Change in conductivity and optical absorption of fluorite after irradiation in a reactor and by a synchrocyclotron

Measurements have been made for pure crystals and for ones containing oxygen after exposure to neutrons and to a 660 MeV proton beam. The conductivity for a pure crystal is unaltered, whereas that of an oxygen-bearing crystal decreases. The two types of crystal differ only slightly in optical absorption. It is concluded that there is no single mechanism responsible for the coloring and conductivity reduction in oxygen-bearing fluorite crystals.