Laser cooling and trapping of single krypton atoms

We are constructing an apparatus to use Atom Trap Trace Analysis (ATTA) to detect trace levels of krypton in ultra‐pure samples of neon and xenon. The next generation of neutrino and dark matter detectors will use noble gasses as scintillation medium, and require extremely pure samples of neon and xenon. Krypton‐85 contamination in these samples causes false positives by releasing electrons via beta decay that cause scintillation light in the detectors. We inject samples of neon or xenon from the detectors into our ATTA apparatus system, excite the krypton contaminants into an excited metastable state, and slow the krypton atoms with a counter‐propagating laser tuned to the resonant wavelength. After this nearly stops the krypton atoms, additional lasers from other directions hold the krypton in place while the krypton scatters photons from the lasers in all directions. We detect this scattered light with an avalanche photodiode and determine the number of krypton atoms trapped by the system in a period of several hours. This information, combined with the input atom flux, gives us the level of krypton contamination in the sample. The ATTA system can measure krypton contamination to .03 ppt in three hours of measurement. However, as we are still perfecting the system we have no quantitative results yet