Particle and Astroparticle Physics Seminar

Dark Matter Search with DEAP-3600 at SNOLAB

Mark Boulay

Carleton University

It has long been known that most of the matter in our Universe is dark - so far evading direct detection since initial observations of galactic rotation curves over 80 years ago were used to infer its existence. A leading explanation suggests that the dark matter is made up of new Weakly Interacting Massive Particles, a hypothesis which can be tested directly by searching for the extremely rare scattering of these particles in a terrestrial detector. DEAP-3600 is a novel experiment searching for these rare dark matter particle interactions on 3.6 tonnes of liquid argon at SNOLAB. The argon is contained in a large ultralow-background acrylic vessel viewed by an array of photomultiplier tubes. Very good pulse-shape discrimination has been demonstrated for scintillation in argon, and the detector has been designed to allow control of (α,n) and external neutron recoils, and surface contamination from ²¹⁰Pb and radon daughters, allowing an ultimate sensitivity to spin-independent scattering of 10^-46 cm² per nucleon at 100 GeV mass. After several years of construction, data collection began in late 2016 and is ongoing. Details of the detector construction, commissioning and the current status of the experiment will be presented.