Beam Team

Never Heard of a Cyclotron? A Physicist Reveals Its Magic
by Chris Carroll | photo by John T. Consoli Waking the machine requires nearly an hour of button pushing, switch flipping and fine tuning of knobs, accompanied by the rising hum of vacuum pumps and cooling fans. Finally, inside a frying pan-sized steel chamber sprouting an octopus-like array of tubes and metal hoses, an intense magnetic field catches an invisible spray of protons and sends it spiraling outward. The result is a particle beam, and as the electric polarities in the two halves of the circular chamber flip rapidly back and forth from positive to negative, the beam is both pushed and pulled to higher and higher levels of speed and energy. This is University of Maryland physicist Tim Koeth’s cyclotron, a type of particle accelerator that won its inventor the Nobel Prize in physics in 1939. The beams that cyclotrons produce, while potentially dangerous, accomplish wondrous things—killing cancer cells with extreme precision, for instance, or changing atoms into a different element altogether. “It’s kind of magical, really—what the medieval alchemists were always trying to do,” says Koeth, an associate research professor in the Institute for Research in Electronics and Applied Physics (IREAP) and UMD’s nuclear reactor and radiation facilities director. The magic of science aside, Koeth’s 12-inch cyclotron is quite modest, both in comparison to the record holder, a giant with a 59-foot magnet located in Canada, and to other radiation-producing devices he’s worked with throughout his career. Those range from giant particle colliders, measuring kilometers in diameter, to nuclear reactors to the University of Maryland Electron Ring (UMER), where the National Science Foundation is funding groundbreaking studies of intense particle beam control.









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richard van veldhuisen
I love the work that Kiersten Ruisard is doing with Professor Koeth at UM