5 research outputs found
Reflectance and fluorescence characteristics of PTFE coated with TPB at visible, UV, and VUV as a function of thickness
Abstract:
Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection systems for particle physics experiments. In noble element systems, it is often coated with tetraphenyl butadiene (TPB) to allow detection of vacuum ultraviolet scintillation light. In this work this dependence is investigated for PTFE coated with TPB in air for light of wavelengths of 200 nm, 260 nm, and 450 nm. The results show that TPB-coated PTFE has a reflectance of approximately 92% for thicknesses ranging from 5 mm to 10 mm at 450 nm, with negligible variation as a function of thickness within this range. A cross-check of these results using an argon chamber supports the conclusion that the change in thickness from 5 mm to 10 mm does not affect significantly the light response at 128 nm. Our results indicate that pieces of TPB-coated PTFE thinner than the typical 10 mm can be used in particle physics detectors without compromising the light signal
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