I am not sure about what particles you are specifically asking, but the neutrino flux on Earth for example is on the order of billions per square centimeter and

I am not sure about what particles you are specifically asking, but the neutrino flux on Earth for example is on the order of billions per square centimeter and second. And there is nothing really special about the detector material, they just detect the tiny fraction of particles that happens to interact by pure chance within the detector while most particles just pass through the entire detector unnoticed.