The third family of neutrinos

Abstract

This paper retraces the 24 years starting with the appearance of the symbol "${\nu }_{\tau }$" in 1977, until the observation of tau neutrino interactions with matter in 2000. The fact that the neutral particle present in tau decays was a neutrino was demonstrated by 1979; its existence as the third neutrino ${\nu }_{\tau }$, iso-spin partner of the tau lepton, was definitely established in 1981-1986; it was demonstrated that the number of light active neutrinos is closed with the known ones (${\nu }_e,{\nu }_{\mu },{\nu }_{\tau }$) in 1989; before 2000 the ${\nu }_{\tau }$ properties had been precisely determined in $e^{+}{e}^{-}$ and $p\bar{p}$ collider experiments.

Comments: Contribution to the Conference on the History of the Neutrino, Paris, 5-7 September 2018, 2d version corrected to improve rendering of references and a few other