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Particles and interactions

Particles and interactions

CERN boss targets linear collider

16 Sep 2009 Matin Durrani

The boss of CERN wants the next big experiment in particle physics after the Large Hadron Collider (LHC) to be built at the Geneva lab. Speaking in an interview with, Rolf-Dieter Heuer said that CERN should host the experiment, which would collide electrons and positrons in a linear accelerator. Although a design for the machine has not been finalized by the international particle-physics community, Heuer is keen to bring the collider to CERN.

“I would be a bad director-general if I did not push for CERN at least bidding for the next global project,” Heuer told “CERN is a fantastic place. [It] has proven that it can host such a project and therefore I think CERN should do it.” However, Heuer is aware that it is far from certain that CERN will host the facility – Fermilab in the US is likely to be a contender – and the CERN chief is looking forward to bids from rival labs. “Competition is always welcome,” he says.

Heuer’s desire to host the linear collider is part of his plan to make CERN a much more global laboratory. Although CERN was set up in 1954 as a European facility, its convention does not prevent countries from outside Europe from becoming members. Several thousand physicists from the US have already helped to build the LHC and its detectors, and Heuer is keen for links with non-European nations to become more permanent.

“Why not involve some of the nations from the Americas or Asia as members [of CERN]?” he asks. “This would enable us to start the next global project as a global project from the very beginning – be it at CERN or elsewhere.” CERN is already developing a blue-print for a future linear collider, known as CLIC, while a rival design known as the International Linear Collider is being drawn up by a team led by Barry Barish of the California Institute of Technology. The precise energy at which such a collider should operate will depend in part on what the LHC discovers.

Switch-on schedule

In his interview, Heuer also confirmed the timetable for switching the LHC back on following the electrical fault that occurred on 19 September last year and led to 53 magnets having to be repaired or replaced. As CERN announced last month, beams will be injected into the 27 km long circular accelerator in mid-November with collisions taking place a few weeks later. “I am pretty confident that we will have the first collisions this year,” says the CERN boss.

CERN engineers will begin by colliding protons at an energy of 450 GeV per beam, before attempting collisions at 3.5 TeV per beam. “We will stay there for several months, depending on what experiments find and on running experience,” says Heuer. “Then in the course of the next year we will go up to 10 TeV in the centre of mass [i.e. 5 TeV per beam]”. The LHC will be kept going until the end of 2010 before it is shut down to prepare the way for collisions at a maximum energy of 14 TeV (i.e. 7 TeV per beam) at some point in 2011. “But if we find something interesting at 10 TeV, we will continue running at 10 TeV,” Heuer added.

Challenges and opportunities

Heuer, who replaced Robert Aymar as CERN’s director-general in January this year, admitted in his interview that one of his challenges as lab boss has been to motivate staff following last year’s accident. He revealed that his tactic has been to get staff involved in technical and scheduling decisions, which “brought the spirit up very quickly”, and to bring the LHC’s users – non-CERN staff from universities around the world – in contact with machine staff.

By the time he steps down as director-general at the end of 2013, Heuer hopes that the LHC will have been running at 14 TeV “for a long time” and that physicists will have been able to make their first discoveries. Although he is cautious not to reveal what those discoveries will be, they are likely to include the Higgs boson, which would be the icing on the cake for the Standard Model, and possibly, exotic new “sparticles” that would reveal a new symmetry of nature called supersymmetry and hint at physics beyond the Standard Model.

The discoveries made with the LHC – particularly the mass of the Higgs boson – will influence the nature of any future linear collider and the energy at which it operates. Although the linear collider will have a lower energy than the LHC, it will be able to make measurements more accurately because electron-positron collisions are “cleaner” than those between protons. “I would hope that I am able to shape the future of particle physics with the discoveries made at the LHC during my mandate,” says Heuer. “That’s at least Heuer’s wishful thinking.”

A question of hype

Meanwhile, in a separate interview with, CERN’s head of communications James Gillies rejected suggestions that the laboratory was guilty of over-hyping the switch-on of the LHC last year, which saw some 340 journalists from over 100 nations attending the opening. “We didn’t over-hype it,” he says. “The hype was there and we lived with it.” Gillies puts the media interest in the LHC down to three factors: fears that the collider would create black holes; Dan Brown’s novel Angels and Demons, part of which is set at CERN; and the lab’s deliberate attempts to tell the world about the LHC.

But with the LHC soon to start running again and taking real data for the first time, Gillies reiterated that CERN wants to improve how it manages the flow of information from the lab to the wider world. In the past, CERN tended to hold onto sensitive information for too long and then was caught out by rumours spreading, particularly from blogs written by particle physicists. “Our whole approach to information is now to be quick [and] honest and to put it out as fast as we can.”

However, Gillies denied that rules imposed by particle-physics collaborations about what bloggers can and cannot say amount to censorship. “The guidelines are not very restraining at all,” he says. “All the guidelines say is follow your collaboration’s internal peer-review guidelines and make sure the information is of sufficient quality to be published before you start talking about it. That’s not over restraining in my opinion – it’s perfectly reasonable.”

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