Disintegrations produced by the Nuclear Capture of Slow Negative -Mesons

Abstract

The `prong distribution' for the disintegrations produced by the σ-mesons of the cosmic radiation in photographic emulsions exposed below ground is found to be different from that observed in emulsions exposed above ground. The underground distribution contains relatively more `stars' consisting of one prong. The observations are consistent with the hypothesis that most of the σ-mesons below ground are in fact negative μ-mesons and not negative π-mesons. It is concluded that 8.7 ± 1.7% of the negative μ-mesons captured in the emulsion lead to disintegrations accompanied by the emission of charged particles. The average number of prongs per disintegration produced by the capture of negative μ-mesons is 0.10 ± 0.02 The mean number of prongs and the associated prong distribution suggest that a nuclear excitation of about 15 MeV is produced by the capture of a μ-meson