Speaker
Description
To search for neutrinoless double-beta decay ($\beta\beta0\nu$) with unprecedented sensitivity, the R2D2 collaboration is developing a radial time projection chamber operating at high pressure, with a fiducial mass of up to half a tonne of enriched $^{136}$Xe and the capability to identify the two emitted electrons.
The strategies adopted to suppress radioactive backgrounds are presented, including detector design, topological reconstruction of event signatures, and precise energy reconstruction. Dedicated analysis tools have been developed to efficiently disentangle the $\beta\beta0\nu$ signal from background events. Prototype detectors have been operated with argon and xenon, showing a similar detector response in the two gases. Energy resolution measurements were carried out in xenon up to 6 bar and in argon up to 16 bar, validating stable operation at high pressure and supporting expectations for detector performance in xenon at higher pressures.
After ten years of data taking, the projected sensitivity reaches half-life limits exceeding $10^{27}$ years, providing significant constraints on the effective Majorana neutrino mass, and could cover a large fraction of the inverted mass hierarchy region, depending on the final experimental background.