Measurement of the positron diffusion constants in polycrystalline molybdenum by the observation of positronium negative ions

[摘要] We have measured the positron diffusion constants in polycrystalline molybdenum by the observation of positronium negative ions (Ps-). The Ps-ions emitted from the sample surface coated with Na were accelerated. The γ-rays from the accelerated Ps-ions were Doppler-shifted and thus the signals of self-annihilation of the Ps-ions were isolated from those of self-annihilation of para-positronium (p-Ps) or pair-annihilation of positrons in the bulk. Clear and reliable values of the diffusion constants have been obtained.

[发布机构] Department of Physics, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku, Tokyo; 162-8601, Japan^1

[效力级别] 化学

[关键词] Diffusion constant;Doppler;Pair annihilations;Polycrystalline;Positron diffusion;Sample surface;Self annihilation