28 research outputs found
Phenomenology of soft hadron interactions and the relevant EAS data
The interpretation of the experimental data in superhigh energy cosmic rays requires the calculations using various models of elementary hadron interaction. One should prefer the models justified by accelerator data and giving definite predictions for superhigh energies. The model of quark-gluon pomeron strings (the QGPS models) satisfies this requirement
The experimental cascade curves of EAS at E sub 0 10(17) eV obtained by the method of detection of Cherenkov pulse shape
The individual cascade curves of EAS with E sub 0 10 to the 17th power eV/I to 3/ were studied by detection of EAS Cherenkov light pulses. The scintillators located at the center of the Yakutsk EAS array within a 500-m radius circle were used to select the showers and to determine the main EAS parameters. The individual cascade curves N(t) were obtained using the EAS Cherenkov light pulses satisfying the following requirements: (1) the signal-to-noise ratio fm/delta sub n 15, (2) the EAS axis-detector distance tau sub 350 m, (3) the zenith angle theta 30 deg, (4) the probability for EAS to be detected by scintillators W 0.8. Condition (1) arises from the desire to reduce the amplitude distortion of Cherenkov pulses due to noise and determines the range of EAS sizes, N(t). The resolution times of the Cherenkov pulse shape detectors are tau sub 0 approx. 23 ns which results in distortion of a pulse during the process of the detection. The distortion of pulses due to the finiteness of tau sub 0 value was estimated. It is shown that the rise time of pulse becomes greater as tau sub 0.5/tau sub 0 ratio decreases
On the determination of the depth of EAS development maximum using the lateral distribution of Cerenkov light at distances 150 m from EAS axis
The Samarkand extensive air showers (EAS) array was used to measure the mean and individual lateral distribution functions (LDF) of EAS Cerenkov light. The analysis of the individual parameters b showed that the mean depth of EAS maximum and the variance of the depth distribution of maxima of EAS with energies of approx. 2x10 to the 15th power eV can properly be described in terms of Kaidalov-Martirosyan quark-gluon string model (QGSM)
Lateral distribution of high energy muons in EAS of sizes Ne approximately equals 10(5) and Ne approximately equals 10(6)
Muon energy spectra and muon lateral distribution in EAS were investigated with the underground magnetic spectrometer working as a part of the extensive air showers (EAS) array. For every registered muon the data on EAS are analyzed and the following EAS parameters are obtained, size N sub e, distance r from the shower axis to muon, age parameter s. The number of muons with energy over some threshold E associated to EAS of fixed parameters are measured, I sub reg. To obtain traditional characteristics, muon flux densities as a function of the distance r and muon energy E, muon lateral distribution and energy spectra are discussed for hadron-nucleus interaction model and composition of primary cosmic rays
Study of the shower maximum depth by the method of detection of the EAS Cerenkov light pulse shape
The results of processing the data on the shape of the EAS Cerenkov light pulses recorded by the extensive air showers (EAS) array are presented. The pulse FWHM is used to find the mean depth of EAS maximum
Region of Excessive Flux of PeV Cosmic Rays in the Direction Toward Pulsars PSR J1840+5640 and LAT PSR J1836+5925
An analysis of arrival directions of extensive air showers (EAS) registered
with the EAS MSU and EAS-1000 prototype arrays has revealed a region of
excessive flux of PeV cosmic rays in the direction toward pulsars PSR
J1840+5640 and LAT PSR J1836+5925 at significance level up to 4.5sigma. The
first of the pulsars was discovered almost 30 years ago and is a well-studied
old radio pulsar located at the distance of 1.7pc from the Solar system. The
second pulsar belongs to a new type of pulsars, discovered by the space
gamma-ray observatory Fermi, pulsations of which are not observed in optical
and radio wavelengths but only in the gamma-ray range of energies
(gamma-ray-only pulsars). In our opinion, the existence of the region of
excessive flux of cosmic rays registered with two different arrays provides a
strong evidence that isolated pulsars can give a noticeable contribution to the
flux of Galactic cosmic rays in the PeV energy range.Comment: 14 pages; v.2: a few remarks to match a version accepted for
Astronomy Letters added. They can be found by redefining the \NEW command in
the preamble of the LaTeX fil
Features of Muon Arrival Time Distributions of High Energy EAS at Large Distances From the Shower Axis
In view of the current efforts to extend the KASCADE experiment
