A variety of astrophysical observations conclusively show that more than 80% of the matter content of the universe is comprised of some, as yet, unknown ‘dark matter’. One of the leading candidates to solve this puzzle are weakly interacting massive particles, or WIMPs. A number of experiments around the world are searching directly for evidence of dark matter WIMPs, including the Dark matter Experiment with Argon Pulse shape discrimination, DEAP.
DEAP-3600 is a single phase 3.6-tonne liquid argon (LAr) experiment, located 2 km underground at SNOLAB, in Sudbury, Ontario. The experiment aims to achieve a sensitivity to spin-independent scattering of 100 GeV WIMPs of 10 -46 cm 2 . The DEAP-3600 background target is <1 background events in the WIMP search region of interest in 3 tonne-years. The strategies to achieve this background are pulse shape discrimination to mitigate electron recoils, ultra-low radioactive materials for detector construction to reduce neutron and alpha backgrounds, and in-situ sanding of the acrylic vessel to mitigate radon exposure of surfaces during construction and fabrication. The detector construction is complete and the initial commissioning and operational phase is underway.
In this talk I will summarize the evidence for dark matter, describe in detail the principle’s and design of the DEAP-3600 experiment, and provide the latest update on detector operations and the DEAP search for dark matter.