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Mark Kerr: Why did you want to come to Queen’s and SNOLAB?

Gilles Gerbier: I’m interested in dark matter physics and this research is performed in underground labs. There aren’t many underground labs in the world and SNOLAB is arguably the best one because it’s very deep and very clean with available space.

Another reason is that I knew most of the team members at SNOLAB and at Queen’s. They’re very good physicists, and I really wanted to work with them.

MK: What is dark matter?

GG: We have many hints that dark matter should exist through observations of celestial bodies: stars moving around in galaxies, galaxies moving relative to each other. All of these observations point to the fact that, in addition to the matter we know such as atoms and nuclei, there is additional mass that accounts for the difference between the higher measured speeds of objects orbiting around each other than what we would expect from only normal/shining matter. So there should be additional matter that we don’t see, which is why we call it “dark.”

MK: What are the goals of your research program?

GG: There is a large consensus among scientists in this field that the dark matter is made up of new particles, yet undiscovered. The goal is to perform studies on the identification of these particles. These particles, if they constitute dark matter, should be around us, crossing the earth, and would interact in detectors that are deep underground at SNOLAB. The research has to take place deep underground to avoid parasitic signals at the surface.

MK: How will Queen’s and SNOLAB serve to advance your research?

GG: So far, we haven’t observed dark matter’s existence so we must do more sensitive experiments in SNOLAB with European and North American teams. One of my goals, which I have already started pursuing the past few years, is to bring together these big groups and have larger experiments that are more sensitive. This is something that could be ideally done in SNOLAB because the North American groups have already planned and been funded to perform experiments there.

The second project is related to a new kind of technology to identify these particles using spherical gaseous detectors. I’ve started this innovative research with a colleague in France. We already have hints that it will bring new insights to dark matter but of course we have to build the experiments and tune them to make them better. SNOLAB is a great site to base this experiment.

MK: Why are you interested in this field?

GG: I came into this research a long time ago after my post-doc at Berkeley. I started in particle physics and found the idea that three-quarters of the mass of the universe is something we don’t know and may be made of new particles to be really intriguing. Now I’ve been in this field for 30 years.

Certainly, it may look a bit discouraging not having found anything, but you have to be patient. Sometimes it takes a long time to find what you are looking for and maybe we are going to find something different than what we thought. So I do hope to contribute and identify dark matter working in a better environment with new people, new ideas and significant funds to do experiments.

MK: Was it a difficult decision to leave France and move to Canada?

GG: Maybe it would have been more comfortable to stay in France, but our kids are grown up and mostly on their own, so in some ways it was less complicated for my wife (Francine) and me to move.

The move was also made easier because of the connections I’ve made in Canada through my work, in particular with the Natural Sciences and Engineering Research Council of Canada (NSERC). For three years, I have served on a committee that dispatches NSERC funds to the particle physics community. I was very impressed with the way it was done and I appreciated the Canadian style.