Updated

The world's biggest particle collider will start up next May, six months behind schedule because of problems, including the failure of a key U.S. designed part, the European Organization for Nuclear Research said Friday.

"We'll be starting up for physics in May 2008, as always foreseen, and will commission the machine to full energy in one go," said project leader Lyn Evans.

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In the meantime scientists will lower the temperature section by section to near absolute zero — colder than outer space — in the circular accelerator in a 17-mile tunnel under the Swiss-French border.

The plan is to fire beams of subatomic particles in opposite directions around the tunnel until they nearly reach the speed of light, then steer them into each other to force collisions and examine the resulting showers of matter and energy with the aid of massive, highly sophisticated detectors.

The low temperatures — which will make the collider the world's largest superconducting installation — will cool the magnets so they can convey extremely high currents without any loss of energy, enabling them to control the path of the protons in the beam, which are much heavier than the electrons used previously.

"The new schedule foresees successively cooling and powering each of the LHC's sectors in turn this year," a CERN statement said. "Throughout the winter, hardware commissioning will continue, allowing the LHC to be ready for high-energy running by the time CERN's accelerators are switched on in the spring."

The laboratory will start injecting beams of particles at low energy and intensity to give operators experience in driving the new machine, it added. Intensity and energy will then slowly be increased.

"There's no big red button when you're starting up a new accelerator," said Evans, "but we aim to be seeing high energy collisions by the summer."

Cooling the first sector of the machine has taken longer than scheduled, but has allowed the operations team to gain experience that will be applied to the machine's seven remaining sectors, CERN said.

In March a magnet assembly provided as part of the U.S. contribution broke in a pressure test. Scientists redesigned the 43-foot magnet, and a repair is being made, CERN said.

The $1.8 billion collider is replacing a less-powerful model that was removed from the tunnel in 2000.

The lab's 20 European member countries, as well as observer states like the United States and Japan, contribute to CERN's annual budget of about $800 million.

CERN also said that its governing council on Friday approved spending an additional 240 million francs ($195 million) over the next four years to improve operations and prepare for upgrades.

About 6,500 scientists from 80 countries — half the world's researchers specializing in particle physics — work at CERN, which became a main focus for world research into the nature of matter and the origins of the universe after the U.S. Congress in 1993 halted construction on the proposed Superconducting Super Collider in Texas.