In swift heavy ion irradiations, the observed defect creation and defect annealing do not only result from nuclear collisions but from inelastic collisions of the incident ion with electrons of target atoms as well. In the present paper we calculate the spatial distributions and the yields of defects induced by nuclear collisions in metals under GeV ion irradiations and then simulate defect annealing by S e using the thermal spike model. For iron, the calculations follow the known experimental conditions of the incident ions. Using the same value of the electron phonon coupling constant as that determined for damage creation by S e, the calculated results suggest that the S e threshold of defect annealing is about 15 keV nm −1 in agreement with experimental results within the experimental errors. Taking into account a normalization factor, the calculated damage efficiency agrees with experimental ones.