[en] 1. Scope of the report; 2. Special features of the diffractometer; 3. Efficiency of the radiation shielding; 4. The beam path; 5. The beam collimation; 6. The sample size; 7. The monochromators available at the guest diffractometer; 8. lambda/2-contamination; 9. The detector; 10. The flux density at the beam tube D1S; 11. The flux density at the sample position; 12. The resolution curve. References. (orig.)

[en] The computer program MONREF was written for calculating the integrated intensity and the k-vector distribution produced by mosaic-crystal monochromators in neutron diffractometers of given geometries. The program treats flat and horizontally curved monochromators in Bragg reflection. Its basic algorithm is derived from Zachariasen's coupled differential equations which were modified to include the case of asymmetrically cut crystals. The calculations are restricted to the scattering in the experimental plane. In the first part of the report the program and its applications are described. In the second part a compilation of intensities is presented, calculated for crystals of Cu, Si, Ge and pyrolytic graphite commonly used as monochromators, in a standard diffractometer configuration. (orig.)

[en] The following topics are dealt with: Development of instruments and methods, magnetic structure, magnetic phase transitions, magnetic excitations, magnetic thin films, chemical structure, structural phase transitions, biological materials, sof condensed matter, soft magnetic matter, nanostructures, strain and stress, cultural heritage, fundamental physics. (HSI)

[en] The following topics are dealt with: Development of instruments and methods, magnetic structure and phase transitions, magnetic excitations, chemical structure, structural excitations, geological materials, biological materials, soft matter, nanostructures, strain and stresses, cultural heritage, fundamental physics. (HSI)

[en] The BER II research reactor, cold source and neutron guides - the instruments of BENSC - an overview; Instrument sites in experiment hall and neutron guide hall - description of the diffractometers. (orig./HP)

[en] Complete text of publication follows. We present a series of measurements on the multidetector Neutron Spin Echo (NSE) Spectrometer SPAN at BENSC with single crystalline samples of the well known cooperative Jahn-Teller system CsCuCl₃. This system undergoes a first order structural phase transition at 423 K between a dynamically disordered high temperature phase and an ordered low temperature phase. We focused on the diffuse scattering around the (002) Bragg peak of the high temperature phase. Surprisingly noticeable influence was found of the structural phase transition on the NSE spectra. The spectra recorded between 430 K and 5 K are a mixture of an elastic (frozen) part and of an inelastic component, which is too fast for the NSE dynamic window. The relative weight of the inelastic component increases with increasing temperature: at 5 K the spectra are purely elastic and they become purely inelastic in the vicinity of the transition temperature. The nature of the excitation is discussed which gives rise to the inelasticity seen on the NSE spectra, in relation with the structural phase transition. (author)

[en] The hexagonal perovskite CsCuCl₃ exhibits a structural phase transition from a dynamically disordered high-temperature phase to an ordered low-temperature phase due to the cooperative Jahn-Teller effect. The lattice dynamics of the high-temperature phase has been studied by inelastic neutron scattering experiments. The investigations concentrated on small wave vectors q, where for the first time renormalized phonons at q=0.02-0.05 A^-1 could be observed. The measurements confirm the predictions of a theoretical approach based on the coupling between dynamic reorientation processes and acoustic lattice waves (pseudo-spin phonon coupling). (author)

[en] Czochralski-grown silicon crystals of approximately 10 cm diameter and 1 cm thickness have been annealed at 1470 K in order to create a homogeneous defect structure, which is a basic condition for all statistical treatment of extinction. Absolute values of the integrated reflecting power of the 220, 440 and 660 reflections have been measured with 0.0392 A γ-radiation in symmetrical Laue geometry for sample thicknesses between 1 and 3 cm. The amount of extinction in the experimental data varies between γ≅0.95 and γ≅0.05. Darwin's extinction theory has been used to describe the thickness dependence of the data sets. Despite some shortcomings of the model, it is shown that the assumption of a physically unrealistic Lorentzian mosaic distribution models the effect of primary extinction in an extinction theory based on the energy-transfer model. The sharp central part of the Lorentzian distribution produces a reduction of the effective sample thickness due to primary extinction, whereas the wings of the distribution dominate the correction for secondary extinction in the remaining part of the sample. A more flexible mosaic distribution function is proposed, which should be useful in cases of severe extinction. (orig.)

No abstract available

[en] The use of intense γ-ray sources for studying electron densities in solids is discussed. Both elastic and inelastic γ-ray scattering experiments are performed at the Hahn-Meitner-Institut, using 412 keV radiation from ¹⁹⁸Au. Both the γ-ray diffractometer and the Compton spectrometer are described in detail, and some recent results are shown. Particular attention has been paid to the practical aspects of working with intense sources, which in this case have a strength of about 100Ci. (Auth.)