The 27-kilometer-circumference LHC (Large Hadron Collider, of recent Higgs boson fame) happens to be off-line at the moment while they double the proton-proton beam collision energy to a huge 13-14 TeV, so the Sci-Am-arranged tour group I was with (led by one of the CERN scientists) was allowed down into the 300-ft-underground tunnel to see one of the four main sub-atomic particle detector machines, the CMS: ‘Compact Muon superconducting Solenoid’ experiment.
If in the picture below I might look a bit underwhelmed, it’s because I was in fact overwhelmed, indeed totally humbled and somewhat tearful. And the photo doesn’t do justice to the cathedral-like cavern, hugeness and complexity of the machine.
ATLAS (on the opposite side of the LHC ring, in Switzerland) is dimensionally bigger, but the CMS (in France) is the heaviest at 40,000 tons of the four collision-point experiments, has the largest magnet of its type ever constructed producing a field 100,000 times that of earth, and registers the counter-rotating proton-proton near-light-speed collision products at the rate of 40 million times per second!
We also visited the cryogenics engineering facility which enables the magnets to superconduct 20,000 amps at just 1.9 degrees Kelvin above absolute zero, half the temperature of outer space.
And yes, there is a customs post between Switzerland & France at ground-level half way across the LHC ring. It happened to be unmanned that day since it was some Saints festival! How weird, I thought, that official territorial suspicion could be briefly suspended due to medieval religious superstition, all amidst the most non-territorial/religious of institutions in the world.
What I found reassuringly ordinary-world was that each of the 400 million tiny hi-tech components within the various detector layers you see all around the central collision point (presently split in half, the other half being off-photo to the right) are actually connected by domestic-sized insulated wires, albeit thousands & thousands of them bunched into thousands of cables that connect to the multiple banks of computers and control rooms on the levels above that we were ushered through, where they are simply plugged into the relevant ports, just the same as your desktop PC. I’m not surprised it apparently took 3 years for the technicians to make the correct connections and test them all.
IMPORTANT NOTE:
Access to the underground LHC tunnel and experiment machines will NOT be possible once it comes back on-line next Spring, and my personal view is that the free public exhibitions at CERN are unlikely to teach you anything more than a regular read of the latest Scientific American, New Scientist or whichever science magazine.
But at least (weather-depending) you could enjoy, as we did, the view toward the Jura mountains to the north and snow-capped Alps including Mont Blanc to the south.
As they emphasise, the extraordinary engineering for CERN, especially in cryogenics, superconductivity, vacuum, microelectronics and civil engineering, gives companies experience that they can apply elsewhere for practical applications such as medical diagnosis and treatment.
All in all, an unforgettable combination of the beauty and wonder of Nature and our best attempts to understand it.
John
