http://www.newscientist.com/article/dn16820
Neutron tracks revive hopes for cold fusion
* 15:33 23 March 2009 by Colin Barras
* For similar stories, visit the Energy and Fuels Topic Guide
Twenty years to the day that two electrochemists ignited controversy by
announcing signs of cold fusion at an infamous press conference in Utah
(watch a video of the 1989 event), a separate team has made a similar
claim in the same US state. But this time, the evidence is being taken
more seriously.
Back in 1989, Martin Fleischmann and Stanley Pons at the University of
Utah announced the tantalising prospect of abundant, almost-free energy,
but their claims of fusion reactions in a tabletop experiment were
dismissed by nuclear physicists, not least because such reactions
normally occur inside stars. The small quantity of extra energy they
found was widely considered a fluke or the result of experimental error.
Now Pamela Mosier-Boss and colleagues at Space and Naval Warfare Systems
Command (SPAWAR) in San Diego, California, are claiming to have made a
"significant" discovery – clear evidence of the products of cold fusion.
On 23 March, the team presented its work at the American Chemical
Society's spring conference in Salt Lake City, Utah, a few months after
the study was published in a peer-reviewed journal (Naturwissenschaft,
DOI: 10.1007/s00114-008-0449-x).
Plastic fantastic
Using a similar experimental setup to Fleischmann and Pons, the
researchers found the "tracks" left behind by high-energy neutrons,
which, they suggest, emerge from the fusion of a deuterium and tritium atom.
The team used a low-tech particle detector: a plastic called CR-39 that
is otherwise used for spectacle lenses. When CR-39 is bombarded with
subatomic charged particles, a small pit forms in the material with each
impact.
The researchers placed a sample of CR-39 in contact with a gold or
nickel cathode in an electrochemical cell filled with a mixture of
palladium chloride, lithium chloride and deuterium oxide (D2O),
so-called "heavy water". When a current was passed through the cell,
palladium and deuterium became deposited on the cathode.
Triple tracks
After two to three weeks, the team found a small number of "triple
tracks" in the plastic – three 8-micrometre-wide pits radiating from a
point (see diagram, top right). The team says such a pattern occurs when
a high-energy neutron strikes a carbon atom inside the plastic and
shatters it into three charged alpha particles that rip through the
plastic leaving tracks. No such tracks were seen if the experiment was
repeated using normal rather than heavy water.
Johan Frenje at the Massachusetts Institute of Technology, an expert at
interpreting CR-39 tracks produced in conventional high-temperature
fusion reactions, says the team's interpretation of what produced the
tracks is valid.
"I must say that the data and their analysis seem to suggest that
energetic neutrons have been produced," he says, although he would like
to see the results confirmed quantitatively.
More controversial is the team's suggestion for the process that
produced the neutrons. High-energy neutrons are unlikely to be produced
by a normal chemical reaction, says Mosier-Boss. So, it's possible, she
says, they are created during the fusion of deuterium and tritium atoms
tightly packed in palladium framework at the cathode. The tritium also
being a product of the fusion of two deuterium atoms.
Some researchers in the cold fusion field agree. "In my view [it's] a
cold fusion effect," says Peter Hagelstein, also at the Massachusetts
Institute of Technology.
Alternative theory
Others, though, are not convinced. Steven Krivit, editor of the New
Energy Times, has been following the cold fusion debate for many years
and also spoke at the ACS conference. "Their hypothesis as to a fusion
mechanism I think is on thin ice … you get into physics fantasies rather
quickly and this is an unfortunate distraction from their excellent
empirical work," he told New Scientist.
Krivit thinks cold fusion remains science fiction. Like many in the
field, he prefers to categorise the work as evidence of "low energy
nuclear reactions", and says it can be explained without relying on
nuclear fusion.
In 2006, Allan Widom at Northeastern University in Boston and Lewis
Larsen of Lattice Energy, LLC, suggested that the key to the process was
oscillating surface plasmons – waves of energy rippling through
electrons on the surface of the electrode.
They said that the rough surface of the palladium on the electrode
focuses the energy into small pits, where it can be transferred to a
single electron. The high-energy electron can then shoot into the
nucleus of a nearby deuterium atom and combine with a proton to release
a neutron and a neutrino (European Physical Journal C, DOI:
10.1140/epjc/s2006-02479-8).
"Electrons and protons don't have trouble attracting," Widom told New
Scientist, and he says the explanation conforms to the Standard Model of
particle physics. He speculates that this theory could explain instances
of exploding laptop batteries, and could be harnessed as an energy
source – something Larsen's company hopes to commercialise.
Journal reference: Naturwissenschaft (DOI: 10.1007/s00114-008-0449-x)
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