Demonstration of Single Barium Ion Sensitivity for Neutrinoless Double Beta Decay using Single Molecule Fluorescence Imaging

TL;DR

This paper demonstrates a novel single-molecule fluorescence imaging technique to detect individual barium ions, advancing the potential for background-free neutrinoless double beta decay detection in xenon gas detectors.

Contribution

It introduces a new method using SMFI to resolve single barium ions on a surface, enabling highly sensitive detection for neutrinoless double beta decay experiments.

Findings

Single barium ions resolved with ~2 nm super-resolution.

Single-ion detection confirmed by photo-bleaching.

Detection significance of 12.9 sigma over background.

Abstract

A new method to tag the barium daughter in the double beta decay of $^{136}$Xe is reported. Using the technique of single molecule fluorescent imaging (SMFI), individual barium dication (Ba$^{++}$) resolution at a transparent scanning surface has been demonstrated. A single-step photo-bleach confirms the single ion interpretation. Individual ions are localized with super-resolution ($\sim$2~nm), and detected with a statistical significance of 12.9~$\sigma$ 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.