AAS 207th Meeting, 8-12 January 2006
Session 81 ISM: From Dark to Blinded
Poster, Tuesday, 9:20am-6:30pm, January 10, 2006, Exhibit Hall

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[81.10] Atmospheric Gamma-Ray Spectrum between 10 and 100 MeV

D.E. Azcarate (Instituto Argentino de Radioastronomia)

The results of two experiments carried out with a large volume balloon-borne omnidirectional plastic scintillator sensitive to 10-100 MeV gamma-radiation are reported here. The two balloons were flown on 18 November 1990 and 24 February 1992, at places of 11.1 and 11.5 GV geomagnetic cut-off rigidities, respectively. For an omnidirectional detector and for energies greater than several MeV, most of the detected photons are secondary \gamma-rays produced through interactions of the charged cosmic rays with the atmosphere. To unfold the observed pulse height spectrum and obtain the incident \gamma-ray spectrum, the detector response function is calculated with some simplifying assumptions. By using this response function, a differential flux dJ/dE=E-1.2 \pm 0.2 photons cm-2 s-1 MeV-1, averaged over all zenithal angles, is estimated for the atmospheric \gamma-radiation, at an atmospheric depth of 5 g cm-2, in the 10-100 Mev energy range. This flux turns out to be compatible with other observations.

The author(s) of this abstract have provided an email address for comments about the abstract: iazcarate@yahoo.com

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