1. |
- Aprile, E., et al.
(author)
-
The XENON1T dark matter experiment
- 2017
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:12
-
Journal article (peer-reviewed)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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2. |
- Kattge, Jens, et al.
(author)
-
TRY plant trait database - enhanced coverage and open access
- 2020
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In: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
-
Journal article (peer-reviewed)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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3. |
- Aprile, E., et al.
(author)
-
First Dark Matter Search Results from the XENON1T Experiment
- 2017
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 119:18
-
Journal article (peer-reviewed)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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4. |
- Aprile, E., et al.
(author)
-
Light Dark Matter Search with Ionization Signals in XENON1T
- 2019
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 123:25
-
Journal article (peer-reviewed)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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5. |
- Aprile, E., et al.
(author)
-
Low-mass dark matter search using ionization signals in XENON100
- 2016
-
In: Physical Review D. - 2470-0010. ; 94:9
-
Journal article (peer-reviewed)abstract
- We perform a low-mass dark matter search using an exposure of 30 kg x yr with the XENON100 detector. By dropping the requirement of a scintillation signal and using only the ionization signal to determine the interaction energy, we lowered the energy threshold for detection to 0.7 keV for nuclear recoils. No dark matter detection can be claimed because a complete background model cannot be constructed without a primary scintillation signal. Instead, we compute an upper limit on the WIMP-nucleon scattering cross section under the assumption that every event passing our selection criteria could be a signal event. Using an energy interval from 0.7 keV to 9.1 keV, we derive a limit on the spin-independent WIMP-nucleon cross section that excludes WIMPs with a mass of 6 GeV/c(2) above 1.4 x 10(-41) cm(2) at 90% confidence level.
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6. |
- Aprile, E., et al.
(author)
-
Material radioassay and selection for the XENON1T dark matter experiment
- 2017
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:12
-
Journal article (peer-reviewed)abstract
- The XENON1T dark matter experiment aims to detect weakly interactingmassive particles (WIMPs) through low-energy interactions with xenon atoms. To detect such a rare event necessitates the use of radiopure materials to minimize the number of background events within the expected WIMP signal region. In this paper we report the results of an extensive material radioassay campaign for the XENON1T experiment. Using gamma-ray spectroscopy and mass spectrometry techniques, systematic measurements of trace radioactive impurities in over one hundred samples within a wide range of materials were performed. The measured activities allowed for stringent selection and placement of materials during the detector construction phase and provided the input for XENON1T detection sensitivity estimates through Monte Carlo simulations.
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7. |
- Aprile, E., et al.
(author)
-
Observation of two-neutrino double electron capture in 124Xe with XENON1T
- 2019
-
In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 568:7753, s. 532-535
-
Journal article (peer-reviewed)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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8. |
- Aprile, E., et al.
(author)
-
Online Rn-222 removal by cryogenic distillation in the XENON100 experiment
- 2017
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:6
-
Journal article (peer-reviewed)abstract
- We describe the purification of xenon from traces of the radioactive noble gas radon using a cryogenic distillation column. The distillation column was integrated into the gas purification loop of the XENON100 detector for online radon removal. This enabled us to significantly reduce the constant Rn-222 background originating from radon emanation. After inserting an auxiliary 222Rn emanation source in the gas loop, we determined a radon reduction factor of R > 27 (95% C.L.) for the distillation column by monitoring the Rn-222 activity concentration inside the XENON100 detector.
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9. |
- Aprile, E., et al.
