391 research outputs found
DAMIC: Dark Matter In CCD
No full textInternational audienceDAMIC is a direct detection dark matter experiment using thick silicon CCDs as target and sensor. This technique is sensitive to nuclear recoil induced by the interaction of low mass WIMP on the target nucleus thanks to the silicon crystal characteristics and low noise readout capabilities. DAMIC is installed at SNOLAB and has set limits on WIMP-nucleon cross section between 1 and 20 Gev/c2 with a detector of 9 grams cumulating an exposure of 0.6 kg.day. After explaining the functioning and the advantages of the technique we will review the performances and results of the DAMIC detector and the status of the current upgrade to DAMIC100. We will also focus on the challenges and the potential of a prospective versions of a kg scale detector
Recent development and results of GIGAS
No full textInternational audienceIn 2008, a laboratory experiment detected a signal in the microwave frequencies produced from the development of an electromagnetic shower in air. This signal was interpreted as Molecular Bremsstrahlung Radiation (MBR). From this interpretation and the measured intensity one rapidly concluded that the detection of this emission from Extensive Air Shower (EAS) would be possible. Furthermore, the isotropic nature of the signal would allow to measure the EAS longitudinal profile, while the large duty cycle of the technique (up to 100) would allow to considerably increase the exposure and thus provide an efficient way to constrain cosmic ray composition at energies above the ankle. Several experiments have been set up to confirm and measure this signal both in the laboratory or in situ within cosmic ray observatories. Among them GIGAS61 is an array of 61 antennas embedded in the Pierre Auger Observatory, operating in the frequency range from 3.4 to 4.2 GHz. The data collected since 2011 have led us to set limits on the expected signal below the original of 2008 experiment. To lower the detection threshold further and comply with the most recent expectations of MBR intensities, we have developed and installed a 14-antennas array with an enhanced sensitivity in two distinct frequency bands. We review in this contribution the concept of GIGAS61 and its results and present the latest developments GIGADuck-C and GIGADuck-L with their expected performances
IceCube-Gen2: A Vision for the Future of Neutrino Astronomy in Antarctica
No full text20 pages, 12 figures. Address correspondence to: E. Blaufuss, F. Halzen, C. Kopper (Changed to add one missing author, no other changes from initial version.)20 pages, 12 figures. Address correspondence to: E. Blaufuss, F. Halzen, C. Kopper (Changed to add one missing author, no other changes from initial version.)20 pages, 12 figures. Address correspondence to: E. Blaufuss, F. Halzen, C. Kopper (Changed to add one missing author, no other changes from initial version.)The recent observation by the IceCube neutrino observatory of an astrophysical flux of neutrinos represents the "first light" in the nascent field of neutrino astronomy. The observed diffuse neutrino flux seems to suggest a much larger level of hadronic activity in the non-thermal universe than previously thought and suggests a rich discovery potential for a larger neutrino observatory. This document presents a vision for an substantial expansion of the current IceCube detector, IceCube-Gen2, including the aim of instrumenting a volume of clear glacial ice at the South Pole to deliver substantial increases in the astrophysical neutrino sample for all flavors. A detector of this size would have a rich physics program with the goal to resolve the sources of these astrophysical neutrinos, discover GZK neutrinos, and be a leading observatory in future multi-messenger astronomy programs
Erratum: Search for photons with energies above 1018 eV using the hybrid detector of the Pierre Auger Observatory (Journal of Cosmology and Astroparticle Physics (2017) 4 (9) DOI: 10.1088/1475-7516/2017/04/009)
No full text1 Exposure calculation Due to a mistake in the numerical integration following eq. (6.2) of the original article [1], the exposure shown in figure 5 of the original article was incorrect. The correct exposure is shown in figure 1. 2 Upper limits on the integral photon flux and fraction The incorrect exposure affects the calculation of the upper limits on the integral photon flux following eq. (6.1) of the original article. The correct values for the upper limits are 0.038, 0.010, 0.009, 0.008 and 0.007 km−2 sr−1 yr−1 for threshold energies of 1, 2, 3, 5 and 10 EeV. The correct values for the upper limits on the integral photon fraction subsequently derived are 0.14 %, 0.17 %, 0.42 %, 0.86 % and 2.9 % for the same threshold energies. 3 Author list The author list of this erratum also corrects a mistake made in the original article, where F. Zuccarello was missing and Z. Zong was listed twice
Measurement of the real dielectric permittivity ϵ_{r} of glacial ice
No full textOwing to their small interaction cross-section, neutrinos are unparalleled astronomical tracers. Ultra-high energy (UHE; E > 10 PeV) neutrinos probe the most distant, most explosive sources in the Universe, often obscured to optical telescopes. Radio-frequency (RF) detection of Askaryan radiation in cold polar ice is currently regarded as the best experimental measurement technique for UHE neutrinos, provided the RF properties of the ice target can be well-understood. To that end, the Askaryan Radio Array (ARA) experiment at the South Pole has used long-baseline RF propagation to extract information on the index-of-refraction (n=√e_{r}) in South Polar ice. Owing to the increasing ice density over the upper 150–200 m, rays are measured along two, nearly parallel paths, one of which refracts through an inflection point, with differences in both arrival time and arrival angle that can be used to constrain the neutrino properties. We also observe (first) indications for RF ice birefringence for signals propagating along predominantly horizontal trajectories, corresponding to an asymmetry of order 0.1% between the ordinary and extra-ordinary birefringent axes, numerically compatible with previous measurements of birefringent asymmetries for vertically-propagating radio-frequency signals at South Pole. Qualitatively, these effects offer the possibility of redundantly measuring the range from receiver to a neutrino interaction in Antarctic ice, if receiver antennas are deployed at shallow (z ∼ −25 m) depths. Such range information is essential in determining both the neutrino energy, as well as the incident neutrino direction
