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Future of Neutrino Research
Lead, South Dakota, population 3,500, a banner
hangs at City Hall proclaiming February 23, 2001, as Neutrino Day. Physicists,
as Dr. Kenneth Lande will attest, get treated very well around here. Mining
operations at the Homestake gold mine, where solar neutrinos were first
detected, will end this year, but Lande, a Penn physics professor, is
part of an effort to convert the space into the Homestake National Underground
Science Laboratory, which would be the premier world location for underground
science. Its organizers are seeking $281 million from the National Science
Foundation. Every death is followed by a birth, says Lande, speaking
from 4,850 feet below the ground, where hes trying to organize the transition
from mine to lab. He says 35 letters of interest have already come
in from physics, biology, and geology researchers who want to use the
lab in a variety of experiments, some involving neutrinos. He expects
Penn to play a major role in the facility.
the meantime, scientists at the Sudbury Neutrino Observatory (SNO) will
continue refining their understanding of how neutrinos transform from
one type to another. After SNO, other questions remain to be answered
about these particles: What are their masses? Does another hidden flavor
exist? According to Lande, there may be a fourth type of sterile neutrinos,
which dont engage in the kinds of reactions the others do.
possibility the next generation of experiments will examine, says Lande,
is whether there are variations in neutrino signals depending on the time
of day or night, or as a function of the seasons. During the day an underground
detector is separated from the suns output of neutrinos by a mile or
so of Earth. At night, there would be 8,000 miles between Earth and the
suns output. Whats the effect on neutrinos as they go through the Earth?
Are there some more neutrino flavor changes as they pass through Earth?
those inquiries, Lande says, now the neutrino can be used to probe the
center of the sun and find out whether it varies its behavior over time.
The neutrino can also be used as a probe to see inside a supernova formed
when a star collapses: Because some exciting things happen there in a
very short period of time.
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