Demonstration of Single-Barium-Ion Sensitivity for Neutrinoless Double-Beta Decay Using Single-Molecule Fluorescence Imaging
A new method to tag the barium daughter in the double-beta decay of <mml:mmultiscripts>Xe 136 </mml:mmultiscripts> is reported. Using the technique of single molecule fluorescent imaging (SMFI), individual barium dication (Ba++ ) resolution at a transparent scanning surface is demonstrated. A single-step photobleach confirms the single ion interpretation. Individual ions are localized with superresolution (̃2 nm ), and detected with a statistical significance of 12.9 σ over backgrounds. This lays the foundation for a new and potentially background-free neutrinoless double-beta decay technology, based on SMFI coupled to high pressure xenon gas time projection chambers.