2. Nuclear reactors use heavy water moderators in which elastic collisions occur between neutrons and deuterons. If a neutron moving with a kinetic energy k0 collides elastically with a deuteron (at

rest initially) whose mass is two times that of the neutron. A) Calculate the remainder fraction of the kinetic energy of the neutron after collision. B) How many such successive collisions will reduce the kinetic energy of the neutron to 1/1,000,000 of its original value?