Electron-Irradiation Damage-Rate Measurements in Aluminum

The resistivity increase upon electron irradiation near 8°K of aluminum was measured as a function of incident electron energy from 0.19 to 1.6 MeV. A value of the displacement threshold energy of 16 eV was determined by extrapolation of the damage-rate curve to zero damage production. A reasonable fit between the experimental and theoretical values of the displacement cross section was achieved with an effective threshold energy of 19 eV, a value of the Frenkel resistivity of (1.32×${10}^{-4\mathrm{}}$ ohm cm)/(fractional concentration), and a unit step-displacement function. The tailing off in the damage rate near threshold that has been observed in Cu, Au, and Pt is apparently absent in Al.