In spring 2020 the European particle physics community will decide on a new European Strategy highlighting the strategic long-term goals in this important field of fundamental research. In December 2018 Swiss scientists – organized by the Swiss Institute of Particle Physics / CHIPP – have formulated their input to the new European Strategy. Günther Dissertori – professor at ETH Zurich, member of the CHIPP Executive Board and incoming Scientific Delegate of Switzerland in the CERN Council – explains the main points of the Swiss strategic input.
Prof. Dissertori, Swiss particle physicists recently have established a new research roadmap. The new strategy will replace the roadmap of 2004 focussing on the CERN particle accelerator LHC which finally started operation in 2009...
Let me clarify: The Swiss roadmap of Particle Physics – the update of the 2004 roadmap – will be worked on only in the upcoming months. What we have provided in December 2018 is the consolidated input of the Swiss particle physicists to the new European Strategy. Our document will be, together with many other documents, an input to the discussions taking place during the next ~twelve months on the European level. The new European Strategy will then be drafted in early 2020 by the European Strategy Group, which was nominated by the CERN Council, and is foreseen to be approved by the Council in late spring 2020. I expect, however, that the update of the Swiss roadmap will not be very different from what we have discussed in the last months by formulating the Swiss input to the European Strategy, but extended to include more on the area of astroparticle physics.
What is – in your personal view – the main outcome of the recent discussions?
A key output has been that the full exploitation of the LHC should remain the first priority for the European particle physics program, also in view of the recently launched upgrades of the LHC and the experiments. In parallel, Swiss scientists think that there should be an intensified R&D effort in order to have a timely preparation of the next large project at CERN. The Swiss community has consensus that this next big project at CERN should be the Future Circular Collider (FCC). I think this is the most relevant statement from Switzerland to the European scientific community.
Particle physics in Switzerland and worldwide has three pillars: High energy/high intensity physics, neutrino physics and astroparticle physics. The FCC is a long-term vision for the first pillar. May you please illustrate the intended further development of the second and the third pillar as well with a striking example?
The big projects in neutrino physics are a bit closer in the future, but we are still talking of about 10, 20 years. Swiss neutrino experts currently plan to participate in DUNE (Deep Underground Neutrino Experiment) in the US and the Hyper-Kamiokande experiment in Japan. Besides these big projects, the neutrino platform that has been established at CERN should be continuously supported. At this platform European physicists can develop and prepare experiments for the aforementioned large neutrino projects. There are also some smaller scale experiments highlighted in the Swiss input, such as the search for the neutrinoless Double Beta decay.
The strategic development of the third pillar, astroparticle physics, is more difficult to summarize briefly, because in this domain many different directions are pursued, like gamma ray astronomy or direct dark matter searches. The key statement for the European Strategy is that we think that CERN should foster the collaboration and synergies between particle physics and astroparticle physics. The synergies are given e.g. by the development of detectors and the related technologies. And CERN has the expertise how to manage large scale projects.
If you allow me to see behind the curtain: Which topic was most controversially discussed by you and your particle physics colleagues in the recent months while establishing the strategy input?
Probably the biggest question was turning around this FCC project. The Future Circular Collider would be a new large-scale research facility at CERN for the time after 2035 when the LHC is expected to go out of service. The FCC is a 100 km long, ring-shaped tunnel, which could offer particle physicists a very broad research program, by hosting first an electron-positron collider of very high luminosity and precision but relatively low energy of up to 365 GeV. Later – when powerful 16 Tesla magnets will become available (these are currently in a multi-year long development program) – this collider could be replaced by a 100 TeV proton-proton collider in the same tunnel. In this later configuration the FCC would provide a seven times higher collision energy than the LHC. There are further possibilities of colliding electrons or positrons with protons and heavy ions. This whole package will provide science for almost a century. The Swiss particle physics community is convinced this is the next big thing to do.
The FCC project is in competition with other projects: Japanese physicists propose to construct a huge International Linear Collider (ILC). Not to mention the ambitions of China to demonstrate its research power by establishing a potent circular collider.
We support the FCC not only as an outstanding research facility in Geneva, but also as a means to ensure Swiss based fundamental science in a very long term. Switzerland is one of the two host countries of CERN. We have the greatest interest to guarantee a prospering future of CERN.
Does that mean you state in your strategy input paper to drop the ILC and not to participate at a future Chinese accelerator project?
No, there is no such statement in our document. There were some discussions among the Swiss scientists if and how to mention the ILC in Japan and the Chinese plans, taking into account that so far there is no statement from the corresponding host country governments expressing their intentions. In the end we agreed to focus on a future CERN project and on the FCC only.
Which are the conditions enabling a giant project like the FCC to be realized? Are the State Secretariat for Education, Research and Innovation (SERI) and the Swiss National Science Foundation in the boat so far?
Swiss particle physicists are fully supporting the FCC – this is the clear statement of this paper. This was the first step, and now the discussion with SERI and on the political level will start. The SERI has been very positive towards supporting CERN and is well aware of this long-term project. In the coming years, if one wants that a big project like FCC is realized, the discussions have to be intensified a lot. The CERN host states Switzerland and France will definitely play a key role in the European and worldwide discussions.
Let’s close with a prophecy: Where do you expect the next ‚big news‘ from particle physics, comparable to the Higgs discovery in 2012?
Oh, that’s a tricky question! At the moment particle physicists are waiting for the publication of the new results from the LHCb experiment at CERN in order to see if they can confirm their measurements done a couple of years ago when they have observed some deviations from the standard model which could be first signs of new physics. If these anomalies are confirmed and the results can only be explained by new physics, that would be very, very exciting.
Interview: Benedikt Vogel