Grant: Canada Research Chairs

Normal matter, which makes up all the things we are familiar with, including ourselves, only accounts for 5% of the universe – the composition of the rest remains a profound mystery. It is understood that there must exist a new form of matter which, although having a very feeble interaction with regular matter, still governs the evolution of the cosmos. This yet-unobserved form of matter is known as dark matter. We can search for it by constructing sensitive detectors for rare interactions of dark matter particles with normal matter. This research is a top international scientific priority. The nominee has been instrumental in developing DEAP-3600, which searches for dark matter particle interactions with 3.3 tonnes of liquid argon at SNOLAB. During the first CRC term Dr. Boulay guided his research team through first operation and experimental results using DEAP-3600. No candidate events were observed in 231 days of operation, placing strict new limits on dark matter models. Dr. Boulay has been instrumental in developing the Global Argon Dark Matter Collaboration, a group of over 400 scientists from 100 institutions in 14 countries that is mounting a phased approach to dark matter searches using liquid argon, with each phase instrumenting ever-larger target masses for increased sensitivity. Upgrades to DEAP-3600, led by Dr. Boulay, will increase its sensitivity and will be completed by 2024. Dr. Boulay and his research team are making critical contributions to the construction of the second phase experiment, DarkSide-20k (using 100 tonnes of argon) at the LNGS laboratory in Italy, which will start operating in 2027. That experiment will extend experimental sensitivity to dark matter particles with argon by a factor of 30. The conceptual design of the final phase, ARGO, which will instrument 400 tonnes of liquid argon and will further increase sensitivity by a factor of 10, will be led by Dr. Boulay. Each of the experiments enables exciting discovery potential and will allow further elucidation of dark matter particle properties if a signal is observed. Dr. Boulay’s research also includes innovative and leading-edge technology development towards improving radioactive background control and light readout systems needed for the next-generation experiments. The research is internationally competitive and will continue to place Carleton University and Canada at the center of activity in this area attracting the highest-caliber researchers and trainees.