NASA NTRS · 19940035196
Balloon observations of Galactic cosmic ray helium before and during a Forbush decrease
Abstract
The energy spectrum of Galactic cosmic ray helium was measured in two different balloon experiments launched four days apart from Canada: SMILI-I on Sept 1, 1989 and MASS on Sept 5, 1989. A slow Forbush decrease began on Sept 4, 1989 and had not reached its maximum at the time of the MASS flight. Comparison of the balloon measurements shows a fractional decrease of 0.37 to 0.15 in the Helium flux between 200 and 450 MeV/nucleon (1.2-2.0 GV). The rigidity dependence is analyzed in two models and found to be steeper than previous observations. Interplanetary particle data and ground-based Neutron Monitor results are consistent with the balloon observations. Probable sources for this Forbush decrease are discussed.
Keep this discovery
Explore connections, maps & timelines
Clem, J. M., Guzik, T. G., Lijowski, M., Wefel, J. P., Beatty, J. J., Ficenec, D. J., Tobias, S., Mitchell, J. W., Mckee, S., Nutter, S.. 1993-09-03. Balloon observations of Galactic cosmic ray helium before and during a Forbush decrease. https://ntrs.nasa.gov/citations/19940035196
Cite the original work for its findings. Save a collection to share your selection of sources.