The decay of the gravitational field

The asymptotic behaviour of Einstein-Rosen waves, a class of nonstationary solutions of Einstein's vacuum equations, is investigated. It is established that solutions of this type exist which admit part ofI ⁺ and a regularI ⁺ in the sense of Penrose.     

Optical measurements of stress distributions in GaAs at low temperature

We have measured the stress distribution at He temperature on two epitaxial GaAs wafers which were compressed along one edge. The stress was determined non-destructively at different points on the wafer surface by using the line-splitting and the lineshifts of the photoluminescence spectra of the acceptor-bound excitons in comparison with calibration spectra at known uniaxial stress.     

Oxygen dissociation relaxation behind oblique shocks

Nearly frozen oxygen dissociation relaxation has been investigated behind oblique shocks. Photographs of the shock have been taken and density profiles of the relaxation zones have been measured by means of a multibeam-laser-differential interferometer. Calculations of the relaxation zones with different published dissociation rate coefficients have been done for evaluating the experiments.     

Kinematically complete measurement of the absorption of stopped pions in 3He

The reactions π^?3He → nnp and π^?3He → nd have been measured in a kinematically complete experiment with stopped pions. The results show strong preference for collinear events. About three quarters of all absorption processes occur as quasi-free absorption on np- or pp-pairs with a ratio of R = 10.1 ± 1.5. The remaining quarter shows energy sharing among all three nucleons and is located in the final-state interaction regions. Branching ratios for all observed final states are given.     

Buchbesprechungen

Ohne Zusammenfassung     

Particle clustering and Mott transitions in hot nuclear matter at finite temperature: (III). Heavy cluster abundances and coulomb interaction

The properties of hot nuclear matter are calculated by considering the Coulomb interaction in a Debye-Thomas-Fermi approach. It is shown that the inclusion of the Coulomb forces implies a decrease of the cluster bound-state energy and a lowering of the nuclear density at the cluster surface. The Coulomb interaction together with consideration of the in-medium corrections leads to significant modification of the abundances of larger clusters compared with the frequently used law-of-mass-action approach.