Abstract
THE deduction of Cowan et al.1, from their radiocarbon measurements of tree rings, that the Tunguska meteorite could not have been made of anti-matter has been called into question recently by R. V. Gentry2. The present communication supports the assumption of Cowan et al. that there are about 8 ± 4 neutrons per nucleon–antinucleon annihilation and reaffirms the validity of their conclusion. Gentry has pointed out that for proton (P)–antiproton (P̄) annihilations which produce two low energy charged pions each on average, the pions decay before they can travel far enough in the atmosphere to interact; and that neutrons cannot therefore be produced to any important extent by P̄–P annihilations in the atmosphere.
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Cowan, C., Atluri, C. R., and Libby, W. F., Nature, 206, 861 (1965).
Gentry, R. V., Nature, 211, 1071 (1966).
Barkas, W. H., Birge, R. W., Chupp, W. W., Ekspong, A. G., Goldhaber, G., Goldhaber, S., Heckman, H. H., Perkins, D. H., Sandweiss, J., Segre, E., Smith, F. M., Stork, D. H., Van Rossum, L., Amaldi, E., Baroni, G., Castognoli, C., Franzinetti, C., and Manfredini, A., Phys. Rev., 105, 1037 (1957).
Chinowsky, W., and Kojan, G., Nuovo Cimento, 43, 684 (1966).
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MARSHALL, L. Non-anti-matter Nature of the Tunguska Meteor. Nature 212, 1226 (1966). https://doi.org/10.1038/2121226a0
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DOI: https://doi.org/10.1038/2121226a0
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