“Discovering the Higgs boson was easy – the work starts here”

In a vast tunnel one hundred metres underground, the Large Hadron Collider (LHC) at CERN’s laboratory on the French-Swiss border, is stirring. The physicists who set in motion powerful subatomic collisions to discover the most elementary particle in the universe, the Higgs boson, are now preparing the €10 billion accelerator complex for the next phase of scientific discovery.

“The machine is coming out of a long sleep after undergoing an important surgical operation,” said Frédérick Bordry, CERN’s director for accelerators and technology. Over the last 16 months, the giant atom-smasher has been set “on snooze”.

It has undergone a programme of maintenance and upgrading, along with the rest of CERN’s accelerator complex, some elements of which have been in operation since 1959. The Higgs boson was discovered on July 4 in 2012, during collisions that brought the temperature inside the collider to around four trillion degrees — the temperature several seconds after the Big Bang that created the universe. During the LHC’s rest period engineers opened every 20 metres of the 27-kilometre length collider to make reinforcements to its huge magnets.

“It’s effectively a new machine, poised to set us on the path to new discoveries,” said CERN Director General Rolf-Dieter Heuer, on 23 June at the EuroScience Open Forum (ESOF) in Copenhagen. “Discovering the Higgs boson was easy – the work starts here.”

What’s next?

The Higgs boson explains why elementary particles like electrons and quarks – the fundamental constituents of all matter including human beings – have mass.  “It is the key particle to understanding why we are here and why the universe is the way it is,” Heuer said.

The big question: can CERN’s researchers produce a second discovery about the nature of matter that matches the breakthrough of the Higgs boson? That’s Heuer’s aim.

When it is back operating fully again, around Easter or so, the collider will slowly start to run collisions with higher energies. Eventually the LHC will attain collision energies running at twice the energy of the collisions that enabled discovery of the Higgs boson. But Heuer is careful not to make any promises. “Unfortunately I left my crystal ball in my office,” he said.

One thing is sure, the Higgs boson will remain centre-stage during the next round of experiments deploying the LHC. There are still many mysteries about it to be unearthed, said Fabiola Gianotti, a particle physicist at CERN and coordinator of the ATLAS project that lead to the discovery of the Higgs boson. One question is why the Higgs boson weighs so little. “Like a new friend, getting to know him or her takes a while,” she said. Measuring how it reacts with other particles will be important too, she added.

Fabiola Gianotti, speaking at the ESOF opening ceremony

CERN’s researchers also aim to wield the LHC to continue probing the nature of antimatter. Explaining why there’s so much matter out there in the universe, and so little antimatter, remains an enigma for scientists. Creating and studying antimatter atoms has been a frustrating mission, but in January, CERN managed to build antihydrogen atoms. “I was recently at the Vatican to ensure the Pope that it’s not dangerous,” said Heuer, referring to the tendency for matter and antimatter to wipe out each other.

One key challenge for Heuer is to ensure sufficient public sector funding for the LHC and the frontier research CERN does. Broadening participation at CERN, which was launched in 1954 as the European Organisation for Nuclear Research is a one solution. CERN has now has 21 member states and a broader constellation of partnerships with third countries and institutions. Israel joined in January – the first new member since Bulgaria in 1999. Romania and Serbia are on track to become full members. There’s signals that Ireland wants to join while Pakistan and Turkey’s participation has been upgraded to associate member status. “The first round was quasi-global but the next round has to be truly global,” he said.

Heuer has half an eye on life after the LHC too with the accelerator complex set to retire in 2035. Proposals for a 100 kilometre collider were heard at a special CERN meeting in February attended by up to 350 scientists and engineers. A high-level group of particle physicists, who form the European Committee for Future Accelerators (EFCA), are preparing a conceptual study.

“We are beginning a study to make a clear case [for its feasibility and need],” said Heuer. Scientists at CERN will advocate the cost savings in keeping any new collider at their Geneva labs: “Building a tunnel is easy, Switzerland knows how to do this,” said Heuer.

It’s early days. The timeline for development is expected to be long – assuming there is any agreement to advance it might take another 15 years or so to work out a detailed design, choose a site, secure international approval and financing and complete installation.

The hope is that a next-generation collider will continue to advance man’s knowledge about matter and the universe. The ‘God particle’, which originated from a book of the same name written by the physicist Leon Lederman, is a much-heard nickname for the Higgs boson. “I don’t like it but I have accepted it,” said Heuer.
 
LHC timeline:
•    Early 2015: Beams sent into the LHC
•    Spring 2015: Full physics programme to restart