APS Physics Tip Sheet #59

News from the American Physical Society

Sonofusion Bubbles Up
R. P. Taleyarkhan, C. D. West, R. T. Lahey Jr., R. I. Nigmatulin, R. C. Block, Y. Xu
Physical Review Letters (upcoming article, available to journalists on request)

Sonofusion works, according the latest volley in the argument over the feasibility of acoustically driven nuclear fusion. A collaboration of researchers from Purdue University and Rensselaer Polytechnic Institute has detected neutrons, with energies typical of certain fusion reactions, emanating from a container of a specially prepared mixture of benzene and acetone that was exposed to high frequency sound waves. The sound waves produce tiny bubbles, which expand and then rapidly contract, generating high temperatures that the researchers believe lead to nuclear fusion reactions. The group announced similar results about two years ago, but faced ardent criticism over aspects of their experimental set up that could have created false positives in their data. In the earlier experiments they had used a beam of neutrons in an attempt to initiate the bubbles leading to sonofusion reactions. Critics claimed the beam could have been mistaken for neutrons emitted by fusion reactions. In the new experiments, the researchers dissolved natural uranium into the solution, which acts as a source of bubble-initiating neutrons. They claim that the new technique eliminates any confusion in identifying the neutrons they measured coming from the experiment as the products of sonofusion reactions.

Stringy Water
M.V. Fernandez-Serra and Emilio Artacho
Physical Review Letters (upcoming article, available to journalists on request)

Water molecules join up in long, squirming filaments, according to researchers at the Universite Claude Bernard Lyon in France and Universidad del Pais Vasco in Spain. Based on water's molecular structure, scientists had long assumed that water molecules associated with each other through net-like webs. But x-ray studies in 2004 showed signs of stringy connections between water molecules. The new research confirms the existence of watery filaments through a study of the electronic bonds between molecules, which the researchers claim provides a clearer picture of water molecule interactions. The water filaments, it turns out, form strings of molecules that effectively hold hands via their hydrogen atoms, changing partners and redefining their molecular Conga lines at a rate of once every 170 femtoseconds (170 millionths of a billionth of a second) or so.

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