A particle of mass m1 and kinetic energy KE1 collides head on
with a stationary particle of mass m2. The two particles then
move apart with the target particle having the kinetic energy
KE
2. (a) Use conservation of momentum and conservation of
kinetic energy in a non-relativistic calculation to show that
KE
2KE1 4(m2m1)(1 m2m1)
2
, which is what is plotted
in Fig. 12.22. (b) What percentage of its initial KE does a neutron
lose when it collides head on with a proton? With a
deuteron? With a 12C nucleus? With a 238U nucleus? (Ordinary
water, heavy water, and carbon in the form of graphite have all
been used as moderators in nuclear reactors.)
12.1