arXiv subjects

F. Retière

Publications and source records attributed to F. Retière.

At least 19 recordsLinked to original sources

arXiv2026

Measurement of the muon flux at SNOLAB using the DEAP-3600 experiment

A direct measurement of the muon flux at SNOLAB is performed using the DEAP-3600 experiment, located 2 km underground at SNOLAB near Sudbury, Canada. Primarily designed for the direct detection of weakly interacting massive particles (WIMPs), a dark matter candidate, DEAP-3600 consists of an inner spherical acrylic vessel containing a liquid argon target; this vessel is enclosed within a steel shell which is submerged in an instrumented water tank, serving as a muon veto for the dark matter search. The muon flux measurement is performed using a cut-and-count analysis of events observed in the muon veto detector and of events which are coincident between the muon veto and the liquid argon target. The requirement that muons traverse both the water and liquid argon minimizes instrumental backgrounds and systematic uncertainties. Using data collected from November 2016 to March 2020, the muon flux is measured by this coincidence analysis to be $(3.71 \pm 0.25_{\textrm{stat}} \pm 0.09_{\textrm{sys}}) \times 10^{-10}\, μ/$cm$^2$/s. The standalone measurement using muon veto data only is compatible within uncertainties. Both measurements agree with the previous result by the SNO experiment and with simulations carried out using the MUTE software. These results provide an important benchmark for future rare-event searches at the SNOLAB facility.

hep-ex↗

arXiv2026

Source of Internal Crosstalk in Silicon Photomultipliers

Silicon Photomultipliers (SiPMs) have been widely adopted for photon detection in next-generation dark matter and neutrino detection experiments. Internal crosstalk, resulting from secondary photons produced during charge avalanches, is a significant noise mechanism in SiPMs and is likely to impact the performance of physics detectors. This work presents experimental data for trends in crosstalk probability with temperature and overvoltage for two different SiPM devices, and demonstrates a novel method for identifying the source mechanisms of crosstalk avalanches. This is done by using measurements of avalanche triggering probabilities for different charge carrier types to identify the device regions in which crosstalk avalanches are produced. This is possible because crosstalk photons absorbed in n-doped regions will produce hole-triggered avalanches, and those absorbed in p-doped regions will produce electron-triggered avalanches. Thus crosstalk probability can be related to device structure to assess the effectiveness of existing crosstalk mitigation methods. We identify optical reflections from the device surface as a significant source of crosstalk, likely to dominate in devices with effective crosstalk mitigation in bulk. Lastly, a diagnostic technique is presented to identify and reduce crosstalk in novel SiPM structures.

physics.ins-det↗

arXiv2026

First evidence of neutrino absorption on argon using $^{8}$B solar neutrinos in DEAP-3600

We report experimental evidence for electron neutrino charged-current interactions (neutrino absorption, CC $ν_e$) from $^{8}$B solar neutrinos on $^{40}$Ar using an exposure of ($7.29 \pm 0.05$) tonne$\cdot$years in the DEAP-3600 detector. A region of interest (ROI) of 10.5-13.0 MeV reconstructed energy calibrated on single-peak events, corresponding to incident neutrino energy in 12.0-14.5 MeV, is used for this measurement. We observe 5 single-peak and 1 double-peak neutrino-like events consistent with the $^{8}$B solar neutrino energy spectrum in the ROI after correcting for nonlinearities in the detector response at high energies. With an expected background of $0.48~^{+0.16}_{-0.15}$ events, the data correspond to a significance of $4.0\,σ$ with respect to the background-only hypothesis. We report an energy-averaged cross section of $(4.0~^{+2.0}_{-1.6}~\mathrm{(stat)}~^{+0.8}_{-0.7}~\mathrm{(sys)})\times 10^{-41}\,\mathrm{cm}^2$ in the ROI for the CC $ν_{e}$ signal, a factor $(2.4~^{+1.3}_{-1.0})$ higher than predicted by Bhattacharya, Goodman and García (2009).

hep-ex↗

arXiv2026

Dark Matter Search with the DEAP-3600 Detector using the Profile Likelihood Ratio Method

