Abstract We use observations from the Anisotropy Telescopes on the Ulysses spacecraft to determine the omnidirectional flux profile of protons in the energy range 0.7 – 1.3 MeV, during the solar proton event that began on 23 Mar 1991. We also show the spectral index throughout the event at 0.7 – 2.2 MeV and at 2.2 – 6.5 MeV, with three example spectra, one from before the event onset, the second near to peak fluxes, and the third on the decay phase of the event. The anisotropy of the flux is determined to second order, on the assumption that the second order anisotropy is symmetric about the magnetic field direction determined from the Ulysses magnetometer measurements. Finally, the first order anisotropy and the spectral index are combined to determine the bulk flow velocity.


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    Title :

    Anisotropy measurements and spectra from a solar proton event in March 1991


    Contributors:
    Staines, K. (author) / Balogh, A. (author) / Cowley, S.W.H. (author) / Forsyth, R.J. (author) / Hynds, R.J. (author)

    Published in:

    Publication date :

    1993-01-01


    Size :

    4 pages




    Type of media :

    Article (Journal)


    Type of material :

    Electronic Resource


    Language :

    English




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