Electrical resistivity and length variations of iron and nickel during low temperature electron irradiations

Low concentrations of Frenkel pairs were produced in polycrystalline iron and nickel targets during irradiation with 1.9 to 2.5 MeV electrons at 5 or 20 K. During irradiation (and subsequent thermal annealing for the nickel target) we simultaneously measured the changes in electrical resistivity, and in target length with two different linear systems: a capacitive and an inductive device. The measured ratios of relative length to electrical resistivity increases are [(Δl/l)/δρ]Fc=260±30(Ωcm)-1 and [(Δl/l)/Δρ]Ni=1020±120(Ωcm)-1. Values of Frenkel pair formation volumes of υFc=1.35±0.25 and υNi=2.06±0.30 atomic volumes are proposed. (author)