> Actually it's pretty easy to generate intense neutrino beams. You just have to accelerate protons and smash them into a lead wall. This produces all kinds of particles, including for instance muons. Since muons are charged, you can filter and focus them into a beam using magnets, and then they rapidly decay in flight, producing a beam of neutrinos going in the same direction.

That's pretty fascinating. When the protons hit the lead wall, are there any other "messy" particles created that are problematic? Filtering and focusing the muons might be relatively easy to handle, but what about the other kinds of particles that will be created?