The Tech - Online EditionMIT's oldest and largest
newspaper & the first
newspaper published
on the web
Boston Weather: 74.0°F | Mostly Cloudy

PFC results said to deal blow to fusion claims

By David P. Hamilton

MIT researchers at the Plasma Fusion Center have dealt a heavy blow to claims of "cold fusion" promulgated by University of Utah researchers Stanley Pons and Martin Fleischmann, according to PFC Research Scientist Richard D. Petrasso.

Fleischmann and Pons claimed in late March to have produced nuclear fusion with a laboratory bench apparatus consisting of palladium rods immersed in a bath of deuterium, or heavy water. The scientists said their device emitted neutrons and gamma rays, which are certain signatures of nuclear, as opposed to chemical, reactions.

Recent work at the PFC, however, raises serious questions about the data Fleischmann and Pons have used to support their claims.

According to the theory offered by Fleischmann and Pons, the fusion reaction should produce a neutron and a helium-3 atom for each fusion of two deuterium atoms. The neutron in turn collides with a hydrogen ion from a water molecule to create another deuterium atom and a high-energy gamma ray, according to the theory.

Petrasso's research team placed a neutron-generating source in a water tank in order to observe the spectrum of gamma rays emitted from collisions between water molecules and neutrons.

Unfortunately for the Pons/Fleischmann theory, Petrasso's research revealed that the gamma ray spectrum could not have resulted from the reaction they described. "It does not work," Petrasso said. "The claim that they saw gamma rays from fusion is specious."

Furthermore, Petrasso said that Pons and Fleischmann had overestimated the number of emitted neutrons by a factor of 40. Calculations based on Petrasso's "absolutely calibrated" neutron source revealed a rate of gamma ray emission 40 times higher than a rate that can be calculated from the Fleischmann/Pons results, Petrasso said.

The PFC research gave no indication as to the reason for the Fleischmann/Pons error except to suggest that an instrumental artifact might bear the blame. The experimental results have been submitted to the refereed British journal Nature for publication.

Petrasso's refutation of the Fleischmann/Pons neutron-gamma ray interaction does not completely rule out the possibility that cold fusion might be occurring. The Utah experimenters also reported observing an energy increase of four times over that supplied to the experimental apparatus, a result obtained by complicated heat measurements. The PFC results offer no insight regarding the possibility or impossibility of these calorimetry claims.

Similarly, these experiments do not significantly affect the viability of the theoretical model of cold fusion offered by MIT Associate Professor Peter L. Hagelstein '76, who has proposed that a very rare reaction dominates the fusion process. In Hagelstein's theory, two deuterium atoms fuse to create a helium-4 atom and excess energy, which is absorbed by the palladium lattice structure as heat instead of radiating away as a gamma ray.

Hagelstein said he'd been advised not to speak to the press, but did say he has not withdrawn any of the four papers outlining his theory he has submitted to Physical Review Letters.

Petrasso said Hagelstein's theory could still prove to be true, although he said he remains skeptical. For one thing, the rare reaction Hagelstein describes happens in free space only about one ten-millionth as often as the more common reaction Pons and Fleischmann used. For another, the absorption of excess energy by the palladium lattice is unsupported by much physical evidence.

"It's two incredibilities," Petrasso said. "Most people think that's unlikely." He added that the Fleischmann/Pons calorimetry could still prove to be correct, although it is now being "heavily questioned."

Another research team at the PFC, led by research scientist Stanley C. Luckhardt, has been attempting to duplicate the actual Fleischman/Pons experiment, so far without success.