First Measurement of Geoneutrinos at KamLAND (Forwarded)

Communications Department
Lawrence Berkeley National Laboratory

Contact:
Lynn Yarris,

July 27, 2005

First Measurement of Geoneutrinos at KamLAND

BERKELEY, CA -- Results from KamLAND, an underground neutrino detector
in central Japan, show that anti-electron neutrinos emanating from the
earth, so-called geoneutrinos, can be used as a unique window into the
interior of our planet, revealing information that is hidden from other
probes.

"This is a significant scientific result," said Stuart Freedman, a
nuclear physicist with a joint appointment at the Lawrence Berkeley
National Laboratory (Berkeley Lab) and the University of California at
Berkeley, who is a co-spokesperson for the U.S. team at KamLAND, along
with Giorgio Gratta, a physics professor at Stanford University.

"We have established that KamLAND can serve as a unique and valuable
tool for the study of geoneutrinos with wide-ranging implications for
physical and geochemical models of the earth," Freedman added.

In a paper presented in the July 28, 2005 issue of the journal Nature,
an international collaboration of 87 authors from 14 institutions spread
across four nations has demonstrated the ability of the KamLAND
detectors to accurately measure the radioactivity of the uranium and
thorium isotopes, the two main sources of terrestrial radiation. The
measurements the collaborators made are in close agreement with the
predictions of the leading geophysical models of our planet's thermal
activities.

KamLAND's geoneutrino experiment was funded by the U.S. Department of
Energy's Office of Science, and the Japanese Ministry of Education,
Culture, Sports, Science and Technology.

Our Mysterious Inner Planet

Surprising as it may seem, for all that we have learned about far
distant astrophysical events like deep-space supernovae, dark energy, or
even the Big Bang itself, the interior of our own planet remains a
mysterious and largely unexplored frontier. Among the many questions is
the source of terrestrial heat. The total amount of heat given off by
the earth at any given moment has most recently been estimated at about
31 terawatts (TW). A terawatt is equivalent to one trillion watts. For
comparison, the average energy consumption of the United States at any
given moment is 0.3 trillion watts.

Much of this heat is re-radiated energy from the sun, but nearly half is
produced from the earth's interior. Radioactivity is known to account
for some of this heat, but exactly how much has been difficult to say
because, until now, there has been no accurate means of measuring
radiogenic heat production.These latest experimental results from
KamLAND indicate that is no longer the case.

"Our results show that measuring the flux of Earth's geoneutrinos could
provide scientists with an assay of our planet's total amount of
radioactivity," said Freedman. "Measuring geoneutrinos could also serve
as a deep probe for studying portions of the planet that are otherwise
inaccessible to us."

Said Stanford's Gratta, "There are still lots of theories about what's
really inside the earth and so it's still very much an open issue. The
neutrinos are a second tool, so we're doubling the number of tools
suddenly that we have, going from using only seismic waves to the point
where we're doing essentially simple-minded chemical analysis."

Added physics Professor Atsuto Suzuki, director of the Research Center
for Neutrino Science, vice president of Tohoku University and
spokesperson for the Japanese team at KamLAND, "We now have a diagnostic
tool for the Earth's interior in our hands. For the first time we can
say that neutrinos have a practical interest in other fields of science."

Dennis Kovar, Associate Director for Nuclear Physics of DOE's Office of
Science, agreed with Suzuki. "I believe the results of the multinational
KamLAND collaboration are very interesting and indicate that science has
a new, powerful tool for peering deep into the core of our planet."

KamLAND and Neutrinos

KamLAND stands for Kamioka Liquid scintillator Anti-Neutrino Detector.
Located in a mine cavern beneath the mountains of Japan's main island of
Honshu, near the city of Toyama, it is the largest low-energy
anti-neutrino detector ever built. KamLAND consists of a weather
balloon, 13 meters (43 feet) in diameter, filled with about a kiloton of
liquid scintillator, a chemical soup that emits flashes of light when an
incoming anti-neutrino collides with a proton. These light flashes are
detected by a surrounding array of 1,879 photomultiplier light sensors
which convert the flashes into electronic signals that computers can
analyze. The photomultipliers are attached to the inner surface of an 18
meters in diameter stainless steel sphere and separated from the weather
balloon by a buffering bath of inert oil and water which helps suppress
interference from background radiation.

Neutrinos and their anti-matter counterpart, anti-neutrinos, are
subatomic particles that interact so rarely with other matter they can
pass untouched through a wall of lead stretching from the earth to the
moon. Neutrinos are produced during nuclear fusion, the reaction that
lights the sun and other stars. Anti-neutrinos are created in fission
reactions, such as those that drive nuclear power plants, and in
radioactive nuclei, such as uranium and thorium, that emit an electron
and an anti-electron neutrino when they decay.

Anti-neutrinos, like neutrinos, come in three different types or
"flavors," electron, muon and tau, with the anti-electron neutrino, or
geoneutrino, being by far the most common. Geoneutrinos can be detected
and measured at KamLAND via a distinctive reaction signature after the
subtraction of anti-neutrinos captured from nearby reactors and in
background events from alpha particles.

