The piece on display outside Science North is the inner vessel from a dark matter experiment that was installed at SNOLAB called MiniCLEAN (mini Cryogenic Low-Energy Astrophysics with Noble liquids).
MiniCLEAN was installed at SNOLAB, 2 kilometers underground, between 2013 and 2019. It was a research and development component of a global program to test new technologies for dark matter searches.
The experiment consisted of the displayed inner vessel made of ultra-clean stainless steel that held 500 kg of liquid argon or neon and was surrounded by 92 sensitive photodetectors watching for particle interactions in the vessel.
The entire vessel was then located in a large cylindrical water tank over 2 stories tall (25’ tall, 18’ diameter) to provide additional shielding from unwanted particle interactions.
SNOLAB continues to search for the elusive dark matter with several experiments currently collecting data and additional experiments being built – each using different detection techniques.