Date of Award
1991
Document Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
First Advisor
W. V. Jones
Second Advisor
J. P. Wefel
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 measured 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 $\pm$ 0.02 for protons and 2.68 $\pm$ 0.03 for helium. The measurements above 200 MeV/nucleon are consistent with rigidity power law interstellar spectra modulated with the solar modulation parameter $\phi$ = 500 MV. The energy dependence of the proton to helium ratio is consistent with rigidity power law injection spectra and rigidity-dependent propagation without re-acceleration.
Recommended Citation
Seo, Eun-suk, "Measurement of Galactic Cosmic Ray Proton and Helium Spectra During the 1987 Solar Minimum." (1991). LSU Historical Dissertations and Theses. 5147.
https://repository.lsu.edu/gradschool_disstheses/5147
Pages
135
DOI
10.31390/gradschool_disstheses.5147