(KASCADE-Grande) for observations of Extensive Air Showers (EAS) of primary
energies up to 1 EeV, the features of muon arrival time distributions and their
correlations with other observable EAS quantities have been scrutinised on
basis of high-energy EAS, simulated with the Monte Carlo code CORSIKA and using
in general the QGSJET model as generator. Methodically various correlations of
adequately defined arrival time parameters with other EAS parameters have been
investigated by invoking non-parametric methods for the analysis of
multivariate distributions, studying the classification and misclassification
probabilities of various observable sets. It turns out that adding the arrival
time information and the multiplicity of muons spanning the observed time
distributions has distinct effects improving the mass discrimination. A further
outcome of the studies is the feature that for the considered ranges of primary
energies and of distances from the shower axis the discrimination power of
global arrival time distributions referring to the arrival time of the shower
core is only marginally enhanced as compared to local distributions referring
to the arrival of the locally first muon.Comment: 24 pages, Journal Physics G accepte
Cosmic Ray Air Shower Characteristics in the Framework of the Parton-Based Gribov-Regge Model NEXUS
The purpose of this paper is twofold: first we want to introduce a new type
of hadronic interaction model (NEXUS), which has a much more solid theoretical
basis as, for example, presently used models like QGSJET and VENUS, and ensures
therefore a much more reliable extrapolation towards high energies. Secondly,
we want to promote an extensive air shower (EAS) calculation scheme, based on
cascade equations rather than explicit Monte Carlo simulations, which is very
accurate in calculations of main EAS characteristics and extremely fast
concerning computing time. We employ the NEXUS model to provide the necessary
data on particle production in hadron-air collisions and present the average
EAS characteristics for energies 10^14 - 10^17 eV. The experimental data of the
casa-blanka group are analyzed in the framework of the new model.Comment: 15 pages, 8 figure
Measuring extensive air showers with Cherenkov light detectors of the Yakutsk array: The energy spectrum of cosmic rays
The energy spectrum of cosmic rays in the range 10^15 eV to 6*10^19 eV has
been studied using the air Cherenkov light detectors of the Yakutsk array. The
total flux of photons produced by relativistic electrons (including positrons
as well, hereafter) of extensive air showers in the atmosphere is used as the
energy estimator of the primary particle initiating a shower. The resultant
differential flux of cosmic rays exhibits, in accordance with previous
measurements, a knee and ankle features at energies 3*10^15 and ~10^19 eV,
respectively. A comparison of observational data with simulations is made in
the knee and ankle regions in order to choose the models of galactic and
extragalactic components of cosmic rays which describe better the energy
spectrum measured.Comment: 27 pages, 22 figures, accepted for publication in New Journal of
Physics (Focus Issue
Astrophysical Origins of Ultrahigh Energy Cosmic Rays
In the first part of this review we discuss the basic observational features
at the end of the cosmic ray energy spectrum. We also present there the main
characteristics of each of the experiments involved in the detection of these
particles. We then briefly discuss the status of the chemical composition and
the distribution of arrival directions of cosmic rays. After that, we examine
the energy losses during propagation, introducing the Greisen-Zaptsepin-Kuzmin
(GZK) cutoff, and discuss the level of confidence with which each experiment
have detected particles beyond the GZK energy limit. In the second part of the
review, we discuss astrophysical environments able to accelerate particles up
to such high energies, including active galactic nuclei, large scale galactic
wind termination shocks, relativistic jets and hot-spots of Fanaroff-Riley
radiogalaxies, pulsars, magnetars, quasar remnants, starbursts, colliding
galaxies, and gamma ray burst fireballs. In the third part of the review we
provide a brief summary of scenarios which try to explain the super-GZK events
with the help of new physics beyond the standard model. In the last section, we
give an overview on neutrino telescopes and existing limits on the energy
spectrum and discuss some of the prospects for a new (multi-particle)
astronomy. Finally, we outline how extraterrestrial neutrino fluxes can be used
to probe new physics beyond the electroweak scale.Comment: Higher resolution version of Fig. 7 is available at
http://www.angelfire.com/id/dtorres/down3.html. Solicited review article
prepared for Reports on Progress in Physics, final versio