The proposed nEXO experiment is searching for neutrinoless double beta decay (0νββ) in 136-Xe in a tonne-scale liquid xenon TPC. If observed, 0νββ will reveal the Majorana nature of neutrinos and violation of lepton number conservation. Searches for such extremely rare events require excellent background suppression and rejection methods to achieve high sensitivities. The identification or “tagging” of the xenon-136 ββ decay daughter barium-136 offers a very powerful discrimination technique and is being investigated as a potential upgrade for nEXO. By leveraging the 3D reconstruction of the TPC, a sample of xenon surrounding a candidate 0νββ can be extracted to tag the Ba daughter, if present. To this end, an apparatus is being developed to take a gaseous sample of xenon and transport a barium ion to high vacuum using an RF ion funnel. The ion is then trapped and identified via laser and mass spectroscopy.
The progress of an apparatus for Ba tagging from Xe gas for a future nEXO upgrade is presented.