Toward a European Network of Positron Laboratories

Some applications of controlled-energy positron beams in material studies are discussed. In porous organic polysilicates, measurements of 3γ annihilation by Doppler broadening (DB) method at the Trento University allowed to trace pore closing and filling by water vapor. In silicon coimplanted by He⁺ and H⁺, DB data combined with positron lifetime measurements at the München pulsed positron beam allowed to explain Si blistering. Presently measured samples of W for applications in thermonuclear reactors, irradiated by W⁺ and electrons, show vast changes of positron lifetimes, indicating complex dynamics of defects.