Fabiola Gianotti shot to prominence on 4 July 2012, with the announcement of the discovery of the Higgs boson. At the time, she was the spokesperson of ATLAS, which along with the Compact Muon Solenoid (CMS) experiment spotted the Higgs at the Large Hadron Collider (LHC) at CERN.
In the excitement over the Higgs discovery, Gianotti was on the cover of Time. She was hailed as among the most influential and the most inspirational women of our time. She was listed among the "leading global thinkers of 2013" by Foreign Policy magazine.
Fabiola Gianotti in December 2015, just before she became CERN’s director general. Credit: CERN
"I am not very comfortable in the limelight," says Gianotti. "Particle physics is a truly collaborative field. The discovery of the Higgs boson is the result of the work of thousands of physicists over more than 20 years."
Gianotti first went to CERN in 1987 as a graduate student at the University of Milan. She has been there ever since. And she seems comfortable at the helm, a job she has held since the beginning of this year.
"The main challenge is to cope with so many different aspects, and switching my brain instantly from one problem to another one," she says. "There are many challenges—human challenges, scientific challenges, technological challenges, budget challenges. But the challenges are interesting and engaging."
As of this summer, the LHC is in the middle of its second run, known as Run 2. In June the collider reached a record luminosity of 1034 cm−2s−1. It produces proton–proton collisions of energy of 13 TeV. A further push to the design energy of 14 TeV may be made later in Run 2 or in Run 3, which is planned for 2021–23. An upgrade following the third run will increase the LHC's luminosity by an order of magnitude.
Physics Today's Toni Feder caught up with Gianotti in June, about six months into her five-year appointment in CERN's top job.
PT: Last fall the ATLAS and CMS experiments both reported hints of a signal at 750 GeV. What would the implications be of finding a particle at that energy?
GIANOTTI: At the moment, we don't know if what the experiments observed last year is the first hint of a signal or just a fluctuation. But if the bump turns into a signal, then the implications are extraordinary. Its presumed features would not be something we can classify within the best-known scenarios for physics beyond the standard model. So it would be something unexpected, and for researchers there is nothing more exciting than a surprise.
The experiments are analyzing the data from this year's run and will release results in the coming weeks. We can expect them on the time scale of ICHEP in Chicago at the beginning of August. [ICHEP is the International Conference on High Energy Physics.]
PT: The LHC is up to nearly the originally planned collision energy. The next step is to increase the luminosity. How will that be done?
GIANOTTI: To increase the luminosity, we will have to replace components of the accelerator—for example, the magnets sitting on each side of the ATLAS and CMS collision regions. These are quadrupoles that squeeze the beams and therefore increase the interaction probability. We will replace them with higher-field, larger-aperture magnets. There are also other things we have to do to upgrade the accelerator. The present schedule for the installation of the hardware components is at the end of Run 3—that is, during the 2024–26 shutdown. The operation of the high-luminosity LHC will start after this installation, so on the time scale of 2027.
The high-luminosity LHC will allow the experiments to collect 10 times as much data. Improving the precision will be extremely important, in particular for the interaction strength—so-called couplings—of the Higgs boson with other particles. New physics can alter these couplings from the standard-model expectation. Hence the Higgs boson is a door to new physics.
The high-luminosity LHC will also increase the discovery potential for new physics: Experiments will be able to detect particles with masses 20% to 30% larger than before the upgrade.
And third, if new physics is discovered at the LHC in Run 2 or Run 3, the high-luminosity LHC will allow the first precise measurements of the new physics to be performed with a very well-known accelerator and very well-known experiments. So it would provide powerful constraints on the underlying theory.
PT: What are some of the activities at CERN aside from the LHC?
GIANOTTI: I have spent my scientific career working on high-energy colliders, which are very close to my heart. However, the open questions today in particle physics are difficult and crucial, and there is no single way to attack them. We can't say today that a high-energy collider is the way to go and let's forget about other approaches. Or underground experiments are the way to go. Or neutrino experiments are the way to go. There is no exclusive way. I think we have to be very inclusive, and we have to address the outstanding questions with all the approaches that our discipline has developed over the decades.
In this vein, at CERN we have a scientific diversity program. It includes the study of antimatter through a dedicated facility, the Antiproton Decelerator; precise measurements of rare decays; and many other projects. We also participate in accelerator-based neutrino programs, mainly in the US. And we are doing R&D and design studies for the future high-energy colliders: an electron–positron collider in the multi-TeV region [the Compact Linear Collider] and future circular colliders.
PT: Japan is the most likely host for a future International Linear Collider, an electron–positron collider (see Physics Today, March 2013, page 23). What's your sense about whether the ILC will go ahead and whether it's the best next step for high-energy physics?
GIANOTTI: Japan is consulting with international partners to see if a global collaboration can be built. It's a difficult decision to be taken, and it has to be taken by the worldwide community.
Europe will produce a new road map, the European Strategy for Particle Physics, on the time scale of 2019–20. That will be a good opportunity to think about the future of the discipline, based also on the results from the LHC Run 2 and other facilities in the world.
PT: How is CERN affected by tight financial situations in member countries?
GIANOTTI: CERN has been running for many years with a constant budget, with constant revenues from member states, at a level of CHF 1.2 billion [$1.2 billion] per year. We strive to squeeze the operation of the most powerful accelerator in the world, its upgrade, and other interesting projects within this budget.
PT: Will Brexit affect CERN?
GIANOTTI: We are not directly affected because CERN membership is not related to being members of the European Union.
PT: You have said you have four areas that you want to maintain and expand at CERN: science, technology and innovation, education, and peaceful collaboration. Please elaborate.
GIANOTTI: Science first. We do research in fundamental physics, with the aim of understanding the elementary particles and their interactions, which also gives us very important indications about the structure and evolution of the universe.
In order to accomplish these scientific goals, we have to develop cutting-edge technologies in many domains, from superconducting magnets to vacuum technology, cryogenics, electronics, computing, et cetera.
These technologies are transferred to society and find applications in many other sectors—for example, in the medical fields with imaging and cancer therapy, but also solar panels, not to mention the World Wide Web. Fundamental research requires very sophisticated instruments and is a driver of innovation.
Another component of our mission is education and training. The CERN population is very young: The age distribution of the 12 000 citizens from all over the world working on our experiments peaks at 27 years, and almost 50% are below 35. About half of our PhD students remain in academia or research, and about half go to industry. It is our duty to prepare them to be tomorrow's scientists or tomorrow's employees of industry—and in any case, good citizens.
How do we prepare them to be good citizens? CERN was created in the early 1950s to promote fundamental research and to foster peaceful collaboration among European countries after the war. Today we have scientists of more than 110 nationalities, some from countries that are in conflict with each other, some from countries that do not even recognize each other's right to exist. And yet they work together in a peaceful way, animated by the same passion for knowledge.
PT: You are the first woman to head CERN. What do you see as the significance of this?
GIANOTTI: The CERN director general should be appointed on the basis of his or her capabilities to run the laboratory and not on the basis of gender arguments. This being said, I hope that my being a woman can be useful as an encouragement to girls and young women who would like to do fundamental research but might hesitate. It shows them they have similar opportunities as their male colleagues.