Description
The NEXT collaboration is searching for neutrinoless double beta decay in xenon-136 using successive generations of high-pressure electroluminescent gaseous time projection chambers. This technology combines high energy resolution (<1% FWHM at the Q-value of the decay) with detailed topological information to discriminate signal from background. Three-dimensional reconstruction relies on electroluminescent light formed when the event ionization electrons cross a high-field gap in front of a SiPM-based tracking plane. The quality of these reconstructed images, and therefore the effectiveness of the topological analysis, depends strongly on the ability to mitigate blurring effects due to electron diffusion during drift and isotropic light emission in the electroluminescence gap. A new reconstruction method using Richardson-Lucy deconvolution was recently developed to this end and demonstrated on data recorded in the NEXT-White prototype. The new method resulted in >5-fold improvement in background rejection and served for the two-neutrino double beta decay analysis with this detector. Current efforts extend this work to accommodate for the larger drift, higher pressure and larger SiPM spacing in NEXT-100. Further studies towards a tonne-scale TPC detector (NEXT-HD) are ongoing, considering the effect of reduced diffusion in Xe/He mixtures, improved SiPM granularity and potentially leveraging additional topological features beyond the identification of one or two regions of high energy deposition by ionization at the track ends.
| Collaboration | NEXT |
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