Exponential rigidity spectrums for solar-flare cosmic rays

Abstract

A study of solar proton spectrums in the range from a few Mev to a few bey reveals that at most times the number spectrums of these particles near the earth may be represented by an exponential rigidity spectrum of the form J = Joe-P/•'o Such a spectral representation also applies to a particles. The rigidity, P, is the momentum per unit charge. Intensity-time characteristics of the solar protons are examined, and it is significant that propagation changes Po and Jo but not the exponential nature of the spectrum. Changes in the intensity and spectrum of the solar protons are investigated at times of magnetic storms. The features of these changes are discussed, and certain relationships between the low-energy plasma producing the magnetic storm and the high-energy solar proton plasma are pointed out. As a result of our observations of expo.nential rigidity spectrums for solar protons and a particles observed at the earth and features of the continuum solar radio emission at the times of flares, a consistent understanding of the acceleration and propagation of the solar protons is obtained if we assume that a very rapid accelerating mechanism exists (about 1 minute or less) and that this mechanism accelerates particles of different ze/m, producing similar rigidity spectrums. These exponential spectrums are then maintained, in general, throughout the propagation of the particles in the interplanetary medium. Biswas, S., C. E. Fichtel, and D. E. Guss, A study of the hydrogen, helium, and heavy nuclei in the November 12, 1960, solar cosmic ray event (to be published in Phys. Rev.), NASA Tech. Rept.

Nuclear Processes in Solar Flares

“…This result is consistent with earlier studies (Freier and Webber 1963) which have shown that exponentials in rigidity provide abetter fit to the solar proton data than do power laws in kinetic energy. Therefore, we shall present new calculations of nuclear reaction yields only for the exponential spectrum of equation (10) and the Bessel function spectrum of equation (11).…”

Contribution of proton and electron precipitation to the observed electron concentration in October–November 2003 and September 2005

“…These data are available online at the NOAA National Geophysical Data Center (http://spidr.ngdc.noaa.gov/ spidr/). An integrated proton flux can be described by an exponential rigidity relation (Freier and Webber, 1963), which is used to convert the GOES measurements to differential proton fluxes over the energy range of 1-500 MeV on a grid of 78 logarithmically spaced energies. The shape of the resulting spectrum is Maxwellian.…”

Modelling the effects of the October 1989 solar proton event on mesospheric odd nitrogen using a detailed ion and neutral chemistry model

“…1, were obtained from the World Wide Web server for the NOAA National Geophysical Data Center at www.ndgc.noaa.gov/stp/ stp.html. The GOES measurements were converted to differential proton flux for 600 keV-2000 MeV range assuming that the flux can be described by the exponential rigidity relation (Freier and Webber, 1963). Because of the high magnetic latitude of our calculation point (66.46 • N), virtually all protons are able to enter the atmosphere (see e.g.…”