Anomalous Mass Research Articles

Massive binaries as the source of abundance anomalies in globular clusters

Abundance anomalies observed in globular cluster stars indicate pollution with material processed by hydrogen burning. Two main sources have been suggested: asymptotic giant branch (AGB) stars and massive stars rotating near the break-up limit (spin stars). We propose massive binaries as an alternative source. We compute the evolution of a 20 Msun star in a close binary and find that it sheds about 10 Msun. The ejecta are enriched in He, N, Na, and Al and depleted in C and O, similar to the abundance patterns observed in gobular cluster stars. In contrast to the fast, radiatively driven winds of massive stars, this material is typically ejected with low velocity. We expect that it remains inside the potential well of a globular cluster and becomes available for the formation or pollution of a second generation of stars. We estimate that the amount of processed low-velocity material ejected by massive binaries is greater than the contribution of AGB stars and spin stars combined, assuming that the majority of massive stars in a proto-globular cluster interact. If we take the possible contribution of intermediate mass stars in binaries into account and assume that the ejecta are diluted with an equal amount of unprocessed material, we find that this scenario can provide enough material to form a second generation of low-mass stars, which is as numerous as the first generation of low-mass stars. In this scenario there is no need to make commonly adopted assumptions, such as preferential loss of the first generation of stars, external pollution of the cluster, or an anomalous initial mass function. [Abridged]

Specifics of the detonation of mixtures of powerful high explosives with W and Pb high-density inert additives

Results of experimental and theoretical studies of the unusual detonation properties of mixtures of high explosives (HEs) with high-density inert additives (W and Pb) were analyzed and systematized. Typical examples of the nonideal detonation of composite explosives for which the measured detonation pressure is substantially lower while the detonation velocity is higher than the values calculated within the framework of the hydrodynamic model, with the specific heat ratio for the detonation products being ∼6–8, are presented. Mathematical models capable of qualitatively and quantitatively describing the specificity of the propagation of detonation in HE-W mixtures. Mechanisms of formation of anomalous pressure and mass velocity profiles, which explain why the correlation between the Chapman-Jouguet pressure for HE-W and HE-Pb mixtures, the velocity of the free surface of duralumin target, and the depth of the dent imprinted in steel witness plates, are described.

Hot subdwarfs from the stable Roche lobe overflow channel

In this study, we concentrate on the formation and evolution of hot subdwarfs binaries through the stable Roche lobe overflow (RLOF) channel of intermediate-mass binaries. We aim at setting out the properties of hot subdwarfs and their progenitors, so that we can understand the formation and evolution of hot subdwarfs comprehensively. We have obtained the ranges of the initial parameters of progenitor binaries and the properties of hot subdwarfs through the stable RLOF channel of intermediate-mass binaries, e.g. mass, envelope mass and age of hot subdwarfs. We have found that hot subdwarfs could be formed through the stable Roche lobe overflow at main sequence and Hertzsprung gap. We have also found that some subdwarf B or OB stars have anomalous high mass (around 1 solar mass) with thick envelope (0.07 solar mass to 0.16 solar mass) in our models. By comparing our theoretical results with observations on the hot subdwarfs in open clusters, we suppose a quantity of hot subdwarfs in binary systems might be found in open clusters in the future.

On features of metal and binary compound sputtering by low-energy ions

Molecular dynamic simulation has been used to study how the characteristics of metal and binary compound sputtering change under the bombardment by different low-energy ions. The influence of the target parameters on the anomalous mass dependence of sputtering yield has been investigated, both for targets with similar and very different values of density, the lattice constant and the surface binding energy. Together with the ratio of the target atoms’ mass to the mass of the ions, the density of the target and the binding energy turn out to be the important parameters that determine the unusual shape of the mass dependence of sputtering by low-energy ions.

Application of Fractional Differential Equations for Modeling the Anomalous Diffusion of Contaminant from Fracture into Porous Rock Matrix with Bordering Alteration Zone

Solute diffusion from a fracture into a porous rock with an altered zone bordering the fracture is modeled by a system of two diffusion equations (one for the altered zone and another for the intact porous matrix) with different coefficients of effective diffusivity. Since experimental studies of diffusion into rock samples with altered zones indicate that mathematical models of diffusion based on Fick’s law do not adequately describe the concentration field in a sample, fractional order diffusion equations are chosen in this study for modeling the anomalous mass transport in the rocks. In the case of significantly higher porosity of the altered zone (e.g., this is typical for carbonates) the effective diffusivity here can be much higher than the effective diffusivity of non-altered rocks. By introducing a small parameter that is the ratio of effective diffusivities in the non-altered and altered regions and applying the technique of perturbations, approximate analytical solutions for concentrations in the altered zone bordering the fracture and in the intact surrounding rocks are obtained. Based on these solutions, different regimes of diffusion into the rocks with different physical properties are modeled and analyzed. It is shown that, using experimentally obtained data, the orders of the fractional derivatives in the differential equations can be readily calibrated for the every specific rock.

