Abstract
The containment lifetime of the cosmic radiation is a crucial parameter in the investigation of the cosmic-ray origin and plays an important role in the dynamics of the Galaxy. The separation of the cosmic-ray Be isotopes achieved by two satellite experiments is considered in this paper, and from the measured isotopic ratio between the radioactive 10Be (half-life = 1.5 × 106 yr) and the stable 9Be, it is deduced that the cosmic rays propagate through matter with an average density of 0.24 ± 0.07 atoms cm-3, lower than the traditionally quoted average density in the galactic disk of 1 atom cm-3.
This paper reviews the implications of this result for the cosmic-ray age mainly in the context of two models of confinement and propagation: the homogeneous model, normally identified with confinement to the galactic gaseous disk, and a diffusion model in which the cosmic rays extend into a galactic halo. The propagation calculations use:
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(1)
a newly deduced cosmic-ray pathlength distribution.
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(2)
a self-consistent model of solar modulation.
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(3)
an up-to-date set of fragmentation cross sections.
The satellite results and their implications are compared with the information on the cosmic-ray age derived from other cosmic-ray radioactive nuclei and the measured differential energy spectrum of high-energy electrons.
It is a major conclusion of this paper that in a homogeneous model the cosmic-ray age is 15(+7, -4) million years, i.e., about a factor 4 longer than early estimates based on the abundances of the light nuclei Li, Be, and B and a nominal interstellar density of 1 atom cm -3. The lifetime is even longer when the satellite results are applied to a diffusion halo model.
The deduced traversed matter density, together with other astrophysical considerations, suggest the population of a galactic halo by the cosmic rays.
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References
Bradt, H. L. and Peters, B.: 1948, Phys. Rev. 74, 1828.
Buffington, A., Orth, C. D., and Mast, T. S.: 1978, Astrophys. J. 226, 355.
Cameron, A. G. W.: 1981, in C. A. Barnes, D. Clayton, and D. N. Schramm (eds.), Essays in Nuclear Astrophysics, Cambridge University Press, Cambridge, pp. 23–43.
Cesarsky C. J. and Volk, H. J.: 1978, Astron. Astrophys. 70, 367.
Cowsik, R., Pal, Y. Tandon, S. N., and Verma R. P.: 1967, Phys. Rev. 158, 1238.
Cummings A. C., Stone, E. C., and Vogt, R. E.: 1973, Proc. 13th. Int. Cosmic Ray Conf. Denver 1, 340.
Dwyer, R. D., Garcia-Munoz, M., Guzik, T. G., Meyer, P., Simpson, J. A. and Wefel, J. P.: 1981, Proc. 17th. Int. Cosmic Ray Conf. Paris 9, 222.
Ekers, R. D. and Sancisi, R.: 1977, Astron. Astrophys. 54, 973.
Evenson, P., Garcia-Munoz, M., Meyer, P., Pyle, K. R., and Simpson, J. A.: 1983, Astrophys. J. 275, L15.
Fermi, E.: 1949, Phys. Rev. 75, 1169.
Freedman, I., Giler, M., Kearsey, S., and Osborne, J. L.: 1980, Astron. Astrophys. 82, 110.
Garcia-Munoz, M., Guzik, T. G., Margolis, S. H., Simpson, J. A., and Wefel, J. P.: 1981a, Proc. 17th Int. Cosmic Ray Conf. Paris 9, 195.
Garcia-Munoz, M., Guzik, T. G., Simpson, J. A., and Wefel, J. P.: 1981b, Proc. 17th. Int. Cosmic Ray Cont. Paris 2, 192.
Garcia-Munoz, M., Simpson, J. A., and Wefel J. P.: 1981c, Proc. 17th Int. Cosmic Ray Conf. Paris 2, 72.
Garcia-Munoz, M., Margolis, S. H., Simpson, J. A., and Wefel, J. P.: 1979a, Proc. 16th. Int. Cosmic Ray Conf. Kyoto 1, 310.
Garcia-Munoz, M., Simpson, J. A., and Wefel, J. P.: 1979b, Astrophys. J. 232, L95.
Garcia-Munoz, M., Mason, G. M., and Simpson, J. A.: 1975, Astrophys. J. 201, L141.
Garcia-Munoz, M., Mason, G. M., and Simpson, J. A.: 1977a, Astrophys. J. 217, 859.
Garcia-Munoz, M., Mason, G. M., and Simpson, J. A.: 1977b, Proc. 15th. Int. Cosmic Ray Conf. Plovdiv 1, 224.
