The replacement parts for the damaged components of the Large Hadron Collider (LHC) are arriving, and cautious estimates push the recommissioning date back to July 2009. We now know the repair job will cost several million dollars (£14 million according to a recent report) and scientists have identified the cause of the September 19th quench that kick-started an explosive helium leak, buckling and ripping the heavy supercooled magnets from their mounts. But how can this be avoided in the future? After all, the LHC is the most complex experiment ever constructed, there are a huge number of variables that could spell disaster when the LHC is switched back on again. The “S34 Incident” was triggered by a small electrical fault, what can prevent this from happening in the future?
According to the official report, the LHC requires an additional “early warning system” that will be tailored to detect small electrical shorts, hopefully shutting the system down before any further damage to the LHC blocks the search for the Higgs boson again…
It looks like official reports are being published thick and fast. Yesterday, I reported on two CERN reports that contained further details behind the problems faced by the engineers and physicists working on the repair of the LHC. One report suggested that it was an option to push back the date of LHC commissioning until 2010, whereas the other identified July 2009 as a good date to begin circulating protons once more. Now, a BBC news item has exposed some more facts behind the future of the LHC, indicating an early warning system is being considered to prevent an accident like the S34 Incident from happening again.
The incident, known as a “quench”, was caused by an electrical short between two of the 1200 electromagnets that make up the ring of the particle accelerator. This seemingly small fault was anything but; it initiated the rapid release of a tonne of helium, buckling and breaking the magnets between Sectors 3-4. Describing what happened, LHC project leader Professor Lyn Evans said, “Basically, they have been pulled off their feet and the interconnects have been broken.”
The electrical fault occurred right at the end of the commissioning process, even after the first protons had circulated around the long accelerator ring on September 10th. At the time, the LHC had seven of its eight sectors powered up to full energy, but the quench occurred right at the end of the process. “We are extremely disappointed, especially as we had already commissioned seven of the eight sections of the LHC up to full energy,” Evans said. “This was the last sector to be commissioned and this was really the very last electrical circuit. I must say it felt like a real kick in the teeth.”
If the experiments had continued as planned, scientists would be analysing the ground-breaking particle collision data by now, but it looks like CERN will be taking an even more cautious approach form here on in. “You can think of the LHC as a Formula 1 racing car. It’s a complex tool, a complex machine,” commented Dr Francisco Bertinelli, one of the engineers repairing the magnets. “We will not run it from zero to top speed over one afternoon. We will build up our confidence and lower our risks.”
Generally, although frustrated, scientists are very excited about the future for the LHC. Prof. Tejinder Verdee of Imperial College London reminds us why this is only a minor glitch in the grand scheme of things: “This science has the potential to alter the way we see nature and the way nature operates at a fundamental level so this potential still remains, albeit a few months delayed. The great science is still out there ahead of us, which is greatly motivating.”
The unravelling of the fabric of the Universe has just been delayed and the physics revolution can wait a few more months…