon, and xenon carrier gases on various types of charcoals have been studied in the temperature range of 190-295 K at flow rates of 0.5 and 2 slpm. Studied charcoals have different adsorbing properties and intrinsic radioactive purities. R&D studies of the radon reduction system for the LZ experiment performed at The University of Michigan will be presented.