[en] The magnon density of states, and hence the magnetic contribution to the specific heat, together with the exchange interaction between ions in the same sub-lattice have been calculated for Tb at 90°K, using experimental results obtained by inelastic neutron scattering. (author)

[en] This paper reviews neutron scattering studies of spin waves in magnetic metals. In the rare earth metals such studies have given rather detailed information on the indirect exchange interaction and its relation to the electronic structure. Measurements on the iron group metals have so far given much less information and no effects which show unambiguously the itinerant character of the magnetic electrons have been observed, probably because spin-wave studies in iron group metals have only been possible for rather low wavevectors of the spin waves. (author)

[en] The incoherent neutron scattering cross-section for a harmonic crystal can be determined from a set of frequency distributions. We compute these frequency distributions for crystalline, syndiotactic polyvinylchloride. We use the force constants introduced by Opaskar and Krimm for the saturated hydrocarbons. We also include a diagonal torsional force constant of 0.06 mdyn Å/rad² . We ignore intermolecular forces in this calculation except for the inclusion of an ϵ² dependence in the frequency distributions at small ϵ. We present representative calculations to indicate the resolution needed to determine the details of the frequency spectra. (author)

[en] The critical neutron scattering above the Néel temperature T_N in Tb has been measured using both double-axis and triple-axis spectrometry. The parameters of the magnetic susceptibility and the spin relaxation function have been deduced in the temperature range 0.005 ≲ (T-T_N)/T_N≲ 0.06. Both the inverse correlation range K₁ and the long wavelength susceptibility X(Q) obey temperature power laws, with the exponents v = 0.66± 0.02 and γ = 1.33 ± 0.02, respectively. The results for the relaxation function show that thermodynamic slowing down of the spin fluctuations does occur in Tb when the temperature approaches the critical temperature. (author)

[en] The method of pseudo-statistical pulsing has been applied only to reactor-kinetic measurements so far. Ohanian, Perez and Uhrig proposed this method for time-of-flight measurements with pulsed accelerators. Comparative studies have shown, however, that it is not possible to give general arguments in favour of either the pseudostatistical or the conventional time-of-flight method. Which of the two methods may be preferred depends on the kind of experiment. Pseudo-statistical pulsing may be especially advantageous for scattering experiments with thermal neutrons. This paper is intended to give a description of a 'statistical' chopper and the method of measurement with this instrument. The different influences on the accuracy of the measurements are discussed and compared to those in a conventional time-of-flight experiment. A few examples of pseudo-statistical experiments have been simulated on a computer. It is shown that a statistical chopper is advantageous for time-of-flight spectra consisting of a number of peaks which are of main interest and have amplitudes greater than the average amplitudes of the spectra. Further, the method is advantageous in all cases where the background is very high. A preliminary experimental arrangement is described. (author)

[en] The energy distribution of neutrons scattered by trivalent rare-earth compounds has been measured at room temperature. The paramagnetic lines, corresponding to transitions within the ground-state multiplet of the rare-earth ion split by the octahedral crystal field, are superposed on the nuclear parts of the energy distribution. Experimental conditions and computational methods are described to determine the position and shape of the paramagnetic lines. The resulting values of the crystal field splitting and the paramagnetic line width are discussed. (author)

[en] The design of the spectrometer for studies of inelastic coherent scattering of thermal neutrons by single crystals at the IBR reactor is described. A polychromatic pulse neutron beam is scattered by a single-crystal sample and the energy of scattered neutrons is analysed by three analysing single crystals (for three different beams of scattered neutrons). The time-of-flight technique is used to measure the incident neutron energy. The spectrometer is adapted for simultaneous structure and lattice dynamics studies of solids. Special features of this spectrometer and its applications are discussed. (author)

[en] Translatory and rotatory frequencies of crystallization molecules of water were determined by the neutron inelastic scattering method in several crystallo-hydrates. The results are compared with those obtained from infrared and nuclear magnetic resonance experiments. (author)

[en] The inelasticity of critical scattering has been investigated in iron using the pulsed monochromatic neutron beam at the IBR-1 reactor in Dubna. The measurement covered the temperature range -2.5 x 10_-3≤τ≤ 6.5 x 10^-3 where τ ≡ T/T_c - 1 and the critical temperature was approached within τ < 5 x 10^-4. The slight temperature dependence of the inelasticity was confirmed for q = 5.7 x 10^-2 Å^-1, but the observed diffusion constant was found to be temperature independent and higher ( μ = 16.5) than the value (μ = 11) reported earlier by other authors. (author)

[en] Proceedings of a Symposium convened by the IAEA and held in Copenhagen, 20-25 May 1968. The meeting was attended by 167 participants from 29 Member States and 4 international organizations. These are the fourth IAEA Symposium Proceedings to have neutron inelastic scattering as their main theme, the previous ones being Inelastic Scattering of Neutrons in Solids and Liquids (Vienna), IAEA (1961), Inelastic Scattering of Neutrons in Solids and Liquids (Chalk River), IAEA (1963), and Inelastic Scattering of Neutrons (Bombay), IAEA (1965). Contents: Dynamics of solids, including: lattice vibrations and local modes (6 papers), lattice dynamics in metals (7 papers), lattice dynamics of metals and alloys (13 papers), lattice dynamics of non-metals (11 papers) and review paper; Dynamics of liquids, including: coherent neutron scattering on systems (13 papers and review paper); Molecular dynamics (9 papers); Experimental methods (17 papers); and Summary. Each paper is in its original language (93 English, 2 French, 4 Russian) and is preceded by an abstract in English with one in the original language where this is not English. Discussions are in English. (author)