The search for neutrinoless double-beta (0νββ) decay aspires to cast light on a critical piece missing in our knowledge: the nature of the neutrino mass. This is the most sensitive experimental way to demonstrate that neutrino is a Majorana particle.
The challenge of observing such a potentially rare process demands a detector with excellent energy resolution, extremely low radioactivity and a large mass of emitter isotope. The R2D2 project is an R&D effort to investigate the feasibility of a high-pressure spherical TPC as a detector for 0νββ decay searches. A prototype has demonstrated excellent resolution with Argon, and preliminary results with Xenon are very promising. Furthermore, the simultaneous read-out of ionisation and scintillation light has been demonstrated, which will facilitate event localisation.
These proof-of-concept results obtained with the first R2D2 prototype will presented, and the next steps in the R&D roadmap will be discussed.