We present here a search for WIMP dark matter using 790.8 live-days of data collected with 3269 kg of liquid argon (1266 kg fiducial) by the DEAP-3600 detector at SNOLAB, using the Profile Likelihood Ratio method. The likelihood model is based on three parameters: estimated energy, pulse-shape discrimination parameter, and reconstructed position within the detector. Using this method, the expected signal sensitivity of DEAP-3600 benefits from an increased fiducial volume and improved event selection acceptance. Alpha-decays from a small number of dust particulates circulating within the liquid argon target are the dominant source of background events and limit the sensitivity of this search. This result provides improved exclusion upper limits on the WIMP-nucleon spin-independent cross section on liquid argon for WIMP masses between 20 GeV/$c^{2}$ and 100 GeV/$c^{2}$. At 100 GeV/$c^{2}$ the observed limit is 3.4 $\times$ 10$^{-45}$ cm$^2$ at 90% confidence level.

hep-ex↗

arXiv2025

Search for Double Beta Decays of $^{134}$Xe with EXO-200 Phase II

EXO-200 was a leading double beta decay experiment consisting of a single-phase, enriched liquid xenon time projection chamber filled with an admixture of 80.672% $^{136}$Xe and 19.098% $^{134}$Xe. The detector operated at WIPP between 2010 and 2018 and was designed to search for double beta decay of $^{136}$Xe. Data was acquired in two phases separated by a period of detector upgrades. We report on the search for $0νββ$ and $2νββ$ decay of $^{134}$Xe with Phase II EXO-200 data, with median 90% C.L. exclusion sensitivity $T_{1/2}^{0ν} \geq 3.7\times 10^{23}$ yr and $T_{1/2}^{2ν} \geq 2.6 \times 10^{21}$ yr, respectively. No statistically significant signal is observed for either decay mode. We set a world-leading lower limit on the half-life of the neutrinoless decay mode of $^{134}$Xe of $T_{1/2}^{0ν} \geq 8.7\times10^{23}$ (90% C.L.) and the second strongest constraint on the two-neutrino decay of $T_{1/2}^{2ν} \geq 2.9\times10^{21}$ (90% C.L.), a 3-fold improvement over the EXO-200 Phase I measurement. New constraints are also set for the $2νββ$ and $0νββ$ decays of $^{134}$Xe to the lowest excited state of $^{134}$Ba.

nucl-ex↗

arXiv2025

Relative Measurement and Extrapolation of the Scintillation Quenching Factor of $α$-Particles in Liquid Argon using DEAP-3600 Data

The knowledge of scintillation quenching of $α$-particles plays a paramount role in understanding $α$-induced backgrounds and improving the sensitivity of liquid argon-based direct detection of dark matter experiments. We performed a relative measurement of scintillation quenching in the MeV energy region using radioactive isotopes ($^{222}$Rn, $^{218}$Po and $^{214}$Po isotopes) present in trace amounts in the DEAP-3600 detector and quantified the uncertainty of extrapolating the quenching factor to the low-energy region.

physics.ins-det↗

arXiv2025

Direct Measurement of the $^{39}$Ar Half-life from 3.4 Years of Data with the DEAP-3600 Detector

The half-life of $^{39}$Ar is measured using the DEAP-3600 detector located 2 km underground at SNOLAB. Between 2016 and 2020, DEAP-3600 used a target mass of (3269 $\pm$ 24) kg of liquid argon distilled from the atmosphere in a direct-detection dark matter search. Such an argon mass also enables direct measurements of argon isotope properties. The decay of $^{39}$Ar in DEAP-3600 is the dominant source of triggers by two orders of magnitude, ensuring high statistics and making DEAP-3600 well-suited for measuring this isotope's half-life. Use of the pulse-shape discrimination technique in DEAP-3600 allows powerful discrimination between nuclear recoils and electron recoils, resulting in the selection of a clean sample of $^{39}$Ar decays. Observing over a period of 3.4 years, the $^{39}$Ar half-life is measured to be $(302 \pm 8_{\rm stat} \pm 6_{\rm sys})$ years. This new direct measurement suggests that the half-life of $^{39}$Ar is significantly longer than the accepted value, with potential implications for measurements using this isotope's half-life as input.

nucl-ex↗

arXiv2025

Characterization of external cross-talk from silicon photomultipliers in a liquid xenon detector

