At long last, the day had come: I was going to visit CERN. For 50 years, the European Center for Nuclear Research (frenchify that to get the CERN acronym) has been home to particle accelerators of increasing power. Particle accelerators are basically state of the art microscopes, the most extreme instruments we have to be able to peer into the structure of the atom. Particle accelerators are rather crude, simply smashing atoms together and watching the pieces that fly out of the collision, and each generation accelerator gets better and better by essentially smashing the atoms together harder and harder.
From the 1950s through the 1980s, CERN operated a series of accelerators, starting with a 600 MeV ring and ending with a 62 GeV system. The "eV" in there stand for "electron Volt", and is how they measure how fast the atoms are going before they smash into each other. These units are metric, and use the SI system, so you'll see a letter in front of the "eV" signifying how many multiples of 1000 to apply. So 1 MeV is one million eV (10 to the 6th power, or 10^6), 1 GeV is one billion eV (10^9), and 1 TeV is one trillion eV (10^12). It's like computer hard drives, which were sized in MB (megabytes) in the early days, then GB, and lately TB.
In 1989, CERN started up the Large Electron–Positron Collider (LEP), which offered collision energies of 200+ GeV (or 0.200 TeV). To achieve this, they built a huge, circular tunnel under the farmland that surrounded CERN, measuring about 12 feet (4 m) wide and 17 miles (27 km) in circumference. Inside that tunnel, they built the electronic pipes that hurled the two beams in two opposite directions around the ring. The LEP ran for 11 years, but was frequently outperformed by US accelerators like the Tevatron.
In 2000, after years of planning, they shut down the LEP and started dismantling it. In its place, in the same tunnel, they would build the Large Hadron Collider (LHC), which would have the same physical dimensions, but would make use of the latest technology to achieve vastly higher energies (speeds). The LHC is designed to hurl particles at energies of 7 TeV in each beam, thus colliding at energies of 14 TeV, or 14,000 GeV, or 70 times more powerful than the LEP that previously occupied the same tunnel. Foremost of the new technologies was superconduction, which can be used to make insanely powerful magnets, which are then strong enough to "steer" a much more powerful particle beam around that same ring. Like they say in NASCAR, go fast and turn left. However, to get those magnets to work, you need to supercool them, hundreds of degrees below what we would call normal.
The United States had planned to build a similar particle accelerator on the same principles, but one that would have utterly dwarfed even today's LHC. It was called the Superconducting Super Collider (SSC) and construction actually got underway in east Texas in the 1980s, but the construction cost (54 miles of tunnels!) became too much for the federal budget to bear, and it was cancelled. Thus began a sort of "brain drain", where our best physicists started to gravitate towards Europe where CERN was building the LHC. Further, in some cases the lure of filthy lucre became too great, and many of these physicists ended up on Wall Street as "quants", essentially harnessing their command of advanced mathematics to model the financial markets and create new ways to conjure money out of thin air. I've heard it argued, perhaps in jest, that the $750 billion bailout of our financial markets in 2008 could have been avoided by simply spending a few billion dollars on the SSC ...
I should mention that it's not just the "eV" power of the accelerator that matters. How those beams get focused, and how the data gets analyzed, are also crucial performance issues that drive how productive an accelerator is.
Where was I? Oh, right, visiting CERN. OK, let's get on with it then.
By nice coincidence (actually some planning), the streetcar that ran past my hotel would take me straight to CERN. CERN is out in the suburbs of Geneva, at the very end of the streetcar line that they had only recently extended out there. All I had to do was hop on, watch Geneva go by for about 30 minutes, and at the end of the line I'd be in the center of the most cutting edge scientific research facility on the face of the planet.
The public face of the CERN complex is a surprisingly modest visitors center, but it hides a large museum, containing seemingly every artifact of 50 years of exploration at the smallest scales. Hardware of all shapes and sizes, displays and movies that explain what they do, examples of how computer storage worked back in the day ... In a courtyard that we couldn't get to, but could see through the windows, they had all sorts of impossibly exotic gear mounted and displayed, literally put out to pasture outside. Signs, signs, I have to read the signs!
To the tour! Months prior to this, I had checked the CERN website and found that while they do offer tours that go to interesting places (e.g. down into the tunnel, not just surface buildings), there weren't any tours available in my timeframe. Oh no! One day later, after an eloquent and pleading email to their tour managers, I had a spot on some other group's tour. And they confirmed that we would go down into the tunnel!
Being able to see the tunnel was actually quite a unique opportunity. As a high energy physics experiment, when the beams are running, it's quite radioactive in the tunnel, and nobody is allowed in there, not even workers. Like a nuclear power plant, everyone clears out of the tunnel and they seal the doors before starting the sequence to fire up the machine. Well, 2013-2014 was a major period or planned downtime, when they would be really shutting the machine down, and basically taking it apart and refurbishing it. So during that extended downtime, they were letting the public get even closer to the equipment than they normally would. However, the shutdown was coming to an end, and some parts of the tunnel were already off limits to even CERN workers. This timing is why I made the effort in the first place to get to Geneva on this trip.
