Low-altitude trapped protons during Solar Minimum Period, 1962-1966

Heckman, H. H.; Nakano, G. H.

doi:10.1029/ja074i014p03575

Cited by 42 publications

(8 citation statements)

References 30 publications

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“…A similar constancy in the 55 MeV proton fluxes was observed at lower altitude in the measurements of Filz and Holeman (1965), Filz (1967), and Heckman and Nakano (1969). These authors showed that this could result from a chance coincidence between the rapid flux decay following "Starfish" and the decreasing atmospheric density correlated to the approaching solar minimum.…”

Section: Resultssupporting

confidence: 62%

Long-Term Intensity Decrease in the 8-25 MeV Proton Fluxes at Low L Values.

Parsignault¹,

Holeman²

1981

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A five year continuous observation, 1963-1968, of the 8-to 25-MeV proton population, at L < 2.0, had shown a monotonic decrease in this population. We have observed the same proton population from 1970 to 1976, using experiments flown on several USAF satellites (72-1, S3-2, S3-3). These data, together with published data from the DIAL satellite, show that the decreases in the proton fluxes first observed from 1963 to 1968 have continued unabated, at least until August 1976, and with the same original mean lives. The proton flux at L = 1.35 decayed over the 13-year period (1963-1976) with a mean life r of 5.7 + 0.5 years. At L --1.90, r was 4.55 + 0.16 years. However, the proton flux at L --1.20, which had first been reported as constant, started decreasing --. 1970-1976 with r =' 3.07 + 0.25 years. Possible explanations for this phenomenon can be divided into the two categories of natural and artificial effects.We reviewed these different effects and conclude that most likely we are seeing the decay of the high energy protons redistributed by the 'Starfish' high-altitude nuclear explosion. 11,447 11,448 PARSIGNAULT ET AL.: BRIEF REPORT

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Section: Resultssupporting

confidence: 62%

Long-Term Intensity Decrease in the 8-25 MeV Proton Fluxes at Low L Values.

Parsignault¹,

Holeman²

1981

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“…Measurements of the 55-to 65-MeV proton population at low altitudes (275-600 km) have shown large changes in the fluxes dosely following the solar cycle induced atmospheric density changes. Heckman and Nakano [1969] examined in detail the inner radiation belt protons at low altitudes for a period concurrent with the solar-minimum activity (September 1962-June 1966). They reported a high degree of stability during that period.…”

Section: Introductionmentioning

confidence: 99%

Solar cycle induced modulation of the 55‐MeV proton fluxes at low altitudes

Parsignault¹,

Holeman²

1981

J. Geophys. Res.

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Experiments flown on U.S. Air Force Satellites from 1961 until 1976 have measured the 55-MeV proton flux at low altitudes, between 275 km and 600 km. The analysis of these data shows that in spite of all the uncertainties involved, the agreement obtained between the theoretical calculations and the data is quite good. We conclude that the major determining factors of the 55-MeV proton fluxes in the inner zone are a nearly constant source coupled with a solar cycle varying atmospheric ionization loss process. to a minimum flux around 1968-69. day duration of the Air Force Satellite flights from 1961-1971. THE EXPERIMENTS The measurements of the 55-MeV proton fluxes from 1961-1971 involved the use of emulsions carried on oriented, recov-

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“…The described method to calculate the exponent n of pitch angle distribution is valid whenever the Liouville theorem is applicable. Near the loss cone, n is not constant, and direct measurements of pitch angle distribution are useful to validate physical models of angular distribution that takes the atmospheric properties into account (Heckman and Nakano, 1969). In order to receive energy dependence of proton fluxes in the inner radiation belt, we used the data obtained in LT (Fig.…”

Section: Pitch Angle Distributions Of Trapped Protonsmentioning

confidence: 99%

Pitch angle distribution of trapped energetic protons and helium isotope nuclei measured along the Resurs-01 No. 4 LEO satellite

et al. 2005

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Abstract. The NINA detector on board the Resurs-01 No. 4 satellite (835 km, 98 • inclination) is equipped with particle trackers based on silicon strip detectors. From the energy deposited in each of its silicon layers the mass, the momentum direction and energy of incident particles have been determined. The resolutions in mass and energy allow identification of H and He isotopes over the 10-50 MeV/n energy range. The angular resolution is about 2.5 • . We present the direct measurements of proton and helium isotopes pitch angle distributions derived from Resurs-01 No.4/NINA observations and their variations as functions of (B, L) coordinates and energy. The measurements of trapped helium isotopes spectrum are also presented.

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Low-altitude trapped protons during Solar Minimum Period, 1962-1966

Abstract: UCRL-18422

Cited by 42 publications

References 30 publications

Long-Term Intensity Decrease in the 8-25 MeV Proton Fluxes at Low L Values.

Long-Term Intensity Decrease in the 8-25 MeV Proton Fluxes at Low L Values.

Solar cycle induced modulation of the 55‐MeV proton fluxes at low altitudes

Pitch angle distribution of trapped energetic protons and helium isotope nuclei measured along the Resurs-01 No. 4 LEO satellite

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