The Light-only Liquid Xenon experiment (LoLX) employs a small-scale detector equipped with 96 Hamamatsu VUV4 silicon photomultipliers (SiPMs) submerged in 5 kg of liquid xenon (LXe) to perform characterization measurements of light production, transport and detection in xenon. In this work, we perform a novel measurement of the "external cross-talk" (ExCT) of SiPMs, where photons produced in the avalanche process escape the device and produce correlated signals on other SiPMs. SiPMs are the photodetector technology of choice for next generation rare-event search experiments; understanding the sources and effects of correlated noise in SiPMs is critical for producing accurate estimates of detector performance and sensitivity projections. We measure the probability to observe ExCT through timing correlation of detected photons in low-light conditions within LoLX. Measurements of SiPM ExCT are highly detector dependent; thus the ExCT process is simulated and modelled using the Geant4 framework. Using the simulation, we determine the average transport and detection efficiency for ExCT photons within LoLX, a necessary input to extract the expected ExCT probability from the data. For an applied overvoltage of 4 V and 5 V, we measure a mean number of photons emitted into the LXe per avalanche of $0.5^{+0.3}_{-0.2}$ and $0.6^{+0.3}_{-0.2}$, respectively. Using an optical model to describe photon transmission through the SiPM surface, this corresponds to an estimated photon yield inside the bulk silicon of $20^{+11}_{-9}$ and $25^{+12}_{-9}$ photons per avalanche. The relative increase in intensity of SiPM ExCT emission between 4 V and 5 V is consistent with expectation for the linear increase of gain with respect to overvoltage.

physics.ins-det↗

arXiv2023

Search for Two-neutrino Double-Beta Decay of $^{136}\rm Xe$ to the $0^+_1$ excited state of $^{136}\rm Ba$ with the Complete EXO-200 Dataset

A new search for two-neutrino double-beta ($2νββ$) decay of $^{136}\rm Xe$ to the $0^+_1$ excited state of $^{136}\rm Ba$ is performed with the full EXO-200 dataset. A deep learning-based convolutional neural network is used to discriminate signal from background events. Signal detection efficiency is increased relative to previous searches by EXO-200 by more than a factor of two. With the addition of the Phase II dataset taken with an upgraded detector, the median 90$\%$ confidence level half-life sensitivity of $2νββ$ decay to the $0^+_1$ state of $^{136}\rm Ba$ is $2.9 \times 10^{24}~\rm yr$ using a total $^{136}\rm Xe$ exposure of $234.1~\rm kg~yr$. No statistically significant evidence for $2νββ$ decay to the $0^+_1$ state is observed, leading to a lower limit of $T^{2ν}_{1/2}(0^+ \rightarrow 0^+_1) > 1.4\times10^{24}~\rm yr$ at 90$\%$ confidence level, improved by 70$\%$ relative to the current world's best constraint.

hep-ex↗

arXiv2023

Generative Adversarial Networks for Scintillation Signal Simulation in EXO-200

Generative Adversarial Networks trained on samples of simulated or actual events have been proposed as a way of generating large simulated datasets at a reduced computational cost. In this work, a novel approach to perform the simulation of photodetector signals from the time projection chamber of the EXO-200 experiment is demonstrated. The method is based on a Wasserstein Generative Adversarial Network - a deep learning technique allowing for implicit non-parametric estimation of the population distribution for a given set of objects. Our network is trained on real calibration data using raw scintillation waveforms as input. We find that it is able to produce high-quality simulated waveforms an order of magnitude faster than the traditional simulation approach and, importantly, generalize from the training sample and discern salient high-level features of the data. In particular, the network correctly deduces position dependency of scintillation light response in the detector and correctly recognizes dead photodetector channels. The network output is then integrated into the EXO-200 analysis framework to show that the standard EXO-200 reconstruction routine processes the simulated waveforms to produce energy distributions comparable to that of real waveforms. Finally, the remaining discrepancies and potential ways to improve the approach further are highlighted.

hep-ex↗

arXiv2023

Search for MeV Electron Recoils from Dark Matter in EXO-200

We present a search for electron-recoil signatures from the charged-current absorption of fermionic dark matter using the EXO-200 detector. We report an average electron recoil background rate of $6.8 \times 10^{-4}\, \mathrm{cts}\,\mathrm{kg}^{-1}\mathrm{yr}^{-1}\mathrm{keV}^{-1}$ above $4\,\mathrm{MeV}$ and find no statistically significant excess over our background projection. Using a total ${}^{136}\mathrm{Xe}$ exposure of $234.1\,\mathrm{kg}\,\mathrm{yr}$ we exclude new parameter space for the charged-current absorption cross-section for dark matter masses between $m_χ= 2.6\,\mathrm{MeV} - 11.6\,\mathrm{MeV}$ with a minimum of $6\times 10^{-51}\,\mathrm{cm}^2$ at $8.3\,\mathrm{MeV}$ at the $90\%$ confidence level.

