1. |
- Aalbers, J., et al.
(författare)
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A next-generation liquid xenon observatory for dark matter and neutrino physics
- 2023
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 50:1
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Forskningsöversikt (refereegranskat)abstract
- The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.
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2. |
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3. |
- Aalbers, Jelle, et al.
(författare)
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Finding dark matter faster with explicit profile likelihoods
- 2020
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 102:7
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Tidskriftsartikel (refereegranskat)abstract
- Liquid xenon time-projection chambers are the world's most sensitive detectors for a wide range of dark matter candidates. We show that the statistical analysis of their data can be improved by replacing detector response Monte Carlo simulations with an equivalent deterministic calculation. This allows the use of high-dimensional undiscretized models, yielding up to similar to 2 times better discrimination of the dominant backgrounds. In turn, this could significantly extend the physics reach of upcoming experiments such as XENONnT and LZ, and bring forward a potential 5 sigma dark matter discovery by over a year.
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4. |
- Aalbers, Jelle, et al.
(författare)
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The triggerless data acquisition system of the XENONnT experiment
- 2023
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 18:7
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Tidskriftsartikel (refereegranskat)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.
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5. |
- Althueser, L., et al.
(författare)
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GPU-based optical simulation of the DARWIN detector
- 2022
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 17:7
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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6. |
- Antochi, Vasile C., 1992-, et al.
(författare)
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Design and performance of the field cage for the XENONnT experiment
- 2024
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Ingår i: European Physical Journal C. - 1434-6044 .- 1434-6052. ; 84:2
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Tidskriftsartikel (refereegranskat)abstract
- 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 83mKr 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.
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7. |
- Antochi, Vasile C., 1992-, et al.
(författare)
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Low-energy calibration of XENON1T with an internal 37Ar source
- 2023
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Ingår i: European Physical Journal C. - 1434-6044 .- 1434-6052. ; 83:6
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Tidskriftsartikel (refereegranskat)abstract
- A low-energy electronic recoil calibration of XENON1T, a dual-phase xenon time projection chamber, with an internal 37Ar source was performed. This calibration source features a 35-day half-life and provides two mono-energetic lines at 2.82 keV and 0.27 keV. The photon yield and electron yield at 2.82 keV are measured to be (32.3±0.3) photons/keV and (40.6±0.5) electrons/keV, respectively, in agreement with other measurements and with NEST predictions. The electron yield at 0.27 keV is also measured and it is (68.0+6.3−3.7) electrons/keV. The 37Ar calibration confirms that the detector is well-understood in the energy region close to the detection threshold, with the 2.82 keV line reconstructed at (2.83±0.02) keV, which further validates the model used to interpret the low-energy electronic recoil excess previously reported by XENON1T. The ability to efficiently remove argon with cryogenic distillation after the calibration proves that 37Ar can be considered as a regular calibration source for multi-tonne xenon detectors.
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8. |
- Aprile, E., et al.
(författare)
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An approximate likelihood for nuclear recoil searches with XENON1T data
- 2022
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 82:11
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Tidskriftsartikel (refereegranskat)abstract
- The XENON collaboration has published stringent limits on specific dark matter – nucleon recoil spectra from dark matter recoiling on the liquid xenon detector target. In this paper, we present an approximate likelihood for the XENON1T 1 t-year nuclear recoil search applicable to any nuclear recoil spectrum. Alongside this paper, we publish data and code to compute upper limits using the method we present. The approximate likelihood is constructed in bins of reconstructed energy, profiled along the signal expectation in each bin. This approach can be used to compute an approximate likelihood and therefore most statistical results for any nuclear recoil spectrum. Computing approximate results with this method is approximately three orders of magnitude faster than the likelihood used in the original publications of XENON1T, where limits were set for specific families of recoil spectra. Using this same method, we include toy Monte Carlo simulation-derived binwise likelihoods for the upcoming XENONnT experiment that can similarly be used to assess the sensitivity to arbitrary nuclear recoil signatures in its eventual 20 t-year exposure.
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9. |
- Aprile, E., et al.
(författare)
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Application and modeling of an online distillation method to reduce krypton and argon in XENON1T
- 2022
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Ingår i: Progress of Theoretical and Experimental Physics. - : Oxford University Press (OUP). - 2050-3911. ; 2022:5
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Tidskriftsartikel (refereegranskat)abstract
- A novel online distillation technique was developed for the XENON1T dark matter experiment to reduce intrinsic background components more volatile than xenon, such as krypton or argon, while the detector was operating. The method is based on a continuous purification of the gaseous volume of the detector system using the XENON1T cryogenic distillation column. A krypton-in-xenon concentration of (360 +/- 60) ppq was achieved. It is the lowest concentration measured in the fiducial volume of an operating dark matter detector to date. A model was developed and fitted to the data to describe the krypton evolution in the liquid and gas volumes of the detector system for several operation modes over the time span of 550 days, including the commissioning and science runs of XENON1T. The online distillation was also successfully applied to remove Ar-37 after its injection for a low-energy calibration in XENON1T. This makes the usage of Ar-37 as a regular calibration source possible in the future. The online distillation can be applied to next-generation liquid xenon time projection chamber experiments to remove krypton prior to, or during, any science run. The model developed here allows further optimization of the distillation strategy for future large-scale detectors.
