Event rate analysis in the DEAP-3600 dark matter experiment

DEAP-3600 is a single-phase dark matter detection experiment using liquid argon as the target material to search for the nuclear recoil signal from the elastic interaction of dark matter candidates, WIMPs, with argon nuclei. Dark matter theories also predict the modulation in the nuclear recoil signal with time due to the rotation of the sun and hence earth around the center of the galaxy. Backgrounds in the experiment are not expected to show this kind of modulation; thus, the observation of this type of modulation signal will extend the sensitivity of the WIMP search in the experiment. To obtain sensitivity to this modulation signal requires a very good calibration and study of systematics. The study of event rates for ³⁹Ar decays with time will also give a precise measurement for the lifetime of the isotope. The detector stability parameters from the physics data of DEAP-3600 show excellent stability which makes it ideal for these studies. In this talk, the detector stability of DEAP-3600 and some preliminary calculations on the ³⁹Ar lifetime measurement will be presented.