| 1. |
- Aprile, E., et al.
(författare)
-
Double-weak decays of 124Xe and 136Xe in the XENON1T and XENONnT experiments
- 2022
-
Ingår i: Physical Review C. - 2469-9985 .- 2469-9993. ; 106:2
-
Tidskriftsartikel (refereegranskat)abstract
- We present results on the search for two-neutrino double-electron capture (2νECEC) of 124Xe and neutrinoless double-β decay (0νββ) of 136Xe in XENON1T. We consider captures from the K shell up to the N shell in the 2νECEC signal model and measure a total half-life of T2νECEC1/2=(1.1±0.2stat±0.1sys)×1022yr with a 0.87 kg yr isotope exposure. The statistical significance of the signal is 7.0σ. We use XENON1T data with 36.16 kg yr of 136Xe exposure to search for 0νββ. We find no evidence of a signal and set a lower limit on the half-life of T0νββ1/2>1.2×1024 yr at 90%CL. This is the best result from a dark matter detector without an enriched target to date. We also report projections on the sensitivity of XENONnT to 0νββ. Assuming a 275 kg yr 136Xe exposure, the expected sensitivity is T0νββ1/2>2.1×1025 yr at 90%CL, corresponding to an effective Majorana mass range of ⟨mββ⟩<(0.19–0.59)eV/c2.
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| 2. |
- Aprile, E., et al.
(författare)
-
Search for New Physics in Electronic Recoil Data from XENONnT
- 2022
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 129:16
-
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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| 3. |
- Aprile, E., et al.
(författare)
-
Emission of single and few electrons in XENON1T and limits on light dark matter
- 2022
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 106:2
-
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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| 4. |
- Aprile, E., et al.
(författare)
-
Material radiopurity control in the XENONnT experiment
- 2022
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 82:7
-
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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| 5. |
- Aprile, E., et al.
(författare)
-
An approximate likelihood for nuclear recoil searches with XENON1T data
- 2022
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 82:11
-
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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| 6. |
- Aprile, E., et al.
(författare)
-
Application and modeling of an online distillation method to reduce krypton and argon in XENON1T
- 2022
-
Ingår i: Progress of Theoretical and Experimental Physics. - : Oxford University Press (OUP). - 2050-3911. ; 2022:5
-
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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| 7. |
- Aprile, E., et al.
(författare)
-
Effective Field Theory and Inelastic Dark Matter Results from XENON1T
-
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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| 8. |
- Aalbers, Jelle, et al.
(författare)
-
Solar neutrino detection sensitivity in DARWIN via electron scattering
- 2020
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:12
-
Tidskriftsartikel (refereegranskat)abstract
- We detail the sensitivity of the proposed liquid xenon 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, 7Be, 13N, 15O and pep. The precision of the 13N, 15O and pep components is hindered by the double-beta decay of 136Xe and, thus, would benefit from a depleted target. A high-statistics observation of pp neutrinos would allow us to infer the values of the electroweak mixing angle, sin2 theta w, and the electron-type neutrino survival probability, Pee, 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, with 10 live years of data and a 30 tonne fiducial volume. An observation of pp and 7Be 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 8B 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 131Xe.
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| 9. |
- Aprile, E., et al.
(författare)
-
Search for Coherent Elastic Scattering of Solar B-8 Neutrinos in the XENON1T Dark Matter Experiment
- 2021
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 126:9
-
Tidskriftsartikel (refereegranskat)abstract
- We report on a search for nuclear recoil signals from solar B-8 neutrinos elastically scattering off xenon nuclei in XENON1T data, lowering the energy threshold from 2.6 to 1.6 keV. We develop a variety of novel techniques to limit the resulting increase in backgrounds near the threshold. No significant B-8 neutrinolike excess is found in an exposure of 0.6 t x y. For the first time, we use the nondetection of solar neutrinos to constrain the light yield from 1-2 keV nuclear recoils in liquid xenon, as well as nonstandard neutrino-quark interactions. Finally, we improve upon world-leading constraints on dark matter-nucleus interactions for dark matter masses between 3 and 11 GeV c(-2) by as much as an order of magnitude.
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| 10. |
- Aprile, E., et al.
