Early in his career, Karl Jakobs worked on physics experiments that had a few hundred collaborators and operated for roughly a decade.
“In the 1980s and 1990s, the experiments were smaller, and there were more of them,” he says.
Today, Jakobs works on the ATLAS experiment at CERN, which has approximately 3,000 scientific authors and a planned operational lifetime of more than 30 years.
“These projects are now on the time scale of our careers,” says Harriet Watson, a postdoc at the University of Edinburgh who is also working on ATLAS.
With the advent of mega science experiments like the LHC, the CERN Council decided in the early 2000s that the physics community needed to have a long-term plan for what would come next. In 2005, they introduced the European Strategy for Particle Physics: an initiative that engages the global physics community to identify the most important questions in physics and the best European infrastructure to explore them.
“This process gives the full particle physics community a proper way to express their views,” says Jakobs, the Chair of the current European Strategy group. “The community has to agree what should be the next big project at CERN because the infrastructure will take a long time to develop and will serve the community for many years.”
During the last week of June, about 600 scientists will meet in Venice with the goal of answering the question “What’s next?”
Prior to this meeting, particle physicists were invited to give their input, and the committee received a total of 263 submissions in the form of individual perspectives, national inputs, and white papers summarizing the views of hundreds of scientists.
One of the white papers was coordinated by Armin Ilg, a postdoc at the University of Zurich, who engaged the early-career research community to understand what is important to them. One priority stood out: a future collider to succeed the LHC.
“We surveyed 800 early-career researchers, and almost 80% said that they support a future collider; even physicists who don’t work on collider physics on average wanted a future collider,” he says.
One prospect is the proposed Future Circular Collider, a 91-kilometer ring that would use CERN’s infrastructure to unlock a completely unexplored energy realm and allow scientists unprecedented access to the properties of the Higgs boson and unexplored laws of nature.
In planning for the future of European particle physics, the European Strategy Group will also consider the sentiments of non-European players, such as the United States, Japan and China.
“In their strategy input, the US made a very strong statement that they would participate in an electron-positron collider at CERN” Jakobs says. “China gives a different view and has expressed interest in constructing their own collider, the CEPC, that would be similar to the FCC-ee.”
Beyond building a new supercollider, the European physics community has expressed interest in maintaining a diverse ecosystem of physics experiments, research and development. “We cannot just define one collider as our priority,” Jakobs says. “We have to think about all the options in case ‘option one’ is not feasible or not competitive with a similar collider somewhere else in the world.”
According to Ilg, the survey of early-career researchers found a strong inclination toward high-risk-high-reward R&D. “Innovation was number one,” Ilg says. “We want to do great physics searches, but the new technology we develop along the way is extremely important.”
After the meeting in June, small groups of particle physicists representing a broad range of subfields will review and compile the community feedback into a physics briefing book. The European Strategy Group will then draft and submit their final recommendations to the CERN Council in December.
According to Ilg, the most important thing for early-career researchers is a clear understanding of where the field is headed, regardless of what projects the community decides to pursue.
“We found in our survey that early-career researchers are actually willing to wait longer for the next machine than the seniors,” he says. “But we want a decision as soon as possible because we need to plan our careers.”
