Development of a Cryoprobe for single Ba atom Extraction and Identification from a liquid 136Xe double beta decay experiment*

Barium tagging is under development for the planned nEXO experiment to reduce backgrounds for the neutrinoless double beta decay search in Xe$^{136}$. One concept for barium tagging involves dipping into, freezing, and extracting xenon on a cryoprobe from the liquid xenon time projection chamber. The development of the cryoprobe and extraction procedure are underway. A possible procedure for extraction on a probe cooled by high pressure argon gas expanding through a Joule Thompson nozzle has been demonstrated. Solid xenon has been frozen on a cryoprobe and has been transported to a laser spectroscopy region. Results of this investigation and examples of possible procedures for extraction are shown.