No abstract available

No abstract available

[en] The peak value as well as the full width at half maximum of the reflectivity of single crystal neutron monochromators may be expressed, besides thickness and mosaic spread, in terms of two material parameters: reflection number and penetration depth in the absence of Bragg scattering. The values of these parameters, as functions of neutron wave length and reflection order, corresponding to reflection as well as to transmission geometry, are calculated for the most representative planes of Be, pyrolitic graphite, Al, Si, Cu, Zn, Ge, Pb and Bi single crystals. (author)

No abstract available

[en] The solution of the general form of the integral transport equation is expanded in terms of orders of scattering. The method is applied to the analysis of multiply Bragg-reflected neutrons in mosaic crystals, making evident the vertical broadening of the reflected beam as well as the consequential neutron leakage in crystal spectrometers. A wavelength-dependent effective vertical mosaic spread of the crystal is defined as a function of the mean number of reflections. A detailed mathematical treatment is performed within the frames of an infinite-plane slab model (both in reflection and in transmission geometry) largely used in the literature in the studies of crystal reflectivity. Experimental results are also presented. (Auth.)

[en] The wavelength-dependent reflecting properties of single crystal neutron monochromators as well as the principles of their experimental determination are analysed in detail. Experimental results obtained for pyrolitic graphite (002), Zn (002), Cu (111) and Pb (111) are reported. (orig.)

[en] Angular distributions of the small-angle critical scattering of 1.25 Å neutrons in cobalt have been measured at temperatures up to 150°C above the Curie point for a large range of scattering vectors (k = 0.03 - 0.6 Å^-1). The experimental data show that the asymptotic form of the instantaneous spin pair correlation function at large distances is that predicted by Fisher. The temperature dependence of the interaction range inferred from experimental data by using the Fisher correlation function is in agreement with theoretical predictions. The exponents of the temperature dependences of the reduced magnetic susceptibility and correlation range are found to be smaller in cobalt than in iron. The critical scattering data are in agreement with classical susceptibility measurements. The angular distributions at relatively large values of the scattering vector show the limited validity of the asymptotic spin correlation function. The variation with k of the position of the maximum scattered intensity as a function of temperature is discussed. (author)

[en] The scatterina law of the heavy water is determined as a function of temperature. The experimental values corresponding to 295degK, 365degK, 453degK and 533degK are reported. (authors)

[en] Experimental values of the cross sections of Al, Si, Cu, Zn, Ge, Pb and Bi at room temperature for several neutron energies between 2 X 10^-3 and 10^-1 eV, are reported. The measurements were repeated for a Bi single crystal at T = 80 K. (Auth.)

[en] The contrast variation method, applied in a neutron small angle scattering experiment, was used to simultaneously obtain information about molecular and magnetic structure of ferrofluids. Limitations caused by size polydispersity of particles were considered. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)