(author)
-
Physics reach of the XENON1T dark matter experiment
- 2016
-
In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :4
-
Journal article (peer-reviewed)abstract
- The XENON1T experiment is currently in the commissioning phase at the Laboratori Nazionali del Gran Sasso, Italy. In this article we study the experiment's expected sensitivity to the spin-independent WIMP-nucleon interaction cross section, based on Monte Carlo predictions of the electronic and nuclear recoil backgrounds. The total electronic recoil background in 1 tonne fiducial volume and (1, 12) keV electronic recoil equivalent energy region, before applying any selection to discriminate between electronic and nuclear recoils, is (1.80+/-0.15) . 10(-4) (kg.day.keV)(-1), mainly due to the decay of Rn-222 daughters inside the xenon target. The nuclear recoil background in the corresponding nuclear recoil equivalent energy region (4, 50) keV, is composed of (0.6 +/- 0.1) (t.y)(-1) from radiogenic neutrons, (1.8+/-0.3) . 10(-2) (t.y)(-1) from coherent scattering of neutrinos, and less than 0.01 (t.y)(-1) from muon-induced neutrons. The sensitivity of XENON1T is calculated with the Pro file Likelihood Ratio method, after converting the deposited energy of electronic and nuclear recoils into the scintillation and ionization signals seen in the detector. We take into account the systematic uncertainties on the photon and electron emission model, and on the estimation of the backgrounds, treated as nuisance parameters. The main contribution comes from the relative scintillation efficiency L-eff, which affects both the signal from WIMPs and the nuclear recoil backgrounds. After a 2 y measurement in 1 tonne fiducial volume, the sensitivity reaches a minimum cross section of 1.6 . 10(-47) cm(2) at m(chi) = 50 GeV/c(2).
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10. |
- Aprile, E., et al.
(author)
-
Removing krypton from xenon by cryogenic distillation to the ppq level
- 2017
-
In: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 77:5
-
Journal article (peer-reviewed)abstract
- The XENON1T experiment aims for the direct detection of dark matter in a detector filled with 3.3 tons of liquid xenon. In order to achieve the desired sensitivity, the background induced by radioactive decays inside the detector has to be sufficiently low. One major contributor is the beta-emitter Kr-85 which is present in the xenon. For XENON1T a concentration of natural krypton in xenon Kr-nat/Xe < 200 ppq (parts per quadrillion, 1 ppq = 10(-15) mol/mol) is required. In this work, the design, construction and test of a novel cryogenic distillation column using the common McCabe-Thiele approach is described. The system demonstrated a krypton reduction factor of 6.4 . 10(5) with thermodynamic stability at process speeds above 3 kg/h. The resulting concentration of natKr/Xe < 26 ppq is the lowest ever achieved, almost one order of magnitude below the requirements for XENON1T and even sufficient for future dark matter experiments using liquid xenon, such as XENONnT and DARWIN.
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11. |
- Aprile, E., et al.
(author)
-
Results from a calibration of XENON100 using a source of dissolved radon-220
- 2017
-
In: Physical Review D. - 2470-0010 .- 2470-0029. ; 95:7
-
Journal article (peer-reviewed)abstract
- A Rn-220 source is deployed on the XENON100 dark matter detector in order to address the challenges in calibration of tonne-scale liquid noble element detectors. We show that the Pb-212 beta emission can be used for low-energy electronic recoil calibration in searches for dark matter. The isotope spreads throughout the entire active region of the detector, and its activity naturally decays below background level within a week after the source is closed. We find no increase in the activity of the troublesome Rn-222 background after calibration. Alpha emitters are also distributed throughout the detector and facilitate calibration of its response to Rn-222. Using the delayed coincidence of Rn-220-Po-216, we map for the first time the convective motion of particles in the XENON100 detector. Additionally, we make a competitive measurement of the half-life of Po-212, t(1/2) = (293.9 +/- (1.0)(stat) +/- (0.6)(sys)) ns.
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12. |
- Aprile, E., et al.
(author)
-
Search for Light Dark Matter Interactions Enhanced by the Migdal Effect or Bremsstrahlung in XENON1T
- 2019
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 123:24
-
Journal article (peer-reviewed)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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13. |
- Aprile, E., et al.
