The bartender says, "We don't serve neutrinos here."
A neutrino walks into a bar.
I don't believe that most people who tour Cern get to experience the pure nerdliness that I had a chance to be a part of this week. Due to an error in emailing, the tour meant for EPFL physics and engineering students had some slots left and I was able to go. This did not change the fact, however, that the tour was designed for -and populated by - people with at least a basic understanding in particle physics.
The trip started at the hilarious intersection of swiss planning and rule-abiding engineers. To accommodate for any potential late-comers, the trip organizers told us all to meet half-an-hour before the bus was meant to leave. With normal humans this would be a practical approach. When your entire population is rule-abiding, graduate and post-graduate engineers, it means that you have 35 people arriving 15 minutes before the deadline, a full 45 minutes before the bus is meant to leave. One of our friends had even skipped buying lunch to make the early deadline and stand in the cold without food just in case the bus might leave. He was eventually persuaded to go buy a sandwich.
We left on schedule and made excellent time on the road to Geneva. This, of course, meant that the one-hour window of extra time that had been blocked into the schedule for late comers and traffic meant that we arrived an hour before our scheduled tour. And what do a group of engineers do with an hour to spare before a three-hour tour? Why they tour the exhibit hall, of course!
In the basement of the welcome center, the exhibit hall is designed for the general public and school-aged children. Here Kris pulls on a lever to demonstrate how hard it is to separate the particles in the nucleus of an atom. Clearly it is difficult. Look at him straining.
There were also exhibits demonstrating the effect of varying gravity on 12 kg weights and one of those lightening ball things you put your hands on.
There there were exhibits whose intended audience was less clear. One enthusiastically told you to reproduce an experiment that went on to earn the nobel prize. It even used multiple exclamation points!! In reality you flipped a switch and turned two knobs until the graph on on the display made a horizontal line. Science! Another instructed you to take measurements and make a histogram of the results. Not to worry, kids. Graph paper and pencils are available at the welcome desk.
One room was enticingly labelled "Mysteries of the Universe." It contained wall-mounted headsets with questions like "Why do particles have mass?" The questions were posed in English, French, Italian, or German and had mini lectures by experts from around the world. Note in the last sentence that I said "or" instead of "and." The mass of particles was introduced in English, but if you wanted to know whether the universe is symmetric, you better speak Italian. See Fabio, Kris, Rick, and Phil being riveted in the pictures below.
The exhibit hall also contained a piece of the tubing used in the Large Hadron Collider, complete with a wall mural to make you actually feel like you are down in the tunnel.
It was a popular spot for group photos. And for people who enjoy awkwardly taking pictures of the backs of other people's group photos.
Finally it was time for our tour, so we headed back up to the welcome center to meet our guide. We were briskly gathered and lead to an adjacent building, passing a yard of structures that could have been a truly epic playground equipment, but instead was some mildly interested outdoor art.
We all filed into a swanky lecture hall and readied ourselves to be amazed. The guide introduced himself and explained that tours are usually preceded by a brief introduction to the facility, but as we were all obviously qualified we would skip the basics, do a quick summary of the current state of particle-physics research and then watch a 10-minute video. He then apologized that we were getting started late, as his talk was 50 minutes and was meant to finish with the video at the top of the hour. We were literally 2 minutes behind schedule. I know, because the wall clock was a Rolex.
Our guide then began his talk, briefly laying out the history of this impressive facility. LIke most people of my age and nationality, I associate CERN with one thing: The Higgs Boson (better known as the God Particle). When I posted my excitement about visiting CERN (yes I did that) my cousin-in-law told me to say hello the the God Particle for her (yes, Alicia did that). And while this recent work is amazing step in particle physics research and our broader understanding of the universe, I found myself being impressed by something else.
CERN (the European Organization for Nuclear Research) started back in 1954. 1954! That means that less than 10 years after the end of World War II the nations of Europe got together and created a nuclear research program that has persisted for more than half a century.
"Feel free to take pictures!" our guide told us. "As we are a government-funded project, we have no secrets." This and my experiences with US-funded government research could not have been in greater conflict.
