7 research outputs found
'Searching for a needle in a haystack;' A Ba-tagging approach for an upgraded nEXO experiment
nEXO is a proposed experiment that will search for neutrinoless double-beta
decay (0) in 5-tonnes of liquid xenon (LXe), isotopically
enriched in Xe. A technique called Ba-tagging is being developed as a
potential future upgrade for nEXO to detect the Xe double-beta decay
daughter isotope, Ba. An efficient Ba-tagging technique has the
potential to boost nEXO's 0 sensitivity by essentially
suppressing non-double-beta decay background events. A conceptual approach for
the extraction from the detector volume, trapping, and identification of a
single Ba ion from 5 tonnes of LXe is presented, along with initial results
from the commissioning of one of its subsystems, a quadrupole mass filter.Comment: 4 pages, 2 figure
An integrated online radioassay data storage and analytics tool for nEXO
Large-scale low-background detectors are increasingly used in rare-event
searches as experimental collaborations push for enhanced sensitivity. However,
building such detectors, in practice, creates an abundance of radioassay data
especially during the conceptual phase of an experiment when hundreds of
materials are screened for radiopurity. A tool is needed to manage and make use
of the radioassay screening data to quantitatively assess detector design
options. We have developed a Materials Database Application for the nEXO
experiment to serve this purpose. This paper describes this database, explains
how it functions, and discusses how it streamlines the design of the
experiment
Imaging of single barium atoms in a second matrix site in solid xenon for barium tagging in a Xe double beta decay experiment
International audienceNeutrinoless double beta decay is one of the most sensitive probes for new physics beyond the Standard Model of particle physics. One of the isotopes under investigation is Xe, which would double beta decay into Ba. Detecting the single Ba daughter provides a sort of ultimate tool in the discrimination against backgrounds. Previous work demonstrated the ability to perform single atom imaging of Ba atoms in a single-vacancy site of a solid xenon matrix. In this paper, the effort to identify signal from individual barium atoms is extended to Ba atoms in a hexa-vacancy site in the matrix and is achieved despite increased photobleaching in this site. Abrupt fluorescence turn-off of a single Ba atom is also observed. Significant recovery of fluorescence signal lost through photobleaching is demonstrated upon annealing of Ba deposits in the Xe ice. Following annealing, it is observed that Ba atoms in the hexa-vacancy site exhibit antibleaching while Ba atoms in the tetra-vacancy site exhibit bleaching. This may be evidence for a matrix site transfer upon laser excitation. Our findings offer a path of continued research toward tagging of Ba daughters in all significant sites in solid xenon
Supernova Electron-Neutrino Interactions with Xenon in the nEXO Detector
International audienceElectron-neutrino charged-current interactions with xenon nuclei were modeled in the nEXO neutrinoless double-beta decay detector (~5-tonne, 90% Xe, 10% Xe) to evaluate its sensitivity to supernova neutrinos. Predictions for event rates and detectable signatures were modeled using the MARLEY event generator. We find good agreement between MARLEY's predictions and existing theoretical calculations of the inclusive cross sections at supernova neutrino energies. The interactions modeled by MARLEY were simulated within the nEXO simulation framework and were run through an example reconstruction algorithm to determine the detector's efficiency for reconstructing these events. The simulated data, incorporating the detector response, were used to study the ability of nEXO to reconstruct the incident electron-neutrino spectrum and these results were extended to a larger xenon detector of the same isotope enrichment. We estimate that nEXO will be able to observe electron-neutrino interactions with xenon from supernovae as far as 5 to 8 kpc from earth, while the ability to reconstruct incident electron-neutrino spectrum parameters from observed interactions in nEXO is limited to closer supernovae
Imaging of single barium atoms in a second matrix site in solid xenon for barium tagging in a Xe double beta decay experiment
International audienceNeutrinoless double beta decay is one of the most sensitive probes for new physics beyond the Standard Model of particle physics. One of the isotopes under investigation is Xe, which would double beta decay into Ba. Detecting the single Ba daughter provides a sort of ultimate tool in the discrimination against backgrounds. Previous work demonstrated the ability to perform single atom imaging of Ba atoms in a single-vacancy site of a solid xenon matrix. In this paper, the effort to identify signal from individual barium atoms is extended to Ba atoms in a hexa-vacancy site in the matrix and is achieved despite increased photobleaching in this site. Abrupt fluorescence turn-off of a single Ba atom is also observed. Significant recovery of fluorescence signal lost through photobleaching is demonstrated upon annealing of Ba deposits in the Xe ice. Following annealing, it is observed that Ba atoms in the hexa-vacancy site exhibit antibleaching while Ba atoms in the tetra-vacancy site exhibit bleaching. This may be evidence for a matrix site transfer upon laser excitation. Our findings offer a path of continued research toward tagging of Ba daughters in all significant sites in solid xenon
Supernova Electron-Neutrino Interactions with Xenon in the nEXO Detector
International audienceElectron-neutrino charged-current interactions with xenon nuclei were modeled in the nEXO neutrinoless double-beta decay detector (~5-tonne, 90% Xe, 10% Xe) to evaluate its sensitivity to supernova neutrinos. Predictions for event rates and detectable signatures were modeled using the MARLEY event generator. We find good agreement between MARLEY's predictions and existing theoretical calculations of the inclusive cross sections at supernova neutrino energies. The interactions modeled by MARLEY were simulated within the nEXO simulation framework and were run through an example reconstruction algorithm to determine the detector's efficiency for reconstructing these events. The simulated data, incorporating the detector response, were used to study the ability of nEXO to reconstruct the incident electron-neutrino spectrum and these results were extended to a larger xenon detector of the same isotope enrichment. We estimate that nEXO will be able to observe electron-neutrino interactions with xenon from supernovae as far as 5 to 8 kpc from earth, while the ability to reconstruct incident electron-neutrino spectrum parameters from observed interactions in nEXO is limited to closer supernovae
An integrated online radioassay data storage and analytics tool for nEXO
International audienceLarge-scale low-background detectors are increasingly used in rare-event searches as experimental collaborations push for enhanced sensitivity. However, building such detectors, in practice, creates an abundance of radioassay data especially during the conceptual phase of an experiment when hundreds of materials are screened for radiopurity. A tool is needed to manage and make use of the radioassay screening data to quantitatively assess detector design options. We have developed a Materials Database Application for the nEXO experiment to serve this purpose. This paper describes this database application, explains how it functions, and discusses how it streamlines the design of the experiment