Developments in Brief : Linear Collider at Stanford Achieves 2 Major Milestones During Test Runs

At least two months before it is expected to achieve full operation, the Stanford Linear Collider has successfully passed two major milestones, including reaching energies far greater than any other electron accelerator in the world.

The successes have provided a little breathing room for scientists here who have yet to learn whether their bold experiment will actually work. The collider, a radical new design created by Nobel laureate Burton Richter, is scheduled to go into operation sometime in June, after scientists finish “fine tuning” it, Richter said at a press briefing last week.

Richter, one of the world’s top experts on high-energy physics, has staked his reputation on the new machine, built at a fraction of the cost of its major competitor now under construction near Geneva. Both machines are expected to shed new light on the weak force of the atomic structure, the force that is so weak it allows some elements to decay into others, thus releasing radiation.

Scientists announced last week that about a month ago electrons passing through the accelerator during test runs achieved energies of 53 billion volts, more than enough to accomplish the objectives of the machine, providing other criteria can also be met.

“That’s a world record,” physicist John Rees said.

Any moving particle, including a baseball thrown across a sand lot, has energy, Richter said. And although electrons are among the smallest particles in the universe, if they can be accelerated fast enough the energy represented by a single moving electron can be enormous.

In its test run, the electrons were accelerated to near the speed of light.

A second major milestone was passed March 27 when scientists managed to get two beams of electrons and positrons traveling in opposite directions to cross each other, a key element in making the machine work.

None of the particles collided during that test because the beams were too broad, thus allowing the particles to pass each other unperturbed, but it was a high point for scientists working with the linear collider.

“People were jumping up and down and running around,” physicist Roger Erickson said.

The next major hurdle will be to condense those beams down to about one-tenth the thickness of a human hair, and focus them so that they will cross each other, thus allowing some electrons to collide with positrons.