The document discusses the removal of Krypton-85 from Xenon gas in order to reduce radioactive backgrounds for the Large Underground Xenon (LUX) dark matter detector. Krypton-85 is present in trace amounts in air and Xenon gas. The system works by flowing a carrier gas like helium through an adsorption charcoal column, where molecules of Xenon and Krypton separate due to differing adsorption constants, removing the Krypton. It is being scaled up for the 350 kg of Xenon in LUX, including a larger charcoal column and storage vessel.

1. Chromatographic Separation of Krypton 85 From Xenon

2. Large Underground Xenon (LUX) DetectorWhat is dark matter?Direct detection of Weakly Interacting Massive Particles (WIMPs) as the leading candidate for dark matterRadioactive backgrounds must be reduced to detect WIMPs

3. Large Underground Xenon (LUX) Detector350 kg of Xenon must be purifiedHeated getter technology removes contaminants except noble gasesKrypton 85: Present in the air in small amountsPresent at ~5ppb in xenonGoal <5ppt in xenon

4. Krypton Removal systemCarrier gas flows through the system (He)Adsorption charcoal column (right)Molecules attracted to the porous surface of adsorberAdsorption constants differ; xenon and krypton separateExisting charcoal column

5. Circulation system and Phases1. Charge with Helium2. Feed3.Purge4.Recovery5. Condenser to Storage6. Kr Trap to Transfer TrapT. Shutt 7/9/2009

7. Krypton Removal Phases

8. Krypton Scale UpStorage and Recovery Vessel (SRV) to be used at the main condenserLarger charcoal adsorber column, with changed geometry (right)

9. Questions?