January 24, 2012
Photo credit: Luther Caverly

Unravelling the mysteries of the universe

It could be the plot of a science fiction movie. Carleton physicist David Sinclair would star in the lead role, joined by a cast of Carleton, Canadian and international researchers.

The set would be two kilometers underground in the Vale-Inco mine where the Sudbury Neutrino Observatory Lab is housed. The plot would involve trying to understand mysteries like dark matter.

Their challenge would be difficult.

But since their scientific breakthrough at the Sudbury Neutrino Observatory, they may be one step closer to explaining why the universe is made up of matter.

“When we started the SNO project, we weren’t seeing as many neutrinos being emitted from the sun as we should,” explains David Sinclair, former deputy director and Carleton SNO researcher.

But like all Hollywood films, there’s a twist.

“The problem wasn’t that the sun was emitting fewer neutrinos, but rather the neutrinos were oscillating as they travelled, which means they have mass,” explains Sinclair.

A true breakthrough in science.

New discoveries, new questions
It opened up new questions. So now it’s onto the next project. Researchers at the Enriched Xenon Observatory (EXO), which Sinclair and Carleton physicist Kevin Graham are also involved in, hope to determine the absolute mass scale of neutrinos and whether the neutrino is in fact its own anti-particle.

To do so, the team is looking for nuclear decay process that only happens if true neutrino-less double beta decay exists and there are a limited number of isotopes in nature that can undergo this process. So the particle of choice is 136Xe, a particular isotope of xenon.

But that’s no easy feat. The rate of decay is rare. In fact in a detector filled with 200 kilograms of 136Xe, you may see a handful of neutrino-less decay a year, explains Graham.

“This process can only occur if neutrinos have mass and anti-neutrinos are the same as neutrinos. Measuring the neutrino-less double beta decay rate tells us the absolute mass of neutrinos. So far other experiments have only been able to measure mass differences,” he says.

Currently the Carleton team is in the research and development phase. “This is very challenging as we need to develop new skills and devices,” says Graham. Yet he’s optimistic. After all, they’re working with David Sinclair who recently received the inaugural CAP-TRIUMF Vogt Medal for Outstanding Experimental or Theoretical Contributions to Subatomic Physics. As Graham says, “if anyone can make it work, it’s David.”

The SNO results really promoted Canada as a high-tech country.

But if they can indeed see neutrino-less double beta decay, it will be another scientific breakthrough as this process has yet to be proven.

“The SNO results really promoted Canada as a high-tech country,” says Sinclair. “We were on the front page of major international publications. You’d spend a lot of money for that kind of advertising.”

Inspiring the next generation of students
Sinclair calls the results “fascinating science” and maintains that this “inspires young people as they see we’re working on projects they can get involved in and hopefully encourages them to choose this field.”

Etienne Rollin was a graduate student at SNO. For him, sitting in a lab two kilometers underground wearing a blue nylon suit and hairnet while collecting data during his eight-hour shift, and then riding the elevator back to the surface with the miners can only be described as “surreal”.

He was tasked with finding a molecule that was both easy to add to the detector and cost efficient with the right optical properties to increase the number of photons in heavy water.

A positive ROI
The Canada Foundation for Innovation initially funded the research as a sunset project, one with a defined start and end date. But since the results have proven so promising, SNO has received additional funding from sources like the Ontario Innovation Fund, Ontario Research Fund, FedNor and continued support from CFI to operate as a permanent facility known as SNOLab.

Today, there are several projects being conducted by international teams.

By creating the leading dark matter detector, researchers on the “Dark matter Experiment with Argon Pulse shape discrimination” or DEAP project, aim to discover dark matter and begin to understand its properties, explains Graham who is a project member on this experiment as well.

The team will search for dark matter by using a detector filled with 3.6 tons of liquid argon and then watching for the process as dark matter enters, scatters on the argon which causes it to recoil, and loses energy, he says.

Biologists have also expressed interest in using SNOLab to understand organisms that can survive deep underground but not on the surface, explains Sinclair.

But for now, we’ll have to wait for a sequel. After all, projects like EXO take time, in fact years. Because unlike in Hollywood, the mysteries of the universe aren’t solved in two hours.

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