Electrically charged instable elementary particle with a rest energyBased on relativity theory, it is concluded that an equivale... of 105.658 MeVMegaelectron volt, 1,000,000 eV. corresponding to 206.786 times the rest energyBased on relativity theory, it is concluded that an equivale... of an electronElementary particle with a negative electrical elementary ch.... The muon has an average half-lifeThe period during which half of the nuclei decay in a quanti... of 2.2·10-6 s. The myon belongs to the elementary particle group of the leptons.