RED-100 is a two-phase liquid xenon time projection chamber with an active volume containing 126 kg of liquid xenon. The detector was exposed to an antineutrino flux of about 1.4×1013 cm−2 s−1 at a distance of 19 m from the 3.1 GW Kalinin nuclear power plant reactor core. The comparison of data from 331 kg·days with the reactor on and 106 kg·days with the reactor off shows no statistically significant excess and the constraint on coherent elastic scattering of antineutrinos off xenon nuclei cross section is given.

Electron antineutrinos are emitted in the decay chains of the fission products inside a reactor core and could be used for remote monitoring of nuclear reactors. The DANSS detector is placed under the core of the 3.1 GW power reactor at the Kalinin Nuclear Power Plant (KNPP) and collects up to 5000 antineutrino events per day. DANSS measured changes of the reactor power by antineutrino counting rates over 7 years with 1.0% accuracy in one week periods. The fission fractions of four major isotopes for the reactor power calculations were provided by KNPP. The systematic uncertainty of this measurement is less than 0.8%. It is comparable to the accuracy of conventional methods of the reactor power measurements while it is based on completely different approach. For the first time the 239Pu and 235U fission fractions were reconstructed using antineutrino inverse beta-decay spectrum which is a completely new technique. This method was applied to the data from three reactor fuel campaigns (approximately 1.5 year each). The reconstructed fission fractions in about two-week measurements and the fission fractions provided by KNPP coincide within better than 3% accuracy. This provides confidence in both completely different approaches of the fission fraction determination.

The yields of the inverse beta decay events produced by antineutrinos from a certain nuclear reactor fuel component are used by many experiments to check various model predictions. Yet measurements of the absolute yields feature significant uncertainties coming, mainly, from the understanding of the antineutrino detection efficiency. This work presents a simple novel approach to directly determine the 235U to 239Pu inverse beta decay yield ratio using the fuel evolution analysis. This ratio can be used for a sensitive test of reactor models, while the proposed method, results in smaller systematic uncertainties. The DANSS result on this ratio is one of the most precise among reactor neutrino experiments, yet does not significantly contradict to any previous measurement.

We report the first detection of coherent elastic neutrino-nucleus scattering (CEvNS) on germanium, measured at the Spallation Neutron Source at Oak Ridge National Laboratory. The Ge-Mini detector of the COHERENT collaboration employs large-mass, low-noise, high-purity germanium spectrometers, enabling excellent energy resolution, and an analysis threshold of 1.5 keV electron-equivalent ionization energy. We observe a on-beam excess of 20.6$_{+7.1}^{-6.3}$ counts with a total exposure of 10.22 GWhkg and we reject the no-CEvNS hypothesis with 3.9 sigma significance. The result agrees with the predicted standard model of particle physics signal rate within 2 sigma.

It was found that overheating (1200 degrees C, 4 h, slow cooling) of low-carbon low-alloy steel Fe-C-Cr-Mo leads to the formation of a Widmanstatten structure and an increase in strength by 1.2-1.5 times while maintaining high ductility. The relationship between changes in the steel mechanical properties and the Widmanstatten' dislocation structure features are discussed.

A technique for producing, adjusting, and testing large-area scintillation detectors (≥1 m2) for active cosmic muon shielding in low-background experiments is presented. The detectors developed feature a high efficiency ( 99.75

The cryogenic system of the RED-100 two-phase emission detector has been modified to enable operation with liquid argon as a working medium with the aim of searching for the effect of coherent elastic scattering of reactor electron antineutrinos by argon nuclei.

DANSS is a spectrometer for reactor antineutrinos based on plastic scintillator. The sensitive volume of the detector is made of 2500 polystyrene based scintillator plates with wavelength shifting (WLS) fiber readout (strips). We present a study of the light yield of strips during 6.5 years of DANSS continuous running. Overall ageing at the rate 0.55 ± 0.05 (syst.) % per year is observed that is considerably smaller than in other similar experiments. We also observe the WLS fiber attenuation length shortening at the rate 0.26 ± 0.04(stat.) % per year.

Neutrinoless 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 ^136Xe, which would double beta decay into ^136Ba. Detecting the single ^136Ba 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.

Neutrinoless 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-136, which would double beta decay into Ba-136. Detecting the single Ba-136 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.

We consider the potential for a 10-kg undoped cryogenic CsI detector operating at the Spallation Neutron Source to measure coherent elastic neutrino-nucleus scattering and its sensitivity to discover new physics beyond the standard model. Through a combination of increased event rate, lower threshold, and good timing resolution, such a detector would significantly improve on past measurements. We considered tests of several beyond-the-standard-model scenarios such as neutrino non-standard interactions and accelerator-produced dark matter. This detector's performance was also studied for relevant questions in nuclear physics and neutrino astronomy, namely the weak charge distribution of CsI nuclei and detection of neutrinos from a core-collapse supernova.

