Plans for a Barium tagging upgrade for n

Plans for a Barium tagging upgrade for n. EXO: next few years Two main methods being explored: (1) Trans-Canadian effort: extract Ba+ daughter from liquid xenon to gas xenon, transport to vacuum and detect it • Xenon ion extraction from Xe gas up to 10 bar demonstrated; working on extraction of barium ions • Single Ba+-ion identification demonstrated with excellent signal to noise • Ion identification under development for sensitive mass and fluorescence spectroscopy of extracted ions • R&D required to develop extraction of Ba+ from LXe to GXe (1) Capture Ba in solid Xe on a cryogenic probe (2) Extract probe to Ba imaging region (2) US effort: capture Ba+/Ba daughter from liquid xenon in solid xenon and transport to single atom/ion imaging station • Single Ba atoms imaged in two solid xenon matrix sites; working on imaging single Ba+ ions in solid xenon • Experiments ongoing on extraction of Ba+ ions from liquid xenon in solid xenon on a cryoprobe; first spectroscopy done (3) Developing plan to study daughter extraction using radioactive ions • Ba desorption from SXe or metal surface studied with isotopes at ANL • Pilot production at TUNL of Cs isotopes in Xe gas with proton beam • Apparatus to test daughter ion extraction in a 100 kg liquid xenon TPC laser fluorescence Ba+ (3) Count Ba atoms by single Ba/Ba+ imaging

Plans for a Barium tagging upgrade for n. EXO: looking toward n. EXO upgrade ISAC II Sample of further R&D toward a n. EXO upgrade with Ba tagging: (1) Measurement of Ba tagging efficiency using radioactive ions at an accelerator facility • Deposit Cs isotopes that beta decay to Ba • • Cs isotopes at CARIBU facility at ANL or ISAC II facility at TRIUMF can be implanted into LXe through foil Create 136 Cs in Xe gas or LXe by (p, n) reactions on 136 Xe at TUNL or UK 6. 7. experiment 5. 4. C B 3. 1. ge tar t 2. • Extract with 1 -D extraction method • Tag extracted Ba daughters • Potential to check Ba tag efficiency with single Cs beta decay events (2) Engineering of 3 -D probe extraction method and test in 100 kg LXe TPC (3) Design and engineering of a new n. EXO TPC that accommodates apparatus for Ba tagging The Ba tagging R&D could benefit not only n. EXO upgrade but also future detectors beyond n. EXO, for example, the kilotonne detector envisioned in another Lo. I. 100 kg LXe TPC test apparatus