Speaker
Description
In xenon-based rare-event search experiments in underground laboratories, radioactive noble gases dissolved in the xenon, in particular 222Rn and its betta-emitting decay products, have become a dominant internal background source. This contribution will present methods for the continuous active removal of radon from xenon, using cryogenic online distillation as implemented in current setups such as XENONnT, where new records in the purity of Ar-39, Kr-85 and Rn-222 have been achieved. First experimental results from the ERC Advanced Grant project LowRad (no. 101055063) will be reported, in which cryogenic distillation and a dedicated cryogenic xenon heat pump test setup for online purification are developed and characterised with the goal of reaching radon activities of order 0.1 µBq/kg xenon (≈1 222Rn atom per 160 mol). Finally, an outlook will be given on how these purification and diagnostic concepts can be further developed and implemented in the next-generation xenon observatory XLZD.
