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Il Nuovo Cimento (1943-1954)

, Volume 7, Issue 5, pp 715–747 | Cite as

Eccesso positivo e asimmetria Est-Ovest della radiazione penetrante tra il livello del mare e 7300 m s.l.m.

  • I. F. Quercia
  • B. Rispoli
  • S. Sciuti
Article

Riassunto

A conclusione di una serie di misure sull'eccesso positivo eseguite mediante lenti magnetiche a diverse quote ed in diverse condizioni sperimentali, si tenta una interpretazione quantitativa di tutti i dati ottenuti, facendo uso della teoria di generazione singola dei mesoni. Si arriva alla conclusione che entro i limiti delle approssimazioni fatte tale teoria è in accordo con i dati sperimentali ottenuti, pur di assumere come equiprobabili i processi di produzione di mesoni carichi e di neutretti, e si trova che negli urti tra nucleoni circa il 20% dell'energia del nucleone incidente viene ceduta al mesone generato. Per quanto riguarda le misure dell'eccesso di carica in direzione inclinata da Est e ad Ovest, la curvatura che subiscono le traiettoria mesoniche nel campo magnetico terrestre sembra giustificare completamente l'effetto di carica negativo misurato ad Ovest. Queste ultime misure, eseguite alla latitudine geografica di 45°50′ Nord, e con angolo zenitahle di 60°, indicano anche una asimmetria est-ovest sulla primaria di circa il 12%. Vengono infine discusse, secondo la nostra interpretazione, le misure dell'eccesso positivo e delle asimmetrie est-ovest sino ad ora eseguite da altri Autori.

Summary

The results of our measurements of the positive excess of the hard component of the cosmic radiation at 90; 3500; 5100; 7300 m altitude in the vertical direction, and at 3500 m altitude in the Eastern and Western direction (60° inclination) are here summarized. We attempt to interpret theoretically our experimental data on the basis of the plural production theory of the mesons, and assuming a protonic primary radiation with a spectrum of the formE−2,8. The comparison between experimental and theoretical data seems to indicate that best agreement is obtained with a production scheme of the following form: with an equal probability for the production of different kind of mesons (positive, negative or neutral mesons). Taking into account the deflection suffered by the mesons in the earth's magnetic field, a quantitative interpretation is possible of the negative «charge effect» that is given by our experimental data on the Eastern direction at 3500 m altitude. No indication is found for the necessity of the hypothesis of a negative charged primary radiation. From our experimental data, interpreted with the above outlined theory, and from the data ofVan Allen about the absolute intensity of the primary charged radiation, we are able to calculate that about 20% of the energy of the primary incoming nucleons is transferred to the generated π-mesons; this figure is in quite good agreement with the theoretical value given byCaldirola andCini, andWataghin. In our measurement at 3500 m altitude, with zenithal inclination of 60°, the minimum energy that mesons must possess at production in order to trigger the apparatus is about 3 GeV, and the corresponding energy of the incoming nucleons of the order of 20 GeV. According to our interpretation the single production theory seems to be satisfactory at least up to this value of energy. The same set of measurements shows that the East-West Asimmetry of the primary radiation at 45° 50′ North latitude, 60° zenithal inclination, is about 12%, leading to the conclusion that the cut-off of the «main cone» at this angle is of the order of 20 GeV or more. The experimental data also allows to conclude that our integrated positive excess remains almost constant between sea level and 7300 m for the vertical direction, and at 3500 m for directions inclined at 60° to the zenith. These results are in agreement with the hypothesis that the positive excess increases with increasing mean energy.

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Copyright information

© Società Italiana di Fisica 1950

Authors and Affiliations

  • I. F. Quercia
    • 1
  • B. Rispoli
    • 1
  • S. Sciuti
    • 1
  1. 1.Centro di studio per la Fisica Nucleare del C.N.R.Istituto di Fisica dell'UniversitàRomaItaly

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