Effects of Core-Hole Screening on Spin-Polarised Auger Spectra from Ferromagnetic Nickel

We calculate the spin- and temperature-dependent local density of states for ferromagnetic Ni in the presence of a core hole at a distinguished site in the lattice. Correlations among the valence electrons and between valence and core electrons are described within a multi-band Hubbard model which is treated by means of second-order perturbation theory around the Hartree-Fock solution. The core-hole potential causes strong screening effects in the Ni valence band. The local magnetic moment is found to be decreased by a factor 5-6. The consequences for the spin polarisation of CVV Auger electrons are discussed.Comment: LaTeX, 4 pages, 1 eps figure included, Acta Physica Polonica A (in press), Physics of Magnetism '99 (Poznan, Poland

Experimental investigation of ultrahigh vacuum adhesion as related to the lunar surface Quarterly progress report, 1 Apr. - 31 Jun. 1969

Electrical charge distribution in ultrahigh vacuum fracture and etching of silicates for lunar simulation studie

Specific heat of the simple-cubic Ising model

We provide an expression quantitatively describing the specific heat of the Ising model on the simple-cubic lattice in the critical region. This expression is based on finite-size scaling of numerical results obtained by means of a Monte Carlo method. It agrees satisfactorily with series expansions and with a set of experimental results. Our results include a determination of the universal amplitude ratio of the specific-heat divergences at both sides of the critical point.Comment: 20 pages, 3 figure

Microchemical, microphysical and adhesive properties of Apollo 11 and 12 Final report, 1 Aug. 1969 - 15 Mar. 1971

Gas exposure experiments of lunar soil with microchemical, microphysical, and adhesion analysi

Flow equations for QED in the light front dynamics

The method of flow equations is applied to QED on the light front. Requiring that the partical number conserving terms in the Hamiltonian are considered to be diagonal and the other terms off-diagonal an effective Hamiltonian is obtained which reduces the positronium problem to a two-particle problem, since the particle number violating contributions are eliminated. No infrared divergencies appear. The ultraviolet renormalization can be performed simultaneously.Comment: 15 pages, Latex, 3 pictures, Submitted to Phys.Rev.

The WARPS survey - IV: The X-ray luminosity-temperature relation of high redshift galaxy clusters

We present a measurement of the cluster X-ray luminosity-temperature relation out to high redshift (z~0.8). Combined ROSAT PSPC spectra of 91 galaxy clusters detected in the Wide Angle ROSAT Pointed Survey (WARPS) are simultaneously fit in redshift and luminosity bins. The resulting temperature and luminosity measurements of these bins, which occupy a region of the high redshift L-T relation not previously sampled, are compared to existing measurements at low redshift in order to constrain the evolution of the L-T relation. We find a best fit to low redshift (z1 keV, to be L proportional to T^(3.15\pm0.06). Our data are consistent with no evolution in the normalisation of the L-T relation up to z~0.8. Combining our results with ASCA measurements taken from the literature, we find eta=0.19\pm0.38 (for Omega_0=1, with 1 sigma errors) where L_Bol is proportional to (1 + z)^eta T^3.15, or eta=0.60\pm0.38 for Omega_0=0.3. This lack of evolution is considered in terms of the entropy-driven evolution of clusters. Further implications for cosmological constraints are also discussed.Comment: 11 pages, 7 figures, accepted for publication in MNRA

An Overabundance of Transient X-ray Binaries within 1 pc of the Galactic Center

During five years of Chandra observations, we have identified seven X-ray transients located within 23 pc of Sgr A*. These sources each vary in luminosity by more than a factor of 10, and have peak X-ray luminosities greater than 5e33 erg/s, which strongly suggests that they are accreting black holes or neutron stars. The peak luminosities of the transients are intermediate between those typically considered outburst and quiescence for X-ray binaries. Remarkably four of these transients lie within only 1 pc of Sgr A*. This implies that, compared to the numbers of similar systems located between 1 and 23 pc, transients are over-abundant by a factor of 20 per unit stellar mass within 1 pc of Sgr A*. It is likely that the excess transient X-ray sources are low-mass X-ray binaries that were produced, as in the cores of globular clusters, by three-body interactions between binary star systems and either black holes or neutron stars that have been concentrated in the central parsec through dynamical friction. Alternatively, they could be high-mass X-ray binaries that formed among the young stars that are present in the central parsec.Comment: 4 pages, including 2 figures (one color). Submitted to ApJ Letter