hep-ex↗

arXiv2022

Neutron Emission Spectrometer To Measure Ion Temperature On The Fusion Demonstration Plant

General Fusion is building the Fusion Demonstration Plant to demonstrate a magnetized target fusion scheme in which a deuterium plasma is heated from 200 eV to 10 keV by piston-driven compression of a liquid-lithium liner. The multilayer coaxial time-of-flight (MCTOF) neutron emission spectrometer is designed to measure the ion temperature near peak compression at which time the neutron yield will approach $10^{18}$ neutrons/s. The neutron energy distribution is expected to be Gaussian since the machine uses no neutral beam or radiofrequency heating. In this case, analysis shows that as few as 500 coincidence events should be sufficient to accurately measure the ion temperature. This enables a fast time resolution of 10 $μs$, which is required to track the rapid change in temperature approaching peak compression. We overcome the challenges of neutron pileup and event ambiguity with a compact design having two layers of segmented scintillators. The error in the ion temperature measurement is computed as a function of the neutron spectrometer's geometric parameters and used to optimize the design for the case of reaching 10 keV at peak compression.

physics.plasm-ph↗

arXiv2022

Constraints on dark matter-nucleon effective couplings in the presence of kinematically distinct halo substructures using the DEAP-3600 detector

DEAP-3600 is a single-phase liquid argon detector aiming to directly detect Weakly Interacting Massive Particles (WIMPs), located at SNOLAB (Sudbury, Canada). After analyzing data taken during the first year of operation, a null result was used to place an upper bound on the WIMP-nucleon spin-independent, isoscalar cross section. This study reinterprets this result within a Non-Relativistic Effective Field Theory framework, and further examines how various possible substructures in the local dark matter halo may affect these constraints. Such substructures are hinted at by kinematic structures in the local stellar distribution observed by the Gaia satellite and other recent astronomical surveys. These include the Gaia Sausage (or Enceladus), as well as a number of distinct streams identified in recent studies. Limits are presented for the coupling strength of the effective contact interaction operators $\mathcal{O}_1$, $\mathcal{O}_3$, $\mathcal{O}_5$, $\mathcal{O}_8$, and $\mathcal{O}_{11}$, considering isoscalar, isovector, and xenonphobic scenarios, as well as the specific operators corresponding to millicharge, magnetic dipole, electric dipole, and anapole interactions. The effects of halo substructures on each of these operators are explored as well, showing that the $\mathcal{O}_5$ and $\mathcal{O}_8$ operators are particularly sensitive to the velocity distribution, even at dark matter masses above 100 GeV/$c^2$.

astro-ph.CO↗

arXiv2022

First direct detection constraints on Planck-scale mass dark matter with multiple-scatter signatures using the DEAP-3600 detector

Dark matter particles with Planck-scale mass ($\simeq10^{19}\text{GeV}/c^2$) arise in well-motivated theories and could be produced by several cosmological mechanisms. Using a blind analysis of data collected over a 813 d live time with DEAP-3600, a 3.3 t single-phase liquid argon-based dark matter experiment at SNOLAB, a search for supermassive dark matter was performed, looking for multiple-scatter signals. No candidate signal events were observed, leading to the first direct detection constraints on Planck-scale mass dark matter. Leading limits constrain dark matter masses between $8.3\times10^{6}$ and $1.2\times10^{19} \text{GeV}/c^2$, and cross sections for scattering on $^{40}$Ar between $1.0\times10^{-23}$ and $2.4\times10^{-18} \text{cm}^2$. These are used to constrain two composite dark matter models.

