Along with the other centres involved in the EYU programme, Sean from our Education Team had the chance to visit CERN as part of the development process. This gave him the chance to see first-hand the amazing physics that is being done there deep underground. When he got back, we asked him a few questions about his trip.
Well firstly, I think everyone who loves science wants to visit CERN. That’s why I was really excited to go. I’m not a physicist but I understand enough to know that the stuff happening at CERN is just about as big as it gets in science!
CERN is French and in English it stands for The European Council for Nuclear Research, but that’s a bit misleading. It’s really about particle physics and the weird and wonderful world of sub-atomics particles like quarks and muons.
CERN has actually been around for a long time. I thought it was new but in fact they have been investigating particles at CERN since 1954.
Yes, it’s very big but in different ways. When I first arrived, I thought it was quite small. The reception desk is tiny and quite old. It did not look like a place of so-called ‘cutting-edge science’. Then someone took me to the cafeteria and I nearly got lost! It’s huge and the busiest I’ve ever seen. But it’s also exciting and full of scientists and engineers talking about physics. I’ve been told that if you’re lucky you might spot a Nobel Prize winner having a cup of coffee and a bun!
Yes. CERN has over 2300 employees of all sorts – scientists, engineers, programmers, administrators, educators and so on. It’s also very international. There are 21 member states and many more associate countries. Thousands more scientists visit CERN every year to do research and work on the experiments.
Although there are lots of experiments happening at CERN, the LHC is the biggest one and the one everyone knows. It started operating in 2008. Basically, it’s a tunnel 100m underground. The tunnel runs in a circle for 27km under the Swiss/French countryside. In the tunnel two beams of protons are accelerated in opposite directions to almost the speed of light. The beams are less than the width of a hair. They travel round the tunnel and are then smashed into each other to see what happens. In particle physics, protons are classed as hadrons. That’s why it is called the ‘large hadron collider’.
No, you’re not allowed. They use liquid helium to cool the magnets that keep the beams from touching the sides of the tunnel and destroying it. The helium is at 1.9 degrees K. That’s the coldest place in the universe! Basically, it’s dangerous so they keep people out when they are preparing for new experiments. But I did go underground to see some pretty amazing stuff, and here’s a picture of me posing by a picture of the tunnel. Looks pretty real, doesn’t it?
Sean ‘in the tunnel’ at the LHHC.
It’s not a stupid question. I didn’t know either but it’s like this; every atom is made up of electrons orbiting a nucleus. The nucleus has two parts, a neutron and a proton. The protons used at CERN are obtained using a simple cylinder of hydrogen. It looks just like a fire extinguisher. Hydrogen atoms are really simple. They only have one electron and don’t have a neutron at all, just a proton. In the LHC, first the electrons are removed with an electric charge, then the acceleration begins. They are accelerated to near the speed of light using an alternating electric current. When it’s operating, CERN uses as much electricity as a large town.
Hydrogen cylinder at LHC
Yes, I saw one of the four large detectors. This was also 100m underground and it was amazing. You might say that the high point of my visit was also the low point, ha ha!
Well, the LHC project has three main parts. We’ve already talked about the accelerator and the beams going round the tunnel. Also deep underground are the detectors. They are huge. They are placed at four different points on the tunnel where the proton beams collide and they record the results of the proton-proton impacts. You see, when the protons collide, other particles are produced and it’s these that the scientists want to find and understand.
Exactly, it was discovered in 2012. Its discovery was a big thing. It helps physicists understand more about what gives things mass.
I suppose it is but I think anyone can understand the science of LHC at a basic level. You don’t have to be a Nobel prize-winner to get the gist, if you know what I mean. If I can understand it, anyone can!
Well, I was lucky enough to see the CMS detector. It’s a massive machine in a huge cavern and going there felt like walking into a cathedral, or maybe a James Bond movie! It was really impressive. CMS is designed to detect particles called muons. It’s 15m across and 21m long and weighs over 12000 tonnes. In the picture you can see the tube that carries the proton beams. This is where the collisions occur and the detector’s magnets and other instruments record the impacts.
Sean in his W5 lab coat next to the CMS detector
That’s the Worldwide LHC Computing Grid. All the data from the collisions has to be analysed for significant results. It takes a lot of special software and computing power to do this and so CERN is supported by a global network that processes the data recorded by the detectors. I saw the computer room at CERN. It’s really big. It has to be. When the LHC is operating there are millions of proton collisions happening every second. They don’t want to miss anything interesting!
A small part of the computer room at CERN
The energies used at CERN are very high. The beam of protons, even though it is very small, has about the same energy as a high-speed train travelling at full throttle. If the magnets or the vacuum in the tube fails there are safety measures which ‘dump’ the beam into dead-end side tunnels in milliseconds and the energy is dissipated. When the LHC is operating normally, most of the energy is absorbed safely by the detectors. There are also rumours about the LHC recreating the Big Bang or creating a black hole. That’s not true. The LHC is trying to create conditions similar to those just after the Big Bang and it won’t create a black hole. High energy collisions like the ones in the LHC happen naturally all the time. For example, when cosmic rays hit our atmosphere.
Good question. The stuff being studied at CERN sometimes seems pretty unreal. I mean, it’s incredible but it can be hard to understand. Basically, physicists want to find out more about how the universe works and what the nature of matter is. At the moment it is only partially understood but CERN and the LHC can really help answer some of those difficult questions like ‘why do things have mass?’ and ‘what is antimatter?’ There are also lots of spin-offs from the technology developed at CERN – things like satellites, communications and medicine. You may have heard of radiation therapy and electron beam therapy. All of that is accelerator physics.
I did and I learned a lot too. CERN is awesome and very inspiring. I want to encourage other people to find out more about this kind of science. At W5 we have a programme called Explore Your Universe and we’re using it to help people get involved and find out more. Also, I have to say a big thanks to the Science & Technology Facilities Council who made my trip to CERN possible. STFC are involved in lots of great science projects in the UK and beyond. They also fund research and support scientists. If you have been inspired to become a scientist then someday, who knows, it could be you. Thanks everybody!