Photon air showers at ultra-high energy and the photonuclear cross-section

Abstract

Experimental conclusions from air shower observations on cosmic-ray photons above 10^19 eV are based on the comparison to detailed shower simulations. For the calculations, the photonuclear cross-section needs to be extrapolated over several orders of magnitude in energy. The uncertainty from the cross-section extrapolation translates into an uncertainty of the predicted shower features for primary photons and, thus, into uncertainties for a possible data interpretation. After briefly reviewing the current status of ultra-high energy photon studies, the impact of the uncertainty of the photonuclear cross-section for shower calculations is investigated. Estimates for the uncertainties in the main shower observables are provided. Photon discrimination is shown to be possible even for rapidly rising cross-sections. When photon-initiated showers are identified, it is argued that the sensitivity of photon shower observables to the photonuclear cross-section can in turn be exploited to constrain the cross-section at energies not accessible at colliders.

Based on a talk presented at the international conference "From Colliders to Cosmic Rays", Prague, September 7-13 (2005)

References in corpus (2)

• Upper limit on the photon fraction in highest-energy cosmic rays from AGASA data
• On the primary particle type of the most energetic Fly's Eye event

Cited by in corpus (7)

• Upper limit on the cosmic-ray photon flux above 10^19 eV using the surface detector of the Pierre Auger Observatory
• Upper limit on the cosmic-ray photon fraction at EeV energies from the Pierre Auger Observatory
• An upper limit to the photon fraction in cosmic rays above 10^19 eV from the Pierre Auger Observatory
• Search for ultra-high energy photons using air showers
• Characteristics of geomagnetic cascading of ultra-high energy photons at the southern and northern sites of the Pierre Auger Observatory
• Review of the Multimessenger Working Group at UHECR-2012
• Readdressing the contribution of photonuclear reactions to the muon content of extensive air showers: a heuristic approach