World and Nation

Caltech Unveils an Innovative But Costly Particle Accelerator Design

CORRECTION TO THIS ARTICLE: The headline of a New York Times article in the World & Nation section of the Tuesday, Feb. 9 issue mistakenly credited only the California Institute of Technology with the design of the International Linear Collider. The particle accelerator was designed by a group of international physicists.

At a news conference in Beijing an international consortium of physicists released the first detailed design of what they believe will be the Next Big Thing in physics: A machine 20 miles long that will slam together electrons and their evil-twin opposites, positrons, to produce fireballs of energy recreating conditions when the universe was only a trillionth of a second old.

It would cost about $6.7 billion and 13,000 person-years of labor to build the machine, the group reported. And that does not include the cafeteria and parking.

“The good thing is that we have developed a design that can address the challenging physics goals and meet the technical requirements, and we have worked very hard to cost-optimize it, yet it (not surprisingly) does remain expensive,” Barry Barish, a physics professor at the California Institute of Technology and chair of the design team, which includes 60 scientists from around the world, said in an e-mail interview before the announcement.

The location of Thursday’s announcement, at the Institute for High Energy Physics in Beijing, underscores the growing role and ambition of Asia, particularly Japan and China, to become major players in high-energy physics, a field that has been dominated by the United States and Europe in the last century.

In its initial phase the collider would be 31 kilometers (20 miles) long and hurl electrons and positrons, their antimatter opposites, together with energies of 500 billion electron volts. Later the collider could be extended to 50 kilometers (31 miles) and a trillion electron volts.

The proposed machine, physicists say, is needed to complement to the Large Hadron Collider now under construction at the European Center for Nuclear Research, CERN, outside Geneva. That machine will be the world’s most powerful when it goes into operation this fall, eventually colliding beams of protons with 7 trillion electron volts of energy apiece. Physicists hope that using it they will detect a long-sought particle known as the Higgs boson, which is thought to endow all the other constituents of nature with mass. They hope, too, to discover new laws and forms of matter.

But protons are bags of smaller particles called quarks and gluons, and their collisions tend to be messy and wasteful. Because electrons and positrons have no innards, their collisions are cleaner, so they can be used to create and study with precision whatever new particles are found at CERN.

The hitch is that until the hadron collider proves its worth by actually finding something new, the governments of the world are unlikely to sign on to contribute a share of the billions.

Particle accelerators derive their punch from Einstein’s equation of mass and energy. The more energy they can pack into their little fireballs, the farther back in time they can go, closer and closer to the Big Bang and perhaps ultimate truth about nature, recreating particles and laws that once ruled the cosmos, but have since vanished more completely than the dinosaurs.