Supersonic Sharpshooter

Mark Raizen and his research group can now stop over 85 percent of the atoms in the periodic table and many molecules. That means big-named, important elements can now be controlled, and in fact, Raizen has already proven it with molecular oxygen. “Our methods open up whole new avenues of research,” says Raizen, professor of physics. The tool he uses to stop atoms—an atomic coilgun—seems lifted from the pages of a sci-fi novel. Inspired by projectile weaponry technology and made out of relatively common materials, the coilgun works by shooting a supersonic beam of cold atoms through a 3-millimeter bore wrapped by 64 magnetic coils made of copper wire. A typical coilgun accelerates projectiles using magnetic coils, but the atomic coilgun works in reverse.

An atom’s energy is reduced as it moves through each coil’s magnetic field until it is finally brought to rest. Raizen aims to use the coilgun system in tandem with another process he invented, single-photon cooling, to super-cool a wide range of particles. To date, cooling atoms to very near Absolute Zero—that’s beyond frigid at -459 degrees Fahrenheit—has been accomplished using laser cooling, but the method only works on a small set of atoms. Raizen’s methods could help scientists determine the mass of the neutrino, a primary candidate for über-mysterious dark matter.

This article also appeared in the Spring 2008 issue of Focus magazine.