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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.
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.
Energy and spatial characteristics of artificial radiation belts were deduced in part 1, where we examined the temporal histories of the VLF phase perturbations produced by the two Soviet high‐altitude nuclear bursts of October 1962. For both bursts the trapped electrons have energies ≲4 Mev, the electron spectrum ≲0.78 Mev resembling that from the radioactive decay of neutrons. This dichotomy of fission and neutron‐decay β particles in the electron spectrum has not been achieved in the satellite particle data so far analyzed, where the energy ranges are either too broad or above 0.78 Mev. For the burst of October 22, the VLF characteristic that electrons ≲4 Mev are trapped in the region encompassing at least 1.75 ≲ L ≲ 3.76 is compatible with the trapped particle flux observed by Explorer 14, Alouette, and Telstar 1. For the burst of October 28, the VLF shows that fission β particles ≳0.78 Mev are not present in L > 2.32 and are confined on shells <2.32. This characteristic agrees with the results for Alouette electrons ≳3.9 Mev, but not with the Explorer 14 results for E > 1.6 Mev or the Explorer 15 results for electrons >1.9 Mev. The Alouette results also show that the energy spectrum extends to about 10 Mev, but that there is a rapid decrease in flux for E > 4 Mev. For the burst of October 28, the VLF shows that neutron‐decay β particles have an outer trapping boundary at 2.32 ≤ L < 2.79, which is compatible with the Explorer 14 results for E > 230 kev but not with the Telstar data for E > 390 kev, where the outer boundary extends to L ∼ 4. The VLF result that protons 2.3 < E < 4.6 Mev are trapped in shells <2.32 complements the Explorer 14 finding that the Soviet bursts produced no discernible changes in the equatorial intensities of protons >500 kev at L = 2.8 and 3.2. The characteristics of protons from nuclear explosions are reviewed, and the electron results are consolidated to form at least a model for additional investigations of the artificial radiation belts formed by the Soviet bursts of October 22 and 28, 1962.
The Soviet high-altitude nuclear burst of 0912 UT on November 1, 1962, produced delayed perturbations of the VLF transmissions monitored at APL/JHU over five paths remote from the burst region. The burst-related VLF effects varied from 6 to 55% and averaged 32% of the normal diurnal variation. It is suggested that the VLF phase perturbations are produced by particles from the burst that drift to the remote regions and produce an ionization enhancement in the lower ionosphere in their first, and sometimes in their second, global orbit. The temporal histories of the VLF phase perturbations are compatible with a model wherein it is assumed that the trapped particles are electrons from the radioactive decay of neutrons, the artificial belt extending from an outer shell of L • 3.4 to at least L ----1.9. Satellite particle data do not show an artificial belt of electrons from the decay of neutrons, a belt which in this case may have been obscured by the background flux of electrons from the natural Van Allen belt and from the artificial belts from the earlier Soviet explosions. Satellite data do, however, show a narrow belt of fission electrons •1 Mev with maximum flux at L • 1.77 and a lower boundary at L --1.73. These fission electrons did not affect the VLF paths intercepted by these shells. The VLF and satellite data agree that fission electrons •1 Mev were not present on shells above L • 1.9. * These drift rates are for electrons mirroring at 80-km altitude at the geomagnetic latitude of the station, but they are not significantly changed for mirroring altitudes at least up to 1000 km.
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