The conductivity measured during the application of pulsed electric fields is used to monitor the damage introduced at 4.2\ifmmode^\circ\else\textdegree\fi{}K by energetic electron irradiation of $n$-type germanium. Fields above about 20 V/cm completely ionize the donor impurities. Radiation-induced defects deplete the electron population of the donors by introducing deeper acceptor levels. A sensitivity to defect concentrations of ${10}^{12}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ is obtained in material containing about ${10}^{14}$ Sb impurities ${\mathrm{cm}}^{\ensuremath{-}3}$. The introduction rates of various defects are studied as a function of irradiation energy. One type, previously identified as a close vacancy-interstitial pair, is removed (presumably by annihilation) in the order of minutes by annealing at 65\ifmmode^\circ\else\textdegree\fi{}K. This defect accounts for 95% of the conductivity change produced by irradiation at 0.7 MeV, but only 50% of the change at 4.5 MeV. Evidently this is the primary defect requiring the least energy for its formation. A second type of primary defect is distinguished by the fact that it is present after annealing to 90\ifmmode^\circ\else\textdegree\fi{}K. The dependence on bombardment energy of the introduction rate of this defect indicates that multiple displacements may be involved in its production, and therefore it may be a double vacancy. A third type of defect is observed only after large fluxes of low-energy electrons, and appears to be a secondary defect resulting from radiation-induced conversion of primary defects. This defect also remains after annealing to 90\ifmmode^\circ\else\textdegree\fi{}K, but it has electrical properties very similar to those of the defect that anneals at 65\ifmmode^\circ\else\textdegree\fi{}K. Trapping properties of the first and third defect types lead to the conclusion that they are both capable of capturing two electrons in $n$-type germanium and are therefore double-acceptor centers.