The world's biggest particle collider will resume operation in the summer of 2009 with a new warning system to prevent further breakdowns, its operators said Friday.

The Large Hadron Collider, which lies underground near the Franco-Swiss border, was shut down after nine days of operation on Sept. 19 when the meltdown of a small electrical connection caused the release of a large amount of liquid helium into the 27-kilometre long tunnel that houses the experiment.

The collider's operators, the European Organization for Nuclear Research, known by the French acronym CERN, released its report Friday on the mishap, confirming that "a faulty electrical connection between two of the accelerator's magnets" was the cause of the initial malfunction.

The CERN report said a dedicated system to detect the appearance of "abnormal electrical resistance" has been designed and prototyped and will be installed to prevent a recurrence of the problem.

The collider is designed to push protons using a ring of super-cooled magnets to speeds and energies never before reached under controlled conditions, and crash them into one another to create and detect a host of new particles. The giant magnets in the LHC — many weighing around 30 tonnes — are cooled at temperatures near absolute zero to make them superconductive and thus better able to accelerate the particles to high speeds.

It is expected to be the most powerful tool yet for physicists hoping to uncover the secrets behind the laws of the universe, both on the tiny scale of quantum mechanics and the huge domain of galaxies and black holes, but the project has been plagued by delays.

Repairing the collider will require 53 of the 57 magnets in the collider's tunnel to be removed and repaired, CERN said Friday. Of these, 28 have already been brought to the surface and the first two replacement units have been installed in the tunnel.

CERN spokesperson James Gillies said the repairs will cost 15 million Swiss francs ($16 million Cdn.), and spare parts will cost another 10 to 20 million Swiss francs, bringing the total cost to as high as $35 million Swiss francs, or $37 million.

Those costs would come out of CERN's existing budget for the project, he said. The collider, built at a cost of $3.8 billion, has a total expected cost of more than $9 billion.

Gillies said if the repairs go according to schedule, the LHC would resume powering tests at the end of June 2009 and possibly be up and running by July or August.