astro-ph.CO↗

arXiv2021

Characterisation of SiPM Photon Emission in the Dark

In this paper, we report on the photon emission of Silicon Photomultipliers (SiPMs) from avalanche pulses generated in dark condition, with the main objective of better understanding the associated systematics for next-generation, large area, SiPM-based physics experiments. A new apparatus for spectral and imaging analysis was developed at TRIUMF and used to measure the light emitted by the two SiPMs considered as photo-sensor candidates for the nEXO neutrinoless double-beta decay experiment: one Fondazione Bruno Kessler (FBK) VUV-HD Low Field (LF) Low After Pulse (Low AP) (VUV-HD3) SiPM, and one Hamamatsu Photonics K.K. (HPK) VUV4 Multi-Pixel Photon Counter (MPPC). Spectral measurements of their light emission were taken with varying over-voltage in the wavelength range of 450--1020\,nm. For the FBK VUV-HD3, at an over-voltage of $12.1\pm1.0$\,V, we measure a secondary photon yield (number of photons ($γ$) emitted per charge carrier ($e^{-}$)) of $(4.04\pm0.02)\times 10^{-6}$ $γ/e^{-}$. The emission spectrum of the FBK VUV-HD3 contains an interference pattern consistent with thin-film interference. Additionally, emission microscopy images (EMMIs) of the FBK VUV-HD3 show a small number of highly localized regions with increased light intensity (hotspots) randomly distributed over the SiPM surface area. For the HPK VUV4 MPPC, at an over-voltage of $10.7\pm1.0$\,V, we measure a secondary photon yield of $(8.71\pm0.04)\times 10^{-6}$ $γ/e^{-}$. In contrast to the FBK VUV-HD3, the emission spectra of the HPK VUV4 don't show an interference pattern -- most likely due to a thinner surface coating. EMMIs of the HPK VUV4 also reveal a larger number of hotspots compared to the FBK VUV-HD3, especially in one of the corners of the device.

physics.ins-det↗

arXiv2020

The liquid-argon scintillation pulseshape in DEAP-3600

DEAP-3600 is a liquid-argon scintillation detector looking for dark matter. Scintillation events in the liquid argon (LAr) are registered by 255 photomultiplier tubes (PMTs), and pulseshape discrimination (PSD) is used to suppress electromagnetic background events. The excellent PSD performance of LAr makes it a viable target for dark matter searches, and the LAr scintillation pulseshape discussed here is the basis of PSD. The observed pulseshape is a combination of LAr scintillation physics with detector effects. We present a model for the pulseshape of electromagnetic background events in the energy region of interest for dark matter searches. The model is composed of a) LAr scintillation physics, including the so-called intermediate component, b) the time response of the TPB wavelength shifter, including delayed TPB emission at $\mathcal O$(ms) time-scales, and c) PMT response. TPB is the wavelength shifter of choice in most LAr detectors. We find that approximately 10\% of the intensity of the wavelength-shifted light is in a long-lived state of TPB. This causes light from an event to spill into subsequent events to an extent not usually accounted for in the design and data analysis of LAr-based detectors.

physics.ins-det↗

arXiv2020

Measurement of the Spectral Shape of the beta-decay of 137Xe to the Ground State of 137Cs in EXO-200 and Comparison with Theory

We report on a comparison between the theoretically predicted and experimentally measured spectra of the first-forbidden non-unique $β$-decay transition $^{137}\textrm{Xe}(7/2^-)\to\,^{137}\textrm{Cs}(7/2^+)$. The experimental data were acquired by the EXO-200 experiment during a deployment of an AmBe neutron source. The ultra-low background environment of EXO-200, together with dedicated source deployment and analysis procedures, allowed for collection of a pure sample of the decays, with an estimated signal-to-background ratio of more than 99-to-1 in the energy range from 1075 to 4175 keV. In addition to providing a rare and accurate measurement of the first-forbidden non-unique $β$-decay shape, this work constitutes a novel test of the calculated electron spectral shapes in the context of the reactor antineutrino anomaly and spectral bump.

nucl-ex↗

arXiv2019

Search for Neutrinoless Double-Beta Decay with the Complete EXO-200 Dataset

A search for neutrinoless double-beta decay ($0νββ$) in $^{136}$Xe is performed with the full EXO-200 dataset using a deep neural network to discriminate between $0νββ$ and background events. Relative to previous analyses, the signal detection efficiency has been raised from 80.8% to 96.4$\pm$3.0% and the energy resolution of the detector at the Q-value of $^{136}$Xe $0νββ$ has been improved from $σ/E=1.23\%$ to $1.15\pm0.02\%$ with the upgraded detector. Accounting for the new data, the median 90% confidence level $0νββ$ half-life sensitivity for this analysis is $5.0 \cdot 10^{25}$ yr with a total $^{136}$Xe exposure of 234.1 kg$\cdot$yr. No statistically significant evidence for $0νββ$ is observed, leading to a lower limit on the $0νββ$ half-life of $3.5\cdot10^{25}$ yr at the 90% confidence level.

hep-ex↗