An exactly soluble relaxation problem

The problem of a particle moving in a two-valued random potential occurred in a recent paper by Pomeau. The exact time-dependent solution is here obtained for a quadratic potential by two different methods. The first method treats the problem as a stochastic differential equation and leads to the characteristic function of the probability distribution of the particle coordinate. In the second method the equation for the joint probability density of particle and potential is solved, which leads to the temporal Laplace transform of the distribution. The spectral properties of the evolution operator are examined.     

A quantitative evaluation of the reliability of calculated decay properties of nuclei in the mass region A=24−28

Electromagnetic transition rates and logft values were calculated for transitions between positive-parity states in theA=24?28 mass region. The wave functions used were taken from a previous paper. In general we found satisfactory agreement with experiment. In order to have a measure of the stability of the results against changes in the Hamiltonian a method was developed for assigning errors to calculated transition properties. The renormalized single-particle matrix elements of theE2 andM 1 transition operators were determined in a phenomenological way. To this end use was made of the errors just mentioned. It was found that good agreement was obtained with bare-nucleonM 1 singleparticle matrix elements and a state independent effective isoscalar charge for theE 2 operator. Predictions for static moments are given.     

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.