(author)
-
Search for two-neutrino double electron capture of Xe-124 with XENON100
- 2017
-
In: Physical Review C. - 2469-9985. ; 95:2
-
Journal article (peer-reviewed)abstract
- Two-neutrino double electron capture is a rare nuclear decay where two electrons are simultaneously captured from the atomic shell. For Xe-124 this process has not yet been observed and its detection would provide a new reference for nuclear matrix element calculations. We have conducted a search for two-neutrino double electron capture from the K shell of 124Xe using 7636 kg d of data from the XENON100 dark matter detector. Using a Bayesian analysis we observed no significant excess above background, leading to a lower 90% credibility limit on the half-life T-1/2 > 6.5 x 10(20) yr. We have also evaluated the sensitivity of the XENON1T experiment, which is currently being commissioned, and found a sensitivity of T-1/2 > 6.1 x 10(22) yr after an exposure of 2 t yr.
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14. |
- Aprile, E., et al.
(author)
-
Signal yields of keV electronic recoils and their discrimination from nuclear recoils in liquid xenon
- 2018
-
In: Physical Review D. - 2470-0010 .- 2470-0029. ; 97:9
-
Journal article (peer-reviewed)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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15. |
- Aprile, E., et al.
(author)
-
The XENON1T data acquisition system
- 2019
-
In: Journal of Instrumentation. - 1748-0221. ; 14
-
Journal article (peer-reviewed)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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16. |
- Aprile, E., et al.
(author)
-
XENON100 dark matter results from a combination of 477 live days
- 2016
-
In: Physical Review D. - 2470-0010 .- 2470-0029. ; 94:12
-
Journal article (peer-reviewed)abstract
- We report on WIMP search results of the XENON100 experiment, combining three runs summing up to 477 live days from January 2010 to January 2014. Data from the first two runs were already published. A blind analysis was applied to the last run recorded between April 2013 and January 2014 prior to combining the results. The ultralow electromagnetic background of the experiment, similar to 5 x 10(-3) events/(keV(ee) x kg x day)) before electronic recoil rejection, together with the increased exposure of 48 kg x yr, improves the sensitivity. A profile likelihood analysis using an energy range of (6.6-43.3) keV(nr) sets a limit on the elastic, spin-independent WIMP-nucleon scattering cross section for WIMP masses above 8 GeV/c(2), with a minimum of 1.1 x 10(-45) cm(2) at 50 GeV/c(2) and 90% confidence level. We also report updated constraints on the elastic, spin-dependent WIMP-nucleon cross sections obtained with the same data. We set upper limits on the WIMP-neutron (proton) cross section with a minimum of 2.0 x 10(-40) cm(2) (52 x 10(-40) cm(2)) at a WIMP mass of 50 GeV/c(2), at 90% confidence level.
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17. |
- Aprile, E., et al.
(author)
-
XENON1T dark matter data analysis : Signal and background models and statistical inference
- 2019
-
In: Physical Review D. - 2470-0010 .- 2470-0029. ; 99:11
-
Journal article (peer-reviewed)abstract
- The XENON1T experiment searches for dark matter particles through their scattering off xenon atoms in a 2 metric ton liquid xenon target. The detector is a dual-phase time projection chamber, which measures simultaneously the scintillation and ionization signals produced by interactions in target volume, to reconstruct energy and position, as well as the type of the interaction. The background rate in the central volume of XENON1T detector is the lowest achieved so far with a liquid xenon-based direct detection experiment. In this work we describe the response model of the detector, the background and signal models, and the statistical inference procedures used in the dark matter searches with a 1 metric ton x year exposure of XENON1T data, that leads to the best limit to date on WIMP-nucleon spin-independent elastic scatter cross section for WIMP masses above 6 GeV/c(2).
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18. |
- Aprile, E., et al.
