Splitting and structure of the giant quadrupole resonances in deformed nuclei

We have performed microscopic calculations of the low-lying and high-lying Kπ=0+, 1+, and 2+ states in deformed rare-earth nuclei. The centroids of the isoscalar giant quadrupole resonance in 160Dy, 170Yb, and 184W are at 11.58, 11.44, and 11.22 MeV, respectively. A broadening of these resonances due to the deformation is predicted which varies appreciably in the different nuclei. About 20% of the monopole strength is found in the same energy range

Isotopic dependence of nuclear charge radii and pairing energies

With a residual interaction consisting of density-independent two- and three-body parts, we obtain within Hartee-Fock-Bogolyubov theory at the same time good results on the odd-even staggering of charge radii and on trends of the pairing energies. We present results for Sn and some isotopic chains in the Ba region

Magnetic dipole strength functions in heavy deformed nuclei

The isovector spin-flip M1 strength function in the deformed heavy nuclei 156Gd and 238U is calculated in the quasiparticle random-phase approximation. Interaction parameters are adjusted to reproduce the energies of isobaric-analog and Gamow-Teller excitations observed in (p,n) charge-exchange reactions. A phenomenological spreading width for decay into background 2p2h states is introduced and adjusted to reproduce the M1 spin-flip strength function recently observed by elastic scattering of tagged photons on 90Zr and 208Pb. With the model parameters fixed in this fashion, our calculations predict large quantities of spin-flip M1 strength (10–20 µ2N) between 5 and 10 MeV excitation in 156Gd and 238U; it is strongly fragmented and should be observable by tagged-photon elastic scattering and proton inelastic scattering but probably not in high resolution inelastic electron scattering

Surface acoustic wave spectroscopy versus nanoindentation: Potentials and limits for coating characterization

Measuring mechanical film properties is essential for understanding and designing coating systems as well for controlling quality in coating manufacturing. Since more than two decades, two methods for determining Young’s modulus and other mechanical properties of thin films are widely used: The instrumented indentation technique (nanoindentation) and the laser-induced surface acoustic wave spectroscopy (LiSAWS). Due to their different physical principles, both methods address different fields of application but also complement each other. This presentation gives an overview for typical applications, strengths and limits for both methods from practical points of view like precision, requirements for sample material, preparation and test setup, additional results, standardization, and measuring time. Several examples for the application of both methods are discussed: • Hard protective coatings (deposited by PVD and thermal spraying) measured with both techniques • Films with less than 15 nm thickness • Effect of texture, microstructure and defects on measured propertie

The Nuclear Scissors Mode from Various Aspects

Three methods to describe collective motion, Random Phase Approximation (RPA), Wigner Function Moments (WFM) and the Green's Function (GF) method are compared in detail and their physical content analyzed on an example of a simple model, the harmonic oscillator with quadrupole--quadrupole residual interaction. It is shown that they give identical formulae for eigenfrequencies and transition probabilities of all collective excitations of the model, including the scissors mode, which is the subject of our special attention. The exact relation between the RPA and WFM variables and the respective dynamical equations is established. The transformation of the RPA spectrum into the one of WFM is explained. The very close connection of the WFM method with the GF one is demonstrated. The normalization factor of the ``synthetic'' scissors state and its overlap with physical states are calculated analytically. The orthogonality of the spurious state to all physical states is proved rigorously. A differential equation describing the current lines of RPA modes is established and the current lines of the scissors mode analyzed as a superposition of rotational and irrotational components.Comment: 52 pages, 2 figure

Injektionsgekoppelte diodengepumpte Nd:YAG- und Nd:YVO4-Laser für terrestrische interferometrische Gravitationswellendetektoren

[no abstract

The GEO 600 laser system

Interferometric gravitational wave detectors require high optical power, single frequency lasers with very good beam quality and high amplitude and frequency stability as well as high long-term reliability as input light source. For GEO 600 a laser system with these properties is realized by a stable planar, longitudinally pumped 12 W Nd:YAG rod laser which is injection-locked to a monolithic 800 mW Nd:YAG non-planar ring oscillator. Frequency control signals from the mode cleaners are fed to the actuators of the non-planar ring oscillator which determines the frequency stability of the system. The system power stabilization acts on the slave laser pump diodes which have the largest influence on the output power. In order to gain more output power, a combined Nd:YAGNd:YVO4 system is scaled to more than 22 W