Anthony Doesburg: Cosmic cook up probes secrets of the universe

By Anthony Doesburg

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Giant experiment is already providing real return for NZ, says physicist.

Emmanuel Tsesmelis says the latest Large Hadron Collider experiment is a big step towards understanding subatomic particles. Photo / CERN
Emmanuel Tsesmelis says the latest Large Hadron Collider experiment is a big step towards understanding subatomic particles. Photo / CERN

When physicist Emmanuel Tsesmelis stepped off a plane in Christchurch last week he was taken aback at the latest accomplishment of the world's largest scientific instrument.

Tsesmelis, who played a key part in development of the Large Hadron Collider, was greeted with the news that while he was in the air, it had successfully switched from smashing protons into each other to creating lead ion collisions.

"It was unbelievably momentous," says Tsesmelis, the switch taking much less time than he expected and representing another step in the search for the elusive Higgs boson subatomic particle.

"I said that can't be true, I was on a plane, I didn't go off the planet, did I?"

The event, which until recently would have been so esoteric as to go unnoticed anywhere but in physics labs, made newspaper headlines. The colliding lead ions, whacking into each other at a rate of 600 to 800 million a second, created temperatures of trillions of degrees.

It's another stage of the instrument's compact muon solenoid (CMS) experiment, a kind of cosmic cook-up. The aim is to try to produce a soup of quarks and gluons, called the quark-gluon plasma, to mimic conditions microseconds after the Big Bang.

Thousands of scientists from around the world, including New Zealand, hope to find evidence in that soup of the existence of the Higgs boson, which will help solve the mystery of how subatomic particles - and the universe itself - have mass.

"There is a symbiosis of the very small, what we're doing now at a level of 10 to the minus 18 metres, to the very large, which is the universe," Tsesmelis says. "For us the driving force is the thorough understanding of the history of the universe, and this is another step in gaining that knowledge."

Tsesmelis had flown from Geneva, headquarters of European particle physics research organisation CERN, for a conference organised by Otago Medical School's Centre for Bioengineering and Nanomedicine. It brought together physicists, mathematicians, chemists, clinicians, pathologists, computer scientists and medical physicists to talk about how latest technologies could be applied to medicine.

One example is a colour CT scanner being developed by MARS Bioimaging, a company part-owned by the university. The scanner is based on the Medipix sensor, a development offshoot of LHC subatomic particle detection technology.

As head of CERN's directorate office, with a role in international relations, Tsesmelis has an interest in the MARS project.

"It fits very nicely into the mission of CERN, which is to do research and discovery in fundamental science to understand the Big Bang and the workings of the universe. But in order to be able to do that you have to develop tools.

"Our tools are a particle accelerator, particle detectors and the high-performance computing which is required to do the science, and you can't just buy that off the shelf. You have to do years and decades of research and development."

The Medipix chip is the result of several years of development in which Canterbury and Auckland universities had a hand. New Zealand's payback is exclusive rights to the chip's use in biomedical small animal and medical imaging.

"We know the photons that come out of x-rays have different frequencies, they have colour, but that colour has never been captured before in a CT scan. This is what the Medipix chip does - it measures the energy very precisely, so you can have a colour picture of a scan, which adds to what you learn from it."

Two MARS scanners have been sold, Tsesmelis says, to the Mayo Clinic and Virginia Tech in the US.

"This is money that comes back into New Zealand, offsetting the country's contribution to the CMS operation. It's not just blue-sky science anymore.

"Particle physics is large science, which means long duration, and funding and commitment is required. This is our way of giving something back to society and the economies of participating countries."

Tsesmelis intends ultimately giving up his administrative and outreach role. "I will go back to the search for the Higgs," he says.

The researchers won't see the Higgs boson itself, because it is so short-lived, but knowing the pattern of its decay into other particles, such as electrons, they will be able to infer its existence. At the rate at which the Higgs is thought to occur, it should be found by 2014.

Then, a new instrument - a linear electron positron collider - will be built to produce the particle in sufficient numbers to be able to study its properties. If it's not found, all will not be lost.

"We already have alternative hypotheses of what could replace the Higgs boson and give mass to all other subatomic particles," Tsesmelis says.

How hot?

Researchers say the latest experiment at the Large Hadron Collider - colliding beams of lead ions - produced fireballs with a temperature of over ten trillion degrees, a million times hotter than the centre of the Sun.

Anthony Doesburg is an Auckland technology journalist

- NZ Herald

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