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10. |
- Aprile, E., et al.
(författare)
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Detector signal characterization with a Bayesian network in XENONnT
- 2023
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 108:1
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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11. |
- Aprile, E., et al.
(författare)
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Effective Field Theory and Inelastic Dark Matter Results from XENON1T
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In this work we expand on the XENON1T nuclear recoil searches and study the individual signals of Dark Matter interactions from operators up to dimension-eight in a Chiral Effective Field Theory (ChEFT) as well as a model of inelastic Dark Matter using data from the two science runs of the detector totalling 1 tonne*year exposure. For these analyses we extended the region of interest from [4.9, 40.9]keVnr to [4.9, 54.4]keVnr to enhance our sensitivity for signals that peak at nonzero energies. We show that the data is consistent with a background only hypothesis, with small excesses in the models which peak between 20 and 50keVnr, obtaining a maximum local discovery significance of 1.7 for the VVs ChEFT model for a WIMP mass of 70GeV/c2, and 1.8 for an iDM particle of 50GeV/c2 with a mass splitting of 100keV/c2. For each model we report 90% confidence level upper limits. We also report limits on three benchmark models of WIMP interaction using ChEFT for which we investigate the effect of isospin breaking interactions, reporting up to 6 orders of magnitude weaker limits with respect to the isospin conserving case driven by cancellations in the expected rate.
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12. |
- Aprile, E., et al.
(författare)
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Emission of single and few electrons in XENON1T and limits on light dark matter
- 2022
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 106:2
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Tidskriftsartikel (refereegranskat)abstract
- Delayed single- and few-electron emissions plague dual-phase time projection chambers, limiting their potential to search for light-mass dark matter. This paper examines the origins of these events in the XENON1T experiment. Characterization of the intensity of delayed electron backgrounds shows that the resulting emissions are correlated, in time and position, with high-energy events and can effectively be vetoed. In this work we extend previous S2-only analyses down to a single electron. From this analysis, after removing the correlated backgrounds, we observe rates <30 events/(electron×kg×day) in the region of interest spanning 1 to 5 electrons. We derive 90% confidence upper limits for dark matter-electron scattering, first direct limits on the electric dipole, magnetic dipole, and anapole interactions, and bosonic dark matter models, where we exclude new parameter space for dark photons and solar dark photons.
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13. |
- Aprile, E., et al.
(författare)
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First Dark Matter Search with Nuclear Recoils from the XENONnT Experiment
- 2023
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 131:4
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Tidskriftsartikel (refereegranskat)abstract
- 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 85Kr and 222Rn 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 cm2 for a WIMP mass of 28 GeV/c2 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.
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14. |
- Aprile, E., et al.
(författare)
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Material radiopurity control in the XENONnT experiment
- 2022
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 82:7
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Tidskriftsartikel (refereegranskat)abstract
- The selection of low-radioactive construction materials is of the utmost importance for rare-event searches and thus critical to the XENONnT experiment. Results of an extensive radioassay program are reported, in which material samples have been screened with gamma-ray spectroscopy, mass spectrometry, and 222Rn emanation measurements. Furthermore, the cleanliness procedures applied to remove or mitigate surface contamination of detector materials are described. Screening results, used as inputs for a XENONnT Monte Carlo simulation, predict a reduction of materials background (∼∼17%) with respect to its predecessor XENON1T. Through radon emanation measurements, the expected 222Rn activity concentration in XENONnT is determined to be 4.2 (+0.5−0.7) μBq/kg, a factor three lower with respect to XENON1T. This radon concentration will be further suppressed by means of the novel radon distillation system.
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15. |
- Aprile, E., et al.
(författare)
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Search for events in XENON1T associated with gravitational waves
- 2023
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 108:7
-
Tidskriftsartikel (refereegranskat)abstract
- 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 cm2/cm2 in the [5.5–210] keV energy range at the 90% confidence level.
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16. |
- Aprile, E., et al.
