The extremely high energy cosmic rays

Yoshida, Shigeru; Dai, H. Y.

doi:10.1088/0954-3899/24/5/002

Cited by 69 publications

(60 citation statements)

References 66 publications

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“…Over the last third of the century, ingenious installations with large effective areas and long exposure times-needed to overcome the steep falling flux-have raised the tail of the spectrum up to an energy of 3 × 10 20 eV, with no evidence that the highest energy recorded thus far is Nature's upper limit [1]. The origin of these extraordinarily energetic particles continues to present a major enigma to high energy physics [2].…”

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confidence: 99%

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Auger Test of the Cen A Model of Highest Energy Cosmic Rays

Anchordoqui

Goldberg²,

Weiler³

2001

Phys. Rev. Lett.

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If, as recently proposed by Farrar and Piran, Cen A is the source of cosmic rays detected above the Greisen-Zatsepin-Kuz'min cutoff, neutrons are ≈ 140 more probable than protons to be observed along its line of sight. This is because the proton flux is rendered nearly isotropic by O(µG) intergalactic magnetic fields. With the anticipated aperture of the Southern Auger Observatory, one may expect on the order of 2 neutron events/year above 10 20 eV in the line of sight of Cen A.The energy spectrum of cosmic rays (CRs) is well fitted by power laws with increasing index for energies above 4 × 10 15 eV (the "knee") flattening again above 5 × 10 18 eV (the "ankle"), yielding the overall shape of a leg. Over the last third of the century, ingenious installations with large effective areas and long exposure times-needed to overcome the steep falling flux-have raised the tail of the spectrum up to an energy of 3 × 10 20 eV, with no evidence that the highest energy recorded thus far is Nature's upper limit [1]. The origin of these extraordinarily energetic particles continues to present a major enigma to high energy physics [2].The main problem posed by the detection of CRs of such energy (if nucleons, gammas, and/or nuclei) is energy degradation through inelastic collisions with the universal radiation fields permeating the universe. Therefore, if the CR sources are all at cosmological distances, the observed spectrum must virtually end with the Greisen-Zatsepin-Kuz'min (GZK) cutoff at E ≈ 8 × 10 19 eV [3]. The spectral cutoff is less sharp for nearby sources (within 50 Mpc or so). The arrival directions of the trans-GZK events are distributed widely over the sky, with no plausible counterparts (such as sources in the Galactic Plane or in the Local Supercluster). Furthermore, the data are consistent with an isotropic distribution of sources in sharp constrast to the anisotropic distribution of light within 50 Mpc [4]. The difficulties encountered by conventional acceleration mechanisms in accelerating particles to the highest observed energies have motivated suggestions that the underlying production mechanism could be of non-acceleration nature. Namely, charged and neutral primaries, mainly light mesons (pions) together with a small fraction (3%) of nucleons, might be produced at extremely high energy by decay of supermassive elementary X particles (m X ∼ 10 22 − 10 28 eV) [5]. However, if this were the case, the observed spectrum should be dominated by gamma rays and neutrinos, in contrast to current observation [6]! Alternative explanations involve undiscovered neutral hadrons with masses above a few GeV [7], neutrinos producing nucleons and photons via resonant Z-production with the relic neutrino background [8], or else neutrinos attaining cross sections in the millibarn range above the electroweak scale [9]. A controversial correlation between the arrival direction of CRs above 10 20 eV and high redshift compact radio quasars seems to support these scenarios [10].Over the last few years, it has become evident tha...

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confidence: 99%

“…We fix ǫ L 41 I = 0.40, after comparing Eq. (5) to the observed CR-flux: E 3 J obs (E) = 10 24.5 eV 2 m −2 s −1 sr −1 [1]. With ǫL 41 ≃ 1, this determines I ≃ 0.40, and consequently the required age of the source T on to be about 400 Myr [32].…”

mentioning

confidence: 99%

Auger Test of the Cen A Model of Highest Energy Cosmic Rays

Anchordoqui

Goldberg²,

Weiler³

2001

Phys. Rev. Lett.

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“…4 The latest versions of these packages are sibyll 2.1 [99], qgsjet 01 [100], and dpmjet III [101]; respectively. In qgsjet, both the soft and hard processes are formulated in terms of Pomeron exchanges.…”

Section: Hadronic Processesmentioning

confidence: 99%

“…The literature abounds in reviews of experimental techniques for detection of cosmic ray air showers [3][4][5][6][7][8][9], as well as overviews of the physics of cosmic ray propagation and possible astrophysical and exotic origins [10][11][12][13][14][15][16][17][18]. This review follows a somewhat different path, focusing exclusively on cosmic ray phenomenology from the top of the atmosphere to the Earth's surface.…”

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confidence: 99%

High energy physics in the atmosphere: phenomenology of cosmic ray air showers

et al. 2004

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The properties of cosmic rays with energies above 10 6 GeV have to be deduced from the spacetime structure and particle content of the air showers which they initiate. In this review we summarize the phenomenology of these giant air showers. We describe the hadronic interaction models used to extrapolate results from collider data to ultra high energies, and discuss the prospects for insights into forward physics at the LHC. We also describe the main electromagnetic processes that govern the longitudinal shower evolution, as well as the lateral spread of particles. Armed with these two principal shower ingredients and motivation from the underlying physics, we provide an overview of some of the different methods proposed to distinguish primary species. The properties of neutrino interactions and the potential of forthcoming experiments to isolate deeply penetrating showers from baryonic cascades are also discussed. We finally venture into a terra incognita endowed with TeV-scale gravity and explore anomalous neutrino-induced showers.

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“…At energies below 10 15 eV, both charge and mass can be measured directly using space detectors, however, the properties of cosmic rays of the highest energies have to be inferred from the features of the shower induced in the atmosphere. Air shower experiments are either ground arrays of detectors that trigger in coincidence when a shower passes through them, or optical detectors that observe the longitudinal development of the extensive air shower (EAS) [1,2,3,4,5,6].…”

Section: Introductionmentioning

confidence: 99%

Time asymmetries in extensive air showers: A novel method to identify UHECR species

Dova

Manceñido

Mariazzi

et al. 2009

Astroparticle Physics

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Azimuthal asymmetries in signals of non vertical showers have been observed in ground arrays of water Cherenkov detectors, like Haverah Park and the Pierre Auger Observatory. The asymmetry in time distributions of arriving particles offers a new possibility for the determination of the mass composition. The dependence of this asymmetry on atmospheric depth shows a clear maximum at a position that is correlated with the primary species. In this work a novel method to determine mass composition based on these features of the ground signals is presented and a Monte Carlo study of its sensitivity is carried out.

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The extremely high energy cosmic rays

Cited by 69 publications

References 66 publications

Auger Test of the Cen A Model of Highest Energy Cosmic Rays

Auger Test of the Cen A Model of Highest Energy Cosmic Rays

High energy physics in the atmosphere: phenomenology of cosmic ray air showers

Time asymmetries in extensive air showers: A novel method to identify UHECR species

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