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The use of the Cherenkov radiation and the fluorescence light to calibrate the energy of giant air showers

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 Added by Leonid Dedenko
 Publication date 2007
  fields Physics
and research's language is English
 Authors L.G. Dedenko




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In terms of the quark-gluon string model the analysis of the classic procedure to estimate the energy of giant air showers with help of the parameter s(600) (a density of energy deposition in the scintillator at a distance of 600 m from the shower core) have been carried out. Simulations of the signal s(600) with help of the CORSIKA code in terms of the hybrid scheme show energy estimates which are approximately a factor of 1.6 times lower than adopted at the Yakutsk array. The energy estimates calculated with the help of the Cherenkov radiation coincide with the experimental data. Simulations of deposited energy distributions in the atmosphere with help of the GEANT4 code and the CORSIKA code show that more than 20% of this energy may be deposited at distances above 100 m from the shower axis.



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The determination of the shower development in air using fluorescence yield is subject to corrections due to the angular spread of the particles in the shower. This could introduce systematic errors in the energy determination of an extensive air shower through the fluorescence technique.
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We have detected Cherenkov light from air showers with Geiger-mode APDs (G-APDs). G-APDs are novel semiconductor photon-detectors, which offer several advantages compared to conventional photomultiplier tubes in the field of ground-based gamma-ray astronomy. In a field test with the MAGIC telescope we have tested the efficiency of a G-APD / light catcher setup to detect Cherenkov light from air showers. We estimate a detection efficiency, which is 60% higher than the efficiency of a MAGIC camera pixel. Ambient temperature dark count rates of the tested G-APDs are below the rates of the night sky light background. According to these recent tests G-APDs promise a major progress in ground-based gamma-ray astronomy.
We present a new method for the reconstruction of the longitudinal profile of extensive air showers induced by ultra-high energy cosmic rays. In contrast to the typically considered shower size profile, this method employs directly the ionization energy deposit of the shower particles in the atmosphere. Due to universality of the energy spectra of electrons and positrons, both fluorescence and Cherenkov light can be used simultaneously as signal to infer the shower profile from the detected light. The method is based on an analytic least-square solution for the estimation of the shower profile from the observed light signal. Furthermore, the extrapolation of the observed part of the profile with a Gaisser-Hillas function is discussed and the total statistical uncertainty of shower parameters like total energy and shower maximum is calculated.
136 - Maria Teresa Dova 2003
Evidence of azimuthal asymmetries in the time structure and signal size has been found in non-vertical showers as a function of zenith angle. These asymmetries arise because of the different paths traveled by particles in the upper and lower sides of the plane perpendicular to the shower axis to reach detectors at the same axial distances. The shower particles are differentially attenuated as they traverse the atmosphere. Furthermore, most particles are not propagating strictly in the shower direction but are on average going away from the axis. This geometrical projection effect also contributes to the final asymmetry. These novel observations must be understood for parameterisation of the lateral distribution function. Additionally, the asymmetry in time distributions offers a new possibility for the determination of the mass composition because its magnitude is strongly dependent on the fraction of electromagnetic signal at the observation level. The asymmetries found in data collected from the Engineering Array of the Auger Observatory will be compared with Monte Carlo data.
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