Capture sites of Ba and Ba+ daughters from double beta decay when frozen into SXe

Determine which solid xenon matrix sites (single-vacancy, tetra-vacancy, hexa-vacancy, and asymmetric 5/7-atom vacancies) capture Ba atoms and Ba+ ions produced by double beta decay in liquid xenon when the daughters are frozen into solid xenon.

Background

Ba tagging in nEXO requires understanding where daughter species reside in SXe to choose suitable excitation wavelengths and predict photobleaching behavior for single-atom imaging.

While several SXe sites have been spectroscopically characterized for Ba under vacuum deposition, the site occupancy following freeze-out from LXe remains unknown and is crucial for designing a robust tagging protocol.