LHC to skip low-energy test runs
Jun 6, 2007
The Large Hadron Collider will not be ready in time to perform a low-energy "engineering run", which was originally scheduled to take place this November, according to an official at CERN. This will leave the operators no chance to gain experience with the particle accelerator's steering and detection systems before the high-energy runs begin in spring next year. The delay is due primarily to the failure of a Fermilab-built magnet during high-pressure tests in March.
When it finally switches on, the €6.3bn Large Hadron Collider (LHC) at CERN – the biggest experiment in particle physics – will accelerate protons in opposite directions around a ring 27 km in circumference and smash them together at energies close to 14 TeV. Researchers hope this will either allow them to glimpse the hotly-predicted Higgs boson or provide a window to "new" physics beyond our current Standard Model of particle physics.
Last year CERN, which is in Geneva, Switzerland, announced that the construction and testing of the LHC would be completed this November to allow for a two-week engineering run before the accelerator complex shuts down for winter maintenance. During this engineering run, the machine's operators would collide the protons at their injection energy of 450 GeV without using any of the ring's accelerating systems. This would have enabled them to gain experience steering the protons and detecting collisions before high-energy collisions take place in 2008.
In March this year, however, one of the superconducting magnets built by Fermilab in the US failed a high-pressure test designed to simulate the warming up or "quenching" that can occur when proton beams career off course into the magnets. This led many to speculate that the LHC's start up schedule would have to be delayed in order to replace the damaged magnet and redesign similar magnets, although CERN itself gave no official statement (see related story: "Large Hadron Collider faces delay").
Now, CERN spokesperson James Gillies has told Physics Web that the lab will announce at the end of June that the engineering run will be left out, although the accelerator will still be switching on in either late March or early April 2008 with an aim to start data collection two months later. "Things have been going well but pretty slowly – slower than the [previous] schedule foresaw," he explained.
Nevertheless, Gillies said that one of the LHC's octants has already been cooled to 1.97 K, and a second, adjacent, octant is following closely behind. Once they are both cooled to 1.9 K they should be able to test the anticlockwise proton beam at injection energy in a quarter of the ring. "So there is something happening this year, but it won't be colliding beams," he said.
About the author
Jon Cartwright is a reporter for Physics Web