Electron　beams　of　0.5,　1.5,　2.0,　and　5.0　MeV　were　used　to　irradiate　n-Si　diodes　to　fluences　of　5.5　x　10(13),　1.7　x　10(14),　and　3.3　x　10(14)　e　cm(-2).　The　forward　voltage　drop,　minority　carrier　lifetime,　and　deep　level　transient　spectroscopy　(DLTS)　characteristics　of　silicon　pn　junction　diodes　before　and　after　irradiation　were　compared.　At　the　fluence　of　3.3　x　10(14)　e　cm(-2),　the　forward　voltage　drop　increased　from　1.25　V　at　0.5　MeV　to　7.96　V　at　5.0　MeV,　while　the　minority　carrier　lifetime　decreased　significantly　from　7.09　mu　s　at　0.5　MeV　to　0.06　mu　s　at　5.　0　MeV.　Six　types　of　changes　in　the　energy　levels　in　DLTS　spectra　were　analyzed　and　discussed.