Inelastic Neutron Scattering Measurements of Phonon Dispersion Curves in Reactor-Irradiated Aluminum at 4.6 K

Abstract

An aluminum single crystal has been irradiated at 4.6 K with fast neutrons to a Frenkel defect concentration of 810 ppm. Inelastic neutron scattering experiments revealed a clear shift of the [$00\zeta$] transverse phonon frequencies with respect to the annealed crystal. In contrast to theoretical predictions, no obvious resonancelike behavior has been observed in the wave-vector range $0.05<\mathrm{}\zeta <0.19\mathrm{}$ ($\zeta$ is in reduced units).