Garcia-Munoz, M., Pyle, K. R., and Simpson, J. A.: 1985, Proc. 19th Int. Cosmic Ray Conf. La Jolla 4, 409.
Garcia-Munoz, M., Simpson, J. A., Guzik, T. G., Wefel, J. P., and Margolis, S. H.: 1987, Astrophys. J. Suppl. 64, 269.
Ginzburg, V. L., Khazan, Ya. M., and Ptuskin, V. S.: 1980, Astrophys. Space Sci. 68, 295.
Gleeson, L. J. and Axford, W. I.: 1968, Astrophys. J. 154, 1011.
Gordon, M. A. and Burton, W. B.: 1976, Astrophys. J. 208, 346.
Guzik, T. G., Wefel, J. P., Garcia-Munoz, M., and Simpson, J. A.: 1985, Proc. 19th. Int. Cosmic Ray Conf. La Jolla 2, 76.
Hagen, F. A., Fisher, A. J., and Ormes, J. F.: 1977, Astrophys. J. 212, 262.
Hayakawa, S., Ito, K., and Terashima, Y.: 1958, Progr. Theor. Phys. Suppl. 6, 1.
Ipavich, F. M.: 1975, Astrophys. J. 196, 107.
Jenkins, E. B.: 1976, Goddard Space Flight Center publication X-662-76-154, p. 239.
Jokipii, J. R.: 1976, Astrophys. J. 208, 900.
Jones, F. C.: 1978, Astrophys. J. 222, 1097.
Jones, F. C.: 1979, Astrophys. J. 229, 747.
Juliusson, E. Meyer, P., and Muller, D.: 1972, Phys. Rev. Letters 29, 445.
Koch, L., Perron, C., Cesarsky, C. J. Juliusson, E., Soutoul, A., and Rasmussen, I. L.: 1981, Proc. 17th Int. Cosmic Ray Conf. Paris 2, 18.
Lerche, I. and Schlickeiser, R.: 1981, Astrophys. Letters 22, 31.
Mayer-Hasselwander, H. A., Bennet, K., Bignami, G. F. and others: 1982, Astron. Astrophys. 105, 164.
McKee, C. F. and Ostriker, J. P.: 1977, Astrophys. J. 218, 148.
Meegan, C. A. and Earl, J. A.: 1975, Astrophys. J. 197, 219.
Owens, A. J. and Jokipii, J. R.: 1977a, Astrophys. J. 215, 677.
Owens, A. J. and Jokipii, J. R.: 1977b, Astrophys. J. 215, 685.
Parker, E. N.: 1965, Planetary Space Sci. 13, 9.
Parker, E. N.: 1968, Stars and Stellar Systems, University of Chicago Press, Chicago, Vol. 7, Chapter 14.
Prince, T. A.: 1979, Astrophys. J. 227, 676.
Prischep, V. L. and Ptuskin, V. S.: 1975, Astrophys. Space Sci. 32, 265.
Savage, B. D. and de Boer, K. S.: 1981, Astrophys. J. 243, 460.
Scott, J. S.: 1975, Nature 258, 58.
Shapiro, R. P. and Field, G. B.: 1976, Astrophys. J. 205, 762.
Shapiro, M. M. and Silberberg, R.: 1970, Ann. Rev. Nucl. Sci. 20, 323.
Simpson, J. A.: 1983, Ann. Rev. Nucl. Part. Sci. 33, 323.
Smith, L. H., Buffington, A., Smoot, G. F., Alvarez, L. W., and Whaling, M. A.: 1973, Astrophys. J. 180, 987.
Spitzer, L.: 1956, Astrophys. J. 124, 20.
Stecker, F. W. and Jones, F. C.: 1977, Astrophys. J. 217, 843.
Tang, K. K.: 1984, Astrophys. J. 278, 881.
Webber, W. R., and Kish, J.: 1979, Proc. 16th Int. Cosmic Ray Conf. Kyoto 1, 389.
Webber, W. R., Lezniak, J. A., Kish, J. C., and Simpson, G. A.: 1977, Astrophys. Letters 18, 125.
Wiedenbeck, M. E.: 1983, Proc. 18th Int. Cosmic Ray Conf. Bangalore 9, 147.
Wiedenbeck, M. E. and Greiner, D. E.: 1980, Astrophys. J. 239, L139.
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Simpson, J.A., Garcia-Munoz, M. Cosmic-ray lifetime in the galaxy: Experimental results and models. Space Sci Rev 46, 205–224 (1988). https://doi.org/10.1007/BF00212240
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DOI: https://doi.org/10.1007/BF00212240