Skip to content

SNOLAB experiment to shed more light on supernovae

When a star reaches the end of its life it releases a massive burst of energy in an explosion called a supernova.
snolabsized
Laurentian University physics professor Clarence Virtue shows his HALO experiment, which is part of the world's Supernova Early Warning System. Photo by Patrick Demers.
When a star reaches the end of its life it releases a massive burst of energy in an explosion called a supernova.

“A single star will glow as brightly as 100 billion stars – as brightly as an entire galaxy for several months,” said Laurentian University physics professor Clarence Virtue.

But all that kinetic force and light, makes up only one per cent of the energy a star releases when it explodes.

More than 99 per cent of a supernova's energy, said Virtue, is released as a short pulse of neutrinos, which are subatomic particles produced by the decay of radioactive elements.

Depending on the size of the star, it can take anywhere from 30 minutes to 10 hours for its final implosion to reach its surface, and become an explosion.

But the neutrino burst travels at the speed of light, and escapes the dying star almost immediately.

Arthur McDonald put neutrinos on the map, and was recently awarded a Nobel Prize in physics for his efforts, when he led the SNO experiment two kilometres below the surface, in Sudbury's Creighton Mine.

The experiment discovered neutrinos had mass, and its success opened the doors for SNOLAB, the underground laboratory that occupies more than 7,000 square metres away from the interference of cosmic rays, where a dozen experiments attempt to expand our understanding of the universe.

One of those experiments – which launched in May 2012 – is Virtue's HALO.

While it shares its name with a popular video game franchise, this HALO stands for Helium and Lead Observatory.

HALO reuses many of the materials from the original Sudbury Neutrino Observatory – and is made up of long cylinders containing a gas called helium-3, wedged in a solid wall of lead.

Virtue got the helium-3, which costs around $20,000 per gram, on loan from the United States Department of Energy.

“We have $4 million worth of gas here in the detector,” he said.

The gas is ideal for capturing neutrinos after they interact with the surrounding lead.

HALO is one of seven detectors around the world that makes up the Supernova Early Warning System.

Because a supernova releases a massive amount of neutrinos, and they escape before the star actually explodes, these seven detectors scan the Milky Way Galaxy 24 hours a day, waiting to alert astronomers about any upcoming supernovae.

“Everyone would stop what they're doing, abandon all of the observing programs, and they would be looking for the supernova, trying to capture that from the earliest possible moment,” said Virtue.

But only around three supernovae occur in the Milky Way per century.

The last time scientists detected a supernova – just outside our galaxy – was in 1987.

“Three detectors were running at that time, and there were 1,000 papers written on what those three detectors saw,” Virtue said.

Today's detectors are much more advanced, and if they detect a supernova, could shed more light on what may be the most powerful phenomenon in the universe.

Comments

Verified reader

If you would like to apply to become a verified commenter, please fill out this form.




Jonathan Migneault

About the Author: Jonathan Migneault

Read more