The XENONnT detector uses the latest and largest liquid xenon-based time projection chamber (TPC) operated by the XENON Collaboration, aimed at detecting Weakly Interacting Massive Particles and ...conducting other rare event searches. The XENONnT data acquisition (DAQ) system constitutes an upgraded and expanded version of the XENON1T DAQ system. For its operation, it relies predominantly on commercially available hardware accompanied by open-source and custom-developed software. The three constituent subsystems of the XENONnT detector, the TPC (main detector), muon veto, and the newly introduced neutron veto, are integrated into a single DAQ, and can be operated both independently and as a unified system. In total, the DAQ digitizes the signals of 698 photomultiplier tubes (PMTs), of which 253 from the top PMT array of the TPC are digitized twice, at \(\times10\) and \(\times0.5\) gain. The DAQ for the most part is a triggerless system, reading out and storing every signal that exceeds the digitization thresholds. Custom-developed software is used to process the acquired data, making it available within \(\mathcal{O}\left(10\text{ s}\right)\) for live data quality monitoring and online analyses. The entire system with all the three subsystems was successfully commissioned and has been operating continuously, comfortably withstanding readout rates that exceed \(\sim500\) MB/s during calibration. Livetime during normal operation exceeds \(99\%\) and is \(\sim90\%\) during most high-rate calibrations. The combined DAQ system has collected more than 2 PB of both calibration and science data during the commissioning of XENONnT and the first science run.
We report on a blinded analysis of low-energy electronic-recoil data from the first science run of the XENONnT dark matter experiment. Novel subsystems and the increased 5.9 tonne liquid xenon target ...reduced the background in the (1, 30) keV search region to \((15.8 \pm 1.3)\) events/(tonne\(\times\)year\(\times\)keV), the lowest ever achieved in a dark matter detector and \(\sim\)5 times lower than in XENON1T. With an exposure of 1.16 tonne-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter.
Understanding propagation of scintillation light is critical for maximizing the discovery potential of next-generation liquid xenon detectors that use dual-phase time projection chamber technology. ...This work describes a detailed optical simulation of the DARWIN detector implemented using Chroma, a GPU-based photon tracking framework. To evaluate the framework and to explore ways of maximizing efficiency and minimizing the time of light collection, we simulate several variations of the conventional detector design. Results of these selected studies are presented. More generally, we conclude that the approach used in this work allows one to investigate alternative designs faster and in more detail than using conventional Geant4 optical simulations, making it an attractive tool to guide the development of the ultimate liquid xenon observatory.
We detail the sensitivity of the liquid xenon (LXe) DARWIN observatory to solar neutrinos via elastic electron scattering. We find that DARWIN will have the potential to measure the fluxes of five ...solar neutrino components: \(pp\), \(^7\)Be, \(^{13}\)N, \(^{15}\)O and \(pep\). The precision of the \(^{13}\)N, \(^{15}\)O and \(pep\) components is hindered by the double-beta decay of \(^{136}\)Xe and, thus, would benefit from a depleted target. A high-statistics observation of \(pp\) neutrinos would allow us to infer the values of the weak mixing angle, \(\sin^2\theta_w\), and the electron-type neutrino survival probability, \(P_e\), in the electron recoil energy region from a few keV up to 200 keV for the first time, with relative precision of 5% and 4%, respectively, at an exposure of 300 ty. An observation of \(pp\) and \(^7\)Be neutrinos would constrain the neutrino-inferred solar luminosity down to 0.2%. A combination of all flux measurements would distinguish between the high (GS98) and low metallicity (AGS09) solar models with 2.1-2.5\(\sigma\) significance, independent of external measurements from other experiments or a measurement of \(^8\)B neutrinos through coherent elastic neutrino-nucleus scattering in DARWIN. Finally, we demonstrate that with a depleted target DARWIN may be sensitive to the neutrino capture process of \(^{131}\)Xe.
The DARWIN observatory is a proposed next-generation experiment to search for particle dark matter and for the neutrinoless double beta decay of \(^{136}\)Xe. Out of its 50\(\,\)t total natural xenon ...inventory, 40\(\,\)t will be the active target of a time projection chamber which thus contains about 3.6 t of \(^{136}\)Xe. Here, we show that its projected half-life sensitivity is \(2.4\times10^{27}\,\)yr, using a fiducial volume of 5t of natural xenon and 10\(\,\)yr of operation with a background rate of less than 0.2\(~\)events/(t\(\cdot\)yr) in the energy region of interest. This sensitivity is based on a detailed Monte Carlo simulation study of the background and event topologies in the large, homogeneous target. DARWIN will be comparable in its science reach to dedicated double beta decay experiments using xenon enriched in \(^{136}\)Xe.
During the COVID-19 pandemic, German early childhood education and care (ECEC) institutions had to limit their provision of ECEC, implement protective measures, and handle new organizational tasks. ...Data from two longitudinal surveys (October 2020 to July 2021) among ECEC managers and pedagogical staff were analysed. Limited staff resources, limited access, and high pandemic-related challenges (i.e. difficulties and conflicts related to implementing protective measures), were negatively associated with the frequency of pedagogical practices (Models 1, 2). Manager ratings suggested increased developmental needs for children with low socio-economic status; also higher frequency of pedagogical practices at early stages of the pandemic (T1) was associated with lower increase of developmental needs at a later stage (T2, about 5 months later). In sum, this contribution provides evidence about how the COVID-19 pandemic might have affected quality in ECEC provision on both the structural and interaction level and how this, subsequently, impacted child outcomes.
Background
During the SARS-CoV-2 pandemic, German early childhood education and care (ECEC) centres organized children's attendance variably (i.e., reduced opening hours, emergency support for few ...children only or full close-down). Further, protection and hygiene measures like fixed children/staff groups, ventilation and surface disinfection were introduced among ECEC centres. To inform or modify public health measures in ECEC, we investigate the occurrence of SARS-CoV-2 infections among children and staff of ECEC centres in light of social determinants (socioeconomic status of the children) and recommended structural and hygiene measures. We focus on the question if the relevant factors differ between the 2nd (when no variant of concern (VOC) circulated) and the 3rd wave (when VOC B.1.1.7 (Alpha) predominated).
Methods
Based on panel data from a weekly online survey of ECEC centre managers (start August 2020, ongoing) including approx. 8500 centres, we estimate the number of SARS-CoV-2 infections in children and staff using random-effect-within-between (REWB) panel models for count data in both waves.
Results
Centres with a high proportion of children with low socioeconomic status (SES) have a higher risk of infections in staff and children. Strict contact restrictions between groups like fixed group assignments among children and fixed staff assignments to groups prevent infections. Both effects tend to be stronger in the 3rd wave.
Conclusions
ECEC centres with a large proportion of children from a low SES background and lack of using fixed child/staff cohorts experience higher COVID-19 rates. Centres should be supported in maintaining recommended measures over the long run. Preventive measures such as vaccination of staff should be prioritised in centres with large proportions of low SES children.
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