(författare)
-
Search for inelastic scattering of WIMP dark matter in XENON1T
- 2021
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 103:6
-
Tidskriftsartikel (refereegranskat)abstract
- We report the results of a search for the inelastic scattering of weakly interacting massive particles (WIMPs) in the XENON1T dark matter experiment. Scattering off Xe-129 is the most sensitive probe of inelastic WIMP interactions, with a signature of a 39.6 keV deexcitation photon detected simultaneously with the nuclear recoil. Using an exposure of 0.83 tonne-years, we find no evidence of inelastic WIMP scattering with a significance of more than 2 sigma. A profile-likelihood ratio analysis is used to set upper limits on the cross section of WIMP-nucleus interactions. We exclude new parameter space for WIMPs heavier than 100 GeV/c(2), with the strongest upper limit of 3.3 x 10(-39) cm(2) for 130 GeV/c(2) WIMPs at 90% confidence level.
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| 11. |
- Aprile, E., et al.
(författare)
-
Energy resolution and linearity of XENON1T in the MeV energy range
- 2020
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 80:8
-
Tidskriftsartikel (refereegranskat)abstract
- Xenon dual-phase time projection chambers designed to search for weakly interacting massive particles have so far shown a relative energy resolutionwhich degrades with energy above similar to 200 keV due to the saturation effects. This has limited their sensitivity in the search for rare events like the neutrinoless double-beta decay of Xe-136 at its Q value, Q(beta beta) similar or equal to 2.46 MeV. For the XENON1T dual-phase time projection chamber, we demonstrate that the relative energy resolution at 1 sigma/mu is as low as (0.80 +/- 0.02)% in its one-ton fiducial mass, and for single-site interactions at Q(beta beta). We also present a new signal correction method to rectify the saturation effects of the signal readout system, resulting in more accurate position reconstruction and indirectly improving the energy resolution. The very good result achieved in XENON1T opens up new windows for the xenon dual-phase dark matter detectors to simultaneously search for other rare events.
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| 12. |
- Aprile, E., et al.
(författare)
-
Excess electronic recoil events in XENON1T
- 2020
-
Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 102:7
-
Tidskriftsartikel (refereegranskat)abstract
- We report results from searches for new physics with low-energy electronic recoil data recorded with the XENONIT detector. With an exposure of 0.65 tonne-years and an unprecedentedly low background rate of 76 +/- 2(stat) events/(tonne x year x keV) between 1 and 30 keV, the data enable one of the most sensitive searches for solar axions, an enhanced neutrino magnetic moment using solar neutrinos, and bosonic dark matter. An excess over known backgrounds is observed at low energies and most prominent between 2 and 3 keV. The solar axion model has a 3.4 sigma significance, and a three-dimensional 90% confidence surface is reported for axion couplings to electrons, photons, and nucleons. This surface is inscribed in the cuboid defined by g(ae) < 3.8 x 10(-12), g(ae)g(an)(eff) < 4.8 x 10(-18), and g(ae)g(a gamma) < 7.7 x 10(-22) GeV-1, and excludes either g(ae) = 0 or g(ae)g(a gamma) = g(ae)ge(an)(eff), = 0. The neutrino magnetic moment signal is similarly favored over background at 3.2 sigma, and a confidence interval of mu(nu) is an element of (1.4, 2.9) x 10(-11) mu(B) (90% C.L.) is reported. Both results are in strong tension with stellar constraints. The excess can also be explained by beta decays of tritium at 3.2 sigma significance with a corresponding tritium concentration in xenon of (6.2 +/- 2.0) x 10(-25) mol/mol. Such a trace amount can neither be confirmed nor excluded with current knowledge of its production and reduction mechanisms. The significances of the solar axion and neutrino magnetic moment hypotheses arc decreased to 2.0 sigma and 0.9 sigma, respectively, if an unconstrained tritium component is included in the fitting. With respect to bosonic dark matter, the excess favors a monoenergetic peak at (2.3 +/- 0.2) keV (68% C.L.) with a 3.0 sigma global (4.0 sigma local) significance over background. This analysis sets the most restrictive direct constraints to date on pseudoscalar and vector bosonic dark matter for most masses between 1 and 210 keV/c(2). We also consider the possibility that Ar-37 may be present in the detector, yielding a 2.82 keV peak from electron capture. Contrary to tritium, the Ar-37 concentration can be tightly constrained and is found to be negligible.
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| 13. |
- Aprile, E., et al.
