The Higgs boson was discovered in the particle accelerator LHC (Large Hadron Collider) at CERN in 2012 – and scientists are expecting to gain more groundbreaking insights from this large research facility in Geneva during the next twenty years of its operation. Nevertheless physicists are already working meticulously on a new and even bigger accelerator with the name FFC that shall make particle collisions of even higher energy possible. Stefan Antusch, Professor for Theoretical Physics at the University of Basel, explains the state and the aim of this new project.
Professor Antusch, the LHC will be operating for another 20 years. Nonetheless particle physicists agonize over the construction of an even bigger particle accelerator. Why such a hurry?
Stefan Antusch: Large research facilities in particle physics need long term planning. The planning phase for the particle accelerator LHC, that went into operation in 2009, started in the 80s of the last century – in other words, it lasted 25 years. The construction of a new particle accelerator requires the development of new technologies, a process that takes time. Moreover, the time is right to think about a new accelerator that can follow the LHC in 20 years. The discovery of the Higgs boson in 2012 has provided us with important insights that are very useful for the design of a new accelerator.
What are the principle features of the planned “Future Circular Collider” FCC, also in comparison to the LHC?
Like the LHC, particle accelerator FFC will operate in an underground tunnel. But its tunnel will cover three times the distance of the LHC´s – it will be 80 to 100 kilometers long. The FFC will accelerate beams of protons and make them collide in order to analyze the particles that emerge from the collision. The FFC is planned to operate with a collision energy of 100 teraelectronvolts, that is ten times the energy of the LHC. The tunnel for the new accelerator could also be used for other purposes, for examples for the collision of electrons and positrons. Such an experiment would be excellent for analyzing with high accuracy the different decay channels of the Higgs boson.
What will the FCC be capable of what LHC is not?
Thanks to the much higher collision energy we might discover new elementary particles and new interactions between them. We know that the standard model of particle physics does not give final answers about the structure of matter. We hope to get answers with the help of the FFC that take us beyond the standard model, the current theory of elementary particle.
A few days ago there was a kick off meeting in Geneva about the new accelerator project. What questions were discussed? What were the results?
Well, the meeting in Geneva marked the start of a concept study that is supposed to show if a new particle accelerator is feasible and what the requirements are for it in order to deliver a maximum of new insights into physics. One important technical question concerns the further development of superconducting magnets. These magnets that keep the particles in the ring circulators on track have to become much more powerful and efficient if we want make the FFC a reality.
How much will the FFC cost?
This is one of the questions that are part of the concept study.
It is no secret that such an accelerator will cost Billions of Swiss Francs. What are your arguments to convince the public that physicists need such an expensive machine?
There is no doubt that FFC won´t be cheap. But particle accelerators have proven to be a good investment. On the one hand they provide us with spectacular insights into physics and enable us to move basic research ahead. Furthermore these accelerators are important for technological developments. We expect the FFC to lead to numerous spin-off projects that will commercialize new technologies and also provide short-term economical benefits.
Besides being an experimentalist you are also a theoretical physicist. What is your personal fascination with the FCC project?
The FCC would provide us theorists with experimental data to develop better theories of elementary particles and the acting forces between them. Another important factor are the unsolved questions concerning dark matter or why neutrinos, that are massless according to the standard model, nevertheless do have mass. We also want to include the gravitational force in our models, one thing that has not been realized with the standard model. Furthermore the exploration of the Higgs boson has only just begun.
The main focus of the physics department at the University of Basel, where you work as a professor, is on nanophysics and quantum physics, a sector with high hopes for commercial applications. A second focus is cosmology and particle physics. Which discipline will bring greater changes to the world in the next 25 years? Particle physics or nano / quantum physics?
At the moment we are experiencing incredible progress in both fields that will have a big impact on the future. Nano and quantum physics are much closer to commercial applications and will definitely cause big changes in the next 25 years. Particle physics will maybe lay the base for the next technological revolution in the same time span. But it will probably take more than 25 years to apply these findings. New findings and insights in the upcoming years could alter our physical conception of the world decisively, for example by new discoveries with the LHC.
Apart from the FFC there are further projects for new accelerators: a linear accelerator with the name ILC that is planned to be built in Japan. Furthermore a linear accelerator CLIC that could be installed at CERN. How realistic is it that several of these projects will be realized simultaneously?
From my personal viewpoint it is possible and desirable, because each of the accelerator is following a separate and complementary goal.
What are the major contributions of Swiss physicists in the FCC project?
Many Swiss groups are doing experimental and theoretical work that is related to the FCC. Therefore many physicists from Swiss institutes participated in the kick off meeting in Geneva. But it is too early to answer your questions in detail.
If no new big accelerator was built – would that be the end of particle physics?
There are other experiments from which physicists can gain new important insights. Nevertheless: For the future of particle physics it is essential to conduct experiments with very high energy. I don´t think that the LHC was the last major accelerator that was built.
Interview Benedikt Vogel (published 26. 2. 2014; translated into English by Petra Krimphove)