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Positron annihilation measurement of the vacancy formation enthalpy in copper. [25 to 1040/sup 0/C]

Description: Doppler-broadening and lifetime data obtained for Cu in the temperature region approx. 25 to 1040/sup 0/C are presented. The experiment utilized a new source-implantation technique. The value of the deduced vacancy formation enthalpy is 1.31 +- 0.05 eV. Since the Doppler-broadening data were the primary source for the determination of the vacancy formation enthalpy, the analysis of these data is discussed. The suitability of introducing divacancies into the analysis is also considered. It is co… more
Date: January 1, 1979
Creator: Fluss, M. J.; Smedskjaer, L. C.; Siegel, R. W.; Legnini, D. G. & Chason, M. K.
Partner: UNT Libraries Government Documents Department
open access

Solid neon moderated electrostatic or magnetic positron beam

Description: A high intensity variable energy positron beam has been constructed at Brookhaven National Laboratory (BNL). Positrons from a 97mCi {sup 22}Na source are moderated by a thin layer of solid neon. A magnetic guiding system delivered up to 5{times}10{sup 6}e{sup +}/sec to an experiment. Currently tests are under way to facilitate the operation with the magnetic guiding system or -- for other experimental sites -- with an electrostatic beam transport. The electrostatic lenses are fabricated from {m… more
Date: January 1, 1991
Creator: Weber, M.; Schwab, A.; Becker, D. & Lynn, K. G.
Partner: UNT Libraries Government Documents Department
open access

Assessment of Positron Annihilation as a Potential Non-Destructive Examination Technique

Description: The positron annihilation technique can provide a sensitive measure of defect density in metals. In this program the technique has been used to monitor defects generated during plastic deformation by cold work or fatigue cycling. The primary goals have been: (1) to assess the degree of sensitivity of the technique; (2) to correlate positron annihilation readings with observed microstructural changes to better understand the physical basis for these readings; and (3) to determine correlations be… more
Date: January 1, 1979
Creator: Jones, W. B.; Van den Avyle, J. A.; Gauster, W. B. & Wampler, W. R.
Partner: UNT Libraries Government Documents Department
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