Report on the North America-Europe workshop on Double Beta Decay
From Sep. 29th until Oct. 1st the LNGS Laboratories hosted an international, hybrid workshop on Neutrinoless Double Beta decay focussed on a common strategy of European and North American agencies on that topic, see https://agenda.infn.it/event/27143/ .
The main projects and experiments included in the APPEC roadmap and the DOE Portfolio Review, the corresponding science, on-going R&D activities for even more ambitious future projects, as well as the capabilities of the relevant Underground Laboratories have been discussed at this workshop. Four major projects have been discussed in depth: CUPID, nEXO, LEGEND and NEXT. CUPID, LEGEND and nEXO were part of the DOE Portfolio Review, while CUPID, LEGEND and NEXT are parts of the APPEC Roadmap on Neutrino-less Double Beta Decay.
After three days of fruitful and deep discussion, the representatives of several European and North American funding agencies, Ministerial representatives and Laboratory Directors have met in a closed session. They unanimously agreed that the strong scientific motivation and the need to cross-check any potential signal with different isotopes justifies the effort to support three experiments, CUPID at Gran Sasso, and LEGEND and nEXO, where one should be located in North America and one in Europe.
The NEXT experiment is highly valued and considered as a future development, but the general consensus is that it then needs to be discussed further once its scalability to large detector masses has been demonstrated.
All participants are aware that this ambitious programme will require additional funding beyond that already secured. Therefore, discussions between the agencies and the scientific community will continue.