(författare)
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Search for New Physics in Electronic Recoil Data from XENONnT
- 2022
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 129:16
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Tidskriftsartikel (refereegranskat)abstract
- 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 ton liquid xenon target reduced the background in the (1, 30) keV search region to (15.8±1.3) events/(ton×year×keV), the lowest ever achieved in a dark matter detector and ∼5 times lower than in XENON1T. With an exposure of 1.16 ton-years, we observe no excess above background and set stringent new limits on solar axions, an enhanced neutrino magnetic moment, and bosonic dark matter.
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17. |
- Aprile, E., et al.
(författare)
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Searching for Heavy Dark Matter near the Planck Mass with XENON1T
- 2023
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 130:26
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Tidskriftsartikel (refereegranskat)abstract
- 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 x 1012 and 2 x 1017 GeV/c2. 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.
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18. |
- Conrad, Jan, 1973-, et al.
(författare)
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Cosmogenic background simulations for neutrinoless double beta decay with the DARWIN observatory at various underground sites
- 2024
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Ingår i: European Physical Journal C. - 1434-6044 .- 1434-6052. ; 84:1
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Tidskriftsartikel (refereegranskat)abstract
- Xenon dual-phase time projections chambers (TPCs) have proven to be a successful technology in studying physical phenomena that require low-background conditions. With 40t 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 (0νββ), 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 137Xe, the most crucial isotope in the search for 0νββ of 136Xe. 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.
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19. |
- Tan, Pueh Leng, 1990-
(författare)
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Solar Reflected Dark Matter with XENON1T and XENONnT : Searching for sub-GeV Dark Matter using liquid xenon Time Projection Chambers
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The XENONnT experiment is a low-background dual phase liquid xenon Time Projection Chamber (TPC) with 5.9 tonnes of instrumented liquid xenon. Improved liquid xenon purification and radon distillation system along with various background mitigation strategies brought the Electronic Recoil (ER) backgrounds down to an unprecedented low of (15.8 ± 1.3) events/(keV tonne years) below recoil energies of 30 keV.Exploring three different ER datasets spanning 10 to 140 keV collected using the XENON1T and XENONnT detector, a search for a signal of sub-GeV Dark Matter boosted by reflection off the sun is conducted. No excess is observed, and novel stringent upper limits on the Dark Matter-electron scattering cross section in the Dark Matter mass range between 5 keV and 9 MeV are reported.
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20. |
- Tan, Pueh-Leng, 1990-
(författare)
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Towards application of explicit likelihoods in inference for Dark Matter Direct Detection
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Despite the many empirical hints for the existence of Dark Matter in the Universe, Dark Matter has yet to be observed experimentally, be it directly through its scatterings in detectors, indirectly through its annihilation in the galaxy, or implicitly through its production and decay in particle colliders. Even though observations from astrophysics and cosmology placed constraints on the Dark Matter energy density and self-interaction cross section and with Standard Model particles, much about the nature of Dark Matter is still unknown, leaving much to the creativity of model builders. Amongst the plethora of Dark Matter candidates, the Weakly Interactive Massive Particle (WIMP) is especially attractive as its coupling automatically emerges at the weak scale from purely cosmological arguments. Out of the various ways of searching for the WIMP, direct detection experiments have been very successful in probing the WIMP parameter space. These low background experiments employ different detector technologies to search for WIMPs in different mass ranges, with the search of WIMPs in the GeV-TeV mass range dominated by noble gas Time Projection Chambers (TPCs). Due to the large atomic mass of xenon and the lack of abundant radioactive xenon isotope, liquid xenon TPCs currently set the strongest limits in the spin-independent WIMP-nucleon cross section and WIMP mass phase space. The detector response of liquid xenon TPCs is defined using histograms in the observable space constructed from Monte Carlo events generated from the detector response model. Separate histograms, also known as 'templates', are constructed using events generated at different discrete points in the model parameter space. During statistical inference of the data, the detector response is interpolated between the templates and this technique is known as 'template morphing'. However, it presents several challenges in terms of computation costs and modelling inflexibility, especially when confronted with high-dimensional observable space and correlated model parameters. In this licentiate, we present an exploration of the usage of the likelihood methods as an alternative to template morphing in fitting and performing statistical inference on liquid xenon TPC data using the likelihood analysis framework provided by the Python software package Flamedisx. We tested this new framework by fitting Monte Carlo (MC) events generated from a model for electronic recoil (ER) events that was employed in the analysis of XENON1T data. We found that the estimators for some of the model parameters were biased but within the uncertainties that one would obtain from fitting actual events. We developed figures of merits to assess the goodness of fits and found that although the estimators for some of the model parameters were biased, the fits from fitting the ER MC events were good and consistent, with p-values > 0.29 in various observable spaces such as energy, interaction depth, and scintillation against ionization signal space. We also found some mismodelling in the corrected scintillation against ionization signal space, and future work should include investigating if the reduction of the number of nuisance parameters improves the fit in the corrected signal space.
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