Summary
The primary cosmic-rayα-particle energy spectrum has been investigated, using photographic emulsions flown from Minneapolis on July 30th, 1957. The total flux observed was (151±9)particles/cm2 sr s. The differential energy spectrum shows a broad maximum between 400 and 600 MeV/nucleon, and appears different in shape from the spectrum observed at solar minimum. No particles were observed to have kinetic energies below 200 MeV/nucleon, but a substantial flux was observed between 200 and 300 MeV/nucleon. From the centered dipole approximation to the geomagnetic field, one would expect a cut-off energy at this latitude of 292 MeV/nucleon. The results presented here are in disagreement with this figure, but do not allow a choice to be made between cut-off energies predicted from other models.
Riassunto
È stato analizzato lo spettro di energia delle particelleα dei raggi cosmici pri mari usando emulsioni fotografiche lanciate da Minneapolis il 30 Luglio 1953. Il flusso totale osservato fu di (151±9) particelle/m2 sr s. Lo spettro differenziale dell’energia presenta un largo massimo fra 400 e 600 MeV/nucleone, ed appare di forma diversa da quello osservato nei minimi solari. Non si osservarono particelle aventi energie cinetiche inferiori a 200 MeV/nucleone, ma si osserva un flusso notevole fra 200 e 300 MeV/nucleone. Dalla approssimazione al campo geomagnetico con dipolo centrato, ci si aspetterebbe a quella latitudine una energia di cut-off di 292 MeV/nucleone. I risultati qui presentati, sono in disaccordo con questo valore, ma non permettono di fare una scelta fra le energie di cut-off predette con altri modelli.
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References
A. Engler, M. F. Kaplon andJ. Klarmann:Nuovo Cimento,12, 310 (1958).
P. H. Fowler andD. H. Perkins:Phil. Mag.,46, 587 (1955).
Preliminary measurements (C. Fichtel:Thesis, W.U. (1959)) indicate theg*-R curve forα-particles to be the same as that obtained byFowler andPerkins (2) for singly charged particles, forg*≳1.2.
Reference (1), eq. (5.b).
V. Y. Rajopadhye andC. J. Waddington:Phil. Mag.,3, 19 (1959).
E. P. Ney andD. M. Thon:Phys. Rev.,81, 1069 (1951).
C. J. Waddington:Phil. Mag.,45, 1312 (1954).
L. R. Davis, M. M. Caulk andC. Y. Johnson:Phys. Rev.,101, 800 (1956).
F. B. McDonald:Phys. Rev.,107, 1386 (1957).
S. E. Forbush:Journ. Geophys. Research,59, 525 (1954).
P. S. Freier, E. P. Ney andC. J. Waddington:Phys. Rev.,114, 365 (1959).
F. B. McDonald:Phys. Rev.,116, 462 (1959).
P. Meyer andJ. A. Simpson:Phys. Rev.,99, 1517 (1955).
P. S. Freier, E. P. Ney andP. H. Fowler:Nature,181, 1319 (1958).
D. C. Rose, K. B. Fenton, J. Katzmann andJ. A. Simpson:Phys. Rev.,102, 1648 (1956).
P. H. Fowler andC. J. Waddington:Phil. Mag.,1, 637 (1956).
P. Rothwell andJ. J. Quenby:Suppl. Nuovo Cimento,8, 249 (1958).
J. J. Quenby andW. R. Webber:Phil. Mag.,4, 90 (1959).
P. H. Fowler:Phil. Mag.,41, 169 (1950).
M. Di Corato, D. Hirschberg andB. Locatelli:Suppl. Nuovo Cimento,4, 448 (1956).
A. Engler, P. B. Jones andJ. H. Mulvey:Proc. Roy. Soc., A254, 425 (1960).
C. Fitchel andM. W. Friedlander:Nuovo Cimento,10, 1032 (1958).
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The flight was made by General Mills Inc. under the supervision ofC. P. Merrill through the arrangements of Cmdr.Cochran.
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Engler, A., Kaplon, M.F., Kernan, A. et al. Primary cosmic-ray α-particles — I. Nuovo Cim 19, 1090–1099 (1961). https://doi.org/10.1007/BF02731385
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DOI: https://doi.org/10.1007/BF02731385