Atomic Energy of Canada Limited

About: Atomic Energy of Canada Limited is a company organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Zirconium alloy & Neutron. The organization has 4845 authors who have published 4826 publications receiving 102951 citations.

Lattice Dynamics of Alkali Halide Crystals. III. Theoretical

Abstract: The "shell model" of an alkali halide is extended to take into account short-range forces between both first- and second-nearest neighbor atoms in the crystal, the polarizability of both ions, and the possibility that the ionic charge may be less than one electronic charge. The arbitrary parameters of the model have been obtained by means of a least-squares fit to the measured dispersion relations for the lattice vibrations, the dielectric constants, and the elastic constants. For NaI and KBr, models have been found which give excellent agreement both with these measurements and with measurements of the specific heat. This good agreement is, however, obtained only when the simple shell-model concept of the ions is to some extent abandoned. The reasons for this, and the connection with work of other authors, are discussed.

A process for flares

Abstract: Solar flare process - solar wind as energy source, magnetic storage of energy, and particle acceleration

Magnetic excitations in the heavy-fermion superconductor URu2Si2.

Abstract: Antiferromagnetic order and fluctuations in the heavy-fermion superconductor ${\mathrm{URu}}_{2}$${\mathrm{Si}}_{2}$ have been studied by magnetic neutron scattering. Below ${\mathit{T}}_{\mathit{N}}$=17.5 K, ${\mathrm{URu}}_{2}$${\mathrm{Si}}_{2}$ is a type-I antiferromagnet with an anomalously small ordered moment of (0.04\ifmmode\pm\else\textpm\fi{}0.01)${\mathrm{\ensuremath{\mu}}}_{\mathit{B}}$ polarized along the tetragonal c axis. Dispersive resonant excitations exist in the ordered state with a zone-center gap of 0.43 THz. The excitations are polarized along the ordered moment and have a large dipolar matrix element, which suggests that they are coupled transitions between singlet crystal-field-like states. For energy transfer above 3 THz, peaks have not been identified in the magnetic excitation spectra, but instead a continuous spectrum of scattering peaked around the ordering wave vector indicates the presence of overdamped antiferromagnetically correlated spin fluctuations. Upon heating above ${\mathit{T}}_{\mathit{N}}$, the resonant excitations abruptly become heavily damped but the magnetic scattering at higher energies does not change at ${\mathit{T}}_{\mathit{N}}$. Instead, the disappearance of the antiferromagnetic modulation of the higher-energy scattering coincides with the maximum in the resistivity of ${\mathrm{URu}}_{2}$${\mathrm{Si}}_{2}$.