[SEMINARI]: Neutrinos have mass and oscillate

[Arcadi Santamaria]

------------ próxima parte ------------
                     University of Hawaii Press Release

                                 EMBARGOED
                   until Noon JUNE 5 Japan Standard Time,
               11PM EDT June 4, 8PM PDT June 4, 5PM HST June 4

Contacts:
Cheryl Ernst, 808 956-8856, ernst en hawaii.edu, University Relations
John Learned, 808 956-2964, jgl en uhheph.phys.hawaii.edu, Department of
Physics and Astronomy

Mass and Oscillations Discovered for Elusive Neutrino

A team of Japanese and American physicists have produced evidence of mass
and oscillations in neutrinos, elementary particles that individually have
the smallest mass yet collectively may account for much of the mass of the
universe. In a paper to be presented at the Neutrino '98 Conference in Japan
on June 5 and submitted to the leading physics journal, the scientists
present evidence that the ghostly elementary particles called neutrinos do
possess mass and that they alternately change their identities in time as
they travel.
The results come from the first two years of data from Super-Kamiokande, a
$100 million experiment in a 12.5-million-gallon, stainless steel-lined
cavity carved out beneath the Japanese alps, filled with ultra pure water
and observed by 13,000 large area light detectors.

One of the three kinds of neutrinos, the muon flavor, has been found to
disappear and reappear as it travels hundreds of kilometers through the
earth. The energy and flight distance, from neutrino production in the
atmosphere by cosmic radiation to the underground instrument, provide a
measure of the difference between neutrino masses. This mass, while the
smallest yet observed for elementary particles, is still sufficient that the
relic neutrinos made in staggering numbers at the time of the Big Bang,
account for much of the mass of the universe.

"These new results could prove to be the key to finding the holy grail of
physics, the unified theory," observes University of Hawaii Professor of
Physics and Astronomy John Learned, one of the authors. "Neutrinos cannot
now be neglected in the bookkeeping of the mass of the universe. One only
gets such great data once or twice in a professional lifetime, maybe never."

The Super-Kamiokande Collaboration will make a major statement June 5 at the
Neutrino '98 Conference in Takayama, Japan. (See the XVIII International
Conference on Neutrino Astrophysics and Astrophysics web site at
www-sk.icrr.u-tokyo.ac.jp). A paper is being submitted at the time of this
release to Physical Review Letters, the premier journal of physics.

The collaboration is led by University of Tokyo's Institute for Cosmic Ray
Research and includes six U.S. groups (Boston University; University of
California, Irvine; University of Hawai'i; Louisiana State University; State
University of New York at Stony Brook; and the University of Washington) and
eight from Japan (Gifu University, High Energy Research Organization (KEK),
Kobe University, Niigata University, Osaka University, Tohoku University,
Tokai University and Tokyo Institute of Technology) as well as other
collaborators from both countries.

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