(författare)
-
Light Dark Matter Search with Ionization Signals in XENON1T
- 2019
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 123:25
-
Tidskriftsartikel (refereegranskat)abstract
- We report constraints on light dark matter (DM) models using ionization signals in the XENON1T experiment. We mitigate backgrounds with strong event selections, rather than requiring a scintillation signal, leaving an effective exposure of (22 +/- 3) tonne day. Above similar to 0.4 keV(ee), we observe <1 event/(tonne day keV(ee)), which is more than 1000 times lower than in similar searches with other detectors. Despite observing a higher rate at lower energies, no DM or CEvNS detection may be claimed because we cannot model all of our backgrounds. We thus exclude new regions in the parameter spaces for DM-nucleus scattering for DM masses m(chi) within 3-6 GeV/c(2), DM-electron scattering for m(chi) > 30 MeV/c(2), and absorption of dark photons and axionlike particles for m(chi) within 0.186-1 keV/c(2).
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| 14. |
- Aprile, E., et al.
(författare)
-
Projected WIMP sensitivity of the XENONnT dark matter experiment
- 2020
-
Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :11
-
Tidskriftsartikel (refereegranskat)abstract
- XENONnT is a dark matter direct detection experiment, utilizing 5.9 t of instrumented liquid xenon, located at the INFN Laboratori Nazionali del Gran Sasso. In this work, we predict the experimental background and project the sensitivity of XENONnT to the detection of weakly interacting massive particles (WIMPs). The expected average differential background rate in the energy region of interest, corresponding to (1, 13) keV and (4, 50) keV for electronic and nuclear recoils, amounts to 12.3 +/- 0.6 (keV t y)(-1) and (2.2 +/- 0.5) x 10(-3 )(keV t y)(-1), respectively, in a 4t fiducial mass. We compute unified confidence intervals using the profile construction method, in order to ensure proper coverage. With the exposure goal of 20 t y, the expected sensitivity to spin-independent WIMP-nucleon interactions reaches a cross-section of 1.4 x 10(-48) cm(2) for a 50 GeV/c(2) mass WIMP at 90% confidence level, more than one order of magnitude beyond the current best limit, set by XENON1T. In addition, we show that for a 50 GeV/c(2) WIMP with cross-sections above 2.6 x 10(-48) cm(2) (5.0 x 10(-48) cm(2)) the median XENONnT discovery significance exceeds 3 sigma (5 sigma). The expected sensitivity to the spin-dependent WIMP coupling to neutrons (protons) reaches 2.2 x 10(-43) cm(2) (6.0 x 10(-42) cm(2)).
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| 15. |
- Aprile, E., et al.
(författare)
-
Search for Light Dark Matter Interactions Enhanced by the Migdal Effect or Bremsstrahlung in XENON1T
- 2019
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 123:24
-
Tidskriftsartikel (refereegranskat)abstract
- Direct dark matter detection experiments based on a liquid xenon target are leading the search for dark matter particles with masses above similar to 5 GeV/c(2), but have limited sensitivity to lighter masses because of the small momentum transfer in dark matter-nucleus elastic scattering. However, there is an irreducible contribution from inelastic processes accompanying the elastic scattering, which leads to the excitation and ionization of the recoiling atom (the Migdal effect) or the emission of a bremsstrahlung photon. In this Letter, we report on a probe of low-mass dark matter with masses down to about 85 MeV/c(2) by looking for electronic recoils induced by the Migdal effect and bremsstrahlung using data from the XENON1T experiment. Besides the approach of detecting both scintillation and ionization signals, we exploit an approach that uses ionization signals only, which allows for a lower detection threshold. This analysis significantly enhances the sensitivity of XENON1T to light dark matter previously beyond its reach.
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| 16. |
- Kulmala, M., et al.
(författare)
-
General overview: European Integrated project on Aerosol Cloud Climate and Air Quality interactions (EUCAARI) - integrating aerosol research from nano to global scales
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:24, s. 13061-13143
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we describe and summarize the main achievements of the European Aerosol Cloud Climate and Air Quality Interactions project (EUCAARI). EUCAARI started on 1 January 2007 and ended on 31 December 2010 leaving a rich legacy including: (a) a comprehensive database with a year of observations of the physical, chemical and optical properties of aerosol particles over Europe, (b) comprehensive aerosol measurements in four developing countries, (c) a database of airborne measurements of aerosols and clouds over Europe during May 2008, (d) comprehensive modeling tools to study aerosol processes fron nano to global scale and their effects on climate and air quality. In addition a new Pan-European aerosol emissions inventory was developed and evaluated, a new cluster spectrometer was built and tested in the field and several new aerosol parameterizations and computations modules for chemical transport and global climate models were developed and evaluated. These achievements and related studies have substantially improved our understanding and reduced the uncertainties of aerosol radiative forcing and air quality-climate interactions. The EUCAARI results can be utilized in European and global environmental policy to assess the aerosol impacts and the corresponding abatement strategies.
