Positron annihilation lifetime measurement has been a destructive analysis method in the sense that it requires cutting the specimen in two pieces, but the anti-coincidence method we developed enables the measurement of positron annihilation lifetime without cutting. In this study, by applying this anti-coincidence method, we developed a small and light portable positron annihilation lifetime measurement equipment for on-site measurements. In order to make the equipment small and light, we used

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... a small photomultiplier tube for the γ-ray detectors, and we determined the detector configuration by simulation and experiment. To evaluate the performance of the developed equipment, we conducted positron annihilation lifetime measurements on shot-peened stainless steel and compared the results to those by the desktop anti-coincidence equipment. Just like the desktop equipment, the developed equipment revealed the increase in the defect density by shot-peening as the change in the positron lifetime, verifying the effectiveness of this equipment.