146 research outputs found
Effective field theory interactions for liquid argon target in DarkSide-50 experiment
No full textWe reanalyze data collected with the DarkSide-50 experiment and recently used to set limits on the spinindependent interaction rate of weakly interacting massive particles (WIMPs) on argon nuclei with an effective field theory framework. The dataset corresponds to a total 16660 ∓ 270Þ kg d exposure using a target of low-radioactivity argon extracted from underground sources. We obtain upper limits on the effective couplings of the 12 leading operators in the nonrelativistic systematic expansio
Latest results of dark matter detection with the DarkSide experiment
No full textIn this contribution the latest results of dark matter direct detection obtained by the DarkSide Collaboration are discussed. New limits on the scattering cross-section between dark matter particles and baryonic matter have been set. The results have been reached using the DarkSide-50 detector, a double-phas
Search for Dark Matter Particle Interactions with Electron Final States with DarkSide-50
No full textThe article presents the results of the search for dark matter particles with masses below GeV/s², in the interaction of which electrons are in the final state, using the DarkSide-50 experiment using (12,306±184) kg/day in liquid argon with low radioactivit
Search for low-mass dark matter WIMPs with 12 ton-day exposure of DarkSide-50
No full textThe article talks about the search for massive particles weakly interacting with dark matter (WIMP) in the mass range less than 10 GeV/s2 based on the analysis of the entire data set obtained using an argon target with low radioactivity during the DarkSide-50 experiment at the Gran Sasso National Laborator
An Indication of Anisotropy in Arrival Directions of Ultra-high-energy Cosmic Rays through Comparison to the Flux Pattern of Extragalactic Gamma-Ray Sources
No full textA new analysis of the data set from the Pierre Auger Observatory provides evidence for anisotropy in the arrival directions of ultra-high-energy cosmic rays on an intermediate angular scale, which is indicative of excess arrivals from strong, nearby sources. The data consist of 5514 events above 20 EeV with zenith angles up to 80 degrees. recorded before 2017 April 30. Sky models have been created for two distinct populations of extragalactic gamma-ray emitters: active galactic nuclei from the second catalog of hard Fermi-LAT sources (2FHL) and starburst galaxies from a sample that was examined with Fermi-LAT. Flux-limited samples, which include all types of galaxies from the Swift-BAT and 2MASS surveys, have been investigated for comparison. The sky model of cosmic-ray density constructed using each catalog has two free parameters, the fraction of events correlating with astrophysical objects, and an angular scale characterizing the clustering of cosmic rays around extragalactic sources. A maximum-likelihood ratio test is used to evaluate the best values of these parameters and to quantify the strength of each model by contrast with isotropy. It is found that the starburst model fits the data better than the hypothesis of isotropy with a statistical significance of 4.0 sigma, the highest value of the test statistic being for energies above 39 EeV. The three alternative models are favored against isotropy with 2.7 sigma-3.2 sigma significance. The origin of the indicated deviation from isotropy is examined and prospects for more sensitive future studies are discussed
Calibration of the logarithmic-periodic dipole antenna (LPDA) radio stations at the Pierre Auger Observatory using an octocopter
No full textAn in-situ calibration of a logarithmic periodic dipole antenna with a frequency coverage of 30 MHz to 80 MHz is performed. Such antennas are part of a radio station system used for detection of cosmic ray induced air showers at the Engineering Radio Array of the Pierre Auger Observatory, the so-called Auger Engineering Radio Array (AERA) . The directional and frequency characteristics of the broadband antenna are investigated using a remotely piloted aircraft carrying a small transmitting antenna. The antenna sensitivity is described by the vector effective length relating the measured voltage with the electric-field components perpendicular to the incoming signal direction. The horizontal and meridional components are determined with an overall uncertainty of 7.4+0.9−0.3% and 10.3+2.8−1.7% respectively. The measurement is used to correct a simulated response of the frequency and directional response of the antenna. In addition, the influence of the ground conductivity and permittivity on the antenna response is simulated. Both have a negligible influence given the ground conditions measured at the detector site. The overall uncertainties of the vector effective length components result in an uncertainty of 8.8+2.1−1.3% in the square root of the energy fluence for incoming signal directions with zenith angles smaller than 60°
Inferences on mass composition and tests of hadronic interactions from 0.3 to 100 EeV using the water-Cherenkov detectors of the Pierre Auger Observatory
No full textWe present a new method for probing the hadronic interaction models atultrahigh energy and extracting details about mass composition. This isdone using the time profiles of the signals recorded with thewater-Cherenkov detectors of the Pierre Auger Observatory. The profilesarise from a mix of the muon and electromagnetic components of airshowers. Using the risetimes of the recorded signals, we define a newparameter, which we use to compare our observations with predictionsfrom simulations. We find, first, inconsistencies between our data andpredictions over a greater energy range and with substantially moreevents than in previous studies. Second, by calibrating the newparameter with fluorescence measurements from observations made at theAuger Observatory, we can infer the depth of shower maximumXmax for a sample of over 81,000 events extending from 0.3 toover 100 EeV. Above 30 EeV, the sample is nearly 14 times larger thanwhat is currently available from fluorescence measurements and extendingthe covered energy range by half a decade. The energy dependence of⟨Xmax⟩ is compared to simulations and interpretedin terms of the mean of the logarithmic mass. We find good agreementwith previous work and extend the measurement of the mean depth ofshower maximum to greater energies than before, reducing significantlythe statistical uncertainty associated with the inferences about masscomposition
Spectral calibration of the fluorescence telescopes of the Pierre Auger Observatory
No full textWe present a novel method to measure precisely the relative spectralresponse of the fluorescence telescopes of the Pierre Auger Observatory.We used a portable light source based on a xenon flasher and amonochromator to measure the relative spectral efficiencies of eighttelescopes in steps of 5 nm from 280 nm to 440 nm. Each point in a scanhad approximately 2 nm FWHM out of the monochromator. Different sets oftelescopes in the observatory have different optical components, and theeight telescopes measured represent two each of the four combinations ofcomponents represented in the observatory. We made an end-to-endmeasurement of the response from different combinations of opticalcomponents, and the monochromator setup allowed for more precise andcomplete measurements than our previous multi-wavelength calibrations.We find an overall uncertainty in the calibration of the spectralresponse of most of the telescopes of 1.5% for all wavelengths; the sixoldest telescopes have larger overall uncertainties of about 2.2%. Wealso report changes in physics measurables due to the change incalibration, which are generally small
Observation of inclined EeV air showers with the radio detector of the Pierre Auger Observatory
No full textContains fulltext :
197333pub.pdf (Publisher’s version ) (Open Access)
Contains fulltext :
197333.pdf (Author’s version preprint ) (Open Access
Energy estimation of cosmic rays with the Engineering Radio Array of the Pierre Auger Observatory
No full textThe Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30-80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy-corrected for geometrical effects-is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal
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