• A S Prakasarao

      Articles written in Proceedings – Section A

    • Isotropic background cosmic X-rays in the energy range 50–290 KeV

      U R Rao E V Chitnis A S Prakasarao

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      The observations of omnidirectional X-ray flux at the top of the atmosphere have been extended upto 200 KeV using a balloon-borne NaI (Tl) scintillator detector at Hyderabad, India. The omnidirectional flux at 60 KeV is found to be 0·0066±0·0014 photons/cm.2 sec. ster. KeV. The X-ray flux in the energy range 50–290 KeV can be adequately represented by the spectrum Ke−2.2±0.4. New upper limits to the hard X-ray flux from the quiet sun have also been obtained from the same measurement.

    • Low energy gamma-ray measurements over Hyderabad, India

      A S Prakasarao V S Iyengar U R Rao

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      The results of the first low energy gamma-ray (0.2 to 1 MeV) measurements at equatorial latitudes conducted by two-balloon flights over Hyderabad, India (7.6° N GM), are presented. The energy resolution of the detectors was sufficient to detect the γ-ray peak at 0.5 MeV due to the electron-positron annihilation. The flux of the 0.5 MeV photons was found to be 0.090 ± 0.012 photons/cm2 sec at an atmospheric depth of 10 gm cm2 and 0.048 ± 0.011 photons/cm2 sec at the top of the atmosphere. Comparison of our results with those obtained at higher latitudes, show the existence of a considerable latitude variation of the 0.5 MeV flux, about a factor of 4 between 55° and 7° latitudes at an altitude of 10 gm/cm2.

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