M. Garcia-Munoz

A quantitative test of solar modulation theory - The proton, helium, and electron spectra from 1965 through 1979

The predictions of a conventional, spherically symmetric model of solar modulation have been compared with the measured spectra of positively and negatively charged galactic cosmic-ray particles at 1 AU throughout the 1965-1976 solar cycle and through the enhanced modulation of 1979. For the proton/helium, proton/electron, and helium/electron flux ratios, there is remarkably good agreement between theory and experiment, except for small differences in 1965 and 1969. Possible systematic experimental errors are discussed, and it is concluded that: (1) the 11 year modulation process is largely independent of the sign of the particle charge; and (2) the assumption of steady state is a fairly good approximation for long term modulation.

The isotopic composition of galactic cosmic ray lithium, beryllium and boron

The isotopes of cosmic-ray Li, Be, and B near 100 MeV per nucleon have been measured with cosmic-ray telescopes on board the IMP-7 and IMP-8 satellites during 1973--1974. The measured isotopic abundances provide a stringent test for models of interstellar propagation and solar modulation. It is found that the isotopic abundances can be explained using a steady-state interstellar propagation model with a 5 g cm

New aspects of the cosmic-ray modulation in 1974-1975 near solar minimum

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Energy dependence of the Si/Fe ratio in the galactic cosmic rays

leakage mean free path. These results, taken along with our

A new test for solar modulation theory - The 1972 May-July low-energy galactic cosmic-ray proton and helium spectra.

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The anomalous He-4 component in the cosmic-ray spectrum at below approximately 50 MeV per nucleon during 1972-1974

Be abundance measurements, indicate a longer lifetime for cosmic rays than that predicted by the usual assumption of an average interstellar density of 1 to 3 atoms cm

The age of the galactic cosmic rays derived from the abundance of Be-10

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The Isotopic Composition of Galactic Cosmic-Ray Elements from Carbon to Silicon: The Combined Release and Radiation Effects Satellite Investigation

. (AIP)

The cosmic-ray age deduced from the Be-10 abundance

Residual cosmic-ray modulation at or near the solar minima of 1965 and 1972-75 is compared on the basis of ground-based and satellite observations of nonrelativistic proton and helium components as well as variations in the relativistic component. It is found that the nonrelativistic fluxes lagged behind the high-energy fluxes to form a hysteresis loop over the period from 1965 to 1973, that the 1975 proton fluxes were about 85% higher than the 1972 level and about 35% higher than the 1965 level, and that the 1975 helium fluxes were about 60% higher than in 1965. Some unique recovery events are discussed, and a time-lag effect dependent on magnetic rigidity is examined which was associated with dynamic changes in the heliosphere. A qualitative explanation is offered for the hysteresis effect.

The abundances of galactic cosmic-ray carbon, nitrogen, and oxygen and their astrophysical implications

New measurements are reported of the Si/Fe ratio and the differential energy spectra of galactic cosmic-ray Si and Fe, taking into account the energy range from 35 MeV to 4 GeV per nucleon. The measured data were obtained with the aid of satellite and balloon-borne instrumentation. It is found that for the region below 1 GeV per nucleon the local interstellar spectra computed are consistent with previous galactic cosmic-ray propagation models obtained by Shapiro and Silberberg (1970) and Mason (1972).