Il Nuovo Cimento (1955-1965)

, Volume 29, Issue 4, pp 867–882 | Cite as

On the inner Van Allen zone of the earth

  • G. Pizzella


A description of the inner Van Allen zone in terms of Mcllwain’s co-ordinates is given. Exponential spectra for electrons and protons are shown to be the most suitable for expressing the results of various experiments. At L=1.2 and at the geomagnetic equator there are 104 exp [—E/160 keV] electrons/(cm2 s sr keV) perpendicular to the field lines, and 23 exp [— E/120 MeV] protons/(cm2 s MeV). The time variations detected by a Geiger counter in Explorer VII, at the magnetic shell with L>1.5 are ascribed to electrons. For ≤1.5 a fractional increase of 2.3 occurs during an 11 months time interval but the inner belt geometry is shown to remain unchanged with time. Therefore it is suggested that the same source which generates the trapped particles is also responsible for the time variation.


La cintura interna di Van Allen è desoritta per mezzo delle coordinate di Mcllwain. Si mostra che i risultati di vari esperimenti per elettroni e protoni vengono espressi nel modo più conveniente facendo uso di spettri di tipo esponenziale. Ad L=1.2 ed all’equatore geomagnetico ci sono 104 exp [-E/160 keV] elettroni/(cm2 s sr keV) perpendicolari alle linee di forza del campo, e 23 exp [-E/120 MeV] protoni/(cm2 sMeV). La variazione temporale individuata per mezzo di un contatore di Geiger su Explorer VII, nella regione con L>1.5, viene attribuita ad elettroni. Per L< 1.5 l’intensità misurata aumenta di un fattore 2.3 durante un periodo di 11 mesi, ma si dimostra che la conflgurazione geometrica della cintura interna rimane la stessa. Pertanto si suggerisce che la variazione temporale sia dovuta alla medesima sorgente che genera le particelle intrappolate.


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Copyright information

© Società Italiana di Fisica 1963

Authors and Affiliations

  • G. Pizzella
    • 1
    • 2
  1. 1.Istituto di Fisica dell’UniversitáRoma
  2. 2.Istituto Nationale di Fisioa NucleareSezione di RomaItalia

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