(author)
-
XENON1T dark matter data analysis : Signal reconstruction, calibration, and event selection
- 2019
-
In: Physical Review D. - 2470-0010 .- 2470-0029. ; 100:5
-
Journal article (peer-reviewed)abstract
- The XENON1T experiment at the Laboratori Nazionali del Gran Sasso is the most sensitive direct detection experiment for dark matter in the form of weakly interacting particles (WIMPs) with masses above 6 GeV/c(2) scattering off nuclei. The detector employs a dual-phase time projection chamber with 2.0 metric tons of liquid xenon in the target. A one metric ton x year exposure of science data was collected between October 2016 and February 2018. This article reports on the performance of the detector during this period and describes details of the data analysis that led to the most stringent exclusion limits on various WIMP-nucleon interaction models to date. In particular, signal reconstruction, event selection, and calibration of the detector response to nuclear and electronic recoils in XENON1T are discussed.
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19. |
- Aprile, E., et al.
(author)
-
Constraining the Spin-Dependent WIMP-Nucleon Cross Sections with XENON1T
- 2019
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 122:14
-
Journal article (peer-reviewed)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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20. |
- Aprile, E., et al.
(author)
-
Dark Matter Search Results from a One Ton-Year Exposure of XENON1T
- 2018
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 121:11
-
Journal article (peer-reviewed)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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21. |
- Aprile, E., et al.
(author)
-
Effective field theory search for high-energy nuclear recoils using the XENON100 dark matter detector
- 2017
-
In: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:4
-
Journal article (peer-reviewed)abstract
- We report on weakly interacting massive particles (WIMPs) search results in the XENON100 detector using a nonrelativistic effective field theory approach. The data from science run II (34 kg x 224.6 live days) were reanalyzed, with an increased recoil energy interval compared to previous analyses, ranging from (6.6-240) keV(nr). The data are found to be compatible with the background-only hypothesis. We present 90% confidence level exclusion limits on the coupling constants of WIMP-nucleon effective operators using a binned profile likelihood method. We also consider the case of inelastic WIMP scattering, where incident WIMPs may up-scatter to a higher mass state, and set exclusion limits on this model as well.
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22. |
- Aprile, E., et al.
(author)
-
First Results on the Scalar WIMP-Pion Coupling, Using the XENON1T Experiment
- 2019
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 122:7
-
Journal article (peer-reviewed)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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23. |
- Aprile, E., et al.
(author)
-
Search for bosonic super-WIMP interactions with the XENON100 experiment
- 2017
-
In: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:12
-
Journal article (peer-reviewed)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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24. |
- Aprile, E., et al.
(author)
-
Search for Electronic Recoil Event Rate Modulation with 4 Years of XENON100 Data
- 2017
-
In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 118:10
-
Journal article (peer-reviewed)abstract
- We report on a search for electronic recoil event rate modulation signatures in the XENON100 data accumulated over a period of 4 yr, from January 2010 to January 2014. A profile likelihood method, which incorporates the stability of the XENON100 detector and the known electronic recoil background model, is used to quantify the significance of periodicity in the time distribution of events. There is a weak modulation signature at a period of 431(-14)(+16) day in the low energy region of (2.0-5.8) keV in the single scatter event sample, with a global significance of 1.9 sigma; however, no other more significant modulation is observed. The significance of an annual modulation signature drops from 2.8 sigma, from a previous analysis of a subset of this data, to 1.8 sigma with all data combined. Single scatter events in the low energy region are thus used to exclude the DAMA/LIBRA annual modulation as being due to dark matter electron interactions via axial vector coupling at 5.7 sigma.
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25. |
- Aprile, E., et al.
