Speaker
Ms
Corina Nantais
(Queen's University)
Description
The spherical acrylic vessel that contains the liquid argon target is the most critical component in the DEAP-3600 dark matter experiment. Alpha decays near the inner surface of the acrylic vessel are one of the main sources of background in the detector. A fraction of the alpha energy, or the recoiling nucleus from the alpha decay, could misreconstruct in the fiducial volume and result in a false candidate dark matter event.
Acrylic has some inherent contamination, including U-238 and Th-232. Another background of particular concern is diffusion of Rn-222 during manufacturing. The maximum acceptable concentrations in the DEAP-3600 acrylic vessel are ppt levels of U-238, Th-232, and 10^-8 ppt of Pb-210.The impurities in the bulk acrylic will be measured by vaporizing a large quantity of acrylic and counting the concentrated residue with an ultra-low background HPGe well detector and a low background alpha spectrometer.
First results from the acrylic assay system at SNOLAB will be presented.
Primary author
Ms
Corina Nantais
(Queen's University)