Electron-neutrino charged-current interactions with xenon nuclei were modeled in the nEXO neutrinoless double-beta decay detector (similar to 5 metric ton, 90% Xe-136, 10% Xe-134) to evaluate its sensitivity to supernova neutrinos. Predictions for event rates and detectable signatures were modeled using the Model of Argon Reaction Low Energy Yields (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 5-8 kpc from Earth, while the ability to reconstruct incident electron-neutrino spectrum parameters from observed interactions in nEXO is limited to closer supernovae.

Abstract The Monument experiment measures ordinary muon capture (OMC) on isotopes relevant for neutrinoless double-beta ( $$0\nu \beta \beta $$ 0 ν β β ) decay and nuclear astrophysics. OMC is a particularly attractive tool for improving the theoretical description of $$0\nu \beta \beta $$ 0 ν β β decay. It involves similar momentum transfers and allows testing the virtual transitions involved in $$0\nu \beta \beta $$ 0 ν β β decay against experimental data. During the 2021 campaign, Monument studied OMC on $$^{76}$$ 76 Se and $$^{136}$$ 136 Ba, the isotopes relevant for next-generation $$0\nu \beta \beta $$ 0 ν β β decay searches, like Legend and nEXO. The experimental setup has been designed to accurately extract the total and partial muon capture rates, which requires precise reconstruction of energies and time-dependent intensities of the OMC-related $$\gamma $$ γ rays. The setup also includes a veto counter system to allow selecting a clean sample of OMC events. This work provides a detailed description of the Monument setup operated during the 2021 campaign, its two DAQ systems, calibration and analysis approaches, and summarises the achieved detector performance. Future improvements are also discussed.

RED-100 is a two-phase Xe detector designed and built for the study of coherent elastic neutrino-nucleus scattering CEvNS of reactor antineutrinos. A comprehensive calibration was performed in order to obtain important parameters of the detector during its exposition at the Kalinin Nuclear Power Plant (Tver, Russia). This paper describes the analysis of calibration data, position and energy reconstruction procedures, and evaluation of the efficiency of electron extraction from the liquid xenon to the gas phase.

Dynamic mechanical analysis is used to perform comparative low-cycle fatigue tests according to the scheme of bending the weld metal of a low-carbon steel 22K welded joint after a high-temperature action according to the following schedule: holding at 1200°C for 3.7 h followed by slow cooling. The weld metal in the initial state is shown to be characterized by low-cycle fatigue high resistance: the fatigue limit for finite life at N = 3.5 × 104 cycles is σRN = 340 MPa. The high-temperature action additionally increases σRN by 23

The Monument experiment measures ordinary muon capture (OMC) on isotopes relevant for neutrinoless double-beta ( 0νββ ) decay and nuclear astrophysics. OMC is a particularly attractive tool for improving the theoretical description of 0νββ decay. It involves similar momentum transfers and allows testing the virtual transitions involved in 0νββ decay against experimental data. During the 2021 campaign, Monument studied OMC on ^76 Se and ^136 Ba, the isotopes relevant for next-generation 0νββ decay searches, like Legend and nEXO. The experimental setup has been designed to accurately extract the total and partial muon capture rates, which requires precise reconstruction of energies and time-dependent intensities of the OMC-related γ rays. The setup also includes a veto counter system to allow selecting a clean sample of OMC events. This work provides a detailed description of the Monument setup operated during the 2021 campaign, its two DAQ systems, calibration and analysis approaches, and summarises the achieved detector performance. Future improvements are also discussed.

Large-scale low-background detectors are increasingly used in rare-event searches as experimental collabora-tions 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.

The COHERENT Collaboration searched for scalar dark matter particles produced at the Spallation Neutron Source with masses between 1 and 220  MeV/c^{2} using a CsI[Na] scintillation detector sensitive to nuclear recoils above 9  keV_{nr}. No evidence for dark matter is found and we thus place limits on allowed parameter space. With this low-threshold detector, we are sensitive to coherent elastic scattering between dark matter and nuclei. The cross section for this process is orders of magnitude higher than for other processes historically used for accelerator-based direct-detection searches so that our small, 14.6 kg detector significantly improves on past constraints. At peak sensitivity, we reject the flux consistent with the cosmologically observed dark-matter concentration for all coupling constants α_{D}<0.64, assuming a scalar dark-matter particle. We also calculate the sensitivity of future COHERENT detectors to dark-matter signals which will ambitiously test multiple dark-matter spin scenarios.

We present an overview of recent progress toward the Ricochet coherent elastic neutrino nucleus scattering (CE ν NS) experiment. The ILL research reactor in Grenoble, France has been selected as the experiment site, after in situ studies of vibration and particle backgrounds. We present background rate estimates specific to that site, along with descriptions of the planned CryoCube and Q-Array detector payloads.