A. Lucasson

Frenkel pair creation and stage I recovery in W crystals irradiated near threshold

Abstract Single crystals of tungsten have been irradiated with electrons in the energy-range 1.4–1.8 MeV, perpendicularly to the three planes (100), (110) and (111). After elimination of the subthreshold effects, the threshold energy for atomic displacement has been determined for the major crystallographic directions. It is found to be minimum in the direction: T100 = 42±1 eV, and only slightly higher in the direction (7111 = 44 ± 1 eV). Three isochronal anneals were performed after irradiations at 1.6, 1.65 and 1.7 MeV. The recovery of the Frenkel defects was found to be nearly complete at 44 K. The analysis of the recovery spectra as a function of the incident electron energy as well as of the sample orientation leads to attribute the 38 K peak to the correlated recombination of freely migrating interstitials. The 11 K and 17 K peaks are attributed to close pairs produced respectively through and displacements.

Subthreshold events and atomic displacements in electron-irradiated cadmium

Abstract High-purity zone refined specimens of cadmium were irradiated at liquid helium temperature with electrons in the energy range 0.5–1.7 MeV. From the measurements of the electrical resistivity change rate per incident electron and from an analysis of the recovery spectra up to ∼ 200 °K we deduce that two simultaneous processes are acting under electron bombardment. The first—a subthreshold process—is of a complicated nature and thought to be due to the interaction of the bombarding electrons with very small amounts (∼ 10−7 per atom) of hydrogen atoms loosely bound to traps, their binding energy being of the order Ts ∼ 10−1 eV. The second is the cadmium atom displacement proper, with an energy threshold of Td = 19±2 eV.

Multiple atom displacements in irradiated metals

Abstract The classical multiple atom displacement theory of Kinchin and Pease is discussed in the light of more recent computer and experimental data. The inadequacy of an isotropic metal model to represent physical processes in a real crystal is emphasized. The relative importances of the crystal anisotropy and of the thermal spike anneal process are discussed. The interest of anisotropic experiments is pointed out.

Recovery of low-temperature electron-irradiated lutetium

Abstract The annealing spectrum of electron-irradiated Lu has been studied between 14 and 135 K and a tentative interpretation of the observed structure given. A comparison with other irradiated h.c.p. metals indicates that the c/a -ratio might be an important parameter for the determination of the interstitial-atom mobility.