Bubble Fusion

Bubble fusion, the apparent generation of fusion energy through the violent collapse of bubbles in a liquid tank, has been reported in a paper about to be published in Physical Review E (Taleyarkhan et al., upcoming, probably March 2004). The paper, a followup to a controversial report published two years ago (Update 579), describes "statistically significant neutron and gamma ray emissions" after sound waves and pulsed neutrons hit a chilled liquid acetone tank spiked with deuterium fuel.

The researchers (Rusi Taleyarkhan, formerly at Oak Ridge but now at Purdue, 765-494-0198, rusi@purdue.edu) report the observation of flashes of light (sonoluminescence) as well as the emission of neutrons with energies of less than or equal to 2.5 MeV---what you would expect if pairs of deuterium nuclei were fusing together to produce energy in their setup.

While the researchers describe various improvements to their experimental setup, in response to comments received on their original paper 2 years ago, critics (including Aaron Galonsky, Michigan State, galonsky@nscl.msu.edu) still have a number of concerns. According to Galonsky, the authors have not demonstrated that the sonofusion data for neutron emission is free of gamma-rays. While separating neutron and gamma-ray signals is challenging, it is necessary to have a clean neutron-only spectrum to have an unambiguous demonstration of nuclear fusion.

Willy Moss of Livermore (925-422-7302, wmoss@llnl.gov) says "Although I believe that thermonuclear sonofusion [not to be confused with cold fusion] may not be impossible...I am still not convinced... I believe that additional tests need to be done and many should have been performed and discussed in the paper, for example...if neutrons are being generated, then how about moving the scintillator further away from the sample to see if the signal decreases, due to the decreasing solid angle of the detector?"

(Other experts, Richard Lahey, RPI, laheyr@rpi.edu, 518-276-6614, a co-author on the paper; Mike Saltmarsh, Oak Ridge, 865-576-6915, saltmars@mail.phy.ornl.gov, co-author of a paper that attempted to duplicate the initial results but reported a null result---see Shapira and Saltmarsh, Phys Rev Lett, 19 August 2002)