[ RadSafe ] Bad news on the Cold Fusion front

[John Jacobus]

Story from news at nature.com:
http://news.nature.com//news/2006/060508/060508-8.html

Published online: 10 May 2006;

Bubble-fusion group suffer setback 
Team admits a mix-up with one of their neutron
detectors.

Eugenie Samuel Reich

A group of researchers making high-profile claims
about fusion energy has admitted to accidentally using
equipment different from that reported in their most
recent paper. 

An erratum providing details of the mistake by Rusi
Taleyarkhan of Purdue University and colleagues has
been published in Physical Review Letters1. Critics
interpret the admission as a sign that the group's
fusion claims2 are unravelling, because it comes in
the wake of serious questions about the original
work's validity (see 'Is bubble fusion simply hot
air?'). 

"Confusing detectors in a discovery of this magnitude
is an embarrassing mistake," says Seth Putterman of
the University of California, Los Angeles. But
Taleyarkhan and colleagues say that their data,
analysis and conclusions are not affected by the
error.

In January, Taleyarkhan published the most recent of a
series of papers in respected journals that claimed to
see neutrons characteristic of fusion reactions coming
from collapsing bubbles in organic fluids.

If validated, such work could pave the way for cheap,
green energy. Taleyarkhan claimed to have deployed
three independent methods of detecting these neutrons,
one of which was a boron trifluoride gas proportional
tube with a polyethylene covering. His erratum notes
that this actually turned out to be a lithium iodide
crystal scintillation detector, also with a
polyethylene covering.

According to the erratum, the error was discovered
"upon disassembly of the outer coverings" of the
detector and is due to "an oversight which was based
on incorrect information from a person's recollection
who loaned this apparatus for the study".

Knowing what you're working with

The mistake does not in itself invalidate the
experiment's conclusions, but experts say it casts
further doubt over the results. Neutron expert Mike
Saltmarsh of Oak Ridge National Laboratory in
Tennessee, where Taleyarkhan previously worked, points
out that doing a good technical job involves knowing
what detector is in use. 

"If you don't know what you're working with, you can
easily make mistakes," says Saltmarsh. 

Manuals provided by Ludlum Measurements, which
manufactures both types of detector, confirm that
different operating voltages and different calibration
checks are recommended for the two, for example.

Source of confusion

Brian Naranjo of the University of California, Los
Angeles, claimed in March that Taleyarkhan's observed
neutrons probably came from a standard lab source
rather than fusion reactions3. Naranjo based his study
on results from a different detector in Taleyarkhan's
setup.

Saltmarsh points out that the data from the lithium
iodide detector, as it is now known to be, are
consistent with Naranjo's claim. In Taleyarkhan's
experiment, the 'boron trifluoride' detector observed
high levels of gamma rays (-rays) alongside the
neutrons, despite the fact that boron trifluoride
detectors are not very sensitive to -rays. Taleyarkhan
and his colleagues suggest that neutrons from fusion
were interacting with the detector's polyethylene
coating to produce a slew of rays.

But the lithium iodide detector is more sensitive to
-rays, says Saltmarsh, and the lab source posited by
Naranjo could easily have provided enough for the
levels observed.

Taleyarkhan's co-author Robert Block, of Rensselaer
Polytechnic Institute in New York, disagrees. Block
says he and Taleyarkhan still think the observed -rays
are produced by fusion neutrons colliding in the
polyethylene covering, no matter what the detector.

A university review of Taleyarkhan's work is under way
and due to finish by 1 June.

 
References
Taleyarkhan R. P., et al. Physical Review Letters, 96.
179903 (2006).

Taleyarkhan R. P., et al. Physical Review Letters, 96.
034301 (2006).

http://xxx.lanl.gov/abs/physics/0603060 (submitted to
Physical Review Letters) 
 
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John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com

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