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Detailed Reference Information
Ryan et al. 1977
Ryan, J.M., Dayton, B., Moon, S.H., Wilson, R.B., Zych, A.D. and White, R.S. (1977). Atmospheric gamma ray angle and energy distributions from 2 to 25 MeV. Journal of Geophysical Research 82: doi: 10.1029/JA082i025p03593. issn: 0148-0227.

Angle and energy distributions are reported for gamma rays near the top of the atmosphere for energies of 2-25 MeV and for zenith angles of 0¿-50¿ (downward moving) and 130¿-180¿ (upward moving). These distributions were obtained with the University of California, Riverside (UCR) double Compton scatter gamma ray telescope flown on a balloon to 3.0 g/cm2 residual atmosphere from Palestine, Texas, on May 13, 1975 (geomagnetic cutoff: 4.5 GV). Growth curves from 3.4 to 100 g/cm2 of residual atmosphere are used to determine to downward-moving atmospheric fluxes. Results are given for six energy intervals from 2-25 MeV and for five angle intervals from 0¿-50¿. The downward fluxes are in reasonable agreement with those of Sch¿nfelder and Lichti (1975, 1976) at the lower energies and with those of Kinzer et al. (1974) at the higher energies, where our respective data overlap. The shape of the angular distribution is consistent with that of Lichti et al. (1975) and Thompson (1974) at higher energies. The absolute fluxes of upward moving gamma rays from 130¿-170¿ at 4.2 g/cm2 are in agreement with the semiempirical values of Ling (1975) but increase away from the vertical contrary to his predictions. Integrating over zenith angles of 10¿-40¿ and 140¿-170¿, our ratios of upward moving to downward moving gamma ray fluxes are 12¿1 and 9¿2 for 3-10 and 10-25 MeV, respectively, in agreement with the theoretical model of Graser and Sch¿nfelder (1977).

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Journal
Journal of Geophysical Research
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