 |
| Sudbury
Neutrino Observatory in Canada |
A neutrino is created, along with
an electron, when the nucleus of an
atom disintegrates through beta decay.
Neutrinos are produced, for example,
in the nuclear reactions that fuel
the burning of stars, such as the
Sun. But for some reason, fewer electron
neutrinos reach the Earth than would
be expected based on known solar processes.
This phenomenon was first suggested
by observations at the oldest solar
neutrino detector (in South Dakota),
for which Raymond Davis of Brookhaven
National Laboratory won the 2000 Wolf
Prize, and a detector in Japan. The
results were confirmed in the 1990s
by precise radiochemical experiments
called SAGE and GALLEX, supported
by the Office of Science. These experiments
differ in design from the previous
two and detect neutrinos of different
energy levels. SAGE and GALLEX also
stimulated searches for neutron oscillations
(conversion from one type to another),
because solar neutrinos may change
as they journey from the Sun to the
Earth. The search for the missing
solar neutrinos continues, led by
Sudbury Neutrino Observatory in Canada
in an effort that involves several
national laboratories, and another
group in Japan (also involving Americans).
Scientific Impact:
Studies of neutrinos have significant
effects on theories in physics, astronomy,
and cosmology. Because of these experiments,
many physicists and astronomers now
believe that the missing neutrinos
are due not to a faulty understanding
of how the Sun works, but rather to
an overly simplistic view of neutrino
behavior.
Social Impact: Research
on solar neutrinos could be the key
to finding the Holy Grail of physics,
the so-called unified theory that
goes beyond the present Standard Model
in explaining matter and the forces
of nature. Thus, this research may
lead to new understanding of the universe
and the place of humans in it.
Reference: "Solar
Neutrino Experiments: The Next Generation,"
Bahcall et al., Physics Today
July: p. 30 (1996).
URL:
http://zebu.uoregon.edu/~soper/Sun/solarneutrinos.html
Technical Contact:
Dr. Peter Rosen, peter.rosen@science.doe.gov
Press Contact: Jeff
Sherwood, DOE Office of Public Affairs,
202-586-5806
SC-Funding Office:
Office of High Energy and Nuclear
Physics |
