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Positron trapping defects in Pt, Al, and Al-0. 1-at. % Mg following d-Be neutron irradiation

Conference ·
OSTI ID:6199025
Specimens of Al, Al--Mg, and Pt were irradiated using the Davis d-Be neutron source which has a spectrum peaking at approx. 15 MeV. Lifetime and Doppler-broadening measurements have been made on these specimens for three fluences in the as-irradiated state and for subsequent anneals to 500/sup 0/C. Saturation of positron trapping at the higher fluences was observed in the Pt specimen, with the average trap size increasing after annealing through stage III (vacancy migration). Surviving traps after 500/sup 0/C are presumed to be voids. The Al and Al--Mg showed some trapping introduced by the room-temperature irradiaion, but complete recovery is seen at 500/sup 0/C. These trapping sites are assumed to be small vacancy clusters or small dislocation loops. Some loops of very low concentration were observed near grain boundaries in the as-irradiated specimen of Al by TEM.
Research Organization:
Brookhaven National Lab., Upton, NY (USA); AN SSSR, Moscow. Inst. Metallurgii; California Univ., Livermore (USA). Lawrence Livermore Lab.
Sponsoring Organization:
USDOE
DOE Contract Number:
EY-76-C-02-0016
OSTI ID:
6199025
Report Number(s):
BNL--26183; CONF-790437--12
Country of Publication:
United States
Language:
English