Speaker
Description
Trace radioactive noble gases are a source of electron recoil backgrounds in liquid xenon dark matter experiments, and cannot be mitigated by self-shielding. Naturally occurring krypton, which contains trace amounts of the beta emitter krypton-85, is found in commercially available research-grade xenon at a level of 1-100 parts-per-billion. In the LZ dark matter experiment, we require the xenon in the detector to contain no more than 300 parts per quadrillion krypton. This limit reduces the rate of electron recoil events from krypton-85 to be comparable to the solar neutrino contribution. To achieve this, krypton is removed from the xenon using gas charcoal chromatography prior to its deployment in the detector. In this talk, I will present an overview of the krypton removal chromatography system, which was designed, built and operated by LZ at SLAC.
