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A Joint Analysis of High-Energy Neutrons and Neutron-Decay Protons from a Flare

  • Authors: Kocharov, L. G.; Torsti, J.; Vainio, R.; Kovaltsov, G. A.; Usoskin, I. G.
  • Publication: Solar Physics, v. 169, Issue 1, p. 181-207, 1996
  • Solar event of 1990 May 24
  • Case study
  • ADS link
  • Abstract: A joint analysis of neutron monitor and GOES data is performed to study production of high-energy neutrons at the Sun. The main objects of the research are the spectrum of >50 MeV neutrons and a possible spectrum of primary (interacting) protons which produced those neutrons during the major 1990 May 24 solar flare. Different possible scenarios of the neutron production are presented. The high magnitude of the 1990 May 24 neutron event provided an opportunity to detect neutron decay protons of higher energies than ever before. We compare the predictions of the proposed models of neutron production with the observations of protons on board GOES 6 and 7. It is shown that the 'precursor' in high-energy GOES channels observed during 20:55-21:09 UT can be naturally explained as originating from decay of neutrons in the interplanetary medium. The ratio of counting rates observedin different GOES channels can ensure the selection of the model parameters.

The set of experimental data can be explained in the framework of a scenario which assumes the existence of two components of interacting protons in the flare. A hard spectrum componenet (the first component) generates neutrons during a short time while the interaction of the second (soft spectrum) component lasts longer. Alternative scenarios are found to be of lesser likelihood. The intensity - time model of neutron - decay protons as predicted in the framework of the two-component exponential model of neutron production (Kocharov et al., 1994a) is in an agreement with the proton profiles observed on board GOES. We compare the deduced characteristics of interacting high-energy protons with the characteristics of protons escaping into the interplanetary medium. It is shown that, in the spectrum of the 100-1000 MeV range, the spectrum of the second component of interacting protons was close to the spectrum of the prompt component of interplanetary protons. However, it is most likely, that, at ~300 MeV, the interacting proton spectrum was slightly softer than the spectrum of interplanetary protons. An analysis of γ-ray emission is required to deduce the spectrum of interacting protons below 100 MeV and above 1 GeV.

Created by mevali. Last Modification: Wednesday 23 of May, 2007 09:40:40 UTC by mevali.