Current status and issues on analytical techniques using slow positron beam

Positron annihilation lifetime spectroscopy (PALS) is a powerful technique to probe nano-scale pore structures such as defects and free-volumes of materials. PALS with a beam of mono-energetic positrons makes it possible to perform local scanning, both along the direction and, by varying the positron energy, depth distributions, of the pore properties in samples. This beam-based technique has been developed and utilized for the analysis of a wide variety of advanced materials. This survey describes the technical details and current status of the PALS technique based on a positron beam, together with issues facing industrial applications. Future prospects and possible research agendas emerging from this survey are also discussed. (author)