Papers Published

1. Jones, P.L. and Schaffer, J.P. and Cocks, F.H. and Clinard, F.W., Jr. and Hurley, G.F., A comparison of the Doppler-broadened positron annihilation spectra of neutron irradiated Al₂O₃ and MgAl₂O₄, J. Nucl. Mater. (Netherlands), vol. 127 no. 2-3 (1985), pp. 221 - 4 [0022-3115(85)90358-7] .
   (last updated on 2007/04/10)

   Abstract:
   As part of a study of the defect structure in radiation damaged ceramics Doppler-broadened positron annihilation spectra have been obtained for a series of single crystal sapphire (α-Al₂O₃) and polycrystal (1:1) and (1:2) magnesium aluminate spinel (MgO.Al₂O₃ and MgO.2Al₂O₃) samples. These samples were irradiated in EBR-II to a fluence of 3×10²⁵ n/m² (E>0.1 MeV) at 740°C, and 2×10²⁶ n/m² (E>0.1 MeV) at ~550°C respectively. Positron annihilation spectra lineshapes for the irradiated, annealed and as-received samples of both materials were compared using S parameter analysis. These calculations were made on deconvoluted gamma ray spectra that were free of any instrumental broadening effects. The observed changes in the S parameter are consistent with independent volume swelling measurements for both the σ-Al₂O₃ and the (1:2) MgAl₂O₄ samples

   Keywords:
   annealing;ceramics;magnesium compounds;neutron effects;positron annihilation in liquids and solids;sapphire;