Upper limit on the ultrahigh-energy photon flux from AGASA and Yakutsk data

Journal Article · Wed Mar 15 04:00:00 EST 2006 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.73.063009· OSTI ID:20782601

Rubtsov, G I ^[1]; Dedenko, L G ^[2]; Fedorova, G F; Fedunin, E Yu; Roganova, T M ^[3]; Glushkov, A V; Makarov, I T; Pravdin, M I; Sleptsov, I E ^[4]; Gorbunov, D S; Troitsky, S V ^[1]

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1. Institute for Nuclear Research of the Russian Academy of Sciences, Moscow 117312 (Russian Federation)
2. Faculty of Physics, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation)
3. D.V. Skobeltsin Institute of Nuclear Physics, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation)
4. Yu.G. Shafer Institute of Cosmophysical Research and Aeronomy, Yakutsk 677980 (Russian Federation)

We present the interpretation of the muon and scintillation signals of ultrahigh-energy air showers observed by AGASA and Yakutsk extensive air shower array experiments. We consider case-by-case ten highest-energy events with known muon content and conclude that at the 95% confidence level none of them was induced by a primary photon. Taking into account statistical fluctuations and differences in the energy estimation of proton and photon primaries, we derive an upper limit of 36% at a 95% confidence level on the fraction of primary photons in the cosmic-ray flux above 10{sup 20} eV. This result disfavors the Z-burst and superheavy dark-matter solutions to the Greisen-Zatsepin-Kuzmin-cutoff problem.

• OSTI ID: 20782601
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 6 Vol. 73; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
COSMIC MUONS
COSMIC PHOTONS
COSMIC PROTONS
COSMIC RAY DETECTION
COSMIC RAY FLUX
EXTENSIVE AIR SHOWERS
FLUCTUATIONS
NONLUMINOUS MATTER