Meandarra Gravity Ridge: symmetry elements of the gravity anomaly and its relationship to the Bowen–Gunnedah–Sydney basin system

The Meandarra Gravity Ridge is one of the major gravity features in eastern Australia. The source(s) for this gravity anomaly is problematic because the ridge, a gravity high, coincides for much of its length with the thickest parts of the Bowen and Gunnedah Basins, areas that would normally be expected to be regional gravity lows. Furthermore, the Meandarra Gravity Ridge is continuous across numerous structural elements and regional terranes, and there is no obvious expression of its source in the surface geology. Construction of a series of gravity profiles across the Meandarra Gravity Ridge in this study has provided detailed analyses of changes in the size and shape of the Bouguer anomaly along the ridge axis. These data suggest that the ridge is composed of a series of offset colinear anomalies, and demonstrate that the magnitude and symmetry of the Bouguer anomaly are different for each segment of the ridge. 3D-mesh diagrams of the total-field Bouguer gravity illustrate that the ridge may be subdivided into at least five segments, each of which is characterised by particular gravity values and shapes for the anomaly profile. 2D gravity modelling of selected Bouguer anomaly profiles suggests that the source for the Meandarra Gravity Ridge anomaly is a dense mafic body in the upper crust. This source has a preferred density contrast of +0.25 tm−3, and probably consists of a pile of mafic volcanics up to 9 km thick. The size and geometry of the modelled anomalous mass supports a rift-type origin for the source of the Meandarra Gravity Ridge. Our modelling predicts that the magnitude and symmetry of the Meandarra Gravity Ridge gravity anomaly are controlled by the geometry of an underlying mafic source and not by interference effects due to density contrasts between sedimentary and metamorphic rocks of adjacent orogens.

Constraints on the location, magnitude, and dimensions of Ganymede's mass anomalies

Previously, radio Doppler data, generated with NASA's Galileo spacecraft during its second encounter with Jupiter's moon Ganymede, were used to infer the locations and magnitudes of mass anomalies on Ganymede using point-mass models. However, the point-mass solutions do not provide the vertical and horizontal extent of the anomalous mass concentrations. Here, we provide the results of a new study using spherical cap disks to model Ganymede's mass anomalies. The spherical cap disk models not only provide the locations and magnitudes of the mass anomalies, but also their vertical and horizontal dimensions. The new models show that three disks, a positive mass located at (53.0° N, 127.0° W) and two negative masses located at (22.0° N, 87.0° W) and (49.0° N, 219.0° W), can explain the data. The magnitudes of the mass anomalies are on the order of 10 18 kg. The diameters of the anomalies are a few thousand kilometers. The positive anomaly is about 100 meters thick and both negative anomalies have a thickness of less than a kilometer. We use the additional information provided by the disk models to investigate the viability of mass anomalies at Ganymede's surface by comparing the diameters of the anomalies to the sizes of regiones and sulci and the anomalies' thicknesses to accumulated layers of rock and clean ice on the surface. We find that the dimensions of the mass anomalies could be explained by concentrations of rock in the regio and rock-free ice in the sulci. These results confirm that mass anomalies may reside on or near Ganymede's surface and that positive mass anomalies are contained within areas of dark terrain and negative mass anomalies within bright terrain.

Possible Measurable Effects of Dark Energy in Rotating Superconductors

We discuss recent laboratory experiments with rotating superconductors and show that three so far unexplained experimentally observed effects (anomalous acceleration signals, anomalous gyroscope signals, Cooper pair mass excess) can be physically explained in terms of a possible interaction of dark energy with Cooper pairs. Our approach is based on a Ginzburg-Landau-like model of electromagnetic dark energy, where gravitationally active photons obtain mass in the superconductor. We show that this model can account simultaneously for the anomalous acceleration and anomalous gravitomagnetic fields around rotating superconductors measured by Tajmar et al. and for the anomalous Cooper pair mass in superconductive Niobium, measured by Cabrera and Tate. It is argued that these three different physical effects are ultimately different experimental manifestations of the simultaneous spontaneous breaking of gauge invariance and of the principle of general covariance in superconductive materials.

