Point defects observed in D-T neutron irradiated copper, silver and gold at 288 K with a rotating target in FNS_JAERI

A 14 MeV D-T(fusion) neutron irradiation was carried out at fusion neutron source facility (FNS) in Japan Atomic Energy Research Institute (JAERI). Specimen temperature was controlled to 15oC. Fluence was 6.1‚˜1013 to 1.1 x 1017 n/cm2. Both TEM thin foil and bulk specimens were irradiated at the same position. At 1014 n/cm2, defects observed were single isolated dot defects. With increasing fluence, dot defects changed to complicate structure and made groupings. In a dot group, interstitial clusters and vacancy clusters were observed together. The present result was explained by the modeling that point defects in a nascent damage cascade move in crystal at 15oC and form their defect groupings