Abstract
The 10-m optical reflector at Mt. Hopkins, Arizona, has been used to search for cosmic γ-rays by the detection of atmospheric Čerenkov radiation from energetic particle showers. Approximately 100 drift scans of the Crab Nebula during 1968–69 have yielded no positive evidence of a γ-ray flux. The upper limit to the flux at 1.7 × 1011 eV is 2.0 × 10−10 photons/cm2 sec. Assuming γ-rays of this energy are produced by Compton scattering, a lower limit on the average magnetic field in the Crab Nebula is 1.5 × 10−4 gauss. This experiment also verifies previous evidence that the high-energy electrons in the Crab Nebula are not the secondary products of high-energy proton interactions but must have been accelerated from lower energies.
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Fazio, G.G., Helmken, H.F., Rieke, G.H., Weekes, T.C. (1970). A Lower Limit to the Magnetic Field in the Crab Nebula from Cosmic γ-Ray Experiments at 1011 eV. In: Gratton, L. (eds) Non-Solar X- and Gamma-Ray Astronomy. International Astronomical Union/Union Astronomique Internationale, vol 37. Springer, Dordrecht. https://doi.org/10.1007/978-94-010-3311-4_42
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DOI: https://doi.org/10.1007/978-94-010-3311-4_42
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