**4. Summary**

Over the past two decades, positron annihilation spectroscopy has proven to be an invaluable characterization tool in various radiation damage studies aimed at the evolution of early-stage microstructures. However, due to the wide variety of materials and irradiation conditions to be studied, and the complexity of data analysis, it is often difficult to reflect the knowledge obtained so far in new irradiation studies. This paper summarizes recent studies of structural materials subjected to different ion beam irradiation experiments and investigated by techniques of positron annihilation spectroscopy. It provides a convenient reference for experiment proposals in the field and enables a quick comparison of the obtained results to the published data. This helps researchers to conduct

more reproducible experiments, and will eventually help them to use positron annihilation spectroscopy as a primary characterization tool.

**Funding:** This research work was supported by the Slovak Research and Development Agency under the contract No. APVV-20-0010, Scientific Grant Agency of the Ministry of Education of Slovak Republic and the Slovak Academy of Sciences VEGA projects No. 1/0382/20 and 1/0395/20 and the European Regional Development Fund, project No. ITMS2014+: 313011W085.

**Conflicts of Interest:** The authors declare no conflict of interest.
