Stored Energy Release in Copper Following Electron Irradiation below 20°K

The stored energy release in copper has been measured in the temperature range 20°-60°K following irradiation with 1.2-Mev electrons. A differential temperature measurement was made between an irradiated specimen and an unirradiated standard. The specimens were immersed in liquid helium during irradiation; subsequent heating of the specimen was carried out in vacuum. A value of the total energy release of 2.5×${10}^{-2\mathrm{}}$ cal/g was observed for an integrated flux of 9×${10}^{17}$ e/${\mathrm{cm}}^2$. The stored energy-resistivity ratio obtained is (5.4±0.8) cal/g per micro-ohm-cm. The energy associated with a Frenkel pair is calculated to be (5.4±0.8) ev for a value of 3.6 micro-ohm-cm per atomic percent Frenkel defects.