Temperature dependence of the threshold energy for Frenkel pair production in copper

Electron irradiations were performed in a Hu-650 kV electron microscope on 99.999% (MRC) copper. Irradiations were performed at 475 and 575 K at accelerating voltages between 650 and 275 kV. To measure Esub(d), the threshold energy, a fully focussed beam was used (2-3 A/cm2) to determine if Frank dislocation loops could be nucleated and grown in a time of 30 minutes. All irradiations were performed along the <110> direction. It was found that the threshold energy decreases to 12 eV at 575 K. (Auth.)