This is an old revision of this page, as edited by Chenyu (talk | contribs) at 05:45, 20 November 2001. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.
Revision as of 05:45, 20 November 2001 by Chenyu (talk | contribs)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)A neutrino is a neutral particle with very low mass, possibly zero. It has spin 1/2 and so is a fermion. It does not interact with the strong force or the electromagnetic force, but does interact with the weak force (and with gravity if it turns out to have mass).
Because the neutrino only interacts with the weak nuclear force the cross section is extremely low. It would take a light year of lead to block half the neutrinos flowing through it.
It comes in three varieties, the electron neutrino νe, the muon neutrino νμ, and the tau neutrino ντ.
See also solar neutrino problem, particle physics.