[en] The objective of the study is to enrich waters of poor tritium concentration, by electrolysis in the same time of an hydrogen emission of low activity. In this framework the hydrogen electrochemical permeation threw Pd-Ag alloy membranes has been used. The first part of the study concerns the hydrogen and the deuterium diffusion threw these membranes. The activation and the thermal treatments influence have been studied. A relation between the membrane microstructure and the diffusion mechanism has been proposed. The second part of the study is devoted to the hydrogen gate mechanism determination in the membrane by impedance spectroscopy. The last part concerns the determination of the isotopic separation factor hydrogen-deuterium. Experimental results agree the calculated theoretical data. The operation of an operational membrane cell has been simulated and the process feasibility has been proved. (A.L.B.)

[en] A method to measure the deuterium concentration in basic solutions, using Attenuated Total Reflection Fourier Transformed Infrared Spectroscopy (ATR-FTIR) is described. Deuterium quantification is based on the O-D bond stretching peak. A calibration curve is drawn, representing the peak intensity versus the deuterium percentage in a neutral solution. No calibration curve can be obtained with basic solutions, because of the strong absorbance due to hydroxide ions. Thus, an acidification is necessary prior to the analysis of a basic solution. The deuterium content of this acid solution is then measured. As we know the dilution caused by the acid addition, we can calculate the deuterium content of the initial basic solution. The relative uncertainty of this method is + or - 2%. (authors)

[en] Palladium and palladium-silver alloys are used in many applied fields involving hydrogen: separation of hydrogen isotopes, purification of gaseous hydrogen, fuel cell, and recently, cold fusion. The microstructure of Pd-23%Ag and the diffusion of hydrogen through this alloy are investigated after different annealings. A direct relation between the grains size and the diffusion coefficient of hydrogen is expressed. Two diffusion mechanisms are highlighted: intergranular for grains size below 40 nm and transgranular for grains size above 100 nm. For grains size between 40 and 100 nm both mechanisms coexist. (authors)

[en] We present a systematic study of the dynamics of non-yrast states using a simple but physically relevant hamiltonian. The emphasis is put on the behavior of 0+ states. When the transition takes place between spherical and gamma-soft nuclei level bunching occurs which is related to the conserved seniority. Similar behavior occurs in the regular region which is not directly connected with the known symmetries. In between spherical and prolate nuclei a sharp increase in the level density of 0+ states is found. We report on recent (p,t) transfer reactions related to these topics which were performed at the Q3D spectrometer in Garching with the aim to measure the 0+ states in a complete way up to high energy

[en] A focus point in this work was the study of the influence of a low substrate temperature, as well as the minor addition of Y (0.1–0.3 at.%), on the formation of the stable Cr_2AlC–MAX (ternary alloy with general formula M_n_+_1AX_n: M = early transition metal, A = A-Group element, mostly IIIA or IVA, X = C or N, n = 1–3) phase. The coatings, deposited by High Power Impulse Magnetron Sputtering, consisted of a mixture of disordered solid solution (Cr,Al)_2C_x and ordered Cr_2AlC–MAX phase. All deposited coatings without and with 0.1–0.3 at.% Y addition were polycrystalline, and showed (110) texture and a columnar morphology. The measured strong lattice distortions along with the existence of the texture in the as-deposited samples indicate that compressive stress acts in the a–b plane and tensile perpendicular to this. A schematic model of the structural and chemical changes in the as-deposited layers due to deposition inhomogeneity and low deposition temperature, based on the X-ray diffraction, energy dispersive X-ray, scanning electron microscopy and magnetic measurements has been developed. - Highlights: • The films deposited at 450 °C both contained the MAX phase and solid solution. • The films were polycrystalline with (110) texture, and columnar growth. • Film stress was compressive in the a–b plane and tensile perpendicular to this. • No difference was found in this result upon the introduction of up to 0.3 at.% Y. • Introduction of a film structure model based on XRD, EDX, SEM and magnetic results

[en] The temperature-dependent energy difference of both spin counterparts of the d_z²-like surface state of Gd(0001) films being held responsible for the surface magnetic properties was investigated by means of variable-temperature scanning tunneling spectroscopy. This exchange splitting amounts to 700 meV at 20 K and decreases down to 400 meV at 300 K. Above 300 K the splitting remains constant. Pure spin-mixing as well as pure Stoner-like behavior can therefore be excluded. A theoretical description explains the observation by a local spin-polarization due to the atomic 4f moments which compete with spin-mixing caused by the thermal fluctuations of these moments. The results suggest that the high spatial localization of the surface states helps to maintain a local exchange splitting even above the Curie temperature but does not cause an enhanced surface Curie temperature. (orig.)

No abstract available

[en] The mechanism of water radiolysis implies several reactions and depends on many parameters such as the radiation characteristics (type of radiation, energy ...), the temperature and the chemical composition of irradiate water. Thus it is very difficult to foresee, without experimental data, the overall effect of these parameters. If radiolysis of pure water under γ rays or α particles has been widely studied, it is not the case for self radiolysis of tritiated water (low energy β^- particles radiation). In order to fill this lack of experimental knowledge and to understand the radiolysis of stored tritiated water produced in tritium plants, we studied the evolution of hydrogen and oxygen concentrations in the gaseous phase above chemically pure tritiated water. The simulation of pure water radiolysis has been carried out and the results are compared with experimental data

No abstract available

[en] Using the U_ν(6/12) x U_π(6/4) extended supersymmetry, we constructed the energy spectrum and electromagnetic transition properties of the supermultiplet member ¹⁹⁸Hg with two proton fermions coupled to a neutron boson core. Consistency between the supersymmetric interacting boson fermion fermion approximation (IBFFA) description and the F-spin symmetric interacting boson approximation (IBA-2) description is shown for this two-fermion-N-boson multiplet member. The data of a γγ angular correlation experiment using the HORUS cube γ-ray spectrometer--determining new multipole mixing ratios, level spins, γ transitions, and energy states--shows quite a good agreement, also for the low-energy part of the spectrum, when comparing theoretical predictions and experimental data. This is contrary to the usual assumption that a two-fermion-N-boson constellation should describe just the excited two-quasiparticle states.