Quantized electronic structure and growth of Pb films on highly oriented pyrolytic graphite

We have measured the electronic structure of thin Pb films grown on highly oriented pyrolytic graphite (HOPG) by angle-resolved photoemission spectroscopy. Quantum well states (QWSs) corresponding to confined Pb valence electrons are observed. Their energy positions are fixed, but their intensities evolve for increasing Pb coverages. The results indicate that the films are rough, consisting of multiple thicknesses. Nevertheless, the thickness distribution is sufficiently narrow to allow a unique assignment for each QWS peak in terms of a quantum number and the exact film thickness in atomic layers. For increasing Pb coverages of up to 10 monolayers (ML), the even film thicknesses of 2, 4, 6, 8, and 10 ML are much more prevalent than the odd film thicknesses of 1, 3, 5, 7, and 9 ML, thus suggesting significant differences in surface energy between the even and odd thicknesses. These results are consistent with an available first-principles calculation of the surface energies of freestanding films; an implication is that the interaction between the Pb film and the HOPG substrate is weak. The in-plane dispersion relations of the QWSs are measured. The effective masses at the surface zone center agree well with the results calculated from the bulk Pb band structure, in sharp contrast to the strongly enhanced or anomalous effective masses in Pb films grown on Si(111) as reported previously. This finding indicates that the anomalous effective masses in Pb/Si(111) are not caused by increased electron correlation effects in a confined geometry, but are rather attributable to a strong interfacial interaction between the QWSs and the substrate electronic structure.

Anomalous Mass Transport in the Pb Wetting Layer on the Si(111) Surface

The temporal evolution of nonequilibrium coverage profiles in the Pb wetting layer on the Si(111) surface is studied using low energy electron microscopy. The initial coverage step profile propagates rapidly at a constant velocity with an unperturbed shape. A model is proposed that attributes this nonclassical equilibration behavior to the diffusion of thermally generated adatoms on top of the wetting layer. This model can account for the observed convectionlike mass transport, as well as its dramatic dependence on Pb coverage. Such anomalous mass transport is believed to facilitate the remarkably efficient self-organization of uniform Pb quantum island height on the Si(111) surface that was observed previously.

Metric fluctuations and the weak equivalence principle

We describe spacetime fluctuations by means of small fluctuations of the metric on a given background metric. From a minimally coupled Klein–Gordon equation we obtain a modified Schrödinger equation within a weak-field approximation up to second order and an averaging procedure over a finite spacetime scale given by the quantum particle in the nonrelativistic limit. The dominant modification consists of an anomalous inertial mass tensor which depends on the type of particle and the fluctuation scenario. The scenario considered in this paper is a most simple picture of spacetime fluctuations and gives an existence proof for an apparent violation of the weak equivalence principle and, in general, for a violation of Lorentz invariance.

Modeling of Copper SIMS Profiles in Thin HgCdTe

Anomalous secondary-ion mass spectroscopy (SIMS) profiles of copper in thin pieces of HgCdTe are explained using the model used for diode formation by ion milling and ion implantation. In this model, the SIMS ion beam injects mercury interstitials into the HgCdTe as it etches the HgCdTe. The interstitials fill metal vacancies and kick copper off the metal lattice sites. The copper interstitials then diffuse either to the surface being etched, where it is removed and detected by the SIMS instrument, or deeper into the HgCdTe, where it annihilates vacancies. Good agreement between model predictions and experimental SIMS profiles are obtained.

Behavior of the mass transfer coefficient during the MADE‐2 experiment: New insights

Using a dual‐porosity transport model, a more complete analysis of the MADE‐2 experiment, a natural gradient tracer (tritium) test, is presented. Results show that a first‐order, mass transfer rate coefficient is scale‐dependent and decreasing with experiment duration. This is in agreement with previous studies and predictions. Factors contributing to the scale‐dependency are errors or approximations in boundary conditions, hydraulic conductivity (K) measurements and interpolations, mass transfer rate expressions and conceptual errors in model development. In order to formulate a self‐consistent, dual‐porosity model, it was necessary to assume that the injected tracer was trapped hydraulically in the vicinity of the injection site. This was accomplished by lowering all K values near the injection site by a factor of 30, while holding all other K values, boundary conditions and parameters at their measured or estimated magnitudes. Resulting simulations, using the same scale‐dependent mass transfer rate coefficient, were then able to reasonably match the movement of the center of mass, overall plume geometry and the anomalous mass recovery ratios observed at each snapshot. The dual‐porosity model is conceptually simple, relatively easy to apply mathematically and it simulates differences in advection that are probably the root cause of dispersion in natural heterogeneous sediments. Also, a small more realistic amount of local hydrodynamic dispersion is not precluded.

GRAVITOELECTROMAGNETISM AND DARK ENERGY IN SUPERCONDUCTORS

A gravitomagnetic analog of the London moment in superconductors could explain the anomalous Cooper pair mass excess reported by Janet Tate. Ultimately the gravitomagnetic London moment is attributed to the breaking of the principle of general covariance in superconductors. This naturally implies nonconservation of classical energy–momentum. A possible relation with the manifestation of dark energy in superconductors is questioned.

Anomalies of the external and internal gravitational fields of the Earth’s isostatically balanced crust in the quadratic approximation

Formulas that include the contribution from dipole-distributed anomalous masses represented as layers distributed in height relative to the reference ellipsoid to the gravitational field in the quadratic approximation have been derived. The relationships between the expansion coefficients of some function and its square in terms of spherical functions have been established. The contribution from the relief masses and the density jump at the Mohorovicic discontinuity is used to illustrate the results.

Anomalies of an external and internal gravitational field of upper Earth layers in square law approximation

The explicit form for the quadratic contribution to the gravitational field from the dipole distributed anomalous masses is found. The anomalous masses are represented in the form of layers of variable height, arranged relative to the reference ellipsoid. The solution is reduced to the mathematical problem of finding an expression for the coefficients of expansion in terms of spherical harmonics of the square of any function that can be presented as a finite series of spherical harmonics, in terms of the coefficients of this initial series. The formulas have been calculated using mathematical modelling of symbol computation using computer algebra packages. The results obtained are illustrated using the example of the contribution from relief masses and density jumps on the Mohorovicic (Moho) discontinuity.

Gravity anomalies in the Earth's crust and upper mantle

The contribution to the Earth external and internal gravity field from isostatically equilibrated masses of relief, density jumps on Moho boundary and anomalous masses of crust and upper mantle of the Earth in linear and quadratic approximation is found. Significant gravity anomalies are revealed in isostatically equilibrated crust and mantle, which can lead to gravitational and dynamic instability. The deviation of the external field of the Earth in isostatic equilibrium from observations demonstrates the disturbance of isostatic equilibrium in Earth.

Anomalous strain dependent effective masses in (111) Si nanowires

First-principles methods are employed to investigate the effect of strain on the carrier effective masses in (111) Si nanowires (SiNWs). It is found that the electron effective masses of SiNWs depend strongly on the applied axial strain. Within a certain range of strain, the electron effective masses are significantly enhanced. Most remarkably, the electron effective masses are anomalous and become infinity at a critical point of strain. This effect is associated with how strain changes the band structure with a single minimum to that with double minima or vice versa. The hole effective masses, on the other hand, decrease with the increase of the tensile strain, as a result of the strain-induced band energy shift in the vicinity of the valence band maximum. It is also shown that the band gaps of SiNWs with diameters ⩾1.16nm increase with the increase of the tensile strain. The tunability of the effective masses and band gaps with strain would be useful in tailoring the transport properties of SiNWs.

Electrodeposition of Ni–Co–Cu/Cu multilayers: 2. Calculations of the element distribution and experimental depth profile analysis

It has long been known that a concentration gradient can develop in electrodeposits along the growth direction as a result of the combined impact of anomalous codeposition and mass trasnport limitation of the reactants. It is shown in the present paper that this composition change in electrodeposited Co–Ni–Cu/Cu multilayers can be verified by secondary neutral mass spectrometry (SNMS). Various electrodeposited samples have been analyzed and the resulting composition profiles have been compared to the calculation based on the non-destructive analysis of the overall composition. The change of the Co:Ni ratio in the magnetic layer along the growth direction has been verified. A calculation method has been proposed by which the local composition of the magnetic layer can be estimated from the thickness dependence of the overall multilayer composition. It has also been shown that the deviation of the experimental depth profile data from the estimation based on the variation of the total composition with the Co–Ni–Cu layer thickness can be ascribed to the roughness increase during the sputtering in the SNMS instrument.

Structures in the gauge/gravity duality cascade

We study corrections to the anomalous mass dimension and their effects in the Seiberg duality cascade in the Klebanov-Strassler throat, where $\mathcal{N}=1$ supersymmetric $SU(N+M)\times SU(N)$ gauge theory with bifundamental chiral superfields and a quartic tree level superpotential in four dimensions is dual to type IIB string theory on $AdS_5 \times T^{1,1}$ background. Analyzing the renormalization group flow of the couplings on the gauge theory side, we propose specific corrections to the anomalous mass dimension. Applying gauge/gravity duality, we then show that the corrections reveal structures on the supergravity side with steps appearing in the running of the fluxes and the metric. The "charges" at the steps provide a gravitational source for Seiberg duality transformations. The finiteness of these corrections suggests that the theory flows to a baryonic branch rather than to a confining branch. The cosmological implication of the duality cascade and the gauge/gravity duality on the brane inflationary scenario and the cosmic microwave background radiation is pointed out.