The NEXT ββ0ν experiment will use a high-pressure gas electroluminescent TPC to search for the decay of Xe-136. The development, construction and installation of NEXT-WHITE (NEW), the first ...radio-pure version of NEXT, will take place this year at Laboratorio Subterráneo de Canfranc. NEW will run initially using 10 kg of natural xenon during which time NEXT technology will be validated and the topological reconstruction algorithms refined. Moreover, the background model will be benchmarked using data. A second run will use enriched xenon and will make a first measurement of the two neutrino channel (ββ2ν) by NEXT. This poster will present the various technical aspects of the detector detailing the radio-pure solutions for a low backgorund experiment and the low noise, high resolution measurement of both energy and position.
We report a measurement of the half-life of the 136Xe two-neutrino double-β decay performed with a novel direct-background-subtraction technique. The analysis relies on the data collected with the ...NEXT-White detector operated with 136Xe-enriched and 136Xe-depleted xenon, as well as on the topology of double-electron tracks. With a fiducial mass of only 3.5 kg of Xe, a half-life of 2.34$_{-0.46}^{+0.80}$(stat)$_{-0.17}^{+0.30}$(sys)×1021yr is derived from the background-subtracted energy spectrum. The presented technique demonstrates the feasibility of unique background-model-independent neutrinoless double-β-decay searches.
Xe–CO2 mixtures are important alternatives to pure xenon in Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification with applications in the ...important field of rare event detection such as directional dark matter, double electron capture and double beta decay detection. The addition of CO2 to pure xenon at the level of 0.05–0.1% can reduce significantly the scale of electron diffusion from 10 mm/m to 2.5 mm/m, with high impact on the discrimination efficiency of the events through pattern recognition of the topology of primary ionization trails. We have measured the electroluminescence (EL) yield of Xe–CO2 mixtures, with sub-percent CO2 concentrations. We demonstrate that the EL production is still high in these mixtures, 70% and 35% relative to that produced in pure xenon, for CO2 concentrations around 0.05% and 0.1%, respectively. The contribution of the statistical fluctuations in EL production to the energy resolution increases with increasing CO2 concentration, being smaller than the contribution of the Fano factor for concentrations below 0.1% CO2.
If neutrinos are their own antiparticles the otherwise-forbidden nuclear reaction known as neutrinoless double beta decay can occur. The very long lifetime expected for these exceptional events makes ...its detection a daunting task. In order to conduct an almost background-free experiment, the NEXT collaboration is investigating novel synthetic molecular sensors that may capture the Ba dication produced in the decay of certain Xe isotopes in a high-pressure gas experiment. The use of such molecular detectors immobilized on surfaces must be explored in the ultra-dry environment of a xenon gas chamber. Here, using a combination of highly sensitive surface science techniques in ultra-high vacuum, we demonstrate the possibility of employing the so-called Fluorescent Bicolor Indicator as the molecular component of the sensor. We unravel the ion capture process for these molecular indicators immobilized on a surface and explain the origin of the emission fluorescence shift associated to the ion trapping.
NEXT is a proposed 100-kg high-pressure xenon gas TPC that will search for neutrinoless double beta decay in 136Xe. Such a detector, thanks to its excellent energy resolution and its powerful ...background rejection provided by the distinct double beta decay topological signature, may become one of the leading experiments of the field. The project is proceeding through a fast research and development phase. The first prototypes, containing about 1 kg of pressurized xenon will be taking data in 2010, and the final detector, NEXT-100, is planned to run in late 2013 at the Laboratorio Subterráneo de Canfranc (LSC), Spain.
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