Go back

Cern can’t brush off German objections to flagship project

 Image: Bjoern Wylezich, via Getty Images

Blunt refusal to fund next-generation particle accelerator should prompt lab to rethink, says John Womersley

The particle physics community found itself in something of a tizzy last month, after a German government representative made unprecedentedly negative public comments about plans by Europe’s particle physics laboratory Cern for a next-generation particle accelerator.  

The intervention from Cern’s single largest contributor, paying 21 per cent of the lab’s roughly SFr1.4 billion (€1.2bn) annual budget, was both very blunt and very public, being made at a meeting of German particle physicists, with slides posted online. The Future Circular Collider (FCC), says the Federal Ministry of Education and Research, “has to be considered as not affordable” and “Germany is not in a position to provide the planned funding”.   

Germany has, I’m told, already made this point privately in Cern’s council. I suspect the ministry felt the message hadn’t hit home.  

The FCC is conceived as a larger successor, roughly 90km in circumference, to the highly successful Large Hadron Collider. It would be built in two stages: the first (FCC-ee) to probe the properties of the Higgs boson discovered in 2012 by the LHC, the second (FCC-hh) opening up new territory by colliding protons at energies roughly seven times higher than the LHC.  

Scientifically and strategically, this is an extremely attractive plan. The challenges are technical, financial and sociological. 

The tunnel, estimated to cost SFr6bn, would be expensive but not technically unprecedented. The magnets needed to collide the particles for the second phase are a different story: technically risky, requiring significant R&D, and with a high and uncertain cost.

Updated estimates have not been released, but an earlier phase of the design study estimated SFr12bn for FCC-ee. Even if Cern devoted close to half its funds to the project, building this within its present budget could take 20 years. It would also require significant borrowing to smooth the cash flow.

It’s complicated…  

I know from my time running a multinational scientific facility, in this case the European Spallation Source in Sweden, that Germany’s federal prohibition on borrowing creates issues with such financing. This may explain some of the unhappiness.  

The choice of a 90km tunnel is partly a down payment on FCC-hh, projected to cost an additional SFr17bn. Germany, and others, may be wary of doing anything that looks like pre-approving such a massively expensive follow-on project.  

The sociological challenge lies in the project’s timescales. Cern plans to run the LHC until 2041, and is currently upgrading the facility under the High-Luminosity LHC project. FCC-ee could not start before 2045 and FCC-hh not before the 2070s. These dates look depressingly remote, especially to younger scientists.  

Many have looked to alternatives, such as a muon collider—a riskier proposition but one offering many interesting projects in the next few years. Cern has the resources to pursue this option, but its natural home would be the US’s Fermilab.

The FCC team has tried to put a positive spin on Germany’s reservations, but this looks increasingly silly. It would be better to listen and rethink.

Contacts tell me that the FCC could find cost savings of 10 or even 20 per cent. Coupled with a general belt-tightening, this should enable a credible plan within Cern’s existing budget.

Budget challenges   

Contributions from other countries, notably the United States, are also part of the solution. Cern recently signed a memorandum of understanding with the US government allowing contributions to the FCC. These, however, are unlikely to be huge: the US Department of Energy is making a very large investment in the Deep Underground Neutrino Experiment, and the National Science Foundation faces big budget challenges. Many Cern member states would also expect the two host nations, France and Switzerland, to step up, given so much of the construction budget would be spent in their territories.  

Second, cutting short the High-Luminosity LHC’s operations could assuage younger scientists’ concerns about the schedule. The FCC will supersede many of the LHC’s measurements, and once its capacity to discover new phenomena has been exhausted, the FCC should take precedence.  

Pooling resources   

Cern is a great institution precisely because it pools resources and allows long-term commitments. But, like any big institution, it needs a realistic vision for the future to keep member states, staff and scientific users engaged. The FCC is not quite there yet.

Cern’s next director-general, to be appointed in December, must treat this problem as a top priority, and be very tough on cost and schedule. The laboratory’s future may depend upon it.  

John Womersley is a special advisor to the College of Science and Engineering, University of Edinburgh, and a visiting professor at the University of Oxford

This article also appeared in Research Europe