More exotic research reports
Posted on Wednesday, September 28, 2005 @ 21:10:19 UTC by vlad
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NUCLEAR SEISMOLOGY. Physicists at the GSI lab in Darmstadt,
Germany have discovered a new excited nuclear state, one in which a
tide of neutrons swells away from the rest of the nucleus.
Ordinarily, in its unexcited state, a typical atomic nucleus consists
of a number of constituent neutrons and protons (collectively known as
nucleons) bobbing around inside a roughly spherical shape.
However, if struck by a projectile from outside, such as a beam
particle supplied by an accelerator, the nucleus can be set to
spinning, or it might distend. In one kind of excited mode called
a dipole resonance, the protons can move slightly in one direction
while the neutrons go the other way.
In another type of excitation, a nucleus might consist of a stable core
blob of nucleons surrounded by a surplus complement of one or two
neutrons, which constitute a sort of halo around the core (see
http://www.aip.org/pnu/2004/split/702-3.html ). In the new GSI
experiment, yet another nuclear mode has been observed. The nuclei
used, two isotopes of tin, are the most neutron-rich among the heavier
nuclei that can be produced at this time. Sn-130 and Sn-132 are so
top-heavy with neutrons that they are quite unstable and must be made
artificially in the lab. At GSI this is done by shooting a uranium
beam at a beryllium target. The U-238 nuclei, agitated by the
collision, eventually fission in flight, creating a swarm of more than
1000 types of daughter nuclei, from which the desired tin isotopes can
be extracted for study. The tin nuclei are excited when they pass
through a secondary target, made of lead. The excited tin states later
disintegrate; the debris coming out allows the researchers to
reconstruct the turbulent nature of the tin nuclei. The dipole
resonance was seen, as expected, but also a new resonance: an excess of
neutrons pushing off from the core nucleus. Furthermore, the neutron
resonance appears at a lower excitation energy than does the dipole
resonance. Team leader Hans Emling (h.emling@gsi.de) says that there
was some previous evidence for the existence for the neutron mode in
work with lighter nuclei, but not the actual oscillation observed in
the present work. (Adrich et al., Physical Review Letters, 23
September 2005.)
(From the PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics
News
Number 747 September 28, 2005 by Phillip F. Schewe, Ben Stein)
-------------------
PURDUE ENGINEERS CREATE SAFER, MORE EFFICIENT NUCLEAR FUEL, MODEL ITS
PERFORMANCE, September 28
Purdue University nuclear engineers have developed
an advanced nuclear fuel that could save millions of dollars annually by lasting
longer and burning more efficiently than conventional fuels, and researchers
also have created a mathematical model to further develop the
technology.
Full story at http://www.physorg.com/news6834.html
MATHEMATICS
UNITES THE HEAVENS AND THE ATOM, September 28
In recent years,
mathematicians have discovered an almost perfect parallel between the motion of
spacecraft through the solar system and the motion of atoms in a chemical
reaction - a hidden unity that has led to innovative new ways to design space
missions.
Full story at http://www.physorg.com/news6827.html
EXPLAIN
PHYSICS WITH THE WHOLE INSTEAD OF PARTICLES, September 28
Physicists usually
describe the world from the vantage point of its smallest component parts. But
quantum theory does not allow itself to be conceptually crammed into such a
framework. Instead, in her dissertation at Uppsala University in Sweden, Barbara
Piechocinska takes her point of departure in the mathematics of the dynamic
whole and finds that time thereby takes on new meaning.
Full story at http://www.physorg.com/news6820.html
'MISSING' DARK MATTER IS REALLY THERE, SAYS HEBREW UNIVERSITY COSMOLOGIST,
September 28
A new analysis that refutes challenges to the existence of dark
matter in certain galaxies appears in an article published this week in the
journal Nature. Leading author of the article is Avishai Dekel, professor of
physics at the Hebrew University of Jerusalem.
Full story at http://www.physorg.com/news6850.html
PHYSICISTS SAY UNIVERSE EVOLUTION FAVORED THREE AND SEVEN DIMENSIONS, September
28
Physicists who work with a concept called string theory envision our
universe as an eerie place with at least nine spatial dimensions, six of them
hidden from us, perhaps curled up in some way so they are undetectable. The big
question is why we experience the universe in only three spatial dimensions
instead of four, or six, or nine.
Full story at http://www.physorg.com/news6842.html
FORECASTERS
WARN OF MORE MAJOR HURRICANES, September 28
U.S. meteorologists say
conditions that spawned hurricanes Rita and Katrina still exist, creating the
likelihood of another intense hurricane next month.
Full story at http://www.physorg.com/news6838.html
ARCTIC SEA ICE CONTINUES DECLINE AS TEMPERATURES RISE, September 28
New
satellite records monitored by a national team of collaborators show a four-year
pattern of extremely low summer sea-ice coverage in the Arctic that continued in
September 2005, which may be the result of warming temperatures and earlier
spring melting.
Full story at http://www.physorg.com/news6835.html
'BIG
BABY' GALAXY FOUND IN NEWBORN UNIVERSE, September 28
The NASA/ESA Hubble
Space Telescope and NASA's Spitzer Space Telescope have teamed up to 'weigh' the
stars in distant galaxies. One of these galaxies is not only one of the most
distant ever seen, but it appears to be unusually massive and mature for its
place in the young Universe.
Full story at http://www.physorg.com/news6832.html
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