From: Blunderov (squooker@mweb.co.za)
Date: Mon Mar 15 2004 - 03:21:29 MST
[Blunderov] Perhaps we will now need some sort of scrutinizing mechanism
for the contents of home chemistry kits?
Best Regards
<q>
Bubble fusion makes controversial return
4 March 2004
The physicist who claimed to have observed nuclear fusion in a beaker of
acetone two years ago has published new data to back up his claim. Rusi
Taleyarkhan, now at Purdue University in Indiana, and colleagues say
that fusion neutrons and tritium are produced when the acetone is
subjected to intense sound waves in a table-top sonoluminescence
experiment (R Taleyarkhan et al. 2004 Phys. Rev. E to be published).
However, other physicists continue to doubt the experiment.
In sonoluminescence, the bubbles in a liquid emit light when they are
forced to expand and collapse by sound waves. Physicists believe that
the pressures and temperatures inside the collapsing bubbles could be
high enough to initiate nuclear reactions. If achieved, such "bubble
fusion" could lead to a new clean energy source.
In a controversial paper published in Science in March 2002 Taleyarkhan
and co-workers described how they had used high-energy neutrons to
create tiny bubbles of gas in a beaker of acetone in which the hydrogen
atoms had been replaced by deuterium (D). Taleyarkhan, who was then
based at the Oak Ridge National Laboratory, claimed that the temperature
inside the collapsing bubbles was in excess of a million degrees - high
enough for two deuterium nuclei to undergo a fusion reaction (Science
295 1868). DD fusion reactions can produce a helium-3 nucleus plus a
neutron, or a tritium nucleus and a proton.
However, the results were questioned by many researchers in the field.
Now, Taleyarkhan says his team has repeated the experiment with more
sensitive detectors. "A fair amount of very substantial new work has
been conducted," he said in a press release issued by Purdue. "And this
time I made a conscious decision to involve as many individuals as
possible - top scientists and physicists from around the world and
experts in neutron science."
As before, the team claims to detect tritium as well as neutrons with
the characteristic energy for DD fusion reactions. Moreover, the fusion
products are not observed in experiments with ordinary acetone.
Taleyarkhan says that chances of the result being due a phenomenon other
than fusion have been reduced from 1 in 100 to 1 in 1011.
Michael Saltmarsh of Oak Ridge says he is "intrigued but sceptical"
about the new work. "Unlike their Science paper, most of the background
notes and supporting information seem to be correct but there are still
some puzzling inconsistencies," he told PhysicsWeb. "In particular, the
estimated neutron detection efficiency is still an order of magnitude
too low. While better than the Science article, the difference would
produce a mismatch between the reported neutron and tritium yields."
"Thermonuclear sono-fusion may not be impossible," says Willy Moss of
the Lawrence Livermore National Lab, "but more tests need to done.
Personally, I would like the results to be real, but I believe that the
nature of these claims requires absolute proof."
"When a startling new discovery is announced, it is the responsibility
of the authors to lay things clear," adds Aaron Galonsky of Michigan
State University. "Taleyarkhan and co-workers have not done that well
enough for me to be able to say whether they have seen nuclear fusion in
a bottle of acetone. With two million 14 MeV neutrons per second
injected into the room where the experiment was performed, there are
opportunities for error in detecting the much rarer, lower-energy
sonoluminescent neutrons."
</q>
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