R2D2 project for the future of double beta decay

To search for $\beta\beta0\nu$ decay with unprecedented sensitivity, the R2D2 collaboration is developing a radial time projection chamber with a fiducial mass of half a tonne of $^{136}$Xe at high pressure able to identify the two emitted electrons. The various approaches implemented to eliminate the radioactive background are presented in terms of detector design, topological recognition of interactions, and event energy reconstruction. The developed tools allow for the disentangling of the sought-after signal from the background, and the projected sensitivity after ten years of data taking yields a half-life limit exceeding $10^{27}$ years, along with a constraint on the effective neutrino mass $m_{\beta\beta}$. With larger mass of $^{136}$Xe, The detector could exclude the inverted neutrino mass hierarchy region, depending on the final experimental background.