In experiments searching for neutrinoless double-beta decay, the possibility of identifying the two emitted electrons is a powerful tool in rejecting background events and therefore improving the overall sensitivity of the experiment. In this paper we present the first measurement of the efficiency of a cut based on the different event signatures of double and single electron tracks, using the data of the NEXT-White detector, the first detector of the NEXT experiment operating underground. Using a 228 Th calibration source to produce signal-like and background-like events with energies near 1.6 MeV, a signal efficiency of 71.6 ± 1.5 stat ± 0.3 sys % for a background acceptance of 20.6 ± 0.4 stat ± 0.3 sys % is found, in good agreement with Monte Carlo simulations. An extrapolation to the energy region of the neutrinoless double beta decay by means of Monte Carlo simulations is also carried out, and the results obtained show an improvement in background rejection over those obtained at lower energies.

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Excellent energy resolution is one of the primary advantages of electroluminescent high-pressure xenon TPCs. These detectors are promising tools in searching for rare physics events, such as neutrinoless double-beta decay (ββ0ν), which require precise energy measurements. Using the NEXT-White detector, developed by the NEXT (Neutrino Experiment with a Xenon TPC) collaboration, we show for the first time that an energy resolution of 1% FWHM can be achieved at 2.6 MeV, establishing the present technology as the one with the best energy resolution of all xenon detectors for ββ0ν searches.

The Neutrino Experiment with a Xenon TPC (NEXT) searches for the neutrinoless double beta (0νββ) decay of 136 Xe using high-pressure xenon gas TPCs with electroluminescent amplification. A scaled-up version of this technology with ∼ 1 tonne of enriched xenon could reach, in a few years of operation, a sensitivity to the half-life of 0νββ decay better than 10 27 years, improving the current limits by at least one order of magnitude. This prediction is based on a well-understood background model dominated by radiogenic sources. The detector concept presented here represents a first step on a compelling path towards sensitivity to the parameter space defined by the inverted hierarchy, and beyond.

Starphenes are attractive compounds due to their characteristic physicochemical properties that are inherited from acenes,m aking them interesting compounds for organic electronics and optics.H owever,t he instability and low solubility of larger starphene homologs make their synthesis extremely challenging.H erein, we present an ew strategy leading to pristine [16]starphene in preparative scale.O ur approach is based on as ynthesis of ac arbonyl-protected starphene precursor that is thermally converted in asolid-state form to the neat [16]starphene,which is then characterised with av ariety of analytical methods,s uch as 13 CC P-MAS NMR, TGA, MS MALDI, UV/Vis and FTIR spectroscopy. Furthermore,h igh-resolution STM experiments unambiguously confirm its expected structure and reveal am oderate electronic delocalisation between the pentacene arms.Nucleus-independent chemical shifts NICS(1) are also calculated to survey its aromatic character.