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This study introduces a new method to locate cracks in wind turbine blades using the support vector machine algorithm and the tangential vibration signal measured at the root blade in static conditions. The method was implemented in hardware and experimentally validated on 200 W wind turbine blades. The blade conditions were healthy, and transverse cracked at the root, midsection, and tip. The experimental procedure is easy, and only one low-cost piezoelectric accelerometer is needed, which is affordable and straightforward to install. The machine learning technique used requires a small dataset and low computing power. The results show exceptional performance, achieving an accuracy of 99.37% and a precision of 98.77%. This approach enhances the reliability of wind turbine blade monitoring. It provides a robust early detection and maintenance solution, improving operational efficiency and safety in wind energy production. K-nearest neighbors and decision trees are also used for comparison purposes.

The High-Altitude Water Cherenkov observatory is a ground-based array designed to study energetic gamma-rays. Experiments with this purpose have to face a huge rate of undesired hadronic background. Motivated by the fact that muon content is quite different in gamma-induced (poor in muons) and hadronic-induced (rich in muons) air-showers, we study the idea of formulating a new variable for background reduction related with counting the number of muons candidates present in such showers. Therefore, in this work we used the time differences between photomultipliers tubes to identify the signature of muons inside the water Cherenkov detectors. Showers with a high presence of muons typically must produce a characteristic time difference around 5 ns among the central detector (PMT_C) and each one of the laterals (PMT: A, B, D).

The DEAP-3600 detector searches for the scintillation signal from dark matter particles scattering on a 3.3 tonne liquid argon target. The largest background comes from 39Ar beta decays and is suppressed using pulse-shape discrimination (PSD). We use two types of PSD estimator: the prompt-fraction, which considers the fraction of the scintillation signal in a narrow and a wide time window around the event peak, and the log-likelihood-ratio, which compares the observed photon arrival times to a signal and a background model. We furthermore use two algorithms to determine the number of photons detected at a given time: (1) simply dividing the charge of each PMT pulse by the mean single-photoelectron charge, and (2) a likelihood analysis that considers the probability to detect a certain number of photons at a given time, based on a model for the scintillation pulse shape and for afterpulsing in the light detectors. The prompt-fraction performs approximately as well as the log-likelihood-ratio PSD algorithm if the photon detection times are not biased by detector effects. We explain this result using a model for the information carried by scintillation photons as a function of the time when they are detected.

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 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.

Abstract The half-life of$$^{39}$$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 ± 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$$^{39}$$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$$^{39}$$39 Ar decays. Observing over a period of 3.4 years, the$$^{39}$$39 Ar half-life is measured to be$$(302 \\pm 8_\\textrm{stat} \\pm 6_\\textrm{sys})$$( 302 ± 8 stat ± 6 sys ) years. This new direct measurement suggests that the half-life of$$^{39}$$39 Ar is significantly longer than the accepted value, with potential implications for measurements using this isotope’s half-life as input.

Abstract The specific activity of theβ β decay of³⁹39 Ar in atmospheric argon is measured using the DEAP-3600 detector. DEAP-3600, located 2 km underground at SNOLAB, uses a total of (3269 ± 24) kg of liquid argon distilled from the atmosphere to search for dark matter. This detector is well-suited to measure the decay of³⁹39 Ar owing to its very low background levels. This is achieved in two ways: it uses low background construction materials; and it uses pulse-shape discrimination to differentiate between nuclear recoils and electron recoils. With 167 live-days of data, the measured specific activity at the time of atmospheric extraction is (0.964 ± 0.001_(\\textrm{stat}{}{})stat ± 0.024_(\\textrm{sys}{}{})sys ) Bq/kg_(\\textrm{atmAr}{}{})atmAr , which is consistent with results from other experiments. A cross-check analysis using different event selection criteria and a different statistical method confirms the result.

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 ± 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 ± 8 stat ± 6 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.

A device filled with pure xenon first demonstrated the ability to operate simultaneously as a bubble chamber and scintillation detector in 2017. Initial results from data taken at thermodynamic thresholds down to ~4 keV showed sensitivity to ~20 keV nuclear recoils with no observable bubble nucleation by \\(\\gamma\\)-ray interactions. This paper presents results from further operation of the same device at thermodynamic thresholds as low as 0.50 keV, hardware limited. The bubble chamber has now been shown to have sensitivity to ~1 keV nuclear recoils while remaining insensitive to bubble nucleation by \\(\\gamma\\)-rays. A robust calibration of the chamber's nuclear recoil nucleation response, as a function of nuclear recoil energy and thermodynamic state, is presented. Stringent upper limits are established for the probability of bubble nucleation by \\(\\gamma\\)-ray-induced Auger cascades, with a limit of \\(<1.1\\times10^{-6}\\) set at 0.50 keV, the lowest thermodynamic threshold explored.

The physics reach of a low threshold (100 eV) scintillating argon bubble chamber sensitive to Coherent Elastic neutrino-Nucleus Scattering (CE\\(\\nu\\)NS) from reactor neutrinos is studied. The sensitivity to the weak mixing angle, neutrino magnetic moment, and a light \\(Z'\\) gauge boson mediator are analyzed. A Monte Carlo simulation of the backgrounds is performed to assess their contribution to the signal. The analysis shows that world-leading sensitivities are achieved with a one-year exposure for a 10 kg chamber at 3 m from a 1 MW\\(_{th}\\) research reactor or a 100 kg chamber at 30 m from a 2000 MW\\(_{th}\\) power reactor. Such a detector has the potential to become the leading technology to study CE\\(\\nu\\)NS using nuclear reactors.

A device filled with pure xenon first demonstrated the ability to operate simultaneously as a bubble chamber and scintillation detector in 2017. Initial results from data taken at thermodynamic thresholds down to ~4 keV showed sensitivity to ~20 keV nuclear recoils with no observable bubble nucleation by \\(\\)-ray interactions. This paper presents results from further operation of the same device at thermodynamic thresholds as low as 0.50 keV, hardware limited. The bubble chamber has now been shown to have sensitivity to ~1 keV nuclear recoils while remaining insensitive to bubble nucleation by \\(\\)-rays. A robust calibration of the chamber's nuclear recoil nucleation response, as a function of nuclear recoil energy and thermodynamic state, is presented. Stringent upper limits are established for the probability of bubble nucleation by \\(\\)-ray-induced Auger cascades, with a limit of \\(<1.110^-6\\) set at 0.50 keV, the lowest thermodynamic threshold explored.