Low-Energy Threshold Analysis Using the DEAP-3600 Dark Matter Detector

Abstract

DEAP-3600 is a single-phase liquid argon WIMP detector located 2 km underground in the SNOLAB research facility. DEAP-3600 is searching for dark matter; an elusive form of matter that was first postulated in the early 20 th century, but has not yet been found. The goal of the following work is to perform a low mass WIMP search. A low mass WIMP search is made possible by lowering the energy threshold of the hardware trigger from 1000 ADC to 150 ADC. Low energy events in the detector are characterized as Cherenkov radiation, low energy retriggers, or high energy retriggers; all of which are background events. The final data set has a live time of 2.10 days and an exposure of 4.41 × 10 3 kg • days using a LAr target mass of (3279±97)kg. The results from the low mass WIMP search is a WIMP-nucleon spin independent cross-section of 3.96 × 10 −42 cm 2 at a 90% CL corresponding to WIMPs with a mass of 55 GeV/c 2. i Lastly, the people I owe the most thanks to; I would like to thank my family, Dad, Sarah, and Chris for all of their support and love over the course of my entire academic career, it would not have been possible without you guys. I would also like to thank Deb, Scarlett, Santana, and Barry for their support as well. To Caidence, I'll never understand how you managed to juggle a masters, full time job, part time job, and life; and also dealt with me and everything I was going through. Even with all of this happening you always provided me with constant love and support; I can never express how much this means to me. You've stayed with me through four years apart for undergrad, and now through this; now that it's over I can't wait to start the next chapter of our lives and see what comes next! iii