"KamLAND is the first detector sensitive enough to measure geoneutrinos
produced in the earth from the decay of uranium- 238 and thorium- 232,"
said Freedman. "Since the geoneutrinos produced from the decay chains of
these isotopes have exceedingly small interaction cross sections, they
propagate undisturbed in the earth's interior, and their measurement
near the earth's surface can be used to gain information on their sources."

In measuring geoneutrinos generated in the decay of natural radioactive
elements in the earth's interior, scientists believe it should be
possible to get a three-dimensional picture of the earth's composition
and shell structure. This could provide answers to such as questions as
how much terrestrial heat comes from radioactive decays, and how much is
a "primordial" remnant from the birth of our planet. It might also help
identify the source of Earth's magnetic field, and what drives the
geodynamo.

The U.S. team at KamLAND includes researchers from Berkeley Lab, UC
Berkeley and Stanford, plus the California Institute of Technology, the
University of Alabama, Drexel University, the University of Hawaii,
Louisiana State University, the University of New Mexico, the University
of Tennessee, and the Triangle Universities Nuclear Laboratory, a
DOE-funded research facility located at Duke University, and staffed by
researchers with Duke, North Carolina and North Carolina State universities.

Berkeley Lab is a U.S. Department of Energy national laboratory located
in Berkeley, California. It conducts unclassified scientific research
and is managed by the University of California. Visit our Website at
http://www.lbl.gov

Additional Information

Stuart Freedman
510-486-7850

Giorgio Gratta, Physics
(650) 725-6509

Atsuto Suzuki
Research Center for Neutrino Science, Tohoku University, Japan
+81-22-795-6720 and +81-22-217-5123

KamLAND Websites with images can be accessed at
http://hep.stanford.edu/neutrino/KamLAND/KamLAND.html
and
http://kamland.lbl.gov/

The Japanese KamLAND Website can be accessed at
http://www.awa.tohoku.ac.jp/html/KamLAND/

[NOTE: Images supporting this release are available at
http://www.lbl.gov/Science-Articles/...neutrinos.html ]

In article ,
Andrew Yee wrote:

Our Mysterious Inner Planet

Surprising as it may seem, for all that we have learned about far
distant astrophysical events like deep-space supernovae, dark energy,
or even the Big Bang itself, the interior of our own planet remains a
mysterious and largely unexplored frontier. Among the many questions
is the source of terrestrial heat. The total amount of heat given off
by the earth at any given moment has most recently been estimated at
about 31 terawatts (TW). A terawatt is equivalent to one trillion
watts. For comparison, the average energy consumption of the United
States at any given moment is 0.3 trillion watts.

Much of this heat is re-radiated energy from the sun, but nearly half
is produced from the earth's interior. Radioactivity is known to
account for some of this heat, but exactly how much has been
difficult to say because, until now, there has been no accurate means
of measuring radiogenic heat production.These latest experimental
results from KamLAND indicate that is no longer the case.

The incoming radiative power from the Sun on the Earth is very nearly
1400 watts per square meter on a surface perpendicular to the direction
to the Sun. This means that the Earth receives some 1.78E+17 watts
which is the same as 178,000 Terawatts. Some 35% of this is reflected
to space, which means that approx. 115,000 Terawatts of the Sun's
radiation is absorbed by the Earth.

Compared to this, 31 Terawatts appears quite negligible. As a matter
of fact, if the heat balance of the Earth is to be preserved, those
115,000 Terawatts from the Sun must be reradiated too. If the weren't,
the oceans would be heated to the boiling point in only somewhat less
than two years....

--
----------------------------------------------------------------
Paul Schlyter, Grev Turegatan 40, SE-114 38 Stockholm, SWEDEN
e-mail: pausch at stockholm dot bostream dot se
WWW: http://stjarnhimlen.se/

(Paul Schlyter) wrote in :

As a matter
of fact, if the heat balance of the Earth is to be preserved, those
115,000 Terawatts from the Sun must be reradiated too.

Not true. Much of that energy is absorbed by chlorophyll and stored in
carbohydrates.

In message , Andrew Yee
writes
Communications Department
Lawrence Berkeley National Laboratory

Contact:
Lynn Yarris,

July 27, 2005

First Measurement of Geoneutrinos at KamLAND



"KamLAND is the first detector sensitive enough to measure geoneutrinos
produced in the earth from the decay of uranium- 238 and thorium- 232,"
said Freedman. "Since the geoneutrinos produced from the decay chains
of these isotopes have exceedingly small interaction cross sections,
they propagate undisturbed in the earth's interior, and their
measurement near the earth's surface can be used to gain information on
their sources."

Interesting that they are looking at uranium/thorium and not
potassium-40.
Could this tell us anything about Marvin Herndon's theory?
--
Remove spam and invalid from address to reply.

"John Schutkeker" wrote in message
3.158...
(Paul Schlyter) wrote in :

As a matter
of fact, if the heat balance of the Earth is to be preserved, those
115,000 Terawatts from the Sun must be reradiated too.

Not true. Much of that energy is absorbed by chlorophyll and stored in
carbohydrates.

Photosynthesis has a woefully low efficiency, on the order
of 1%.