James Dunlop re-creates the big bang. At Brookhaven National Laboratory in the USA, he uses the electric fields of a particle accelerator to speed up gold nuclei racing around a 3,9-kilometre track. When the nuclei, guided by the accelerator’s powerful magnets, reach 99,9995 per cent of the speed of light, Dunlop makes them collide. Each 4 trillion degree crash shatters the gold particles into quarks and gluons, the tiniest building blocks of a proton. The accelerator’s STAR detector, above, photographs the atomic bits and pieces, allowing him to study matter at its most fundamental level. It’s not just a desk job, either. “There’s also a component when you’re going out to the detector with a soldering iron or a roll of duct tape,” Dunlop says. “You’ve just got to make it work.” – Sarah Fecht
Name: James dunlop
Years on job: 8
What Dunlop studies:
Protons spin. So do the quarks and gluons that constitute them. But scientists don't understand how the subatomic particles' rotations contribute to the spin of the proton. To figure it out, Dunlop runs proton beams through a magnet that makes nearly all of the protons spin in the same direction. When the beams collide, splashes of quarks and gluons bounce off into the detector. The number, shape and direction of the sprays tell him the directions in which the subparticles were rotating. Understanding how these spins make the proton rotate could advance electronics that use spin to store information.
When you add heat to ice, it melts. Add more heat and it turns to gas. But what happens when you add 4 trillion degrees? Dunlop wants to know how matter behaves under conditions similar to those one microsecond after the big bang. "You're melting normal matter," he says, "and breaking down the protons into quarks and gluons." After clouds of protons collided inside the STAR detector, the stripped-off quarks and gluons created a plasma that, rather than acting like a gas, acted like a superfluid: a liquid with almost no stickiness. Previously, superfluids had been created only at extremely low temperatures.
String theory, which claims the universe is made of tiny vibrating strings and multiple dimensions, is said to be impossible to confirm. But Dunlop's team put the theory's predictions to the test when they created the quark.gluon plasma. While standard theories stated the plasma would be gas-like, string theory calculated it would be a slippery fluid. Dunlop is now pitting the theories against one another for a rematch, this time investigating how a quark slows down as it passes through the plasma.