Roger Rusack
Professor of Physics
University of Minnesota

Our understanding of the fundamental constituents of nature requires that a
tau neutrino exist as a partner to the tau lepton discovered 25 years ago at
SLAC.  The definitive proof of the existence of a neutrino has always been
to observe its interaction with matter and determine the identity of the
lepton produced.  The DONUT (Direct Observations of NU Tau) experiment used
a Fermilab high-energy proton beam to produce neutrinos and then detected
the interaction of those neutrinos producing tau leptons.  This talk will
describe the experiment, its difficulties, and the results obtained.