Determination of hydrogen and deuterium in zircaloy by vacuum extraction and mass spectrometry

Summary An apparatus is described for the determination of hydrogen and deuterium in zircaloy by vacuum extraction at 1000–1100 C and mass spectrometry. The procedure is given in detail and items like blanks, sensitivity, reproducibility, and isotope effects are discussed.

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Bestimmung von Wasserstoff und Deuterium in Zircaloy durch Vakuumextraktion und Massenspektrometrie

Zusammenfassung Eine apparative Anordnung zur H- und D-Bestimmung in Zircaloy durch Vakuumextraktion bei 1000–1100° C und anschließende massenspektrometrische Messung wird beschrieben. Blindwerte, Empfindlichkeit, Reproduzierbarkeit und Isotopeneffekte werden diskutiert.

     

Noble-gas broadening of an optical transition of I2 measured by coherent transients. III. Two-pulse photon echo and free induction decay

We report two-pulse photon echo decay and free induction decay measurements of iodine as a function of noble-gas pressure. The non-exponential behavior of the two-pulse photon echo decay which in contrast to the free induction decay shows a t³ dependence, is extensively discussed. A comparison with the results of the three-pulse stimulated echo measurements is made. The results are interpretated in terms of a quantum mechanical transport equation, and analytical expressions are derived for the three-pulse stimulated echo, two-pulse echo and free induction decay.     

The smallest length of binary 7–dimensional linear codes with prescribed minimum distance

Let n(k,d) denote the smallest value of n for which a binary (n,k,d) code exists. Then n(k, d) was known for all d, when k ?6. All values of n(7, d) will now be presented.     

Loss of ferromagnetism in YNi3 after H2 absorption

The compound YNi₃ ($\text{PuNi}{}_3\text{-}\text{type}\text{,}\text{a}\text{= 4.973}\text{A}\text{?}\text{,}\text{c}\text{= 24.42}\text{A}\text{?}$) is ferromagnetic below T_c = 35 K. After hydrogen absorption it loses its ferromagnetic character and becomes Pauli paramagnetic. The composition of the ternary hydride is approximately YNi₃H₄. The lattice constants are $\text{a}\text{= 5.267}\text{A}\text{?}$, $\text{c}\text{= 26.57}\text{A}\text{?}$.     

Excitation energies of strontium mono-hydroxide bands measured in flames

Experiments are described to yield more decisive information about the excitation energies of visible strontium monohydroxide bands appearing in flames. Excitation energy differences are derived directly from the ratio of thermal band intensities measured as a function of temperature. Absolute excitation energies are derived from the temperature dependence of the ratio of thermal band to strontium line intensity, while assuming a value for the dissociation energy of SrOH. Flames with temperatures ranging from 1907 to 2886 K were used. A level diagram is proposed for the strontium bands at 6060, 6470, 6690, and 6820 Å. From the results obtained, two conclusions may be drawn: (i) the bands considered are non-resonance bands and (ii) the uncertainty in the excitation energy as a result of the unknown molecular configuration is 0·25 eV.     

A cellular model for the Mössbauer isomer shift of 99Ru, 193Ir, 195Pt and 197Au in transition metal alloys

It is demonstrated that the isomer shift of Mössbauer nuclei in transition metal alloys can be quantitatively described in terms of an atomic cell model. The isomer shift ΔE, relative to the pure metal as a reference, is derived from a change in boundary conditions for the atomic cell; $\text{ΔE = PΔφ}{}^1\text{+ QΔn}{}_{\mathrm{ws}}$, where ø¹ is the electronegativity parameter, n_ws the cell boundary electron density and P and Q are constants for a given Mössbauer nucleus. For solid solutions there is in addition a relatively small size mismatch term.     

A theoretical model for core-annular flow of a very viscous oil core and a water annulus through a horizontal pipe

A theoretical model has been developed for core-annular flow of a very viscous oil core and a water annulus through a horizontal pipe. Special attention was paid to understanding how the buoyancy force on the core, resulting from any density difference between the oil and water, is counterbalanced. This problem was simplified by assuming the oil viscosity to be so high that any flow inside the core may be neglected and hence that there is no variation of the profile of the oil-water interface with time. In the model the core is assumed to be solid and the interface to be a solid/liquid interface.By means of the hydrodynamic lubrication theory it has been shown that the ripples on the interface moving with respect to the pipe wall can generate pressure variations in the annular layer. These result in a force acting perpendicularly on the core, which can counterbalance the buoyancy effect.To check the validity of the model, oil-water core-annular flow experiments have been carried out in a 5.08 cm and an 20.32-cm pipeline. Pressure drops measured have been compared with those calculated with the aid of the model. The agreement is satisfactory.