• TCDFT predicts comparable positron-annihilation characteristics for vacancy clusters in Mo and W, showing similar evolution from isolated V₁ to clusters saturated at V₃₅ (∼0.5 nm in radius). • First quantitative analysis of vacancy clusters proportion in Mo and W by combining PAS, TCDFT, and a positron-trapping-model-based simulated annealing algorithm. • Dose-dependent defect evolution: isolated V₁ dominates at 0.01 dpa; V₁₅ clusters appeared at 0.3 dpa; steady-state vacancy population is established at 0.5 dpa or higher with defect fractions estimated at each damage level. • Greater Vacancies aggregation in Mo than in W: quantitative analysis revealed the differences in vacancy proportion V₁ fraction of about 20 % in Mo compared with 40% in W. • Depth-resolved PAS profiling indicated the damaged region extends deeper than SRIM/OKMC predictions for each damage levels, likely due to ion-channeling effect during irradiations.
Hu et al. (Fri,) studied this question.