We perform a blind search for particle signals in the XENON1T dark matter detector that occur close in time to gravitational-wave signals in the LIGO and Virgo observatories. No particle signal is ...observed in the nuclear recoil and electronic recoil channels within ±500 seconds of observations of the gravitational-wave signals GW170104, GW170729, GW170817, GW170818, and GW170823. We use this null result to constrain monoenergetic neutrinos and axion-like particles emitted in the closest coalescence GW170817, a binary neutron star merger. We set new upper limits on the fluence (time-integrated flux) of coincident neutrinos down to 17 keV at the 90% confidence level. Furthermore, we constrain the product of the coincident fluence and cross section of axion-like particles to be less than 10 −29 cm 2 /cm 2 in the 5.5–210 keV energy range at the 90% confidence level.
We developed a detector signal characterization model based on a Bayesian network trained on the waveform attributes generated by a dual-phase xenon time projection chamber. By performing inference ...on the model, we produced a quantitative metric of signal characterization and demonstrate that this metric can be used to determine whether a detector signal is sourced from a scintillation or an ionization process. We describe the method and its performance on electronic-recoil (ER) data taken during the first science run of the XENONnT dark matter experiment. We demonstrate the first use of a Bayesian network in a waveform -based analysis of detector signals. This method resulted in a 3% increase in ER event-selection efficiency with a simultaneously effective rejection of events outside of the region of interest. The findings of this analysis are consistent with the previous analysis from XENONnT, namely a background-only fit of the ER data.
We report on the first search for nuclear recoils from dark matter in the form of weakly interacting massive particles (WIMPs) with the XENONnT experiment, which is based on a two-phase time ...projection chamber with a sensitive liquid xenon mass of 5.9 ton. During the (1.09±0.03) ton yr exposure used for this search, the intrinsic ^{85}Kr and ^{222}Rn concentrations in the liquid target are reduced to unprecedentedly low levels, giving an electronic recoil background rate of (15.8±1.3) events/ton yr keV in the region of interest. A blind analysis of nuclear recoil events with energies between 3.3 and 60.5 keV finds no significant excess. This leads to a minimum upper limit on the spin-independent WIMP-nucleon cross section of 2.58×10^{-47} cm^{2} for a WIMP mass of 28 GeV/c^{2} at 90% confidence level. Limits for spin-dependent interactions are also provided. Both the limit and the sensitivity for the full range of WIMP masses analyzed here improve on previous results obtained with the XENON1T experiment for the same exposure.
Multiple viable theoretical models predict heavy dark matter particles with a mass close to the Planck mass, a range relatively unexplored by current experimental measurements. We use 219.4 days of ...data collected with the XENON1T experiment to conduct a blind search for signals from multiply interacting massive particles (MIMPs). Their unique track signature allows a targeted analysis with only 0.05 expected background events from muons. Following unblinding, we observe no signal candidate events. This Letter places strong constraints on spin-independent interactions of dark matter particles with a mass between 1×10^{12} and 2×10^{17} GeV/c^{2}. In addition, we present the first exclusion limits on spin-dependent MIMP-neutron and MIMP-proton cross sections for dark matter particles with masses close to the Planck scale.
