Magazine article Science News

Wake Up, Little Surfers: Riding Waves toward Tabletop Accelerators

Magazine article Science News

Wake Up, Little Surfers: Riding Waves toward Tabletop Accelerators

Article excerpt

Many physics discoveries of the past century have emerged from giant particle accelerators costing up to billions of dollars and sprawling over acres. Now, three independent research groups in the United States, France, and England have simultaneously passed a major milestone toward a laser-based electron accelerator that could fit inside a room and cost only a fraction of the price of a conventional machine.

The new work pushes forward an accelerator scheme that uses extremely brief and intense laser pulses (SN: 9/5/98, p. 157). As each pulse plows through a puff of gas, it pulls electrons from the gas into its wake. Over distances hardly more than the thickness of a coin, such laser "wakefield" accelerators can pump electrons to high energies, the scientists report.

Whereas previous experiments demonstrated the principle behind wakefield accelerators, the energy of the electrons wasn't uniform enough for precision research, says Wim P. Leemans of the Lawrence Berkeley (Calif.) National Laboratory, leader of the team based in the United States.

That flaw has become a thing of the past. In back-to-back-to-back reports in the Sept. 30 Nature, each of the three teams reports finding virtually the same sweet spot of operating conditions. All the laser-driven apparatuses emit extremely brief, narrowly confined pulses of electrons in which all the particles in the pulse race at nearly the same speed and therefore have nearly the same energy.

"These results represent the most significant step so far for laser-based accelerators and should stimulate further advances in the near future" says Thomas Katsouleas of the University of Southern California in Los Angeles in a commentary accompanying the reports.

The newly achieved electron pulses, which last only tens of femtoseconds, pack energy up to 1,000 times as densely as did electron packets produced by wakefield accelerators of the past, Katsouleas notes. …

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