(author)
-
Search for magnetic inelastic dark matter with XENON100
- 2017
-
In: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :10
-
Journal article (peer-reviewed)abstract
- We present the first search for dark matter-induced delayed coincidence signals in a dual-phase xenon time projection chamber, using the 224.6 live days of the XENON100 science run II. This very distinct signature is predicted in the framework of magnetic inelastic dark matter which has been proposed to reconcile the modulation signal reported by the DAMA/LIBRA collaboration with the null results from other direct detection experiments. No candidate event has been found in the region of interest and upper limits on the WIMP's magnetic dipole moment are derived. The scenarios proposed to explain the DAMA/LIBRA modulation signal by magnetic inelastic dark matter interactions of WIMPs with masses of 58.0 GeV/c(2) and 122.7 GeV/c(2) are excluded at 3.3 sigma and 9.3 sigma, respectively.
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26. |
- Aprile, E., et al.
(author)
-
Search for WIMP inelastic scattering off xenon nuclei with XENON100
- 2017
-
In: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:2
-
Journal article (peer-reviewed)abstract
- We present the first constraints on the spin-dependent, inelastic scattering cross section of weakly interacting massive particles (WIMPs) on nucleons from XENON100 data with an exposure of 7.64 x 10(3) kg . days. XENON100 is a dual-phase xenon time projection chamber with 62 kg of active mass, operated at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy and designed to search for nuclear recoils from WIMP-nucleus interactions. Here we explore inelastic scattering, where a transition to a low-lying excited nuclear state of Xe-129 is induced. The experimental signature is a nuclear recoil observed together with the prompt deexcitation photon. We see no evidence for such inelastic WIMP-Xe-129 interactions. A profile likelihood analysis allows us to set a 90% C.L. upper limit on the inelastic, spin-dependent WIMP-nucleon cross section of 3.3 x 10(-38) cm(2) at 100 GeV/c(2). This is the most constraining result to date, and sets the pathway for an analysis of this interaction channel in upcoming, larger dual-phase xenon detectors.
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27. |
- Spinozzi, Daniele, et al.
(author)
-
Evaluation of the Suitability of Biocompatible Carriers as Artificial Transplants Using Cultured Porcine Corneal Endothelial Cells
- 2019
-
In: Current Eye Research. - : TAYLOR & FRANCIS INC. - 0271-3683 .- 1460-2202. ; 44:3, s. 243-249
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Journal article (peer-reviewed)abstract
- Purpose/Aim: Evaluating the suitability of bioengineered collagen sheets and human anterior lens capsules (HALCs) as carriers for cultivated porcine corneal endothelial cells (pCECs) and in vitro assessment of the cell-carrier sheets as tissue-engineered grafts for Descemet membrane endothelial keratoplasty (DMEK). Materials and Methods: pCECs were isolated, cultured up to P2 and seeded onto LinkCell (TM) bioengineered matrices of 20 mu m (LK20) or 100 mu m (LK100) thickness, and on HALC. During expansion, pCEC viability and morphology were assessed by light microscopy. ZO-1 and Na+/K+-ATPase expression was investigated by immunohistochemistry. Biomechanical properties of pCEC-carrier constructs were evaluated by simulating DMEK surgery in vitro using an artificial anterior chamber (AC) and a human donor cornea without Descemet membrane (DM). Results: During in vitro expansion, cultured pCECs retained their proliferative capacity, as shown by the positive staining for proliferative marker Ki67, and a high cell viability rate (96 +/- 5%). pCECs seeded on all carriers formed a monolayer of hexagonal, tightly packed cells that expressed ZO-1 and Na+/K+-ATPase. During in vitro surgery, pCEC-LK20 and pCEC-LK100 constructs were handled like Descemet stripping endothelial keratoplasty (DSEK) grafts, i.e. folded like a "taco" for insertion because of challenges related to rolling and sticking of the grafts in the injector. pCEC-HALC constructs behaved similar to the DMEK reference model during implantation and unfolding in the artificial AC, showing good adhesion to the bare stroma. Conclusions: In vitro DMEK surgery showed HALC as the most suitable carrier for cultivated pCECs with good intraoperative graft handling. LK20 carrier showed good biocompatibility, but required a DSEK-adapted surgical protocol. Both carriers might be notional candidates for potential future clinical applications.
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