One source of background is the shower of cosmic rays that constantly bombard the Earth. While the space particles don’t affect most experiments, they could completely drown out the whisper of a faint ...

So it’s “one particle in, one particle out and nothing ... particles could be a sort of spurious events, what we called ...

A potential signal from an undiscovered particle needs to be strong enough to rise above this background noise. Scientists carefully estimated the number of background events in Xenon1T.