235 research outputs found
A new bound on Lorentz violation based on the absence of vacuum Cherenkov radiation in ultra-high energy air showers
In extensive air showers induced by ultra-high energy (UHE) cosmic rays,
secondary particles are produced with energies far above those accessible by
other means. These extreme energies can be used to search for new physics. We
study the effects of isotropic, nonbirefringent Lorentz violation in the photon
sector. In case of a photon velocity smaller than the maximum attainable
velocity of standard Dirac fermions, vacuum Cherenkov radiation becomes
possible. Implementing this Lorentz-violating effect in air shower simulations,
a significant reduction of the calculated average atmospheric depth of the
shower maximum \left is obtained. Based on
\left and its shower-to-shower fluctuations
, a new bound on Lorentz violation is derived which
improves the previous one by a factor of 2. This is the first such bound based
on the absence of vacuum Cherenkov radiation from fundamental particles
(electrons and positrons) in air showers. Options for further improvements are
discussed.Comment: 14 pages, 5 figures, accepted for publication in Phys. Rev. D. arXiv
admin note: text overlap with arXiv:2106.0101
Energy Release in Air Showers
A simulation study of the energy released in air due to the development of an
extensive air shower has been carried out using the CORSIKA code. The
contributions to the energy release from different particle species and
energies as well as the typical particle densities are investigated. Special
care is taken of particles falling below the energy threshold of the simulation
which contribute about 10% to the total energy deposition. The dominant
contribution to the total deposition stems from electrons and positrons from
sub-MeV up to a few hundred MeV, with typical transverse distances between
particles exceeding 1 mm for 10 EeV showers.Comment: 12 pages, 3 figures, accepted by Astropart. Phys.; small content
changes in final versio
Sensitivity of the correlation between the depth of shower maximum and the muon shower size to the cosmic ray composition
The composition of ultra-high energy cosmic rays is an important issue in
astroparticle physics research, and additional experimental results are
required for further progress. Here we investigate what can be learned from the
statistical correlation factor r between the depth of shower maximum and the
muon shower size, when these observables are measured simultaneously for a set
of air showers. The correlation factor r contains the lowest-order moment of a
two-dimensional distribution taking both observables into account, and it is
independent of systematic uncertainties of the absolute scales of the two
observables. We find that, assuming realistic measurement uncertainties, the
value of r can provide a measure of the spread of masses in the primary beam.
Particularly, one can differentiate between a well-mixed composition (i.e., a
beam that contains large fractions of both light and heavy primaries) and a
relatively pure composition (i.e., a beam that contains species all of a
similar mass). The number of events required for a statistically significant
differentiation is ~ 200. This differentiation, though diluted, is maintained
to a significant extent in the presence of uncertainties in the phenomenology
of high energy hadronic interactions. Testing whether the beam is pure or
well-mixed is well motivated by recent measurements of the depth of shower
maximum.Comment: Accepted for publication in Astroparticle Physics, LA-UR-12-2008
Extensive air shower simulations at the highest energies
Air shower simulation programs are essential tools for the analysis of data from cosmic ray experiments and for planning the layout of new detectors. They are used to estimate the energy and mass of the primary particle. Unfortunately the model uncertainties translate directly into systematic errors in the energy and mass determination. Aiming at energies > 1019 eV, the models have to be extrapolated far beyond the energies available at accelerators. On the other hand, hybrid measurement of ground particle densities and calorimetric shower energy, as will be provided by the Pierre Auger Observatory, will strongly constrain shower models. While the main uncertainty of contemporary models comes from our poor knowledge of the (soft) hadronic interactions at high energies, also electromagnetic interactions, lowenergy hadronic interactions and the particle transport influence details of the shower development. We review here the physics processes and some of the computational techniques of air shower models presently used for highest energies, and discuss the properties and limitations of the models.Facultad de Ciencias Exacta
Extensive air shower simulations at the highest energies
Air shower simulation programs are essential tools for the analysis of data from cosmic ray experiments and for planning the layout of new detectors. They are used to estimate the energy and mass of the primary particle. Unfortunately the model uncertainties translate directly into systematic errors in the energy and mass determination. Aiming at energies > 1019 eV, the models have to be extrapolated far beyond the energies available at accelerators. On the other hand, hybrid measurement of ground particle densities and calorimetric shower energy, as will be provided by the Pierre Auger Observatory, will strongly constrain shower models. While the main uncertainty of contemporary models comes from our poor knowledge of the (soft) hadronic interactions at high energies, also electromagnetic interactions, lowenergy hadronic interactions and the particle transport influence details of the shower development. We review here the physics processes and some of the computational techniques of air shower models presently used for highest energies, and discuss the properties and limitations of the models.Facultad de Ciencias Exacta
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