The 2023 Long Range Plan report by the Nuclear Science Advisory Committee (NSAC) identified the delivery of the “tonne-scale” 0? double beta decay program as the top new projects priority for nuclear physics. Recommendation #2 of the report reads:
“As the highest priority for new experiment construction, we recommend that the United States lead an international consortium that will undertake a neutrinoless double beta decay campaign, featuring the expeditious construction of ton-scale experiments, using different isotopes and complementary techniques.”
The recommendation continues, including: “An extraordinary discovery of this magnitude requires multiple experiments using different techniques for a select set of isotopes. Such measurements demand unprecedented sensitivity and present unique challenges. Since the 2015 Long Range Plan, the US-led CUPID, LEGEND, and nEXO international collaborations have made remarkable progress with three distinct technologies. An independent portfolio review committee has deemed these experiments ready to proceed now.“