In a direct elastic collision, the neutron will give all its momentum to the hydrogen nucleus. (nuclearstreet.com)
I'd love to know more about the details: is this case like a perfectly elastic collision, or are there subtler effects on the radiation's characteristics (polarization, phase shifts, frequency shifts?) (realclimate.org)
If the particles collide and separate without changing, the process is called an elastic collision rather than a reaction. (sciencedaily.com)