Titre du document

Proton and helium nuclei cosmic?ray spectra and modulations between 100 and 2000 Mev/nucleon

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Nom du Corpus

AstroConcepts

Auteur(s)
  • J. F. Ormes
  • W. R. Webber
Résumé

During the years 1963 through 1966, as the sun passed through its period of minimum activity, an extensive series of balloon flights was conducted to study the primary cosmic radiation and its time variations. The instrument used is a Cerenkov?scintillation counter telescope, the most recent version of which contains two dE/dX detectors, a combination Cerenkov and scintillation detector and a range scintillator. This telescope and its response characteristics to protons and helium nuclei are described. Convolution techniques are used to unfold the Landau fluctuations in energy loss, thereby allowing derivation of the differential energy spectrum from 100 Mev/nucleon up to 2 Gev/nucleon. The differential energy spectra derived by this technique are presented from five balloon flights at Fort Churchill, Canada. The spectra are found to be in generally good agreement with those of other workers but significantly more accurate. The data are examined to determine the functional form of the 11?year solar modulation by comparing the sunspot minimum spectrum obtained in 1965 with the pre?sunspot minimum spectrum obtained in 1963 and the post?sunspot minimum spectrum obtained in 1966. The modulation data do not follow a functional form of either 1/? or 1/?R but rather a form more nearly like 1/?R1/2 between 0.4? and 4?Gv rigidity. A theoretical picture is considered in which this behavior can be ascribed to the statistical distribution of magnetic scattering center sizes in the interplanetary medium. In this model the exponent of the rigidity dependent term in the modulation can be related to the slope of the power spectrum of magnetic scattering centers. The data are compared with those of other workers and are found to be consistent with a picture in which the form of the modulation above 200 Mev/nucleon changes from 1/?R1/2 near sunspot minimum to almost 1/?R near sunspot maximum. It also appears that, at all levels of solar modulation, there is a rigidity below which the form of the modulation becomes ?1/?. The rigidity below which the form 1/? holds varies systematically during the solar cycle but differently for protons and helium nuclei in a manner that is difficult to understand within the framework of the current models.

Langue(s) du document
Anglais
Année de publication
1968
Revue

Journal of Geophysical Research

Éditeur
Wiley
Type de publication
journal
Type de document
article
Présence de XML structuré
Non
Version de PDF
1.3
Score de qualité du texte
10
Nom du concept
  • Landau fluctuations
Catégories Science-Metrix
  • 1 - natural sciences ; 2 - earth & environmental sciences ; 3 - meteorology & atmospheric sciences
Catégories Scopus
  • 1 - Physical Sciences ; 2 - Earth and Planetary Sciences ; 3 - Palaeontology
  • 1 - Physical Sciences ; 2 - Earth and Planetary Sciences ; 3 - Space and Planetary Science
  • 1 - Physical Sciences ; 2 - Earth and Planetary Sciences ; 3 - Earth and Planetary Sciences (miscellaneous)
  • 1 - Physical Sciences ; 2 - Earth and Planetary Sciences ; 3 - Atmospheric Science
  • 1 - Physical Sciences ; 2 - Earth and Planetary Sciences ; 3 - Earth-Surface Processes
  • 1 - Physical Sciences ; 2 - Earth and Planetary Sciences ; 3 - Geochemistry and Petrology
  • 1 - Life Sciences ; 2 - Agricultural and Biological Sciences ; 3 - Soil Science
  • 1 - Physical Sciences ; 2 - Environmental Science ; 3 - Water Science and Technology
  • 1 - Physical Sciences ; 2 - Environmental Science ; 3 - Ecology
  • 1 - Life Sciences ; 2 - Agricultural and Biological Sciences ; 3 - Aquatic Science
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  • 1 - Physical Sciences ; 2 - Earth and Planetary Sciences ; 3 - Oceanography
  • 1 - Physical Sciences ; 2 - Earth and Planetary Sciences ; 3 - Geophysics
Catégories WoS
  • 1 - science ; 2 - geosciences, multidisciplinary
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