Reexamination of Cosmic‐Ray Composition around 10<sup>18</sup>eV from Fly's Eye Data

Ding, Lei; Jing, C. L.; Jing, Gongchao; Ren, Jing; Zhu, Q. Q.; Dai, H. Y.; Loh, E. C.; Sokolsky, P.; Sommers, P.; Tang, J. K. K.

doi:10.1086/303453

Cited by 13 publications

(11 citation statements)

References 27 publications

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“…The X max behaviour of our MOCCA+SIBYLL generated showers is similar to that used in [14]. At a given energy, proton X max values differ by around 20 g cm −2 and iron values differ by around 30 g cm −2 .…”

Section: Treatment Of Detector Effectssupporting

confidence: 57%

“…The triggering and reconstruction biases of the Fly's Eye have previously been studied in great detail by ourselves and others. We have used one such study [14] to apply corrections to the MOCCA+SIBYLL-simulated elongation rate for proton and iron showers. That study generated proton and iron showers with energies sampled from a E −3 differential spectrum.…”

Section: Treatment Of Detector Effectsmentioning

confidence: 99%

“…At a given energy, proton X max values differ by around 20 g cm −2 and iron values differ by around 30 g cm −2 . From [14] we parametrize triggering and reconstruction shifts in terms of energy and X max . Because of the two-dimensional parametrization we feel confident applying these shifts to our data, despite slight differences in X max .…”

Section: Treatment Of Detector Effectsmentioning

confidence: 99%

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A comparison of cosmic ray composition measurements at the highest energies

Dawson

Meyhandan

Simpson

1998

Astroparticle Physics

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In recent years the Fly's Eye and Akeno groups have presented analyses of the cosmic ray mass composition at energies above 10 17 eV. While the analysis of the Fly's Eye group points to a likely change in mass composition from heavy to light at energies above 10 18 eV, the Akeno analysis favours an unchanging composition. However, the two groups base their conclusions on simulations using quite different hadronic models. Here we present a comparison of the experiments using the same hadronic model and find that the agreement between the experiments is much improved. Under this model, both experiments measure a composition rich in iron around 10 17 eV which becomes lighter at higher energies. However, the agreement is not complete, which indicates scope for improvement of the interaction model, or perhaps the need for a re-examination of the experimental results.

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Section: Treatment Of Detector Effectssupporting

confidence: 57%

Section: Treatment Of Detector Effectsmentioning

confidence: 99%

Section: Treatment Of Detector Effectsmentioning

confidence: 99%

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A comparison of cosmic ray composition measurements at the highest energies

Dawson

Meyhandan

Simpson

1998

Astroparticle Physics

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“…Additionally there is no difficulty in explaining the isotropy as a reasonable fraction of the particles may be iron nuclei. This is allowed by the necessarily model-interpretation of the Fly's Eye data and the limited statistics (Bird et al 1995, Ding et al, 1997. Iron nuclei cannot, of course, be created by the decay of dark matter particles.…”

Section: Comments On Related Workmentioning

confidence: 99%

Dark matter halos and the anisotropy of ultra-high energy cosmic rays

Tanco

Watson

1999

Astroparticle Physics

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“…The insensitivity of the ρ(600) to the interaction model does not exempt its model dependence totally. The MOCCA (or pre-MOCCA) models [49] used by the Haverah Park experiment, no doubt represented the best knowledge of hadronic interactions in the 1970's, however recent Fly's Eye, AGASA and Yakutsk data favor models which are more consistent with a quicker dissipation of energy (faster than the scaling models used by Haverah Park) [71,72,73]. Evidence shows that the MOCCA program, which was used to determine the relation between the primary energy and ρ(600), underestimates the muon density by almost a factor of two at large distances from the core for showers between 10 18 and 10 19 eV.…”

Section: Absolute Energy Calibration and Energy Resolutionmentioning

confidence: 99%

The extremely high energy cosmic rays

Yoshida

Dai

1998

J. Phys. G: Nucl. Part. Phys.

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Experimental results from Haverah Park, Yakutsk, AGASA and Fly's Eye are reviewed. All these experiments work in the energy range above 10 17 eV. The 'dip' structure around 10 18.5 eV in the energy spectrum is well established by all the experiments, though the exact position differs slightly. Fly's Eye and Yakutsk results on the chemical composition indicate that the cosmic rays are getting lighter over the energy range from 10 17 eV to 10 19 eV, but the exact fraction is hadronic interaction model dependent, as indicated by the AGASA analysis. The arrival directions of cosmic rays are largely isotropic, but interesting features may be starting to emerge. Most of the experimental results can best be explained with the scenario that an extragalactic component gradually takes over a galactic population as energy increases and cosmic rays at the highest energies are dominated by particles coming from extragalactic space. However, identification of the extragalactic sources has not yet been successful because of limited statistics and the resolution of the data.

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Reexamination of Cosmic‐Ray Composition around 10¹⁸eV from Fly's Eye Data

Cited by 13 publications

References 27 publications

A comparison of cosmic ray composition measurements at the highest energies

A comparison of cosmic ray composition measurements at the highest energies

Dark matter halos and the anisotropy of ultra-high energy cosmic rays

The extremely high energy cosmic rays

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Reexamination of Cosmic‐Ray Composition around 1018eV from Fly's Eye Data

Cited by 13 publications

References 27 publications

A comparison of cosmic ray composition measurements at the highest energies

A comparison of cosmic ray composition measurements at the highest energies

Dark matter halos and the anisotropy of ultra-high energy cosmic rays

The extremely high energy cosmic rays

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Product

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Reexamination of Cosmic‐Ray Composition around 10¹⁸eV from Fly's Eye Data