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| 17. |
- Aprile, E., et al.
(författare)
-
First Results on the Scalar WIMP-Pion Coupling, Using the XENON1T Experiment
- 2019
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 122:7
-
Tidskriftsartikel (refereegranskat)abstract
- We present first results on the scalar coupling of weakly interacting massive particles (WIMPs) to pions from 1 t yr of exposure with the XENON1T experiment. This interaction is generated when the WIMP couples to a virtual pion exchanged between the nucleons in a nucleus. In contrast to most nonrelativistic operators, these pion-exchange currents can be coherently enhanced by the total number of nucleons and therefore may dominate in scenarios where spin-independent WIMP-nucleon interactions are suppressed. Moreover, for natural values of the couplings, they dominate over the spin-dependent channel due to their coherence in the nucleus. Using the signal model of this new WIMP-pion channel, no significant excess is found, leading to an upper limit cross section of 6.4 x 10(-46) cm(2) (90% confidence level) at 30 GeV/c(2) WIMP mass.
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| 18. |
- Aprile, E., et al.
(författare)
-
Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T
- 2019
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 122:14
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first experimental results on spin-dependent elastic weakly interacting massive particle (WIMP) nucleon scattering from the XENON1T dark matter search experiment. The analysis uses the full ton year exposure of XENON1T to constrain the spin-dependent proton-only and neutron-only cases. No significant signal excess is observed, and a profile likelihood ratio analysis is used to set exclusion limits on the WIMP-nucleon interactions. This includes the most stringent constraint to date on the WIMP-neutron cross section, with a minimum of 6.3 x 10(-42) cm(2) at 30 GeV/c(2) and 90% confidence level. The results are compared with those from collider searches and used to exclude new parameter space in an isoscalar theory with an axial-vector mediator.
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| 19. |
- Aprile, E., et al.
(författare)
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Dark Matter Search Results from a One Ton-Year Exposure of XENON1T
- 2018
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 121:11
-
Tidskriftsartikel (refereegranskat)abstract
- We report on a search for weakly interacting massive particles (WIMPs) using 278.8 days of data collected with the XENON1T experiment at LNGS. XENON1T utilizes a liquid xenon time projection chamber with a fiducial mass of (1.30 +/- 0.01) ton, resulting in a 1.0 ton yr exposure. The energy region of interest, [1.4; 10.6] keV(ee) ([4.9; 40.9] keV(nr)), exhibits an ultralow electron recoil background rate of [82(-3)(+5) (syst) +/- 3 stat)] events/ton yr keV(ee)). No significant excess over background is found, and a profile likelihood analysis parametrized in spatial and energy dimensions excludes new parameter space for the WIMP-nucleon spin-independent elastic scatter cross section for WIMP masses above 6 GeV/c(2), with a minimum of 4.1 x 10(-47) cm(2) at 30 GeV/c(2) and a 90% confidence level.
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| 20. |
- Aprile, E., et al.
(författare)
-
First Dark Matter Search Results from the XENON1T Experiment
- 2017
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 119:18
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first dark matter search results from XENON1T, a similar to 2000-kg-target-mass dual-phase (liquid-gas) xenon time projection chamber in operation at the Laboratori Nazionali del Gran Sasso in Italy and the first ton-scale detector of this kind. The blinded search used 34.2 live days of data acquired between November 2016 and January 2017. Inside the (1042 +/- 12)-kg fiducial mass and in the [5, 40] keV(nr) energy range of interest for weakly interacting massive particle (WIMP) dark matter searches, the electronic recoil background was (1.93 +/- 0.25) x 10(-4) events/(kg x day x keV(ee)), the lowest ever achieved in such a dark matter detector. A profile likelihood analysis shows that the data are consistent with the background-only hypothesis. We derive the most stringent exclusion limits on the spin-independent WIMP-nucleon interaction cross section for WIMP masses above 10 GeV/c(2), with a minimum of 7.7 x 10(-47) cm(2) for 35-GeV/c(2) WIMPs at 90% C.L.
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| 21. |
- Aprile, E., et al.
