The number of neutrons produced per incident proton increases with energy but not linearly. This may be viewed by considering the part below about 100 MeV where the neutron yield is quite small as an off-set. Only the part above 100 MeV plays a role and here the dependence is roughly linear. Thus at higher beam energies the relative importance of the off-set becomes smaller. At the high end of the energy scale (> 1 GeV) the neutron yield per proton tends to level off. |