Chronology of Milestone Events in Particle Physics - CHRETIEN 1962
Chronology of Milestone Events in Particle Physics


Chretien, M. et al.
Evidence for Spin Zero of the from the Two Gamma-Ray Decay Mode
Phys. Rev. Lett. 9 (1962) 127;

Recent experiments by Pevsner et al. (Phys. Rev. Lett. 7 (1961) 421) and others (Bastien et al., Phys. Rev. Lett 8 (1962) 114) report the existence of a mass 546 MeV particle (called the ) which has both charged and neutral modes of decay. The charged mode of decay is + o. Present experimental evidence assigns isotopic-spin zero to this particle.
The original work was done in the reaction + d p p .(1) The proton in the deuteron plays a spectator role, hence the primary reaction is + n p . The cross section reported for the charged mode of decay of the is 0.22 0.06 mb and the cross section measured for the neutral modes of decay is 0.8 0.2 mb. The experiment of reference 4 reports a flat plateau for the cross section in the region from 1700-1850 MeV, total energy in the center-of-mass system. The experiment reported here makes use of the reaction p n .(2) From charge symmetry, reaction (2) will have the same cross section as reaction (1) at the same energy. This experiment covers an energy band from 1707-1740 MeV and thus one expects a production cross section for the of about 1 mb. (Extracted from the introductory part of the paper.).

Accelerator BNL-COSMOTRON Detectors HLBC-50LIT

Related references
Analyse data from
A. Pevsner et al., Phys. Rev. Lett. 7 (1961) 421;
D. D. Carmony, A. H. Rosenfeld, and R. T. van de Walle, Phys. Rev. Lett. 8 (1962) 117;
P. Bastien et al., Phys. Rev. Lett. 8 (1962) 114;

  p n 2 1140 MeV (Plab) mass
  p n 1140 MeV (Plab) cs

Particles studied

Record comments
Confirmation of the existence and evidence for spin zero of the meson.
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