Experimental determination of energy spectrum of atmospheric gamma rays. [0. 9 to 18. 0 MeV]

Technical Report · Wed Jan 01 00:00:00 EST 1975

OSTI ID:7344849

Martin, I M; Dutra, S L.G.; Palmeira, R A.R.; Vedrenne, G; Albernhe, F

The energy spectrum of atmospheric gamma rays from 0.9 to 18.0 MeV was measured as a function of altitude in a series of two balloon flights from Sao Jose dos Campos, Sao Paulo, Brasil (12 GV cut-off rigidity). The detector used was a NaI(T1) crystal with a 1-cm-thick plastic scintillator anti-coincidence shield, connected to a 128-channel pulse height analyzer. Above 20 g/cm/sup 2/ the energy spectrum could be fitted to a power law with exponent 1.0 + or - 0.1 independent of the altitude. From 20 to 760 g/cm/sup 2/ the spectrum was found to be somewhat steeper, with the exponential index being 1.3 + or - 0.1. At 3.5 g/cm/sup 2/ the gamma ray flux was 0.30 photons/cm/sup 2/ -s at 1 MeV. These measurements are discussed and compared with calculated results. (auth)

• Research Organization: Instituto de Pesquisas Espaciais, Sao Jose dos Campos (Brazil)
• OSTI ID: 7344849
• Report Number(s): N-76-18032; INPE-588-RI/277
• Country of Publication: United States
• Language: English

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MEV RANGE 01-10
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