Jeremy Mock with Prof. Thomas Shutt

Removing Krypton Impurities from Xenon with Chromatographic Adsorption

The Large Underground Xenon (LUX) detector uses high-purity xenon to search for WIMP dark matter particles which are theorized to interact rarely. Thus the xenon must be free of as much background radiation as possible, and krypton is a radioactive impurity found in commercial xenon. To remove the krypton, a chromatographic adsorption method is used in which xenon contaminated with krypton is carried through a charcoal column. Because the two gases have different molecular weights, the krypton drifts through the column at a faster rate and can be removed from the xenon. The theory of chromatographic adsorption predicts that a vacuum stage technique could be used to improve the rate of separation by a factor of 10. The current system purifies xenon from krypton at a rate of about 2 kg/day, and that could be increased to 20 kg/day. I will study the response of the system as a function of pressure to achieve this desired increase so the system can be realistically used to purify xenon for the LUX experiment.