Erratum: Search for photons with energies above 1018 eV using the hybrid detector of the Pierre Auger Observatory
No full textExposure calculation Due to a mistake in the numerical integration following eq. (6.2) of the original article [1], the exposure shown in figure 5 of the original article was incorrect. The correct exposure is shown in figure 1. 2 Upper limits on the integral photon flux and fraction The incorrect exposure affects the calculation of the upper limits on the integral photon flux following eq. (6.1) of the original article. The correct values for the upper limits are 0.038, 0.010, 0.009, 0.008 and 0.007 km−2 sr−1 yr−1 for threshold energies of 1, 2, 3, 5 and 10 EeV. The correct values for the upper limits on the integral photon fraction subsequently derived are 0.14 %, 0.17 %, 0.42 %, 0.86 % and 2.9 % for the same threshold energies. 3 Author list The author list of this erratum also corrects a mistake made in the original article, where F. Zuccarello was missing and Z. Zong was listed twice
IceCube-Gen2 - The Next Generation Neutrino Observatory at the South Pole: Contributions to ICRC 2015
No full text85 pages, 52 figures, Papers submitted to the 34th International Cosmic Ray Conference, The Hague 2015, v2 has a corrected author list85 pages, 52 figures, Papers submitted to the 34th International Cosmic Ray Conference, The Hague 2015, v2 has a corrected author listPapers submitted to the 34th International Cosmic Ray Conference (ICRC 2015, The Hague) by the IceCube-Gen2 Collaboration
Impact of atmospheric effects on the energy reconstruction of air showers observed by the surface detectors of the Pierre Auger Observatory
No full textPublished version ; see paper for full list of authorsInternational audienceAtmospheric conditions, such as the pressure (P), temperature (T) or air density (), affect the development of extended air showers initiated by energetic cosmic rays. We study the impact of the atmospheric variations on the reconstruction of air showers with data from the arrays of surface detectors of the Pierre Auger Observatory, considering separately the one with detector spacings of 1500 m and the one with 750 m spacing. We observe modulations in the event rates that are due to the influence of the air density and pressure variations on the measured signals, from which the energy estimators are obtained. We show how the energy assignment can be corrected to account for such atmospheric effects
Large-scale distribution of arrival directions of cosmic rays detected above 10(18) ev at the Pierre Auger observatory
No full textA thorough search for large-scale anisotropies in the distribution of arrival directions of cosmic rays detected above 10¹⁸ eV at the Pierre Auger Observatory is presented. This search is performed as a function of both declination and right ascension in several energy ranges above 10¹⁸ eV, and reported in terms of dipolar and quadrupolar coefficients. Within the systematic uncertainties, no significant deviation from isotropy is revealed. Assuming that any cosmic-ray anisotropy is dominated by dipole and quadrupole moments in this energy range, upper limits on their amplitudes are derived. These upper limits allow us to test the origin of cosmic rays above 10¹⁸ eV from stationary Galactic sources densely distributed in the Galactic disk and predominantly emitting light particles in all directions.The Pierre Auger Collaboration, P. Abreu ... K. B. Barber ... J. A. Bellido ... R. W. Clay ... M. J. Cooper ... B. R. Dawson ... T. A. Harrison ... A. E. Herve, G. C. Hill ... V. C. Holmes ... J. Sorokin ... P. Wahrlich ... B. J. Whelan ... et al
The Lateral Trigger Probability function for the Ultra-High Energy Cosmic Ray showers detected by the Pierre Auger Observatory
No full textIn this paper we introduce the concept of Lateral Trigger Probability (LTP) function, i.e., the probability for an Extensive Air Shower (EAS) to trigger an individual detector of a ground based array as a function of distance to the shower axis, taking into account energy, mass and direction of the primary cosmic ray. We apply this concept to the surface array of the Pierre Auger Observatory consisting of a 1.5 km spaced grid of about 1600 water Cherenkov stations. Using Monte Carlo simulations of ultra-high energy showers the LTP functions are derived for energies in the range between 1017 and 1019 eV and zenith angles up to 65°. A parametrization combining a step function with an exponential is found to reproduce them very well in the considered range of energies and zenith angles. The LTP functions can also be obtained from data using events simultaneously observed by the fluorescence and the surface detector of the Pierre Auger Observatory (hybrid events). We validate the Monte Carlo results showing how LTP functions from data are in good agreement with simulations. © 2011 Published by Elsevier B.V.The Pierre Auger Collaboration... P. Abreu... K. B. Barber... J. A. Bellido... R. W. Clay... M. J. Cooper... B. R. Dawson... A. E. Herve... V. C. Holmes... J. S. Sorokin... P. S. Wahrlich... M. G. Winnick... et al.http://www.journals.elsevier.com/astroparticle-physics
- …
