Chronology of Milestone Events in Particle Physics - CARLSON 1950
Chronology of Milestone Events in Particle Physics

CARLSON 1950

Carlson, A.G.; Hooper, J.E.; King, D.T.;
Nuclear Transmutations Produced by Cosmic-Ray Particles of Great Energy. - Part V. The Neutral Meson
Phil. Mag. 41 (1950) 701;

Summary
The spectrum of the -radiation in the atmosphere at 70,000 ft has been determined by observation on the scattering of pairs of fast electrons recorded in photographic emulsions exposed in high-flying balloons. The detailed form of the spectrum is consistent with the assumption that the -rays originate by the decay of neutral mesons. It is found that the mass of the neutral-mesons is 295 ± 20 me, and that they are created in nuclear explosions with an "energy spectrum'' similar to that of the charged -particles. A method is described for determining the lifetime of the neutral mesons and their frequency of occurrence compared with charged -particles. The lifetime, o, is less than 5 x 10-14 sec. It may be possible to determine the lifetime, by observations of greater statistical weight, if it is longer than 2 x 10-14 sec. The ratio of the number of neutral mesons to charged mesons, produced in nuclear explosions of great energy, is equal to 0.45 ± 0.10.

Accelerator COSM Detectors EMUL

Related references
More (earlier) information appears in
U. Camerini et al., Phil. Mag. 40 (1949) 1073;
See also
M. F. Kaplon, B. Peters, and H. L. Brandt, Helv. Phys. Acta 23 (1950) 24;
P. H. Fowler, Phil. Mag. 41 (1950) 169;
R. Bjorklund et al., Phys. Rev. 77 (1950) 213;
O. Piccioni, Phys. Rev. 77 (1950) 1;

Reactions
  unspec nucleus X p
  unspec nucleus o X p, cs
  o 2

Particles studied
  o ex, w, mass

Record comments
Confirmation of the existence of the o, first estimation of the o lifetime.
    
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