[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 principal activities in the fields of solid-state physics (neutron scattering), plasma physics and meteorology are presented in this report that covers the period 1 January to 31 December 1976. In addition, research on nuclear spectroscopy was carried out up until March 31, 1976. The experimental and theoretical work in solid-state physics is roughly divided into the following main subject fields: investigations of the dynamic and static properties of magnetic and superconducting solids; studies of various kinds of phase transitions in magnetic and molecular systems; and investigations of the dynamic and static properties of molecular crystals and adsorbed monolayers. The main object of basic research in plasma physics is to investigate waves and instabilities in a relatively cold steady state plasma (produced in a Q-machine). Turbulence, ion cyclotron waves, and ion-acoustic waves in the presence of electron plasma waves are the chief phenomena investigated. Work on nuclear spectroscopy was concentrated on problems relating to fission. The meteorology section is primarily engaged in studies of the planetary boundary layer. (B.R.H.)

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[en] The principal activities in these fields are presented in this report that covers the period from 1 January to 31 December 1977. Introductions to the work in each of the main fields are given in the respective sections of the report. (Auth.)

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[en] The lifetimes of magnons propagating in the c-direction of Tb at 4.2 K have been measured by inelastic neutron scattering. In contrast to the behaviour at higher temperatures, where magnon-magnon scattering predominates, the broadening of the magnons increases towards the boundary of the single Brillouin zone, both in the acoustic and optical branches. This suggests that the scattering of the magnons by conduction electrons is important, and the observed lifetimes are consistent with a recent estimate of the magnitude of this effect. The acoustic magnons of very long wavelength behave anomalously, presumably due to dipolar interactions

[en] The flow pattern in a liquid layer heated from below changes character as the vertical temperature gradient is increased. A review is given for the sequence of instabilities connected with the different flow regimes, with emphasis on their phase-transition aspects. Utilizing the coupling that exists between the molecular orientation and flow in a liquid crystal, we have used neutron scattering to explore these phenomena. The special features of liquid crystals in this respect are pointed out. Experiments near the lowest lying instability, the Rayleigh-Benard transition, verify the mean-field predictions for the change of the threshold gradient with the applied magnetic field, the behaviour of the order parameter (the fluid velocity) versus epsilon (the reduced gradient scale), the time-dependent growth and the critical slowing down of the growth rate of the order parameter. A pre-transitional tail of intensity is analysed within the same formalism and it is suggested that it arises from hydrodynamic fluctuations driven by the microscopic fluctuations of the liquid. Experiments at higher gradients reveal a time-periodic flow regime with frequencies down to cycles per hour. These observations lend support to modern theories for the transition to turbulence. (author)