Читать книгу A Day at CERN - Gautier Depambour - Страница 8

I’m here with the ATLAS cap on — hello! And welcome to CERN’s entrance. You arrived as planned from Geneva, by the tramway. I am delighted by the curiosity that has led you to come here, and I am pleased to welcome you to the Franco-Swiss border to show you this exceptional place dedicated to particle physics. I will be your guide throughout the day.

I will give you an overview of the research being carried out at CERN, the “Conseil Européen pour la Recherche Nucléaire,” renamed in 1954 the “European Organization for Nuclear Research,” although the old acronym has been retained. I will of course mention the famous Higgs boson, and I will show you how the world’s largest particle accelerator works, the LHC (Large Hadron Collider), located about 100 m below our feet, as well as one of the four detectors where particle collisions occur: ATLAS.

But even more importantly, I intend to immerse you in CERN’s daily life in order to make you feel the atmosphere of this place; you will see it in a way completely out of the ordinary. During my five-month internship in the ATLAS detector communication group, I had the opportunity to meet some very nice people, and I now want you to benefit from this. That’s why I have organized several meetings with people who work in various fields, from accelerator physics to artificial intelligence used for data analysis. Today, I would like to share with you my enthusiasm for CERN and research in high-energy physics as it is carried out there!

Well, let’s take a look around us. First of all, you will have admired this imposing wooden structure: it is the Globe of Science and Innovation, which has become CERN’s emblem over the years. In addition to a large conference room, it houses a magnificent exhibition, both informative and poetic, entitled “Universe of Particles,” which allows one to discover what research at CERN is all about — and makes it a must for visitors.

The Globe of Science and Innovation

The Globe was built in Neuchâtel for the 2002 Swiss National Exhibition and symbolized sustainable development, because wood behaves like a carbon sink and thus reduces the greenhouse effect. At the end of the Exhibition, the future of the Globe was the subject of reflection. There was no question of burning it — that would have been inappropriate for a building supposed to represent sustainable development. Finally, the Swiss Confederation decided to offer it to CERN on the occasion of the Organization’s 50th anniversary in 2004. That’s why it ended up here! However, the Globe in front of you is not completely identical to the original: it was necessary to change the outer arches, which had not initially been made of wood that could withstand decades. Now reinforced, this building will continue to accompany CERN’s history throughout this century, while remaining a symbol for Geneva and its region. Now, let’s turn around...

Flags at CERN’s entrance

Do you see this line of flags? They correspond to all the member countries participating in this immense scientific collaboration. Could you guess in which order the flags are arranged? Answer: In alphabetical order, according to the names of countries in French. So the line starts with Germany and ends with... Switzerland, as you can see.

CERN was initially a European project, whose Convention was signed by 12 founding countries in 1954. By 2016, this number had risen to 22 Member States — including one that is not European, Israel — and six Associate States: India, for example, joined CERN as an Associate State in December 2016. An Associate State does not have the same status as a Member State: it contributes financially in the same way, and, above all, does not have the right to vote in the CERN Council, the highest ruling body of the Organization, where important decisions are taken. Finally, there are universities that have cooperation contracts with CERN. In all, about a hundred nationalities are represented here: that is quite exceptional.

First, let’s head to building 33: this is the reception area, where visitors are welcomed.

CERN’s entrance for visitors

As we walk, let me give you an overview of the day’s programme — without revealing everything, of course.

In order for you to understand our journey, one thing must already be clear. Do not confuse detector and accelerator! 100 m underground is a circular accelerator with a circumference of 27 km, the LHC, which accelerates particles. And at four different locations on this accelerator are arranged the four main detectors where particles collide. Their names? ATLAS, CMS, ALICE and LHCb. Keep in mind for now this distinction between the LHC accelerator and the four large detectors at the collision points.

I now come to the programme for the visit. First, by way of introduction, we will go to the Globe to visit the exhibition I was talking about a moment ago. Then, our journey through CERN’s various facilities will follow the same path as protons do, from their injection into accelerators to their collision inside detectors. Then, our visit will follow the logic of data analysis, from the acquisition of raw data by a detector to the discovery of a new particle.

But before getting to the heart of the matter and getting to the Globe, I imagine that you are spontaneously asking yourself some questions about CERN, such as: what research is being done here? What is all this for, and why should I feel conCERNed? How many people work at CERN, and in what professional capicities? To answer all these questions, I have arranged a meeting with Bernard Pellequer, who is responsible for the Globe exhibition in particular. We’ll meet him in his office soon.

We have arrived in the reception hall: nice, isn’t it? All the people who work at CERN can become guides, and that makes the visits very lively and authentic. Follow me to the desk on the right to pick up your visitor’s card; you can already take out your ID card.

The reception hall

“Hello madam, I ordered a pass on Indico... Yes, that’s it, thank you.” Here’s your card. For my part, I have to get my badge out if we want to get through that glass door. I always thought the picture of me looked strange; I have asked several people who I reminded them of. I have been given answers that I am still trying to analyze: Michael Scofield in Prison Break, Robert De Niro in Taxi Driver, Mark Ruffalo in Avengers before becoming Hulk (fortunately not after), and even a lifeguard, which is in my case a remarkable misunderstanding.

My access badge

I won’t hide from you the fact that I’m rather proud to own this badge. For you, it is a small piece of cardboard valid for one day with your name on it — and mine, because I am responsible for you. Be aware that “normal” visitors, if I may put it that way, do not even have this pass. With this, you are privileged, and you can legally access a large part of CERN without having to be in a group accompanied by a guide. In other words, you are freer, even if you depend on me!

Let’s go through that glass door. That’s it, we’re going into CERN’s inner sanctum. Here we go. Like a guide opening the hidden door of a library leading to the secret cabinet of an old castle, I am taking you into the nooks and crannies of the world’s greatest scientific collaboration...

Ah, stop! Not too fast. I can see that you are eager to go further, but we will stay for a while in building 33. Bernard’s office is there, just on the left. I think he’s coming to open the door, he must have seen our silhouettes through the tinted window of his door. If I need to talk to you discreetly during the interview, I will whisper. There he is.

Bernard Pellequer