Atomic tour de force

Ian Clark

"Just thinking about the new areas of research we can now explore with this facility, the only one of its kind in Canada, is exhilarating, to say the least."

 – Ian Clark


It filled five 12-metre shipping containers on its overseas journey to Canada from the Netherlands, where it was built. Fully assembled, it is 25 metres long and more than nine metres wide, weighing in at a fearsome 44 tonnes.  It took an industrial overhead crane to lower its mega magnets onto a nearly one-metre-thick concrete slab on 40 piles driven down to solid bedrock. Everything about the new $10-million accelerator mass spectrometer (AMS) in the University of Ottawa’s Advanced Research Complex (ARC) is emphatically big, which is somewhat ironic, as its main job is to parse out reality one atom at a time.

The novel AMS is housed in a spacious and bright laboratory named after the late André E. Lalonde, a former University of Ottawa geologist and dean of the Faculty of Science. The spectrometer rockets ions to a few percent of the speed of light with very little contamination. This will detect the presence of trace radioisotopes at much lower concentrations than traditional mass spectrometers do.

“Big, new equipment is always exciting, but this is just in a class of its own,” says Ian Clark, a professor in the Department of Earth Sciences at the University of Ottawa, known for his pioneering work in using isotopes in environmental and Earth sciences research. “Just thinking about the new areas of research we can now explore with this facility, the only one of its kind in Canada, is exhilarating, to say the least.”

The AMS will enable scientists to conduct the most advanced environmental research and unlock important natural resource, climate and health mysteries. From radiocarbon dating of archaeological finds to monitoring nuclear waste disposal sites and advancing biomedical research in drug discovery and toxicology, the spectrometer’s applications are wide-ranging and impressive.

Clark, one of the key players responsible for establishing the AMS facility, along with physics professor and lab director Liam Kieser, is especially excited about the Isobar Separator, a component of the AMS that was developed in Toronto to tackle one the main issues when measuring rare isotopes — interference by background isotopes.

“When you are measuring isotopes, you are selecting them by their mass,” he explains. “The problem is that different isotopes from different elements can have the same mass.” Mass spectrometry measurements are therefore often filled with a lot of interfering isotopes, or isobars, that make it very difficult to tell one isotope from another with the same mass.

An example is chlorine-36, a rare isotope that is very important in dating and tracing hydrological samples. Sulphur-36, an isotope found pretty well everywhere and in everything, from the food we eat to the air we breathe, has the same mass, making it exceedingly difficult to obtain samples of chlorine-36 without sulphur-36 contamination.

Built onto the front end of the AMS, the Isobar Separator uses chemical reactions to clean up this kind of competing background noise. It opens up new possibilities for Clark and his research team when measuring radioactive isotopes, such as monitoring emissions from nuclear activities.

 “This is one of the great things about our new AMS, that we can now analyze our target isotopes from extremely low sample sizes and partition our understanding down to very small compartments,” explains Clark. “So, for example, if there is a major nuclear leak, it will allow us to start probing not just what amount of tritium accumulates, say, in an apple, but how tritium actually moves through the entire food chain. With our new machine, we can separate out movement by the atom. ”

Using the same principle, Clark and his team will be able to use AMS measurements of radionuclides in the environment to trace a cornucopia of contaminants, from Fukushima nuclear emissions to methane released from shale gas exploitation.

“When methane is found in a farmer’s well near a shale gas fracking site, we’ll now be able to tell if that methane was there beforehand and is naturally occurring, or is due to leakage from the fracking activity,” says Clark.  “So many areas of research are now possible. It’s a new frontier for us.”


by Sean Rushton

Back to top