4-88
A fast neutron can displace about 50 to 100 atoms before it comes
to rest.  Most of the damage is done by the recoiling atoms.  Net result
is that each neutron can cause numerous vacancies and interstitials.
(1)
(2)
(3)
(4)
Neutron Damage
   Shown above is the typical sequence of events when an energetic neutron strikes a crystal.  In (1), a neutron has arrived and has dislodged a single atom.  The (2), (3) and (4) drawings show how the process builds up and ends, with both the neutron and the recoiling atoms dislodging further atoms.  The end result is a number of vacant sites and interstitial atoms.


F. Seitz and E. P. Wigner, “The Effects of Radiation on Solids,” Scientific American, pp. 76-84, August 1956.