Simultaneous quiet time observations of energetic radiation belt protons and helium ions: the equatorial. cap alpha. /p ratio near 1 MeV
Simultaneous monitoring of energetic helium ions and protons in the earth's radiation belts has been carried out with the satellite Explorer 45 in the immediate vicinity of the equatorial plane. Protons were measured from <1 keV to 1.6 MeV in differential energy detector channels and above 3.3 MeV in a quasi-integral channel responsive up to 22 MeV; helium ions were monitored in three differential energy passbands in the range 910 keV to 3.15 MeV and in a differential channel with double passband: 590--910 keV and 2.0--3.99 MeV. The measurements permit determination of the equatorial helium ion to proton flux ratios (..cap alpha../p) both at equal energy per nucleon and equal energy per particle in the heart of the radiation belts on L shells below the spacecraft apogee at Lapprox.5.25. The flux ratios are found to vary significantly with energy and location in the radiation belts. At equal energy per nucleon a range of variability for ..cap alpha../p from 10/sup -4/ to well above 10/sup -3/ is found, and at equal energy per ion the corresponding variability is from 10/sup -3/ to above 10. The latter findings emphasize the relative importance of the very energetic helium ions in the overall radiation belt ion populations. Comparison is made with theoretical equatorial predictions of the ..cap alpha../p ratios that were made by Cornwall (1972) based on the radial diffusion, charge exchange, and Coulomb interactions; the observational findings support many of the theoretical results.
- Research Organization:
- Space Environment Laboratory, NOAA/ERL, Boulder, Colorado 80302
- OSTI ID:
- 5981607
- Journal Information:
- J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 84:A6; ISSN JGREA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALPHA PARTICLES
BARYONS
CHARGED PARTICLES
CHARGED-PARTICLE PRECIPITATION
EARTH ATMOSPHERE
ELEMENTARY PARTICLES
ENERGY RANGE
EXPLORER SATELLITES
FERMIONS
HADRONS
MAGNETOSPHERE
MEV RANGE
NUCLEONS
PROTONS
RADIATION BELTS
SATELLITES
TRAPPED PROTONS