10 research outputs found
On the determination of the interaction time of GeV neutrinos in large argon gas TPCs
Next-generation megawatt-scale neutrino beams open the way to studying
neutrino-nucleus scattering resorting, for the first time, to gaseous targets.
This could lead to deeper knowledge of neutrino cross sections in the energy
region between hundreds of MeV and a few GeV, of interest for the upcoming
generation of long-baseline neutrino oscillation experiments. The challenge is,
therefore, to accurately track and (especially) time the particles produced in
neutrino interactions in large and seamless volumes down to few-MeV energies.
We propose to accomplish this through an optically-read time projection chamber
(TPC) filled with high-pressure argon and equipped with both tracking and
timing functions. In this work, we present a detailed study of the time-tagging
capabilities of such a device, based on end-to-end optical simulations that
include the effect of photon propagation, photosensor response, dark-count rate
and pulse reconstruction. We show that the neutrino interaction time could be
reconstructed from the primary-scintillation signal with a precision in the
range 1--2.5~ns () for point-like deposits with energies down to 5~MeV,
and well below 1~ns for minimum-ionizing particle tracks. A discussion on
previous limitations towards such a detection technology, and how they can be
realistically overcome in the near future thanks to recent developments in the
field, is presented (particularly the strong scintillation yields recently
reported for Ar/CF mixtures). The performance presented in our analysis
seems to be well within reach of next-generation neutrino-oscillation
experiments through the instrumentation of the proposed TPC with conventional
reflective materials and a SiPM carpet behind a transparent cathode
NEXT-CRAB-0: A High Pressure Gaseous Xenon Time Projection Chamber with a Direct VUV Camera Based Readout
The search for neutrinoless double beta decay () remains one
of the most compelling experimental avenues for the discovery in the neutrino
sector. Electroluminescent gas-phase time projection chambers are well suited
to searches due to their intrinsically precise energy
resolution and topological event identification capabilities. Scalability to
ton- and multi-ton masses requires readout of large-area electroluminescent
regions with fine spatial resolution, low radiogenic backgrounds, and a
scalable data acquisition system. This paper presents a detector prototype that
records event topology in an electroluminescent xenon gas TPC via VUV
image-intensified cameras. This enables an extendable readout of large tracking
planes with commercial devices that reside almost entirely outside of the
active medium.Following further development in intermediate scale
demonstrators, this technique may represent a novel and enlargeable method for
topological event imaging in .Comment: 32 Pages, 22 figure
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
Ba+2 ion trapping using organic submonolayer for ultra-low background neutrinoless double beta detector
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
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Measurement of the Xe 136 two-neutrino double- β -decay half-life via direct background subtraction in NEXT
We report a measurement of the half-life of the Xe136 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 Xe136-enriched and Xe136-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
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The dynamics of ions on phased radio-frequency carpets in high pressure gases and application for barium tagging in xenon gas time projection chambers
Radio-frequency (RF) carpets with ultra-fine pitches are examined for ion transport in gases at atmospheric pressures and above. We develop new analytic and computational methods for modeling RF ion transport at densities where dynamics are strongly influenced by buffer gas collisions. An analytic description of levitating and sweeping forces from phased arrays is obtained, then thermodynamic and kinetic principles are used to calculate ion loss rates in the presence of collisions. This methodology is validated against detailed microscopic SIMION simulations. We then explore a parameter space of special interest for neutrinoless double beta decay experiments: transport of barium ions in xenon at pressures from 1 to 10 bar. Our computations account for molecular ion formation and pressure dependent mobility as well as finite temperature effects. We discuss the challenges associated with achieving suitable operating conditions, which lie beyond the capabilities of existing devices, using presently available or near-future manufacturing techniques
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
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
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
Measurement of the Xe two-neutrino double beta decay half-life via direct background subtraction in NEXT
We report a measurement of the half-life of the Xe two-neutrino
double beta decay performed with a novel direct background subtraction
technique. The analysis relies on the data collected with the NEXT-White
detector operated with Xe-enriched and Xe-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
is derived from the background-subtracted energy spectrum. The presented
technique demonstrates the feasibility of unique background-model-independent
neutrinoless double beta decay searches.Comment: 9 pages, 7 figures, and 1 appendi