The gas SF6 has become of interest as a negative ion drift gas for use in directionaluddark matter searches. However, as for other targets in such searches, it is important that radonudcontamination can be removed as this provides a source of unwanted background events. In thisudwork we demonstrate for the first time filtration of radon from SF6 gas by using a molecularudsieve. Four types of sieves from Sigma-Aldrich were investigated, namely 3Å, 4Å, 5Å and 13X.udA manufactured radon source was used for the tests. This was attached to a closed loop system inudwhich gas was flowed through the filters and a specially adapted Durridge RAD7 radon detector.udIn these measurements, it was found that only the 5Å type was able to significantly reduce theudradon concentration without absorbing the SF6 gas. The sieve was able to reduce the initial radonudconcentration of 3875 ± 13 Bqm−3udin SF6 gas by 87% when cooled with dry ice. The ability ofudthe cooled 5Å molecular sieve filter to significantly reduce radon concentration from SF6 providesuda promising foundation for the construction of a radon filtration setup for future ultra-sensitive SF6udgas rare-event physics experiments.ud
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