NEXT: A new neutrinoless double beta decay experiment

The goal of the next generation of ββ 0ν experiments is to fully explore the degenerate hierarchy (see Figure 1(a)), which is corresponding to an effective neutrino mass up to 50 meV. This neutrino mass range will be only accessible for experiments that can simultaneously achieve a large fiducial mass and negligible backgrounds. A high-pressure, gaseous Xenon TPC has good prospects to combine many desirable features to reach this goal. The isotope 136 Xe, which is one of the few elements producing a double beta decay, is almost 9 % of natural Xenon. Enrichment is relatively easy as demonstrated by the EXO collaboration. The detector can be extrapolated to large masses. The energy resolution in gas is expected to be in the order of 1 %. The detector is fully active and the detector gas can be continuously circulated and purified, which, together with the existence of a kinematical signature gives an excellent handle against backgrounds. The NEXT collaboration is planing a Xenon detector of a mass of about 100 kg. Such an object will explore the degenerated hierarchy and provide a deep understanding of the experimental techniques to suppress backgrounds required for larger detectors. The current status of our R&D towards a Neutrino Experiment with a Xenon TPC (NEXT) is presented.