Chronology of Milestone Events in Particle Physics - KALBFLEISCH 1964
Chronology of Milestone Events in Particle Physics

  Nobel prize to L. W. Alvarez awarded in 1968 "for his decisive contribution to elementary particle physics, in particular the discovery of a large number of resonance states, made possible through his development of the hydrogen bubble chamber technique and data analysis''  

KALBFLEISCH 1964

Kalbfleisch, G.R.; Alvarez, L.W.; Barbaro-Galtieri, A.; Dahl, O.I.; Eberhard, P.H.; Humpfrey, W.E.; Lindsey, J.S.; Merrill, D.W.; Murray, J.J.; Rittenberg, A.; Ross, R.R.; Shafer, J.B.; Shively, F.T.; Siegel, D.M.; Smith, G.A.; Tripp, R.D.;
Observation of a Nonstrange Meson of Mass 959 MeV
Phys. Rev. Lett. 12 (1964) 527;

Summary
We present here evidence showing the existence of a nonstrange meson of mass 959 MeV.
In the current experiment, the 72-in. hydrogen bubble chamber was exposed to a separated beam of 2.45, 2.63, and 2.70 BeV/c K- mesons from the Bevatron. Approximately 370000 pictures were taken to date; approximately 300000 have been scanned ... Figure 1(a) shows clearly the existence of the 959 MeV meson as an enhancement in the + + 0 - - spectrum from reaction (K- p + + 0 - -). The mass is 959 2 MeV and the full width is < 12 MeV. We observe 35 events in the interval 0. 86 < M2(5) < 0. 98 BeV2. The background is estimated to be less than 10% of the peak ... (Extracted from the introductory part of the paper.).

Accelerator LBL Detectors HBC-72IN

Related references
See also
M. Gell-Mann and J. Schwinger, Phys. Rev. Lett. 12 (1964) 237;
M. Goldberg et al., Bull.Am.Phys.Soc. 9 (1964) 23;

Reactions
  K p + o 2.45,2.63,2.7 GeV (Plab) mass
  K p + 2.45,2.63,2.7 GeV (Plab) mass
  K p neutral (neutrals) 2.45,2.63,2.7 GeV (Plab) mass
  K p + (neutrals) 2.45,2.63,2.7 GeV (Plab) mass
  K p 2+ 2 2.45,2.63,2.7 GeV (Plab) mass
  K p 2+ o 2 2.45,2.63,2.7 GeV (Plab) mass
  K p 2+ 2 (neutrals) 2.45,2.63,2.7 GeV (Plab) mass

Particles studied
  mesono ex, mass
  ' ex, mass

Record comments
First evidence for the ' meson.
    
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