Since we needed to drive through Geneva on the way to Montreux to start our train holiday, the physics geeks in us couldn’t resist the opportunity to visit CERN.
Taking the tram from city center to the CERN campus 30 minutes away
CERN is the Centre European de Recherche Nucléaire – the home of world-class research in particle physics. CERN was founded after WWII by a consortium of European countries. After the devastation of the war, and the exodus of Europe’s best scientific minds, the founders wanted to reestablish cutting-edge scientific inquiry on the continent.
The focus at CERN is on particle accelerators whose purpose is to explore the basic building blocks of nature: atomic and subatomic particles, such as electrons, protons, and quarks.
CERN has most recently made news because of its confirmation of the existence of the Higgs boson, the particle that purportedly gives mass to other particles. (You fellow geeks out there are sitting forward in your seats; the rest of you are just about ready to move on to Instragram…)
What I love about this place and what people do here is the audacious exploration of nature at its tiniest and most fundamental — and so far from our day-to-day experiences.
The tour web page warned us that we wouldn’t be able to see any of the current equipment, accelerators, or sensors. So, I worried a bit that the tour would be thin and cosmetic. No need to have worried.
Our tour guide was a very wiry PhD candidate whose area of research is dark matter. Think Sheldon Cooper, but with much better people skills. We couldn’t place his accent: not quite Slavic or Spanish. He seemed nervous at the start. But he spoke quickly in a charmingly geeky way, and answered every question with an assurance that revealed great depth. We wondered what he thought about this job of being a tour guide to lay people from all over the world. Was it just a part of his student obligations, a way to pay for his time at CERN? We hope that his tour-guide duty is just a small price to pay to be part of this rarest institution.
Our fellow tourers came from all over the world. We heard voices from the US, Britain, Australia, the Middle East, India, and more. This was certainly a self-selecting group: interested enough in particle physics to achieve a spot on the tour and to come to Geneva. Most of our fellow geeks had lots of questions for our tour leader. It was a joy to be part of a group that was so interested in this remarkable place.
Getting two places on the tour took some determination. We learned online that the tour spots are taken within minutes of their being offered online. 15 days before each tour date, at 8:30 am Europe time, 10 tour spots are made available. In the three days right before the tour, another 10 spots are released. The morning 15 days before our target tour date was the day that we were driving with Jef and Val from Carcassonne to the Auvergne. Fortunately, we were having a coffee together just before departing. Via iPad, I got into the CERN site at 8:31 and locked in our spots. The geek jumped up and down.
Since the late 1950s, successively larger and more powerful particle accelerators have been built on this site outside Geneva. (CERN and I are the same age!) The current accelerator is a ring 23 km in circumference, 30 m beneath the Swiss and French countryside.
Four gargantuan and astoundingly complex sensors straddle this ring. They are:
- ATLAS (A Toroidal LHC Apparatus), and LHC stands for Large Hadron Collider, and a hadron is a kind of atomic particle; the proton is a hadron. The purpose of this detector is to search for extra dimensions, dark matter, and Higgs bosons.
- CMS (Compact Muon Solenoid) has the same purpose as ATLAS but with a different detection method. Having these two methods is essential to confirm any discoveries, and rule out experimental errors.
- ALICE (A Large Ion Collider Experiment) has the objective to study what the universe was thought to have been made of in its first instants.
- LHCb (Large Hadron Collider beauty) has the goal of detecting a specific antimatter particle, as part of trying to understand why the universe is full of matter but not antimatter.
Something amazing, at least to us, is that all the protons that currently are used in the accelerator come out of a modest tank of hydrogen, the size of your home fire extinguisher. Our guide said that, at its current rate of usage, this tank will not run out for thousands of years! When the 23-km-circumference ring is operational, about 10 to the 15th power (1,000,000,000,000,000) protons speed around it. This huge number of protons only weigh about 2 nanograms. A nanogram is one billionth of a gram! These 2 nanograms of protons collide a billion times a second. But the current cutting-edge detector technology can only (only!) measure 600 collisions each second. Beyond comprehension.
The power to run this accelerator is equivalent to about half of what the city of Geneva uses. Most of that energy is needed to cool down the superconducting magnets (which cost about a million euros each, and there are 9,593 of them!) so that the protons can be kept in the ring.
The last stop on the tour was the site of the first accelerator built at CERN, the Synchrocyclotron, in 1957. It isn’t used any more, but resides in its original building, which has concrete walls 10 m thick so as to stop any errant radiation. We entered a dark room. Our guide said that there would be a video on the far wall. I thought, “Oh great. Another film about founding scientists and politicians.” But it turned out to be an ingenious and engaging video and sound-and-light show that helped us understand the accomplishment of the first accelerator. Sure, there was a short rehash of CERN’s inception. But the projections and lights on the actual equipment explained what this mute piece of machinery actually did, how it spun particles and made them collide, and how scientists studied the results. This was at a time before computers. The researchers needed to study traces of particles on paper photographs, one by one.
We came away with an immense respect for the engineering prowess and determination to discover how to discover what nature does at incomprehensibly small scales.
These discoveries and this knowledge made possible so much of what we enjoy today, and take for granted. Such as MRI and PET scans, radiation treatments for cancer, and touch screens.
Our guide told how the discovery of the Higgs boson was the final confirmation of what is known as The Standard Model. That name is dry compared to what it is: The most successful model every developed of how nature works at its most fundamental.However, The Standard Model describes only the part of the universe that we observe as visible matter. It turns out that this is only about 5% of the universe. There is another 27% that is cryptically called Dark Matter, because scientists don’t know what it is, but they know it is there because of its gravitational effects. And then there is Dark Energy, which causes the universe to expand at ever faster rates, and it accounts for another 68% of what’s out there and all around us.
We are excited that our tour guide and his colleagues at CERN are working on ways to find Dark Matter too.
Links for more information about CERN:
