Temperature and Magnetic Field Dependencies in a Model of Diamagnetic Hysteresis in Beryllium

The model of diamagnetic hysteresis loop of strongly correlated electron gas at the conditions of dHvA effect is developed. It is shown, that in the framework of Rayleigh theory for magnetization loop, the coercive force and remnant magnetization in every period of dHvA oscillations are characterized by strong dependencies on temperature, magnetic field and Dingle temperature.Comment: 7 pages, 4 figure

X-ray bursters and the X-ray sources of the galactic bulge

Type 1 X-ray bursts, optical, infrared, and radio properties of the galactic bulge sources, are discussed. It was proven that these burst sources are neutron stars in low mass, close binary stellar systems. Several burst sources are found in globular clusters with high central densities. Optical type 1 X-ray bursts were observed from three sources. Type 2 X-ray bursts, observed from the Rapid Burster, are due to an accretion instability which converts gravitational potential energy into heat and radiation, which makes them of a fundamentally different nature from Type 1 bursts

Tightly Correlated X-ray/Hα\alpha Emitting Filaments in the Superbubble and Large-Scale Superwind of NGC 3079

Using Chandra and HST we show that X-ray and H$\alpha$ filaments that form the 1.3-kpc diameter superbubble of NGC 3079 have strikingly similar patterns at 0."8 resolution. This tight match seems to arise from cool disk gas that has been driven by the wind, with X-rays being emitted from upstream, stand-off bowshocks or by conductive cooling at the cloud/wind interfaces. We find that the soft X-ray plasma has thermal and kinetic energies of $2\times10^{56}\sqrt{\eta_x}$ and $5\times10^{54}\sqrt{\eta_X}$ erg respectively, where $\eta_X$ is the filling factor of the X-ray gas and may be small; these are comparable to the energies of the optical line-emitting gas. X-rays are also seen from the base of the radio counterbubble that is obscured optically by the galaxy disk, and from the nucleus (whose spectrum shows the Fe K$\alpha$ line). Hydrodynamical simulations reproduce the obbservations well using large filling factors within both filament systems; assuming otherwise seriously underestimates the mass loss in the superwind. The superbubble is surrounded by a fainter conical halo of X-rays that fill the area delineated by high angle, H$\alpha$-emitting filaments, supporting our previous assertion that these filaments form the contact discontinuity/shock between galaxy gas and shocked wind. About 40\arcsec (3 kpc) above the disk, an X-ray arc may partially close beyond the bubble, but the north-east quadrant remains open, consistent with the superwind having broken out into at least the galaxy halo.Comment: 8 pages, 3 figures, to appear in Sept. 10 Ap

Hysteresis in the de Haas-van Alphen Effect

A hysteresis loop is observed for the first time in the de Haas-van Alphen (dHvA) effect of beryllium at low temperatures and quantizing magnetic field applied parallel to the hexagonal axis of the single crystal. The irreversible behavior of the magnetization occurs at the paramagnetic part of the dHvA period in conditions of Condon domain formation arising by strong enough dHvA amplitude. The resulting extremely nonlinear response to a very small modulation field offers the possibility to find in a simple way the Condon domain phase diagram. From a harmonic analysis, the shape and size of the hysteresis loop is constructed.Comment: 4 pages, 5 figures, submitted to PR

Implementing generalized deep-copy in MPI

In this paper we introduce a framework for implementing deep copy on top of MPI. The process is initiated by passing just the root object of the dynamic data structure. Our framework takes care of all pointer traversal, communication, copying and reconstruction on receiving nodes. The benefit of our approach is that MPI users can deep copy complex dynamic data structures without the need to write bespoke communication or serialize / deserialize methods for each object. These methods can present a challenging implementation problem that can quickly become unwieldy to maintain when working with complex structured data. This paper demonstrates our generic implementation, which encapsulates both approaches. We analyze the approach with a variety of structures (trees, graphs (including complete graphs) and rings) and demonstrate that it performs comparably to hand written implementations, using a vastly simplified programming interface. We make the source code available completely as a convenient header file

Direct Observation of Condon Domains in Silver by Hall Probes

Using a set of micro Hall probes for the detection of the local induction, the inhomogeneous Condon domain structure has been directly observed at the surface of a pure silver single crystal under strong Landau quantization in magnetic fields up to 10 T. The inhomogeneous induction occurs in the theoretically predicted part of the H-T Condon domain phase diagram. Information about size, shape and orientation of the domains is obtained by analyzing Hall probes placed along and across the long sample axis and by tilting the sample. On a beryllium surface the induction inhomogeneity is almost absent although the expected induction splitting here is at least ten times higher than in silver.Comment: 4 pages, 6 figures, submitted to PR

An experimental investigation and evaluation of a Doppler radar technique for the measurement of the flow generated by wing tip vortices Final summary report

Doppler radar measurements of flow generated by wing tip vortices using reflective chaff dispensed into vortice