The CERN folks corralled us onto a bus and we headed off into the Swiss countryside. Well, actually, the French countryside, because right after pulling out of the parking lot, we crossed the Swiss-French border. There hasn't been any border control in most of Europe since the Schengen Area was agreed to in the mid-90s, which the Swiss finally joined in 2008. So there are all these abandoned border posts, and we just drove right through it.
Our first stop would be the LHCb. At each of four points around the 17-mile ring, CERN built a massive underground cavern around the precise spot where they would collide the beams. With a 7 TeV beam going in one direction around the ring, and a 7 TeV beam going the other direction, they would have 14 TeV collision energies, and the cavern was built to house the colossal machinery that would be needed to detect and measure the sub-atomic bits that came flying off. The "LHC-beauty" experiment was one of those four collision points, and was designed to examine and characterize the "beauty" particle, so named because physicists have a sense of humor ...
Our tour guide was a young Polish physicist named Agnieszka, and she led us first through the small displays they had set up in a waiting area at the surface level. The bulk of the machinery was below us, but they still need a hall at the surface to stage material and raise from / lower to the tunnel. Also up here was the main control room, unmanned because of the long-term shutdown, but which would be humming again soon enough.
Right about this point is where I realized something horrible: my battery camera was almost dead. I had obviously been planning the logistics of this visit for a very long time, and I had packed extra camera batteries and made sure to charged them up. But I had left them at the hotel! Oh shiiiiiiiiit. I was about to into the CERN tunnel, and my camera would be dead!
Now I started to be very miserly about photos, and the camera's power. Turn camera on, take a photo, turn off. In the end, I got the minimum amount of pictures I needed to be happy, but it was a stupid mistake.
Agnieszka handed us off to her colleague (and fellow Pole) Rafal, who would take us down to the tunnel. They handed us all hardhats (color coded to our tour group) and had us go through the security checkpoint. This was basically a fancier version of what you go through at the airport, or what I used to do when working in nuclear power plants.
After all of us had scanned through, we got into a freight elevator and went down.
Down.
Down.
About 300 feet down, we got off at one of the cavern levels. The cavern is about 70 feet high, with metal lattice work forming multiple levels (stories) for workers to use to access equipment. Our first stop was in a side section of the cavern containing a monstrous instrument left over from the LEP days. This same cavern had been used in the LEP, and when they dismantled that system and started building the LHC, they had room in this cavern to just shove this instrument off to the side. Since it obviously had been decommissioned, we were allowed to get up close and personal with it.
A panorama photo of the LHCb cavern!
A short walk away and (cue angelic choirs) the LHCb experiment! This machine was basically a horizontal stack of vertical layers. The beam would come in from the right, the collision would occur in the right side of the cavern, and the particles would spray off to the left, through all those detector layers. If you scrutinize the smaller LHCb photo above, you will see a man wearing a yellow hardhat. Go to the upper left corner of the blue and white "LHCb" sign, go to the left past the white circle with the red object in the center, and just to the left of that you'll see him.
On our way out, we passed a large wall that had a big picture of the tunnel on it, and we got to pose in front of it. So, it looks like I'm in the tunnel, not actually in the tunnel.
Also they had a nice poster of the women working on LHCb. Girl Power! Also, note the Comic Sans, which is a bit of a running joke at CERN.
Back on the bus, back across the French country side, back across the "border", back to the visitor's center.
Now, I wasn't done. Not even close. In short, I sweet-talked the tour operators into finding an empty spot for me to join another group on another tour tomorrow! To a different cavern! And to the magnet test facility! Oh my god, I was so happy. In fact, after I finishing writing this, I'm going to email them and send them the link to this so they know how much I appreciated it.
And now, finally, to the gift store! The store was tiny (by US standards) but chock full of the most incredible books and science tchotchkes. I literally would have bought everything in the store, but everything was going to eventually need to fit into my suitcase, and later in this same trip I'd be lugging this suitcase onto a sailboat ... So I bought some more compact items, took pictures of the bulkier items for future wishlist purposes, and headed back to the hotel.
After resting at the hotel for a bit, and soaking up some internet, I struck out on an evening jaunt. One of the first high-power EV charging stations had supposedly been installed in a suburb just west of Geneva. The streetcars didn't run out there, but the busses did. So, in the failing light of mid-evening, I literally got off a bus in the middle of some strange residential neighborhood and hunted around for this charging station. Walked up and down little alleyways, through parking lots, all over the place. In the end, the charging station was located a good bit away from the map marker I was chasing -- at a Volkswagen dealership, duh. But I found it!