Relativmessung der longitudinalen β-Polarisation des141Ce

We have measured the longitudinal polarization of the β-particles of¹⁴¹Ce. Whereas Lipnik and Sunier predicted a polarizationP approximate ?0.5v/c we get for an energyE=400 keV a valueP=?(0.91±0.09)v/c. The dependence ofP on the parameterY is discussed.     

Relativmessung der longitudinalen Polarisation der β-Teilchen des Eu152

The longitudinal polarizationP of theΒ-rays from the 1.49 MeV transition of Eu¹⁵² (T=13 y) has been measured relatively to P³² using the MØeller-scattering method (electron-electron-scattering). Taking the polarization of P³² asP(P³²)=?(v/c) we getP(Eu¹⁵²)=?(0.959±0.028) (v/c) at a mean energy of 1100 keV. This result is in good agreement with the set of matrix elements taken from measurements of other observables.     

Resonanzstreuung von Licht in magnetischen und elektrischen Feldern zur Untersuchung der Hyperfeinstruktur des 7d 2 D 3/2-Terms im Thallium I-Spektrum

Observing the resonance fluorescence of the transition 7d ² D _3/2-6p ² P _1/2 (λ=2379 Å) in the Tl I-spectrum the level crossing technique with combined electric and magnetic fields was used to investigate the hyperfine structure and the Stark effect of the 7d ² D _3/2-state. For electric field strengthsE?25 kV/cm the Stark shifts are considerably greater than the hyperfine splitting. Therefore the crossing signals for the case of decoupled hyperfine structure could be detected. The following values of the magnetic hyperfine constantA and the Stark parameterβ were deduced: ¦A¦=55(1) Mc/sec·g _J /0.8, ¦β¦=0.20(4) Mc/sec/(kV/cm)²·g _J /0.8 andA/β>0. The widths of the signals yielded the mean lifetimeτ=2.7(5)·10^?8 sec· 0.8/g _J . Sign and values ofA andβ are discussed.     

Das Konsistenzproblem der Greenfunktion eines A-Hyperons in Kernmaterie

An iteration procedure is derived for determining a self-consistent approximation for the one-particle Green's function in any order, starting from perturbation theory. This method is used to calculate the second Born approximation of the self energy of a Λ-particle in nuclear matter. After one iteration the approximation is nearly self-consistent. The value of the binding energy of the Λ-paiticle is only slightly decreased from the value of perturbation theory. Because of the vanishing particle density of the Λ-hyperon the quasiparticle energy depends on the square of the momentumk, the width of the spectral function is proportional tok ⁴ and the imaginary part of the self energy operator is proportional to (Ω-μ)^5/2 for Ω approaching the chemical potential μ.     

Das Spektrum der Bremsstrahlung eines 500 MeV-Elektronen-Synchrotrons

At the Bonn 500 MeV Electronsynchrotron the spectrum of the Bremsstrahlung has been investigated for several maximum-energies between 250 MeV and 450 MeV and under various angles to the axes of theγ-ray. The upper limit of the spectrum has been measured carefully in respect to later experiments with photon difference method. The absolute errors of 4.5% permitted a control of the quantameter calibration or the cross-section for electron pair production.     

Bestimmung des Abschirmtensors der magnetischen Kernresonanz und des Tensors der magnetischen Suszeptibilität durch numerische Berechnung der Stromdichte in der Ladungsverteilung diamagnetischer Moleküle

Determination of the NMR Shielding Tensor and of the Tensor of Magnetic Susceptibility by Numerical Calculation of the Current Density in the Chargedistribution of Diamagnetic Molecules In papers [1] and [2] a semiclassical approach for calculation of the NMR shielding tensor and of the tensor of magnetic susceptibility of diamagnetic molecules was represented by SCHMIEDEL. In this method the equation of continuity for the currents in the electronic cloud induced by an external magnetic field must be solved. In this paper a method of numerical solution of this partial differential equation is developed. The H₂-molecule serves as an example to present the possibilities of this method.     

Die Änderung der Elektronenstruktur des Nickels durch Wasserstoffbeladung

TheK-absorption spectrum of nickel charged with hydrogen has been investigated using a Bragg spectrograph with photographic registration. The fine structure of the absorption edge of the nickel hydride as compared with that of nickel shows that the electrons of the dissolved hydrogen fill up the empty 3d- and 4s-states of the conduction band of the metal.