Three-Body Halos. II. from Two- to Three-Body Asymptotics

The large distance behavior of weakly bound three-body systems is investigated. The Schr\"{o}dinger equation and the Faddeev equations are reformulated by an expansion in eigenfunctions of the angular part of a corresponding operator. The resulting coupled set of effective radial equations are then derived. Both two- and three-body asymptotic behavior are possible and their relative importance is studied for systems where subsystems may be bound. The system of two nucleons outside a core is studied numerically in detail and the character of possible halo structure is pointed out and investigated.Comment: 16 pages, compressed and uuencoded PosrScript file, IFA-94/3

A non trivial extension of the two-dimensional Ising model: the d-dimensional "molecular" model

A recently proposed molecular model is discussed as a non-trivial extension of the Ising model. For d=2 the two models are shown to be equivalent, while for d>2 the molecular model describes a peculiar second order transition from an isotropic high temperature phase to a low-dimensional anisotropic low temperature state. The general mean field analysis is compared with the results achieved by a variational Migdal-Kadanoff real space renormalization group method and by standard Monte Carlo sampling for d=3. By finite size scaling the critical exponent has been found to be 0.44\pm 0.02 thus establishing that the molecular model does not belong to the universality class of the Ising model for d>2.Comment: 25 pages, 5 figure

Three-body halos. V. Computations of continuum spectra for Borromean nuclei

We solve the coordinate space Faddeev equations in the continuum. We employ hyperspherical coordinates and provide analytical expressions allowing easy computation of the effective potentials at distances much larger than the ranges of the interactions where only s-waves in the different Jacobi coordinates couple. Realistic computations are carried out for the Borromean halo nuclei 6He (n+n+\alpha) for J\pi = 0+-, 1+-, 2+- and 11Li (n+n+9Li) for (1/2)+-, (3/2)+-, (5/2)+-. Ground state properties, strength functions, Coulomb dissociation cross sections, phase shifts, complex S-matrix poles are computed and compared to available experimental data. We find enhancements of the strength functions at low energies and a number of low-lying S-matrix poles.Comment: 35 pages, 14 figure

Zur Gitterdynamik von Chlor und Brom bei hohem Druck

With many refs.SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

EFFECT OF PRESSURE ON INTERMOLECULAR BONDS IN SOLID HALOGENS

Un modèle de charge liée a été développé pour décrire la variation avec la pression des phonons de centre de zone actifs en Raman de Cl, Br, et I. L'augmentation de la covalence des liaisons intermoléculaires se traduit par une augmentation de la charge liée avec la pression.A bond charge model has been developed for the description of the pressure dependence for the Raman-active zone centre phonon frequencies of Cl, Br and I. The increase in covalency of the intermolecular bonds shows up in increasing values of the bond charges under pressure

EFFECT OF PRESSURE ON RAMAN-SPECTRA OF SOLID HCl AND HBr

Des résultats de diffusion Raman sur HCl et HBr, à des températures de 100 à 250 K et des pressions jusqu'à 40 GPa sont présentés. Une nouvelle procédure de chargement avec ces produits réactifs est décrite. L'argon et l'azote sont utilisés comme milieux transmetteurs de pression. Dans HBr, une nouvelle phase a été détectée -probablement avec des liaisons hydrogène symétriques- à 100 K et à des pressions supérieures à 32 GPa.Raman data are presented for HCl and HBr at temperatures between 100 and 250 K and pressures up to 40 GPa. A new procedure is described for loading a DAC with these reactive materials. Argon and nitrogen are used as pressure media. A new phase, probably with symmetric hydrogen bonds, is detected in HBr at 100 K and pressures above 32 GPa

INFRARED AND RAMAN STUDIES ON VARIOUS PHASES OF ICE UNDER PRESSURES UP TO 53 GPa

Infrared absorption spectra are presented for ice VII and VIII for the spectral range between 80 and 10 000 cm-1. The charges in the spectral features are compared with earlier results from Raman measurements on ice VII, VIII and X up to 53 GPa (Hirsch and Holzapfel, 1986). Effects of pressure on the phase boundaries and on the hydrogen bonding will be discussed

Editorial: EADC (European Alzheimer Disease Consortium) Recommendations for Future Alzheimer Disease Research in Europe.

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