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'Tip of the iceberg': South Pole researchers make groundbreaking physics discovery

University of Alberta professor is part of a team that observed neutrinos being absorbed by matter for the first time

The IceCube Lab with the South Pole station in the background, taken in March 2017.

Martin Wolf / IceCube/NSF

The IceCube Lab with the South Pole station in the background, taken in March 2017.

A University of Alberta researcher is part of an international team that stationed in the South Pole to make a groundbreaking particle physics discovery.

The IceCube Collaboration, which includes U of A physics professor Darren Grant, announced Wednesday it observed neutrinos being absorbed by matter for the first time.

The discovery about the subatomic particles – previously dubbed “ghost particles” because they were thought to pass through nearly everything – could lay the groundwork to answer long-sought questions about the composition of the earth’s core.

“This is sort of the – terrible pun – tip of the iceberg,” said Grant, who is also the Canada Research Chair in Astroparticle Physics.

“It’s the first time we’ve looked at it, it’s the first time anyone has seen a measurement of these energies. Where that takes us, that’s going to play out over the next number of years.”

Raffaella Busse and Johannes Werthebach and the soon-to-leave James Casey and Martin Wolf send a salute to their collaborators up north. The building behind them is the IceCube Lab, which hosts the computers that collect raw data from the detector. Taken in November 2017.

Martin Wolf/IceCube/NSF

Raffaella Busse and Johannes Werthebach and the soon-to-leave James Casey and Martin Wolf send a salute to their collaborators up north. The building behind them is the IceCube Lab, which hosts the computers that collect raw data from the detector. Taken in November 2017.

The IceCube team is made up of about 300 researchers from 48 institutions in 12 countries.

Researchers used the IceCube detector, a machine with 5,160 basketball-sized optical sensors deeply encased within a cubic kilometre of ice, to observe that high-energy neutrinos were absorbed by the earth, rather than passing through its core.

Grant was living in the United States when he joined the project in 2007 and remembers being struck by the location when he arrived.

“It’s absolutely stark. You land on skis, which is pretty cool. You’re at a high altitude because the glacier is nearly three kilometres thick,” he said.

“It’s cold. There’s no living thing anywhere on the horizon.”

Researchers got one news broadcast on a screen each day during dinner, which would include information about what the coldest place on earth was that day.

The IceCube Lab and the Milky Way with an aurora on the horizon. Image taken in May 2017.

Martin Wolf/IceCube/NSF

The IceCube Lab and the Milky Way with an aurora on the horizon. Image taken in May 2017.

“Six days out of the week it was South Pole station, where we were. Usually one day out of the week it was somewhere in Russia,” Grant said.

“And I do remember, (one day) I looked up at dinner and it said the coldest place on the earth today is Edmonton, Alberta. This was just before I had moved to join the U of A – I had been hired but I hadn’t moved up here yet – and I kind of paused in my meal.

“And then it sort of clicked. I said, ‘Well, I’ve got the right gear.’ ”

The results announced Wednesday come from data collected in 2010-11 that took years to analyze, so the team already has seven more years’ worth of data in the bag.

Meanwhile, the researchers are working to replicate the study over multiple years and upgrade their detector to increase its sensitivity and unlock more discoveries.

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