Physics with positrons

Use of positrons for studies in materials physics is reviewed under the headings: fundamental facts, lifetime measurements in condensed matter, angular correlation studies, the effective mass of the positron msub(+)*, realisation of the positron beam, two dimensional angular correlation machines, and study of defects and vacancies in metals. Finally, the state-of-the-art of use of positrons in research in India is briefly surveyed. (M.G.B.)