Australasian Science: Australia's authority on science since 1938

Hunting for the Higgs Boson

By Stephen Luntz

Geoff Taylor has played a key role in the discovery of the Higgs boson.

When the world was transfixed this year with the announcement of the discovery of the Higgs boson, Prof Geoff Taylor had reason to be particularly proud. Taylor led the Australian involvement in the ATLAS project, which was one of the big detectors responsible for the discovery. He had also played a part in ensuring the announcement was being made in his home city.

“I started this project in 1989, bringing together Melbourne and Sydney efforts,” Taylor says. “We were involved in design work on the hardware and simulations.”

The major Australian contribution came in the form of silicon inner detectors to identify the particles given off when the Higgs boson decays. “The original challenge was to get detector technology that could operate in the extreme conditions involved. It had to be 100 times larger than anything we had then, 50 times faster and withstand radiation 1000 times as powerful,” Taylor says.

Solving these problems required “lots of simulation work” and testing first at the Australian Nuclear Science and Technology Organisation and later at CERN and in Japan to establish that the detectors Taylor and his team had produced could dissipate the extreme heat produced in such an environment. “Material degrades the performance of the detectors, so we needed to withstand the radiation while being made out of effectively nothing at all and still getting the heat out,” Taylor says.

The Australian components ended up costing $48 million – not an insignificant portion of the $600 million cost of the detectors overall.

The discovery has confirmed the validity of the Standard Model of particle physics, for which the idea of the Higgs boson was initially a sort of mathematical patch with no experimental evidence.

Taylor notes how remarkable the physics around the Higgs boson is. “It permeates the universe and it is the only scalar field we know of, the only field without a direction.”

The Standard Model explains three of the four forces of the universe, but has yet to be integrated with general relativity’s description of gravity or explain the accelerating expansion of the universe. More exotic models have been built upon it, and Taylor says the Higgs finding has ruled out some of these models of the universe and “given us a place to start in exploring others”.

He adds that the Large Hadron Collider used to locate the Higgs will be shut down for 18 months from March 2013 so it can be upgraded to full power and seek evidence for theories such as supersymmetry or the existence of other dimensions of spacetime.

The quest for extra dimensions is something Taylor has been part of in his other research work, along with studies of neutrinos, positrons and B mesons. Chasing the smallest particles in the universe is not easy, and Taylor admits, “We were looking for neutrinos in the wrong place – since then they’ve been discovered at a different energy regime.”

On the other hand, his work on B mesons has proven useful in getting to grips with the great mystery of why matter in the universe dominates over antimatter, when most models suggest they should exist in equal quantities – something that would make life more difficult for everyone.

Taylor says he was “always interested in things” but fell into science by chance and at the suggestion of “some very good teachers”. Having grown up near the beach at Rockingham, he studied undergraduate physics at the University of Western Australia. His PhD was at the University of Hawaii where a muon detector was to be built under the ocean.

This sounded ideal to a keen surfer, but Taylor discovered that the detector was beset with delays, and would not be built in time to allow him to complete his PhD on schedule. He adds ruefully: “The American work ethic also didn’t allow much time for surfing”.

Instead his PhD sought the transformation of neutrinos from one form to another, which would have settled the question as to whether neutrinos have mass. While Taylor did not find the oscillation he was seeking, a different change has since been detected, leading to general acceptance that neutrinos have mass that is so small we are yet to be able to measure it.

Taylor settled at the University of Melbourne’s Physics Department, where he has been based ever since, although his field has led him to spend time at the world’s largest particle accelerators.

As leader, Taylor was involved in the bid to bring the biennial High Energy Physics conference to Melbourne. “Paris bid to have it in 2010 because they thought that would be when the Higgs discovery would be announced, and we couldn’t argue against that given their leading role, but we got Melbourne as a consolation prize.” Delays meant that the two teams searching for the Higgs only solidified their evidence early this year, allowing Melbourne to play host to one of the great announcements in scientific history.