No one knows if it’s big enough—-that depends on the properties of dark matter and its interaction with xenon.
What I was addressing was whether this detector is big enough for a reliable discovery. In that case what you really want to constrain is the rate, such-and-such events per kilogram of xenon per year (the per-kilogram-of-xenon can be traded for a per-liter rate given the density of the xenon).