In-situ Surface Contamination Removal and Cool-down Process of the DEAP-3600 Experiment

Abstract

The DEAP-3600 experiment is a single-phase detector that uses 3600 Kg of liquid argon to search for Dark Matter at SNOLAB, Sudbury, Canada, 6800 ft. underground. The projected sensitivity to the spin-independent WIMP-nucleon cross-section is $10^{-46}$ cm$^{2}$ for a WIMP mass of 100 GeV. A key experimental requirement is the reduction of any possible source of background that would mimic a Dark Matter signal. This document will review how radiogenic surface backgrounds were reduced in-situ by removing 500 microns of acrylic from the innermost part of the detector with a resurfacing robot. Furthermore, it will review the transient cool-down process of the experiment, necessary to reach cryogenic operating temperature.