Measurement of cosmic-ray proton and helium spectra during the 1987 solar minimum

  • Seo E
  • Ormes J
  • Streitmatter R
  • et al.
123Citations
Citations of this article
12Readers
Mendeley users who have this article in their library.

Abstract

The differential cosmic-ray proton and helium spectra have been measured during the 1987 solar minimum using a balloon-borne superconducting magnetic spectrometer launched from Prince Albert, Canada. The changing geomagnetic cutoff along the balloon trajectory was observed in the low-energy proton data to be about 25% below the nominal calculated values. The absolute particle fluxes were approximately equal to the highest fluxes observed at the previous solar minimum in 1977. Above 10 GV the observed spectra are represented by a power law in rigidity with spectral indices of 2.74 ± 0.02 for protons and 2.68 ± 0.03 for helium. The measurements above 200 MeV per nucleon are consistent with rigidity power-law interstellar spectra modulated with the solar modulation parameter φ = 500 MV. The energy dependence of the proton-to-helium ratio is consistent with rigidity power-law injection spectra and rigidity-dependent propagation without reacceleration.

Cite

CITATION STYLE

APA

Seo, E. S., Ormes, J. F., Streitmatter, R. E., Stochaj, S. J., Jones, W. V., Stephens, S. A., & Bowen, T. (1991). Measurement of cosmic-ray proton and helium spectra during the 1987 solar minimum. The Astrophysical Journal, 378, 763. https://doi.org/10.1086/170477

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free