Browsing by Autor "J. Abraham"
Now showing 1 - 13 of 13
- Results Per Page
- Sort Options
Item type: Item , A study of the effect of molecular and aerosol conditions in the atmosphere on air fluorescence measurements at the Pierre Auger Observatory(Elsevier BV, 2010) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; E. J. Ahn; D. Allard; I. Allekotte; Jeff Allen; Jaime Álvarez-Muñiz; M. AmbrosioItem type: Item , An upper limit to the photon fraction in cosmic rays above 1019eV from the Pierre Auger Observatory(Elsevier BV, 2007) J. Abraham; M. Aglietta; C. Aguirre; D. Allard; I. Allekotte; P. Allison; C. Álvarez; Jaime Álvarez-Muñiz; M. Ambrosio; Luis A. AnchordoquiItem type: Item , Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory(Elsevier BV, 2007) J. Abraham; M. Aglietta; C. Aguirre; D. Allard; I. Allekotte; P. Allison; C. Álvarez; Jaime Álvarez-Muñiz; M. Ambrosio; Luis A. AnchordoquiItem type: Item , Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory(Elsevier BV, 2009) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; E. J. Ahn; D. Allard; I. Allekotte; J. Allen; P. Allison; Jaime Álvarez-MuñizItem type: Item , Correlation of the highest-energy cosmic rays with the positions of nearby active galactic nuclei(Elsevier BV, 2008) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; D. Allard; I. Allekotte; Jeff Allen; P. Allison; Jaime Álvarez-Muñiz; M. AmbrosioItem type: Item , Erratum to “Atmospheric effects on extensive air showers observed with the surface detector of the Pierre Auger observatory” [Astroparticle Physics 32(2) (2009), 89–99](Elsevier BV, 2010) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; E. J. Ahn; D. Allard; I. Allekotte; J. Allen; P. Allison; Jaime Álvarez-MuñizItem type: Item , Limit on the diffuse flux of ultrahigh energy tau neutrinos with the surface detector of the Pierre Auger Observatory(American Physical Society, 2009) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; E. J. Ahn; D. Allard; I. Allekotte; Jeff Allen; P. Allison; Jaime Álvarez-MuñizData collected at the Pierre Auger Observatory are used to establish an upper limit on the diffuse flux of tau neutrinos in the cosmic radiation. Earth-skimming ${\ensuremath{\nu}}_{\ensuremath{\tau}}$ may interact in the Earth's crust and produce a $\ensuremath{\tau}$ lepton by means of charged-current interactions. The $\ensuremath{\tau}$ lepton may emerge from the Earth and decay in the atmosphere to produce a nearly horizontal shower with a typical signature, a persistent electromagnetic component even at very large atmospheric depths. The search procedure to select events induced by $\ensuremath{\tau}$ decays against the background of normal showers induced by cosmic rays is described. The method used to compute the exposure for a detector continuously growing with time is detailed. Systematic uncertainties in the exposure from the detector, the analysis, and the involved physics are discussed. No $\ensuremath{\tau}$ neutrino candidates have been found. For neutrinos in the energy range $2\ifmmode\times\else\texttimes\fi{}{10}^{17}\text{ }\text{ }\mathrm{eV}<{E}_{\ensuremath{\nu}}<2\ifmmode\times\else\texttimes\fi{}{10}^{19}\text{ }\text{ }\mathrm{eV}$, assuming a diffuse spectrum of the form ${E}_{\ensuremath{\nu}}^{\ensuremath{-}2}$, data collected between 1 January 2004 and 30 April 2008 yield a 90% confidence-level upper limit of ${E}_{\ensuremath{\nu}}^{2}d{N}_{{\ensuremath{\nu}}_{\ensuremath{\tau}}}/d{E}_{\ensuremath{\nu}}<9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}\text{ }\text{ }\mathrm{GeV}\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}2}\text{ }{\mathrm{s}}^{\ensuremath{-}1}\text{ }\text{ }{\mathrm{sr}}^{\ensuremath{-}1}$.Item type: Item , Observation of the Suppression of the Flux of Cosmic Rays above<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mn>4</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mn>19</mml:mn></mml:msup><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>eV</mml:mi></mml:math>(American Physical Society, 2008) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; D. Allard; I. Allekotte; J. Allen; P. Allison; Jaime Álvarez-Muñiz; M. AmbrosioThe energy spectrum of cosmic rays above 2.5 x 10;{18} eV, derived from 20,000 events recorded at the Pierre Auger Observatory, is described. The spectral index gamma of the particle flux, J proportional, variantE;{-gamma}, at energies between 4 x 10;{18} eV and 4 x 10;{19} eV is 2.69+/-0.02(stat)+/-0.06(syst), steepening to 4.2+/-0.4(stat)+/-0.06(syst) at higher energies. The hypothesis of a single power law is rejected with a significance greater than 6 standard deviations. The data are consistent with the prediction by Greisen and by Zatsepin and Kuz'min.Item type: Item , Properties and performance of the prototype instrument for the Pierre Auger Observatory(Elsevier BV, 2004) J. Abraham; M. Aglietta; I.C. Aguirre; M. Albrow; D. Allard; I. Allekotte; P. Allison; Jaime Álvarez-Muñiz; Marcelo Amaral; M. AmbrosioItem type: Item , The fluorescence detector of the Pierre Auger Observatory(Elsevier BV, 2010) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; E. J. Ahn; D. Allard; I. Allekotte; Jeff Allen; P. Allison; Jaime Álvarez-MuñizItem type: Item , Upper limit on the cosmic-ray photon flux above 1019eV using the surface detector of the Pierre Auger Observatory(Elsevier BV, 2008) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; D. Allard; I. Allekotte; J. Allen; P. Allison; Jaime Álvarez-Muñiz; M. AmbrosioItem type: Item , Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory(Elsevier BV, 2009) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; E. J. Ahn; D. Allard; I. Allekotte; J. Allen; P. Allison; Jaime Álvarez-MuñizItem type: Item , Upper Limit on the Diffuse Flux of Ultrahigh Energy Tau Neutrinos from the Pierre Auger Observatory(American Physical Society, 2008) J. Abraham; P. Abreu; M. Aglietta; C. Aguirre; D. Allard; I. Allekotte; Jeff Allen; P. Allison; Jaime Álvarez-Muñiz; M. AmbrosioThe surface detector array of the Pierre Auger Observatory is sensitive to Earth-skimming tau neutrinos that interact in Earth's crust. Tau leptons from nu(tau) charged-current interactions can emerge and decay in the atmosphere to produce a nearly horizontal shower with a significant electromagnetic component. The data collected between 1 January 2004 and 31 August 2007 are used to place an upper limit on the diffuse flux of nu(tau) at EeV energies. Assuming an E(nu)(-2) differential energy spectrum the limit set at 90% C.L. is E(nu)(2)dN(nu)(tau)/dE(nu)<1.3 x 10(-7) GeV cm(-2) s(-1) sr(-1) in the energy range 2 x 10(17) eV< E(nu)< 2 x 10(19) eV.