Stored energy release in electron-irradiated graphite

The stored energy release in electron-irradiated pyrolytic graphite was measured during annealing from around 80 K to 320 K by using a method of differential thermal analysis. For converting the recorded temperature difference into the energy release rate, the heat transfer coefficients and heat capacities of samples were measured as a function of temperature. A useful method of data analysis in differential calorimetry is presented; it gives the reproducible base line of stored energy release curves even if the heating rate is not strictly controlled. The energy release curves show peaks near 105, 150, 200, 250 and 295 K. The amount of the energy released around each peak is obtained for a pair of Frenkel defects produced by irradiation. The formation energy of a Frenkel defect and annealing of defects are discussed. (auth.)