We have Studied the annealing of vacancy defects in neutron and proton irradiated germanium After neutron irradiation the Sb-doped samples were annealed at 473, 673 and 773 K for 30 min The positron lifetime was measured as a function of temperature (30 - 295 K) A lifetime component of 330 ps with no temperature dependence is observed in as irradiated samples. identified as the positron lifetime in a neutral divacancy The average positron lifetime in the samples annealed at 473 K has a definite temperature dependence, suggesting that the divacancies become negative as the crystal recovers and the Fermi level moves upward in the band gap Proton irradiation of germanium at 37 K with subsequent room temperature annealing also resulted in a similar lifetime component 315 ps. in good agreement with the neutron irradiation experiment (C) 2009 Elsevier B V All rights reserved