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

## TL;DR

This paper details the in-situ removal of surface contamination and the cool-down process of the DEAP-3600 dark matter detector, enhancing its sensitivity by reducing background noise and achieving cryogenic temperatures.

## Contribution

It introduces a novel in-situ acrylic resurfacing technique and describes the cool-down procedure for the DEAP-3600 detector, improving background suppression and operational readiness.

## Key findings

- 500 microns of acrylic were successfully removed in-situ
- The cool-down process was optimized for cryogenic operation
- Background contamination was significantly reduced

## 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.