In a hole in the ground there lived a particle accelerator. Not a big, empty echoing hole, filled with the ends of datacentres, chemical plants and an oozy smell, nor yet a rusty, corroded, abandoned hole with nothing in it to accelerate or to measure: it was a LHC-hole, and that means comfort.
Apologies, Mr. Tolkien. Most ‘umble apologies, but I simply couldn’t resist. It was a very, very special visit, worthy of being linked to a very, very special book. It all started with the good folks at CERN, who, bless their hearts, open up their doors (and lifts and tunnels and experiements) to the general public, but only on an irregular and infrequent basis. Now, you can visit CERN ‘most every day, and you can book visits to their surface facilities ‘most every weekend, but a subterranean visit, to pace those circular walls where protons are flung around at frankly ludicrous speeds and made to overcome their mutual repulsion before whamslamming into each other in detectors the size of houses… that, my friends, is a rare privilege indeed. The last chance was in 2004, and there won’t be another before at least 2018, when the LHC is warmed up again, a process that takes a month.
I was very glad, therefore, when Evelyne spotted this chance and asked if I wanted to go. I believe the speed of my reply might have exceeded the speed of the aforementioned protons, and, after some mad clicking on buttons to secure tickets as they were released at randomly chosen intervals – really – we were all set, and all I had to do was wait. Like a kid just before Christmas, with clenched teeth and barely controlled excitement.
My ticket was full of dire warnings about not being late, and so when we realised just how long it would take to trundle across Geneva in a tram, take a bus to the central campus and then another bus to the detector itself, I was starting to get a little worried. The staff at the check-in point, thankfully, took a far more relaxed and very un-Swiss attitude towards all of this (at this point, however, we were in France, so perhaps that’s fitting), and soon we were all standing a queue of varying excitement, as you can see above. At this point I was abandoned by Evelyne, because we had all got tickets at different times, and mine was the bright and early visit.
I shuffled along with the rest of the pack to the front of the building, where we were told to pick a helmet – any helmet – and then told to put them back and take a yellow helmet only, please, and assigned to Filippo, who was to be our native guide to the wilderness below. Filippo bravely shouldered his rustic dosimeter and we made our way to the lift. Everyone who works at CERN is required to wear a dosimeter at all times to measure their cumulative exposure to radiation, and this is specially true underground, where certain experiments have been gradually absorbing particles and becoming ever more radioactive over the last 20 years or so. He assured us that it was perfectly safe, and of course we believed him. As it turned out, I probably got several times the dose of radiation on the flight over from London to Geneva.
As we got into the lift and dropped 50m to the tunnel below us, I was conscious of a sense of remote other-worldliness. I couldn’t believe this was actually happening, that I was actually a few seconds away from stepping out into the tunnels of the LHC. I must have been grinning like an idiot all the way down, but thankfully there is no photographic evidence of this.
At this point I have to make a confession. The first sighting of the LHC was not a stunning symphony of awe-inspired appreciation. The lift stops, the doors open – just normal lift doors, which feels wrong in a place so unique – and you step out into a space that is remarkably mundane. Yes, there are lots more pipes and warning signs than you’d expect in a basement garage, and the curved walls are certainly a nice change, but honestly, if you didn’t know where you were, you wouldn’t be thunderstruck.
However, knowing where you are sweeps all the mundanity away on a tide of disbelief – this is a place you have seen in dozens of pictures and videos; and it’s right there, physically in front of you. You almost don’t want to reach out and touch it in case it’s just a dream. It took a while for that sense to fade, and even when it did, I was always conscious that this was a rare opportunity to go somewhere special.
We rounded a corner and saw the collider itself; astonishingly svelte in the tunnel. Inside all of this is a “mostly closed cooling system with a few leaks”, as a technician we met later put it, and two pipes, each about an inch across, that contain the circulating particle beams, each a few millimetres wide. It’s not really very large at all.
What is stunningly, magnificently enormous is the detector itself. It’s so large you climb scaffolding to get to a viewing platform several meters above the ground, and still it looms over you, almost inconceivably intricate and complex, vast and ponderous, and yet made with astonishing precision. ALICE, disassembled, looks like something almost alien, a science fiction parody of what complex machines should look like. Okay,it also looks a bit like the mouth of a steampunk robot Kraken, but let’s ignore that in the midst of our silent, awed admiration.
The beam pipes at the heart of all of this, where the collision magic happens, are entirely lost in this tangle of pipes, cables, struts, calorimeters and sensors, all cupped in a giant red metal yoke. Amazing, really, but we only had a few minutes to stand around and gawk before men in hi-vis jackets labelled “FLOW CONTROL” chivvied us on. I did manage to take a few pictures, including a request from a friend to “get a picture of you kissing ALICE”.
A slightly dazed ascent to the surface followed, and a quick walk around the ALICE exhibition, where we got a closer look at the detectors that are used, along with a novel “cosmic ray piano”, randomly playing notes when incoming cosmic rays hit a series of detectors. The music of the universe, thus translated, is slightly chaotic but also strangely mesmerising. It’s a bit like listening to the constantly-changing sound of falling water – you can almost persuade yourself that there are patterns and notes in there, but when you look more closely it all falls apart. Still, the man who built it was there to speak to, and very cheerful indeed.
Just to say I’d been there, done that and got the t-shirt, I went and got the t-shirt (and discovered that it was a bad time of year to be buying mugs at CERN, but a good time of year to be given mugs at CERN) and, very satisfied, we wandered over to the CERN control centre, the wonderfully named CCC.
This, of course, is the place where all the media broadcasts happen, and we walked in casually on our way to lunch, which really was a good idea, because we had the chance to have a chat with one of the technicians who actually runs the beam, and she told us a great many fascinating things about what it’s like to actually work there. Astonishingly, during routine operations, it only takes about 8 people to manage the entire beam, including producing the particles, pre-accelerating them, maintaining the beam and keeping the whole thing cool. Here, of course, is the most important one.
After all that excitement, we headed back towards the central campus to get some lunch. I discovered, to my complete satisfaction and glee, that salt and pepper packets at CERN, when placed randomly on a table, spontaneously arrange themselves into the following configuration. Really.
This is already much longer than I planned, so I’ll have to break this into two parts. Next time: Beauty!