Cloud-Chamber Observations of the Heavy Charged Unstable Particles in Cosmic Rays

Phys. Rev. 90, 921 – Published 1 June 1953
H. S. Bridge, C. Peyrou, B. Rossi, and R. Safford


In a series of pictures taken with a multiplate cloud chamber, we have observed a number of charged unstable particles considerably heavier than π-mesons, of which some decay at rest (S particles) and some decay in flight (V± particles). In each case the charged decay product is a particle of mesonic mass. From our results, which are not yet completely conclusive, it appears that most of the observed events can be explained by the two-body decay of a single kind of particle. The evidence concerning the mass of this particle, its mean life, and the nature of the neutral decay product is discussed. Our observations are compared with those of other experiments.


  • Received 26 February 1953
  • Published in the issue dated June 1953

© 1953 The American Physical Society

Authors & Affiliations

H. S. Bridge, C. Peyrou*, B. Rossi, and R. Safford

  • Department of Physics and Laboratory for Nuclear Science, Massachusetts Institute of Technology, Cambridge, Massachusetts

  • *On leave of absence from the Laboratoire de l'Ecole Polytechnique, Paris, France.

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