April 30, 2007—The final megamagnet of the Large Hadron Collider—the world's soon-to-be largest particle accelerator—was ceremonially lowered into place through a special shaft on April 26, as seen in this image released by the European Organization for Nuclear Research (CERN).

Geneva, Switzerland-based CERN will run the collider and is overseeing its construction, including the installation of 1,700 superconducting magnets.

When the device is operational, the magnets will guide positively charged particles called protons in two intersecting loops around a 17-mile-long (27-kilometer-long) circular tunnel deep below the French-Swiss border.

Researchers hope the collisions of these particles will create rarer, heavier particles that will help solve some of the great mysteries of physics, such as why objects have mass and what the universe was like seconds after the big bang.

But just days before the last magnet was put into place, CERN officials announced that the collider probably won't be fully functional until next year.

The start-up, which was originally slated for November 2007, will likely be delayed by several months due to a superconducting magnet that broke during a routine pressure test in late March.

Scientists with CERN have been scrambling to fix the busted part and ensure there are no other hidden defects. But the magnet's "serious failure" is now poised to push back the scheduled launch.

"It's possible now, even likely, that the November date will fall off the map and we will be going straight into high-energy running next spring," CERN spokesperson James Gillies told the Associated Press.

"We're mostly there, actually. There are problems happening here and there, and it would be strange if there weren't at a project of this magnitude."

—Victoria Jaggard

• More Photos in the News
• Today's 15 Most Read Stories
• Free Email Newsletter: Focus on Photography