Atmospheric neutrons at 8. 5-GV cutoff in the southern hemisphere
We report here, for the first time, southern hemispheric measurements of the altitude, latitude, angle, and energy distributions of atmospheric neutrons from 5 to 80 MeV. The data were obtained with the University of California, Riverside, balloon-borne telescope flown from Alice Springs, Australia, on November 10, 1981, at 29/sup 0/ south geomagnetic latitude (SGML). The efficiencies required to evaluate the fluxes for both the upward and the downward moving neutrons were obtained from a Monte Carlo program tested against neutron calibrations. The counting rates of the upward and the downward moving neutrons increase from a residual altitude of 4 gcm/sup 2/ to a maximum at 100 gcm/sup 2/ and then decrease rapidly. These variations agree well with the previous results of Preszler et al. (1974) at 41/sup 0/ north geomagnetic latitude (NGML). The escape current calculated at 29/sup 0/ SGML, 8.5-GV cutoff, for neutron energies between 20 and 70 MeV, is 0.059 +- 0.008 neutronscm/sup 2/ s, adding another point to the latitude distribution, in good agreement with the theoretical predictions of Merker (1972). The angular distributions at all altitudes are similar, with dips near 60/sup 0/ and 130/sup 0/ from the zenith direction. The energy distributions decrease with energy at all altitudes but flatten at energies around 25 MeV. The albedo neutron current decreases as E/sup -1.61//sup +- //sup 0.28/ at 4.1 gcm/sup 2/. These values are compared with the experimental results of Preszler et al. (1974, 1976), Lockwood et al. (1976, 1979) and Bhatt (1983, 1986) and to the theoretical results of Armstrong et al. (1973) and Merker (1972,1975). copyright American Geophysical Union 198
- Research Organization:
- Physics Department and Institute of Geophysics and Planetary Physics, University of California, Riverside
- OSTI ID:
- 5229242
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 93:A4
- Country of Publication:
- United States
- Language:
- English
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GENERAL PHYSICS
COSMIC NEUTRONS
ENERGY SPECTRA
EARTH ATMOSPHERE
COSMIC PROTONS
ENERGY DENSITY
LATITUDE EFFECT
MONTE CARLO METHOD
NITROGEN
OXYGEN
PARTICLE INTERACTIONS
RADIATION BELTS
SOUTHERN HEMISPHERE
VARIATIONS
BARYONS
COSMIC RADIATION
EARTH PLANET
ELEMENTARY PARTICLES
ELEMENTS
FERMIONS
GEOGRAPHICAL VARIATIONS
HADRONS
INTERACTIONS
IONIZING RADIATIONS
NEUTRONS
NONMETALS
NUCLEONS
PLANETS
PROTONS
RADIATIONS
SPECTRA
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena