Abstract
Neutrinoless double beta decay ((Formula presented.)) provides a way to probe physics beyond the Standard Model of particle physics. The upcoming nEXO experiment will search for (Formula presented.) decay in 136Xe with a projected half-life sensitivity exceeding (Formula presented.) years at the 90% confidence level using a liquid xenon (LXe) Time Projection Chamber (TPC) filled with 5 tonnes of Xe enriched to ∼90% in the (Formula presented.) -decaying isotope 136Xe. In parallel, a potential future upgrade to nEXO is being investigated with the aim to further suppress radioactive backgrounds and to confirm (Formula presented.) -decay events. This technique, known as Ba-tagging, comprises extracting and identifying the (Formula presented.) -decay daughter 136Ba ion. One tagging approach being pursued involves extracting a small volume of LXe in the vicinity of a potential (Formula presented.) -decay using a capillary tube and facilitating a liquid-to-gas phase transition by heating the capillary exit. The Ba ion is then separated from the accompanying Xe gas using a radio-frequency (RF) carpet and RF funnel, conclusively identifying the ion as 136Ba via laser-fluorescence spectroscopy and mass spectrometry. Simultaneously, an accelerator-driven Ba ion source is being developed to validate and optimize this technique. The motivation for the project, the development of the different aspects, along with the current status and results, are discussed here.
Original language | English |
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Article number | 71 |
Journal | Atoms |
Volume | 12 |
Issue number | 12 |
DOIs | |
State | Published - Dec 2024 |
Externally published | Yes |
Funding
This work has been supported by the Natural Sciences and Engineering Research Council of Canada (NSERC) under Grant No. SAPPJ-2019-00058 and SAPPJ-2024-00034, the Canada Foundation for Innovation (CFI) through the John R. Evans Leaders Fund under Fund No. 35700, and the Canada First Research Excellence Fund (CFREF) through the Arthur B. McDonald Canadian Astroparticle Physics Research Institute. In the USA, support has been provided by the National Science Foundation (NSF) under Grant No. 2011948. The ion funnel device and parts of the ion transport system were funded by NSF grant PHY-0918469 at Stanford University. The nEXO experiment is supported in Canada through NSERC Grant No. SAPPJ-2022-00021 and CFI Fund No. 43140 and 39881.
Keywords
- Ba-tagging
- laser-fluorescence spectroscopy
- linear Paul trap
- multi-reflection time-of-flight mass spectrometry
- neutrinoless double beta decay
- nEXO upgrade