Describe one of the discovery experiment for the elementary particle
or interaction of the Standard Model:
  --> of positron by Anderson (1932)
  --> of muon by Anderson and Neddermeyer (1937)
  --> of pion (lightest muon) by Powel (1947)
  --> of electron anti-neutrino by Cowan and Reimes (1957)
  --> of J/Psi at Brookhaven and SLAC (1974)
  --> P violation in EW interactions by C. S. Wu