The measurement of the cutoff rigidity at Minneapolis using solar protons and α particles from July 10, 1959, flare

Journal Article · Sun Jul 01 04:00:00 EDT 1962 · Journal of Geophysical Research

DOI:https://doi.org/10.1029/JZ067i007p02617· OSTI ID:4789939

Freier, Phyllis S.

The integral energy spectra of solar protons and alpha particles were obtained during six balloon flights in the three days following the solar flare of 0210 UT, July 10, 1959. Three of the flights occurred at Fort Churchill, Canada, where the cutoff rigidity imposed by the earth's magnetic field was very much less than the cutoff imposed by the air above the balloon. Therefore, in these two flights the measured energy spectra were those existing in the solar beam. In four flights at Minneapolis, the measured energy spectra represented the spectra in the solar beam modified by the earth's magnetic field. From an analysis of both counter results and emulsion results, the time variation of the cutoff rigidity at Minneapolis is obtained. The quite time cutoff at Minneapolis was 1.2 bv but showed a sharp decrease even before the sudden commencement of the magnetic storm that followed the flare. During the magnetic storm the cutoff rigidity was reduced to 0.7 bv or less. In the rigidity interval 0.8 to 1.0 bv the abundance of protons to alpha particles was 1.4 from 30 to 35 hours after the flare. The alpha particle flux decreased faster than the proton flux, and 59 to 70 hours after the flare the proton-to- alpha -particle ratio was 5.

• Research Organization: Univ. of Minnesota, Minneapolis
• Sponsoring Organization: USDOE
• NSA Number: NSA-16-029619
• OSTI ID: 4789939
• Journal Information: Journal of Geophysical Research, Journal Name: Journal of Geophysical Research Journal Issue: 7 Vol. 67; ISSN 0148-0227
• Publisher: American Geophysical Union
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ALPHA PARTICLES
BALLOONS
COSMIC RADIATION
COUNTERS
DISTRIBUTION
EARTH
ENERGY
GEOMAGNETIC CUT-OFF RIGIDITY
GEOPHYSICS
LEVELS
MAGNETIC FIELDS
MEASURED VALUES
MINNESOTA
NUCLEAR EMULSIONS
PARTICLE TRACKS
PRODUCTION
PROTONS
SOLAR FLARES
SPECTRA
STRATOSPHERE
SUN
TURBULENCE
VARIATIONS