Simulation study on the measurements of diffusion coefficients in solid materials by short-lived radiotracer beams

We have examined, by a computer simulation, an on-line measurement of diffusion coefficients by using a short-lived alpha particle emitter, ⁸Li (half life of 0.84s), as a radiotracer. The energy spectra of alpha particles emitted from diffusing ⁸Li primarily implanted in the sample of LiAl are simulated as a measure of the diffusion of ⁸Li in the sample. As a possible time sequence for the measurement, a time cycle of 6 s, i.e. the implantation of ⁸Li for 1.5 s and subsequent diffusion for 4.5 s, is supposed. The sample is primarily set on a given temperature for the measurement. The time-dependent yields of alpha particles during the time cycle reveal the possibility to measure the diffusion coefficient with an accuracy of 10% if larger than 1 × 10^-9 cm²/s, by the comparison with the experimental spectra measured at the temperature, i.e. at a certain diffusion coefficient.