(författare)
-
Observation of two-neutrino double electron capture in 124Xe with XENON1T
- 2019
-
Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 568:7753, s. 532-535
-
Tidskriftsartikel (refereegranskat)abstract
- Two-neutrino double electron capture (2νECEC) is a second-order weak-interaction process with a predicted half-life that surpasses the age of the Universe by many orders of magnitude. Until now, indications of 2νECEC decays have only been seen for two isotopes, 78Kr and 130Ba, and instruments with very low background levels are needed to detect them directly with high statistical significance. The 2νECEC half-life is an important observable for nuclear structure models and its measurement represents a meaningful step in the search for neutrinoless double electron capture—the detection of which would establish the Majorana nature of the neutrino and would give access to the absolute neutrino mass. Here we report the direct observation of 2νECEC in 124Xe with the XENON1T dark-matter detector. The significance of the signal is 4.4 standard deviations and the corresponding half-life of 1.8 × 1022 years (statistical uncertainty, 0.5 × 1022 years; systematic uncertainty, 0.1 × 1022 years) is the longest measured directly so far. This study demonstrates that the low background and large target mass of xenon-based dark-matter detectors make them well suited for measuring rare processes and highlights the broad physics reach of larger next-generation experiments.
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| 22. |
- Aprile, E., et al.
(författare)
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Search for bosonic super-WIMP interactions with the XENON100 experiment
- 2017
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:12
-
Tidskriftsartikel (refereegranskat)abstract
- We present results of searches for vector and pseudoscalar bosonic super-weakly interacting massive particles (WIMPs), which are dark matter candidates with masses at the keV-scale, with the XENON100 experiment. XENON100 is a dual-phase xenon time projection chamber operated at the Laboratori Nazionali del Gran Sasso. A profile likelihood analysis of data with an exposure of 224.6 live days x34 kg showed no evidence for a signal above the expected background. We thus obtain new and stringent upper limits in the (8-125) keV/c(2) mass range, excluding couplings to electrons with coupling constants of g(ae) > 3 x 10(-13) for pseudo-scalar and alpha'/alpha > 2 x 10(-28) for vector super-WIMPs, respectively. These limits are derived under the assumption that super-WIMPs constitute all of the dark matter in our galaxy.
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| 23. |
- Aprile, E., et al.
(författare)
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Signal yields of keV electronic recoils and their discrimination from nuclear recoils in liquid xenon
- 2018
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 97:9
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the response of liquid xenon to low energy electronic recoils below 15 keV from beta decays of tritium at drift fields of 92 V/cm, 154 V/cm and 366 V/cm using the XENON100 detector. A data-to-simulation fitting method based on Markov Chain Monte Carlo is used to extract the photon yields and recombination fluctuations from the experimental data. The photon yields measured at the two lower fields are in agreement with those from literature; additional measurements at a higher field of 366 V/cm are presented. The electronic and nuclear recoil discrimination as well as its dependence on the drift field and photon detection efficiency are investigated at these low energies. The results provide new measurements in the energy region of interest for dark matter searches using liquid xenon.
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| 24. |
- Aprile, E., et al.
(författare)
-
The XENON1T dark matter experiment
- 2017
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Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:12
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Tidskriftsartikel (refereegranskat)abstract
- The XENON1T experiment at the Laboratori Nazionali del Gran Sasso (LNGS) is the first WIMP dark matter detector operating with a liquid xenon target mass above the ton-scale. Out of its 3.2t liquid xenon inventory, 2.0t constitute the active target of the dual-phase time projection chamber. The scintillation and ionization signals from particle interactions are detected with low-background photomultipliers. This article describes the XENON1T instrument and its subsystems as well as strategies to achieve an unprecedented low background level. First results on the detector response and the performance of the subsystems are also presented.
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| 25. |
- Aprile, E., et al.
(författare)
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The XENON1T data acquisition system
- 2019
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- The XENON1T liquid xenon time projection chamber is the most sensitive detector built to date for the measurement of direct interactions of weakly interacting massive particles with normal matter. The data acquisition system (DAQ) is constructed from commercial, open source, and custom components to digitize signals from the detector and store them for later analysis. The system achieves an extremely low signal threshold by triggering each channel independently, achieving a single photoelectron acceptance of (93 +/- 3)%, and deferring the global trigger to a later, software stage. The event identification is based on MongoDB database queries and has over 98% efficiency at recognizing interactions at the analysis threshold in the center of the target. A readout bandwidth over 300 MB/s is reached in calibration modes and is further expandable via parallelization. This DAQ system was successfully used during three years of operation of XENON1T.
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