Many of my experiences with scientific equipment in the US has been with University labs that could not afford to have the proper technician on staff, so microscopes, probes, and lasers were maintained by an ever-changing cycling set of graduate students or simply fall into disrepair. One of the detectors at CERN has more than 20,000 components. Experiments are run simultaneously by scientists from multiple countries and have goals on the scale of decades. When asked how much the swiss population pays in taxes for their share of this pan-european collaboration, our guide told us, "About 2.20 CHF per citizen per year. The equivalent of one nice cup of coffee."
While I was marveling at the ability for countries who had only a few years previously been at war to agree to an international tax to fund scientific research, when my own country's politicians earn votes by slashing funding science in their state, my guide moved on to the "review" of particle physics.
I had not had a physics class since high school, so I was alternating between being deeply interested and completely snowed. In the end I came out with something like this:
We know that particles have mass. We know this because this mass causes particles to slow down from shooting around the universe at the speed of light enough to form stars and planets and trees and people. We also know that all of those stars and planets and trees and people, when you look at them close enough are made up of atoms ; which are made up of protons, neutrons, and electrons; which are made up of quarks and leptons. And this is great! By looking at the little pieces that make up the universe and looking at the way they interact we can fill in some of those "Mysteries of the Universe" from the room in the exhibit hall.
It lets us ask questions like "Why do particles have mass?" We know that they do, because we are surrounded by stars and planets and trees and people. But, when we look at the tiny pieces that make us up, no matter how close we look we can't find anything that gives them mass.
Likewise, when we look at galaxies spinning far away we find that they are spinning too fast for how much matter we can see. Imagine swinging a lead weight around on the end of a string. Eventually, if you swing it too fast the string will break. Well, for these galaxies the string should break. But it doesn't ... they just keep on spinning. It's a mystery.
It's a mystery that we can get closer to understanding by smashing particles together at incredibly high speeds. And to do that, you need a particle accelerator and a huge damn tube lined with magnets. And at CERN, they have been doing that since 1954.
From here the lecture started to focus on numbers. Like the 100 billion protons in each packet that is accelerated and then launched into the Large Hadron Collider. Or how 3,000 of these packets can be cycling at through the collider at any given time, crossing paths and colliding ~40 times per second in the 4 simultaneous detectors. These detectors, by the way, have tens of thousands of pieces and vary in size from your house to your office building. This part of the lecture also featured phrases like "quark gluon plasma," "cosmic microwave background radiation," and "as we all remember about the behavior of depleted uranium."
After the lecture we watched a video that seemed to feature a rogue woman who had secretly entered the Large Hadron Collider tunnels with a bicycle and had decided to film herself describing the experiments video-ing herself on a helmet cam while peddling around a multi-million dollar international nuclear research facility. She also felt tribal drums and the Beatles were the appropriate soundtrack for such an endeavor. I'm not sure it is the video I would have made to explain my facility to the public.
Finally it was time to tour the actual facilities. Because the Large Hadron Collider was running (with its millions of billions of particles flying around) we couldn't actually go down into the tunnels, but we would get to see one of the smaller accelerators and the computing center. Starting in March the Large Hadron Collider will be shut down for improvements (to allow for 7000 packets of protons) and I hope to go back and see one of the detectors. We broke into smaller groups and our set headed to the accelerator first.
Our tour started with an explanation that due to the presence of radioactive materials, our guide was wearing a radiation-detection badge on behalf of all of us. If his detector read zero at the end of the day, we were all in the clear. If it didn't, we wold all be getting a phone call. In all of the years CERN has been giving tours, no one has gotten a phone call.
We went into a building roughly the size of an airplane hangar and though we could hear the hum and click of active machinery, our tour started with a bunch of shelves. This wing had originally housed a detector, but with improvements since the 1960s, it became obsolete and eventually got broken down.
"The blue shelves hold parts from the old instrument, scheduled to be repurposed for new experiments in coming years," our guide explained. "The green shelves hold all of the parts that have become mildly radioactive. We have to house them for a couple of decades before they can be scrapped." Simple enough.
Then we turned around and faced a row of windows that locked into a large lab filled with desks, computers, and a dozen or so graduate students. I had seen a similar setup before at the LRO lab in Arizona. One of the prices you pay for working on cutting-edge research is that tours get to ogle you through glass like you are part of a zoo.
