[en] This report describes the design of the superconducting solenoid CRYEBIS 2. With the prescribed parameters (5 Teslas central field, 120mm for inner diameter, 1600 mm for length), one determinates the dimensions of coil, its energy, the conductor, the working point of the magnet with its critical limits (intensity, field, temperature). The superconducting switch is calculated in the same manner. The study of a quench shows the good behaviour of the coil which is always safe even the detection system is in failure. In final, the mechanical stresses are verified lower than yield strength

[en] A superconductive magnet system for optic spectroscopy has been built. It includes an elaborate support structure, a LN2/LHe cryostat with its supplies and controls and a superconductive magnet of the split pole type equipped with a superconductive switch. A vertically introduced sample in the LHe bath, on request subcooled down to 2.2K is observed through two optical passages. Magnet characteristics are as follows : - clear bore 35mm - clear split 20mm - central field 6.33 Teslas - homogeneity over 10mm D.S.V.: 1%

[en] The situation regarding transverse axial tomography, at present expanding rapidly, is reviewed. Owing to modern computing and data processing means and methods it is no longer necessary to use water around the head and the examinations may be extended to the whole body. The technique of image reconstitution by absorption measurement is the only method employed in practice because, although calculations show that the use of Compton radiation would lead to comparable results, a much more complex detection system and above all a monoenergetic incident beam would be necessary. The gain on the scanning time can be considerable. The use of N elements detecting simultaneously should reduce it by about a factor N. The main features of tomographs proposed by different makers are described

[en] An impact wear model, based on the load-sliding distance proportionality of wear and the mechanical response of the impacting bodies, was derived and tested against experiment. The experimental work was carried out on a twin vibrator rig capable of repetitive impact of a moving specimen against a stationary target material. The impact wear characteristics of three materials (mild steel, 9Cr-1Mo steel and austenitic 316 steel) against 310 stainless steel were examined over a range of temperatures (18-600⁰C). Additionally the effects of variations in the mechanical parameters (incident energy, ξ_i, number N of impacts and angle of incidence φ) as a function of temperature were evaluated for mild steel only. The model was verified for impacting within a stable wear regime at 100⁰C for 9Cr-1Mo steel. The emergence of a severe-to-mild wear transition at elevated temperatures (200-400⁰C), however, introduced an energy and a 'numbers of cycles' effect that caused apparent deviations from theory. It was concluded that for stable single-mechanism wear regimes (metallic, oxidative etc.) oblique elastic impacts with a gross slip component were accurately described by the proposed impact wear model. (orig.)

[en] The quality of scintigraphic images is shown to depend on the efficiency of both the input collimator and the detector. Methods are described by which the quality of these images may be improved by adaptations to either the collimator (Fresnel zone camera, Compton effect camera) or the detector (Anger camera, image amplification camera). The Anger camera and image amplification camera are at present the two main instruments whereby acceptable space and energy resolutions may be obtained. A theoretical comparative study of their efficiencies is carried out, independently of their technological differences, after which the instruments designed or under study at the LETI are presented: these include the image amplification camera, the electron amplifier tube camera using a semi-conductor target CdTe and HgI² detector

[en] We report on the results of scanning tunneling spectroscopy measurements on single crystals of MgB₂. Tunneling was performed parallel to the crystalline c-axis, and a single superconducting gap (Δ_π=2.2 meV) associated with the π-band is observed. Vortex imaging in the π-band was performed with the field parallel to the c-axis. The vortices are found to be organized in a well-ordered hexagonal lattice

[en] Two systems using large superconducting solenoids are described. The first, SOLENO, is composed of two magnets (3T, 600 KJ each) and will replace a standard triplet of magnetic lenses; for the moment only the first magnet has gone into operation. The second system, a 5T solenoid, CRYEBIS II, is built in duplicate and will be used on heavy ion sources: one for our laboratory and the other one for the Research Institute of Physics/STOCKHOLM (Sweden). This system employs a superconducting switch to short-circuit the current on the magnet

[en] We report on the results of scanning tunneling spectroscopy measurements on single crystals of MgB₂. Tunneling was performed both parallel and perpendicular to the crystalline c-axis. In the first case, a single superconducting gap (Δ_π=2.2 meV) associated with the π-band is observed. Tunneling parallel to the ab-plane reveals an additional, larger gap (Δ_σ∼7 meV) originating in the highly 2D σ-band. Vortex imaging in the π-band was performed with the field and tunnel current parallel to the c-axis. The vortices have a large core size compared to estimates based on H_c2, and show an absence of localized states in the core. Furthermore, superconductivity between the vortices is rapidly suppressed by an applied field. A comparison to specific heat measurements is performed

[en] The AGOR project is a close cooperation between the Dutch Kernfysisch Versneller Instituut (KVI) and the French Institut de Physique Nucleaire (IPN). The purpose of the project is to install a superconducting cyclotron at the KVI in 1992, that will be able to accelerate both light and heavy ions at central field strengths ranging from 1.7 T to 4.07 T. This field is generated by a set of four fully vacuum impregnated superconducting coils, cooled by liquid helium at the total outer perimeter. They will be housed in a split cryostat in which roomtemperature access is provided to most of the mid-plane. In the design of the cooling system much effort has been given to enhance the overall efficiency. (author)

No abstract available