Development of an ISO technical specification for evaluation of pore size in materials via the positron annihilation lifetime technique

Résumé fourni par la source

Abstract We have developed a Technical Specification (TS) under the International Organization for Standardization (ISO) for the evaluation of pore size in materials via the positron annihilation lifetime technique (ISO/TS 23878:2024). This TS outlines a standard procedure for measuring the ortho -positronium ( o -Ps) lifetime in Ps-forming materials, employing a conventional sandwich configuration with two γ-ray photon detectors. The TS describes the measurement procedure, data analysis, and conversion from measured o -Ps lifetime to nanopore size via the Tao-Eldrup formula, largely based on a previous Japanese domestic standard (JIS TS Z 0031:2012). To ensure the validity of measurement and data analysis procedures, an inter-laboratory comparison involving eight institutions was conducted using two types of reference materials: fused silica and polymethyl methacrylate.

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