An upper limit to the photon fraction in cosmic rays above 10**19-eV from the Pierre Auger Observatory

Journal Article · Thu Jun 01 00:00:00 EDT 2006 · Astropart.Phys.27:155-168,2007

OSTI ID:892379

Abraham, J; Aglietta, M; Aguirre, C; Allard, D; Allekotte, I; Allison, P; Alvarez, C; Alvarez-Muniz, J; Ambrosio, M; Anchordoqui, L; Anjos, J C

An upper limit of 16% (at 95% c.l.) is derived for the photon fraction in cosmic rays with energies above 10{sup 19} eV, based on observations of the depth of shower maximum performed with the hybrid detector of the Pierre Auger Observatory. This is the first such limit on photons obtained by observing the fluorescence light profile of air showers. This upper limit confirms and improves on previous results from the Haverah Park and AGASA surface arrays. Additional data recorded with the Auger surface detectors for a subset of the event sample, support the conclusion that a photon origin of the observed events is not favored.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-76CH03000
• OSTI ID: 892379
• Report Number(s): FERMILAB-PUB-06-210-A; arXiv eprint number astro-ph/0606619
• Journal Information: Astropart.Phys.27:155-168,2007, Journal Name: Astropart.Phys.27:155-168,2007 Vol. 27
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
Astrophysics
FLUORESCENCE
ORIGIN
PHOTONS