"See here, young scientists in their natural habitat. They work in packs to learn the skills to survive the academic wild. Very few of them will actually make it. Notice the extensive consumption of coffee and inappropriate wearing of pajama pants in a professional environment."
The lab was actually quite swank, with a quad-monitor setup at every station.
Here is the output from one of the recent collision.
We then proceeded to a room of monitors with the real-time output from each of the detectors and accelerators and a large cartoon of the entire CERN setup.
Our guide summarized the history of some of the more recent experiments, including the one last year in which an instrumentation error made it appear that neutrinos had travelled faster than the speed of light. This, of course, got a lot of media attention even though the scientists were still in the process of trying to reproduce the results.
A check of the instruments and a rerun of the experiment showed that neutrinos, like everything else, do not travel faster than the speed of light. If they could, we would be facing all kinds of questions about relativity and whether effect could precede cause. Hence the joke at the top of the page:
The bartender says, "We don't serve neutrinos here."
A neutrino walks into a bar.
The fact that the results had been discounted did not make many headlines, and the ones it did make focused mainly on how speculation about how such a mistake could have been made. Even with precision instruments, shooting a bunch of neutrinos from Geneva through the mountains and measuring them as they pass a detector somewhere in central Italy is no trivial matter. There is a reason such experiments are run numerous times.
We walked over to the other side of the building where the LEIR ( Low Energy Ion Ring) was running, accelerating particles to be sent off to one of the other instruments. The LEIR is maybe 1/3 third the size of a high-school track and uses a "race track" set up with accelerating straightaways paired with magnetized curves. A rhythmic clicking noise announced every time a flap opened to allow particles to pass from one vacuum to another. This instrument was used as part of a multi-stage process to get particles moving fast enough to collide with other particles or metal plates miles away. You can use the ladder bridge over the near side of the accelerator to give some scale.
We peeked through a window at the proton synchrotron, which we could not approach while it was running. Next to the door was a huge slug of iron someone had apparently had a desperate need to set down. The cardboard they had opted for clearly could not hold the weight. While everyone else was peeking through the window, I was staring at this cardboard thinking, "well, clearly that didn't go as planned."
We did get to see a retired piece from one of the accelerators where alternating charges are used to pull particles through different chambers. See a brief explanation in French below.
The arrival of another tour group signaled that it was our turn to head to the computing facility, which was a couple of buildings away. In France. The French-Swiss boarder runs through the middle of CERN, with small stone markers indicating where one country stops and another begins. See that dumpster? That dumpster is in Switzerland.
See that white car? That car is in France!
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The computing center, which houses over 200,000 pc's, is the building with all of the air conditioners sticking out of the top. If you have ever have a laptop get hot while sitting on your thighs, you can imagine the heat generated by 200,000 of them.
Just outside of the building is this little sanctuary for computer mice.
Inside, the facility looked something like this.
And for any evil villain hoping to sabotage CERNs work, the sections are clearly labelled for "Mail Services" and "Network Backbone."
Back in the 1960s, the computers were run using punch cards and the data was stored on giant disk that held only 10mb of data. (see the cd on the second shelf for scale).
Now for all of you asking why we should go through all of this effort, those who think: Even if these experiments will let us answer some questions about the first moments of our universe, so what? Knowing a little bit more about why particles have mass has not real effect on you... here is why I disagree.
In order to create experiments and facilities and instruments, scientists are constantly pushed to create new technology. When the magnets available weren't good enough, CERN made better ones. They are what we use for MRIs. When this team of international scientists needed a way to communicate about their experiments, one of them created the World Wide Web. You know that "www" at the start of the website? He created that. The first website was http://info.cern.ch
The first server was here, with a had-written note reminding others not to turn it off, because, you know, it was a server.
And because it was created by an international government project, it wasn't patented. So instead of paying every time you use that "www" you just type and go.
It may not seem like scientific research has any practical impact on your daily life, and it may seem appealing to disregard the scientists as selfish people who just want money for their pet projects. But remember, what we understand about genetics came from studying insects, the LEDs we use everyday were created to grow plants in space, and a particle accelerator gave us the World Wide Web. When scientists passionately push the boundaries of what is possible, everyone benefits.
I have to say, it was a pretty good tour.
