Name

Leptons

Name

Symbol

Mass

Lifetime

Charge

Spin

Date

Source

Note

Family 1

Electron	e	0.511 Mev	Stable	-1	1/2	1897	Cathode Ray Tube (Carrier of Electricity)	Common Matter, Discovered By J.J. Thompson
Positron	e +	0.511 Mev	Stable	+1	1/2	1932	Cosmic Radiation	Common Anti-Matter Formed by Cosmic Radiation
Electron Neutrino	v _e	0 (?) < 50 ev	Stable (?)	0	1/2	1956	Nuclear Reactor	Common Matter, Produced by Weak Force
Electron Anti-Neutrino	v _e	0 (?) < 50 ev	Stable (?)	0	1/2	1956	Nuclear Reactor	Common Anti-Matter, Produced by Weak Force

Family 2

Muon		105.6	2x10^-6	-1	1/2	1937	Cosmic Radiation Pion, Kaon -> Muon	Uncommon Matter
Anti -Muon		105.6	2x10^-6	+1	1/2	1937	Cosmic Radiation	Uncommon Matter, Compose Cosmic Radiation
Muon Neutrino	v _u	0 (?) < .5 Mev	Stable (?)	0	1/2	1962	Pion Decay in	Uncommon Matter,
Muon Anti-Neutrino	v _u	0 (?) < .5 Mev	Stable (?)	0	1/2	1962	Pion Decay in Accelerators	Uncommon Matter Produced by Weak Force

Family 3

Tau	t +	1.784 Gev	3x10^-13	-1	1/2	1975	Electron-Positron Annihilation	Rare Matter
Anti-Tau	t -	1.784 Gev	3x10^-13	+1	1/2	1975	Electron-Positron Annihilation	Rare Anti-Matter
Tau Neutrino	v_t	0 (?) < 70 Mev	Stable (?)	0	1/2	---	Inferred from Tau Decay	Rare Matter
Tau Anti-Neutrino	v_t	0 (?) < 70 Mev	Stable (?)	0	1/2	---	No Direct Generation	Rare Anti-Matter