This paper details the first application of a software tagging algorithm to reduce radon-induced backgrounds in liquid noble element time projection chambers, such as XENON1T and XENONnT. The ...convection velocity field in XENON1T was mapped out using Rn 222 and Po 218 events, and the rms convection speed was measured to be 0.30 ± 0.01 cm / s . Given this velocity field, Pb 214 background events can be tagged when they are followed by Bi 214 and Po 214 decays, or preceded by Po 218 decays. This was achieved by evolving a point cloud in the direction of a measured convection velocity field, and searching for Bi 214 and Po 214 decays or Po 218 decays within a volume defined by the point cloud. In XENON1T, this tagging system achieved a Pb 214 background reduction of 6.2 − 0.9 + 0.4 % with an exposure loss of 1.8 ± 0.2 % , despite the timescales of convection being smaller than the relevant decay times. We show that the performance can be improved in XENONnT, and that the performance of such a software-tagging approach can be expected to be further improved in a diffusion-limited scenario. Finally, a similar method might be useful to tag the cosmogenic Xe 137 background, which is relevant to the search for neutrinoless double-beta decay. Published by the American Physical Society 2024
Xenon dual-phase time projections chambers (TPCs) have proven to be a successful technology in studying physical phenomena that require low-background conditions. With
40
t
of liquid xenon (LXe) in ...the TPC baseline design, DARWIN will have a high sensitivity for the detection of particle dark matter, neutrinoless double beta decay (
0
ν
β
β
), and axion-like particles (ALPs). Although cosmic muons are a source of background that cannot be entirely eliminated, they may be greatly diminished by placing the detector deep underground. In this study, we used Monte Carlo simulations to model the cosmogenic background expected for the DARWIN observatory at four underground laboratories: Laboratori Nazionali del Gran Sasso (LNGS), Sanford Underground Research Facility (SURF), Laboratoire Souterrain de Modane (LSM) and SNOLAB. We present here the results of simulations performed to determine the production rate of
137
Xe, the most crucial isotope in the search for
0
ν
β
β
of
136
Xe. Additionally, we explore the contribution that other muon-induced spallation products, such as other unstable xenon isotopes and tritium, may have on the cosmogenic background.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The precision in reconstructing events detected in a dual-phase time projection chamber depends on an homogeneous and well understood electric field within the liquid target. In the XENONnT TPC the ...field homogeneity is achieved through a double-array field cage, consisting of two nested arrays of field shaping rings connected by an easily accessible resistor chain. Rather than being connected to the gate electrode, the topmost field shaping ring is independently biased, adding a degree of freedom to tune the electric field during operation. Two-dimensional finite element simulations were used to optimize the field cage, as well as its operation. Simulation results were compared to
83
m
Kr
calibration data. This comparison indicates an accumulation of charge on the panels of the TPC which is constant over time, as no evolution of the reconstructed position distribution of events is observed. The simulated electric field was then used to correct the charge signal for the field dependence of the charge yield. This correction resolves the inconsistent measurement of the drift electron lifetime when using different calibrations sources and different field cage tuning voltages.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
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 ×10 and ×0.5 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 ∼30 s 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 ∼500 MB/s during calibration.
Livetime during normal operation exceeds 99% and is ∼90% 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 present the first measurement of nuclear recoils from solar $^8$B
neutrinos via coherent elastic neutrino-nucleus scattering with the XENONnT
dark matter experiment. The central detector of ...XENONnT is a low-background,
two-phase time projection chamber with a 5.9\,t sensitive liquid xenon target.
A blind analysis with an exposure of 3.51\,t$\times$y resulted in 37 observed
events above 0.5\,keV, with ($26.4^{+1.4}_{-1.3}$) events expected from
backgrounds. The background-only hypothesis is rejected with a statistical
significance of 2.73\,$\sigma$. The measured $^8$B solar neutrino flux of
$(4.7_{-2.3}^{+3.6})\times 10^6\,\mathrm{cm}^{-2}\mathrm{s}^{-1}$ is consistent
with results from dedicated solar neutrino experiments. The measured neutrino
flux-weighted CE$\nu$NS cross-section on Xe of
$(1.1^{+0.8}_{-0.5})\times10^{-39}\,\mathrm{cm}^2$ is consistent with the
Standard Model prediction. This is the first direct measurement of nuclear
recoils from solar neutrinos with a dark matter detector.
The XENONnT experiment searches for weakly-interacting massive particle (WIMP) dark matter scattering off a xenon nucleus. In particular, XENONnT uses a dual-phase time projection chamber with a ...5.9-tonne liquid xenon target, detecting both scintillation and ionization signals to reconstruct the energy, position, and type of recoil. A blind search for nuclear recoil WIMPs with an exposure of 1.1 tonne-years yielded no signal excess over background expectations, from which competitive exclusion limits were derived on WIMP-nucleon elastic scatter cross sections, for WIMP masses ranging from 6 GeV/\(c^2\) up to the TeV/\(c^2\) scale. This work details the modeling and statistical methods employed in this search. By means of calibration data, we model the detector response, which is then used to derive background and signal models. The construction and validation of these models is discussed, alongside additional purely data-driven backgrounds. We also describe the statistical inference framework, including the definition of the likelihood function and the construction of confidence intervals.
