DarkSide-50 is a direct detection experiment at LNGS in Italy searching for dark matter. It utilizes a dual-phase argon time projection chamber. On the basis of the ionization spectrum alone, it
has established the most stringent exclusion limit for dark matter candidates with masses below \(1.4 GeV/c^2\). By exploiting the expected variation of the relative velocity between dark matter and Earth, one can search for dark matter in a model-independent manner. We describe the first search for such an event rate modulation with argon using the DarkSide-50 ionization signal. Likelihood and Lomb–Scargle analyses were used to look for a 1 year period peaking at June 2nd. As a result of years of stable operation of the detector and a thorough knowledge of its response, we were able to obtain the lowest energy threshold, \(0.04 keV_{𝑒𝑒}\), ever achieved in this kind of experiments.