Abstract
The Doppler-broadening of the radiation from positrons annihilating in lead has been measured over the temperature range 4·2–600 K. The creation of mono-vacancies at the higher temperatures has been studied. On the basis of several hypotheses, including positron self-trapping and divacancy production, values of the monovacancy formation enthalpy have been estimated. The trapping of positrons by defects introduced by compression of the lead at 77 K has been investigated : complete annealing occurs before 300 K.