The Hunt for neutrinoless double beta decay with the NEXT experiment
  The NEXT-100 detector will search for the neutrinoless double beta decay of $^{136}$Xe using an electroluminescent high-pressure xenon gas TPC filled with 100 kg of enriched Xe. An observation of this hypothetical process would establish a Majorana nature for the neutrino and prove the violation of lepton number. A scaled-down prototype, NEXT-DEMO, has been built to demonstrate the feasibility of the technology. NEXT-DEMO includes an energy plane made of PMTs and a tracking plane made of SiPMs. X-ray energy depositions, produced by the de-excitation of xenon atoms after their interaction with gamma rays, have been used to characterize the detector response. With this method, the released energy by gammas coming from $^{22}$Na source has been corrected, achieving an energy resolution of 5.691% FWHM and 1.62% FWHM at the 29.7 keV and 511 keV peaks respectively, which extrapolate to 0.62% FWHM and 0.73% FWHM at Q$_{\beta \beta}$ value of Xenon. 
D. Lorca (for the NEXT Collaboration)
physics.ins-det hep-ex nucl-ex