Measured Displacement Energies of Oxygen Ions in Zirconolite and Rutile

ABSTRACTOptical emission spectra in the 300-700 nm range were collected from zirconolite and rutile specimens irradiated with a 3 μs pulsed electron beam using a Febetron 706 variable energy pulsed electronbeam generator. The long-lived emissions (up to microseconds after the electron pulse) consist of broad (halfwidths ~ 100 nm) bands centred around ~400 nm. Over the range 0.2 MeV to 0.6 MeV, the emission intensity per unit dose versus electron beam energy data from the rutile sample showed a single stage dependence on electron beam energy, whereas the zirconolite data suggested a two stage dependence. Rutile has a threshold of 0.23 ½ 0.02 MeV, which gives an Ed value of 39 ½ 4 eV for oxygen. Zirconolite has a threshold of 0.26 ½ 0.02 MeV, which gives an Ed value of 45 ½4 eV for oxygen. These data are discussed in the context of previously measured and calculated Ed values for other oxides.