The expansion of the world's deepest and cleanest underground physics laboratory is now complete in Sudbury.   SNOLAB is an expansion of the existing lab constructed for the Sudbury Neutrino Observatory (SNO) solar neutrino experiment two kilometres under the city.

For years, the lab has been home to experiments about dark matter — invisible mass that makes up about a quarter of the universe — and neutrinos, electrically neutral subatomic particles.

But the new space will allow for new experiments, such as using helium and lead to do research on supernovas, large exploding stars.

Clarence Virtue works in the SNOLAB and said, until now, there hasn't been a lot of research on supernovas.

"People who build models and numerically simulate that, and try to understand all of the physical processes of why the stars explode, and the only data that you can obtain that they can really compare their models to, are data from detectors like this," Virtue said.

The director of the underground lab, Nigel Smith, said Thursday that working in a construction zone has been a challenge.

"We needed to make sure we were co-ordinating between all of the groups, so if we were doing excavation, people were aware that their data may see some rather strange artifacts when you're removing the rock and blowing the rock out," Smith said.

The lab has received $70 million in funding from various levels of government to get to where it is today.

The mining company Vale Canada Ltd. (formerly Vale Inco.) has also played a key role, because the lab is located in an extension of its Creighton Mine.