CERN Accélérateur de science

CERN’s main restaurant, imaginatively named Restaurant 1, is a vital part of the life of any physicist on the campus. At any moment — weekends and nights included — you’ll find groups of young, enthusiastic students chattering animatedly about their work, or individuals hunched over laptops, clutching coffee and wearing huge headphones.

Sat on the end of one of these high, long tables discussing what makes a successful physicist, Dr Anne-Marie Magnan giggles: “For a while I was interested in philosophy but I think it was just because I had a crush on the teacher… I quickly went back to physics!”

“Opportunities came up, I was interested so I applied and got them. For me, it was physics from early on.” She explains that being able to change direction, and be open to what life throws at you is, she believes, key to being a good experimental physicist. 

“Sometimes the best physicist is one that’s able to take us in a new direction, to see a new way where you might be more successful,” she continues. 

Magnan now works for CERN’s CMS experiment and supervises several of the collaboration’s budding young scientists. “The absolute best physicists I’ve ever seen are people who are very good at building on what they know by seeing a way to change it slightly and finding a new path,” she explains. 

These qualities don’t just help a physicist to do the most interesting science, they’re also vital for building a career in the field. In a subject where new theories are constantly being formed and new facilities and experiments are being built around the world, being open to moving country for your work, or to letting go of a theory you’ve been working on for many years, is vital to staying relevant and becoming successful.

Magnan’s own route sounds surprisingly simple, she was good at physics in school, was inspired by her teachers, aimed to go to a physics school in Grenoble, heard of a PhD being offered in particle physics, applied, and has been at CERN since 2009. But this simple path is all down to her enthusiasm for the subject and openness to pursue anything within the field – passion that’s desperately needed when she works overnight as a shift leader, making sure the detector is running properly.

 “Sometimes the best physicist is one that’s able to take us in a new direction, to see a new way where you might be more successful.”– Anne-Marie Magnan.  

Her early interest in the subject is a common theme for the physicists at CERN. Many are inspired by the stars and questions about our universe. Some chose to answer these questions by pursuing theoretical physics and others experimental.

Practical, logical people

I met Dr Leticia Cunqueiro Mendez in her tiny office in one of CERN’s many industrial, grey buildings. She laughs that when she was a student she was given a better, bigger room than now she’s a staff member. A leading force in one of the ALICE physics programmes and coordinator for one of the biggest gaseous detectors in ALICE, she seems the ideal no-nonsense, efficient person for this – exactly the qualities which led her to ALICE, despite having a PhD in theoretical physics. 

“I got a nice offer, it was practical. There weren’t many openings when I finished my PhD. I know several cases where young physicists were prevented from becoming theorists because there are just more opening in experiments,” she explains.“There is only one important difference for working in experimental physics. It requires really good social skills, to work in a huge collaboration of 2000 people or more gets complicated. When you’re a theorist you can go to your table, sit down, and work on your idea on your own but if you’re in experimental physics you need to collaborate. That’s a basic need,” says Mendez.

Working in huge collaborations is vital to the discoveries being made at CERN, which is one of the reasons Restaurant 1 is such a hub of activity as people move out of their offices to interact with each other. Here, theoreticians meet with experimentalists, technicians meet with project leaders and computer scientists work with physicists. 

“If you want to learn how to design and build experiments, or analyse data, or find something interesting, then contact with people is necessary” says David Francis, who works on systems for data acquisition for the ATLAS collaboration. “To some extent, if that’s what interests you, you naturally interact with those people and that’s where you build up the relationships and the friendships. Whether it’s over coffee or in meetings at CERN or back in your home institute, you should be interacting with other people all the time.” 

"It's really hard. We work together, we eat lunch together, we become friends, but we're competing for a job," laments Barbara Storaci who, like Mendez for ALICE, coordinates operations for the LHCb experiment.

Being a physicist doesn’t guarantee a smooth ride for the rest of their career. Young physicists have to be passionate and stubborn, since permanent positions are rare. When they finally land one, it is often after working through several post-doctorates (the first career step after a PhD) or temporary contracts. In short, the competition is fierce.

Has the field changed too much?

Larger collaborations are a relatively new concept in the field of experimental physics, born along with CERN’s Large Electron-Positron Collider  – the LHC’s predecessor. The huge experiments at LEP, and in turn the LHC required the expertise of so many individuals that the field had to adjust to acknowledge that collaborations would now be made up of far more people.

But as the field of research has progressed to focus on ever longer-term, larger experiments with collaborations of thousands or more researchers, it seems younger physicists may not be getting the overview of the field they need to stay creative, open to new ideas and to glimpse possible promising new paths.

“It used to be that you’d be doing your PhD and in the first year you’d build [the experiment], the second year you'd make it work and in the third year you’d do the physics analysis. But now those three years are spread over thirty years so in a three or four year PhD you just can’t get the nice overview you'd have got in the past,” explains Jamie Boyd, the LHC programme coordinator.

“Now those three years [of a PhD] are spread over thirty years so in a three or four year PhD you just can’t get the nice overview you'd have got in the past.” – Jamie Boyd.

PhD’s and post-doctoral positions to work on experiments at CERN are often just three-year contracts. When the LHC was being built these three years were spent building tiny pieces of the machines, or working on specific technical problems. Now, these young scientists spend their time gaining a specialized knowledge of a small subset of the data that comes out of the experiment.

With 80% of particle physicists in the world working on the LHC, many PhD students now spend their full three years analysing just a fraction of the LHC data, or learning about one part of an experiment or detector. They don’t get the overview that physicists once did while working on smaller experiments that they designed and built.

Some researchers working at CERN think this is a problem, as it means scientists are becoming less flexible, less able to move between different experiments or understand why something might have gone wrong.

 “I envy the people who were involved in the building of the machine because I feel that they are the only people who have a deep understanding of all the detectors. The young people who are in the control room will never have such a deep understanding,” Manuela Venturi, who is still in the early-stages of her career, working on her first research position after her PhD, says.

But Magnan disagrees.

“If everyone had to redo the basics no one would progress.” – Anne-Marie Magnan

“The machine is built, the software is built and we need to analyse huge amounts of data. So why would we try and teach each new PhD student everything from scratch?” Magnan shrugs. She thinks that building on the work of predecessors, seeing how it can be used, is the route to the next discovery. “It’s one way to make progress faster. If everyone had to redo the basics no one would progress,” Magnan asserts.

It’s this openness to embrace the changes in the field that she asserted was so vital to building a brilliant physicist in the first place.

Read the other articles in the In Practice series here.