[ExI] Neutrino interaction web

[Anders Sandberg]

I just spent an evening playing boardgames with a neutrino physicist. It 
seems that, yes, neutrinos can interact with neutrons. A neutrino can 
scatter off neutrons in a simple bounce, scatter and create a pi-0 meso, 
or can make it turn into a proton and a suitable lepton (depending on 
neutrino type). Neutrons are slightly better than protons since they 
have extra energy to turn into other particles, so the neutrino doesn't 
have to provide as much kinetic energy for making particles as as in the 
case of hitting a proton.

But these reactions are all wimpy weak interactions with low cross 
sections. So it is unlikely to matter in practice.

However, an interesting possibility might be if you excited neutrons to 
the right energy level, then they might have a resonant absorbtion of 
neutrinos of the right energy. Doubtful if we can get that to do any 
useful work, but it just might bring the neutrino catcher from absurd to 
merely very, very hard.

-- 
Anders Sandberg,
Future of Humanity Institute
Philosophy Faculty of Oxford University