Barium Tagging for Background Free Neutrinoless Double Beta Decay Searches

New ultra-sensitive technologies are likely to be required for an observation of neutrinoless double beta with lifetimes in excess of the limits set by existing experiments. A promising avenue to a zero-background experiment is the identification of the daughter ion produced in the decay. The NEXT collaboration is developing techniques to collect and image single barium ions that result from the double beta decay of xenon-136 in high-pressure gas time projection chambers. The approach described in this poster uses dry-functional, on-off fluorophores imaged with single molecule fluorescence microscopy coupled to high-pressure RF carpets. I will present the latest status of these techniques, including new data on custom-made, single ion sensitive fluorescent molecules; new in-situ microscopy techniques, and progress on high-pressure RF carpet R&D.