## An Atom Trap Trace Analysis System for Measuring Krypton Contamination in Xenon Dark Matter Detectors    [PDF]

Elena Aprile, Taehyun Yoon, Andre Loose, Luke W. Goetzke, Tanya Zelevinsky
We have developed an atom trap trace analysis (ATTA) system to measure Kr in Xe at the part per trillion (ppt) level, a prerequisite for the sensitivity achievable with liquid xenon dark matter detectors beyond the current generation. Since Ar and Kr have similar laser cooling wavelengths, the apparatus has been tested with Ar to avoid contamination prior to measuring Xe samples. A radio-frequency (RF) plasma discharge generates a beam of metastable Ar which is optically collimated, slowed, and trapped using standard magneto-optical techniques. We detect the fluorescence of single trapped $^{40}$Ar atoms with a signal to noise ratio of 5. The measured system efficiency of $3 \times 10^{-9}$ for Ar corresponds to an expected Kr in Xe sensitivity at the ppt level.
View original: http://arxiv.org/abs/1305.6510