A study of charged particles in the Earth's outer radiation zone with explorer 14

Abstract

A comprehensive study of the intensities of electrons and protons near the equatorial plane in the earth's outer radiation zone is presented. The data were obtained with SUI equipment on Explorer 14 during the five-month period October 1962 through February 1963. Emphasis is on the radial distribution of absolute intensities of protons and electrons and on the time variations of the energy spectrum and radial distribution of electrons. Typical omnidirectional intensities of electrons in the heart of the outer zone (L ∼ 4.0, on the equator) are: Jo(Ee > 40 kev) = 3 × 107(cm2 sec)−1 Jo(Ee > 230 kev) = 3 × 106(cm2 sec)−1 Jo(Ee > 1.6 Mev) = 3 × 105(cm2 sec)−1 The three-point integral energy spectrum of electrons over the range 40 kev to 1.6 Mev is represented by E−1.0(±0.5) at L = 4.8 for most of the period of the present investigation except during short periods of low-energy (Ee > 40 kev) electron enhancement. The gross temporal variation of the intensities of electrons increases markedly as L increases from 3.2 to 4.8 and at 4.8 is by factors of about 100 for Ee > 40 kev, about 10 for Ee > 230 kev, and about 100 for Ee > 1.6 Mev. A positive correlation between Kp daily sums and equatorial intensities of electrons Ee > 40 kev is demonstrated. Detailed time histories are given. Slow, inward radial motion of the distribution of energetic electrons Ee > 1.6 Mev with an apparent velocity of about 0.02Re/day is observed between radial distances of 3 and 4Re after poststorm enhancement of intensity. Typical omnidirectional intensities of protons Jo (Ep > 0.5 Mev) are 7 × 106 (cm2 sec)−1 near the equator for 2.8 < L < 3.6 and do not vary with time by more than a factor of 2 during the period of observation. Artificial radiation belts produced by the Soviet nuclear bursts at high altitudes during late October and early November 1962 are also detected, and their time decays are plotted.