5 research outputs found
A Compact Dication Source for Ba Tagging and Heavy Metal Ion Sensor Development
We present a tunable metal ion beam that delivers controllable ion currents
in the picoamp range for testing of dry-phase ion sensors. Ion beams are formed
by sequential atomic evaporation and single or multiple electron impact
ionization, followed by acceleration into a sensing region. Controllability of
the ionic charge state is achieved through tuning of electrode potentials that
influence the retention time in the ionization region. Barium, lead, and cobalt
samples have been used to test the system, with ion currents identified and
quantified using a quadrupole mass analyzer. Realization of a clean
ion beam within a bench-top system represents an important
technical advance toward the development and characterization of barium tagging
systems for neutrinoless double beta decay searches in xenon gas. This system
also provides a testbed for investigation of novel ion sensing methodologies
for environmental assay applications, with dication beams of Pb and
Cd also demonstrated for this purpose
Demonstration of neutrinoless double beta decay searches in gaseous xenon with NEXT
The NEXT experiment aims at the sensitive search of the neutrinoless double
beta decay in Xe, using high-pressure gas electroluminescent time
projection chambers. The NEXT-White detector is the first radiopure
demonstrator of this technology, operated in the Laboratorio Subterr\'aneo de
Canfranc. Achieving an energy resolution of 1% FWHM at 2.6 MeV and further
background rejection by means of the topology of the reconstructed tracks,
NEXT-White has been exploited beyond its original goals in order to perform a
neutrinoless double beta decay search. The analysis considers the combination
of 271.6 days of Xe-enriched data and 208.9 days of Xe-depleted
data. A detailed background modeling and measurement has been developed,
ensuring the time stability of the radiogenic and cosmogenic contributions
across both data samples. Limits to the neutrinoless mode are obtained in two
alternative analyses: a background-model-dependent approach and a novel direct
background-subtraction technique, offering results with small dependence on the
background model assumptions. With a fiducial mass of only 3.500.01 kg of
Xe-enriched xenon, 90% C.L. lower limits to the neutrinoless double
beta decay are found in the T
yr range, depending on the method. The presented techniques stand as a
proof-of-concept for the searches to be implemented with larger NEXT detectors
Demonstration of neutrinoless double beta decay searches in gaseous xenon with NEXT
Abstract The NEXT experiment aims at the sensitive search of the neutrinoless double beta decay in 136Xe, using high-pressure gas electroluminescent time projection chambers. The NEXT-White detector is the first radiopure demonstrator of this technology, operated in the Laboratorio Subterráneo de Canfranc. Achieving an energy resolution of 1% FWHM at 2.6 MeV and further background rejection by means of the topology of the reconstructed tracks, NEXT-White has been exploited beyond its original goals in order to perform a neu- trinoless double beta decay search. The analysis considers the combination of 271.6 days of 136Xe-enriched data and 208.9 days of 136Xe-depleted data. A detailed background modeling and measurement has been developed, ensuring the time stability of the radiogenic and cosmogenic contributions across both data samples. Limits to the neutrinoless mode are obtained in two alternative analyses: a background-model-dependent approach and a novel direct background-subtraction technique, offering results with small dependence on the background model assumptions. With a fiducial mass of only 3.50 ± 0.01 kg of 136Xe-enriched xenon, 90% C.L. lower limits to the neutrinoless double beta decay are found in the T 1 / 2 0 ν > 5.5 × 1023 − 1.3 × 1024 yr range, depending on the method. The presented techniques stand as a proof-of-concept for the searches to be implemented with larger NEXT detectors
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Demonstration of event position reconstruction based on diffusion in the NEXT-white detector
Noble element time projection chambers are a leading technology for rare event detection in physics, such as for dark matter and neutrinoless double beta decay searches. Time projection chambers typically assign event position in the drift direction using the relative timing of prompt scintillation and delayed charge collection signals, allowing for reconstruction of an absolute position in the drift direction. In this paper, alternate methods for assigning event drift distance via quantification of electron diffusion in a pure high pressure xenon gas time projection chamber are explored. Data from the NEXT-White detector demonstrate the ability to achieve good position assignment accuracy for both high- and low-energy events. Using point-like energy deposits from 83mKr calibration electron captures (E∼45 keV), the position of origin of low-energy events is determined to 2 cm precision with bias <1mm. A convolutional neural network approach is then used to quantify diffusion for longer tracks (E≥1.5 MeV), from radiogenic electrons, yielding a precision of 3 cm on the event barycenter. The precision achieved with these methods indicates the feasibility energy calibrations of better than 1% FWHM at Qββ in pure xenon, as well as the potential for event fiducialization in large future detectors using an alternate method that does not rely on primary scintillation