Yeah, I was just wondering if you could filter based on wavelength or polarization, like photons. Isn't it really hard to "block" neutrinos coming from other directions though?
If the beam is narrow enough, you'll have a larger number of detections inside the region the beam occupies while the rest of your detector will present normal activity. While you can't be sure if the neutrinos are coming or going, the odds some unknown neutrino beam source appeared in direct opposition to the one you knew about are very slim.
You can also filter by time - you create a source and expect a surge of detections shortly after. In this specific case, they saw the surge before they expected it, indicating the neutrinos traveled faster than they should.
>the odds some unknown neutrino beam source appeared in direct opposition to the one you knew about are very slim. //
Look any direction in the night sky. Do you see a star. The odds of not seeing a star in the direction you're looking are far greater than the odds that you don't have neutrinos coming from that direction.
You can't shield against neutrinos, you can't currently detect a neutrinos position at two points in spacetime. Haven't yet read the details about this if they repeated several times with the same result then it looks interesting - have you a link to their paper (to save me looking!) thanks.
My first thought was that I wonder if this might be a simple case of super-luminal group velocities or something similar.
