Atmospheric gamma rays in the energy region 40-1000 GeV

Anand, K. C. ; Daniel, R. R. ; Stephens, S. A. (1973) Atmospheric gamma rays in the energy region 40-1000 GeV Pramana - Journal of Physics, 1 (1). pp. 2-11. ISSN 0304-4289

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A large stack of lead-emulsion sandwich detector assembly was flown over Hyderabad, India. High energy gamma rays at the float altitude were unambiguously identified from the cascades they induced, and their energies reliably determined by improved methods. From an analysis of 163 gamma rays of energy ≥ 30 GeV, it is found that the differential energy spectrum is represented by the power law Fγ(E)= 129.4E-2.62±0.12 photons m-2 sr-1sec-1 GeV-1 at an effective atmospheric depth of 14.3 g cm-2; this is the first reliable balloon measurement of atmospheric gamma rays in the energy range 40-1000 GeV. After correcting for the gamma rays radiated by the primary cosmic ray electrons, the production spectrum of gamma rays, resulting from the collisions of cosmic ray nuclei with air nuclei, at the top of the atmosphere is Pγ(E, 0)=8.2 × 10-4 E2.60±0.09 photons g-1sr-1sec-1 GeV-1. The atmospheric propagation of the electromagnetic component due to the cascade process is also derived from the gamma ray production spectrum.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Gamma Rays; Cascade Process; Production Spectrum; Cosmic Rays
ID Code:16979
Deposited On:16 Nov 2010 13:13
Last Modified:17 May 2016 01:41

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