Gravimagnetism,causality, and aberration of gravity in the gravitational light-ray deflection experiments

Experimental verification of the existence of gravimagnetic fields generated by currents of matter is important for a complete understanding and formulation of gravitational physics. Although the rotational (intrinsic) gravimagnetic field has been extensively studied and is now being measured by the Gravity Probe B, the extrinsic gravimagnetic field generated by the translational current of matter is less well studied. The present paper uses the post-Newtonian parametrized Einstein and light geodesics equations to show that the extrinsic gravimagnetic field generated by the translational current of matter can be measured by observing the relativistic time delay and/or light deflection caused by the moving mass. We prove that the extrinsic gravimagnetic field is generated by the relativistic effect of the aberration of the gravity force caused by the Lorentz transformation of the metric tensor and the Levi–Civita connection. We show that the Lorentz transformation of the gravity field variables is equivalent to the technique of the retarded Lienard–Wiechert gravitational potentials predicting that a light particle is deflected by gravitational field of a moving body from its retarded position so that both general-relativistic phenomena—the aberration and the retardation of gravity—are tightly connected and observing the aberration of gravity proves that gravity has a causal nature. We explain in this framework the 2002 deflection experiment of a quasar by Jupiter where the aberration of gravity from its orbital motion was measured with accuracy 20%. We describe a theory of VLBI experiment to measure the gravitational deflection of radio waves from a quasar by the Sun, as viewed by a moving observer from the geocentric frame, to improve the measurement accuracy of the aberration of gravity to a few percent.     

Monolayer deposition of L10 FePt nanoparticles via electrospray route

The deposition monolayers of L1₀ FePt nanoparticles via an electrospraying method and the magnetic properties of the deposited film were studied. FePt nanoparticles in a size of around 2.5 nm in diameter, prepared by a liquid process, were used as a precursor. The size of the deposited particles can be controlled up to 35 nm by controlling the sprayed droplet size that is formed by adjusting the precursor concentration and the precursor flow rate. The droplets were heated in a tubular furnace at a temperature of up to 900 °C to remove all organic compounds and to transform the FePt particles from disordered face centered cubic to an ordered FCT phase. Finally, the particles were deposited in the form of a monolayer film on a silicon substrate by electrostatic force and characterized by scanning electron microscopy. The monolayer of particles was obtained by the high charge on particles obtained during the electrospraying process. The magnetic properties of the monolayer were investigated by magneto-optic Kerr effect measurements. Coercivity up to 650 Oe for a film consisting of 35 nm L1₀ FePt nanoparticles was observed after heat treatment at a temperature of 800 °C.     

Synthesis,growth and characterization of l-asparagine cadmium bromide: A novel semiorganic nonlinear optical single crystal

Single crystal of l-asparagine cadmium bromide (LACB), a semiorganic nonlinear optical material was grown by solution growth method at the room temperature. The grown crystals were characterized by single crystal and powder X-ray diffraction analysis and it was found to be the structure of the crystal was belongs to orthorhombic system. The UV–vis–NIR spectroscopic study revealed that the crystal has good optical transparency and lower cut off wavelength was found to be 230 nm. The presence of functional group was identified by Fourier transform infrared (FTIR) analysis. The chemical composition was confirmed by elemental analysis. The mechanical strength was studied and found to be 100 g by using Vicker's micro hardness tester. The thermal stability was found to be 218 °C by using TGA and DTA analysis. The second harmonic generation efficiency was carried out by using Kurtz–Perry powder technique and it was found to be 3.4 times higher than KDP crystal.     

A selection rule for K-harmonics for H and He

Wave functions for ³H and ⁴He are formed by combining K-harmonics of definite permutation symmetry with spin-isospin functions of adjoint symmetry. Applying Young operators to K-harmonics formed by vector coupling gives the required symmetrized functions, which are then expressed as linear combinations of the vector-coupled K-harmonics to allow potential matrix elements to be written down by techniques used in shell-model calculations. Explicit formulas are given for central and tensor potentials. Results obtained by other authors suggest that for convergence expansions in K-harmonics should be taken to about K = 8, so that some selection of states is essential. A rule used previously in variational calculations is to take only those states coupled by the potential to the zeroth approximation (K = 0). The form obtained here for the matrix elements and some properties of Young operators lead to a method of constructing these states.     

In-situ and ex-situ study of crystallization behaviour of magnetron sputtered Ni63Zr37 amorphous thin film

ABSTRACT

The stages of crystallization of magnetron sputter-deposited Ni₆₃Zr₃₇ film with mostly amorphous structure have been investigated by differential scanning calorimetry (DSC) and in-situ annealing at 300°C by use of heating stage on a high-resolution transmission electron microscope (HRTEM). These results have been further confirmed by grazing incidence X-ray diffraction analyses of thin film specimens annealed ex-situ at 300°C for various durations. The temperature for crystallization found by DSC has been found to increase from 371°C to 434°C with an increase in heating rate from 3°C/min to 10°C/min, and the apparent activation energy for amorphous to crystalline transformation has been found as ～260.2?kJ/mol from the Kissinger plot. Studies on HRTEM using in-situ heating stage have shown the crystallization to occur on annealing at 300°C for ～10?min. Crystallization at a temperature lower than that found by DSC is attributed to structural relaxation with reduction of free volume due to thermal activation. It has been observed that Ni₃Zr forms first due to its large negative enthalpy of formation, and is followed by the formation of Ni-rich solid solution (Ni_ss) grains. HRTEM studies have shown grain rotation with the formation of partial dislocations at Ni₃Zr-Ni_ss interfaces as well as twinning followed by detwinning with dislocation formation in the Ni_ss matrix possibly to reduce the interfacial energy.     

La/B4C small period multilayer interferential mirror for the analysis of boron

An La/B₄C multilayer interferential mirror with small period d (4.8 nm) was produced by diode sputtering for the detection of the boron K emission by wavelength‐dispersive x‐ray spectrometry at a large Bragg angle (close to 45°). The structure of the mirror was characterized by grazing incidence x‐ray reflectometry and its performance at the energy of the boron K emission (183 eV) was evaluated by means of polarized synchrotron radiation. Spectrometric measurements showed that the La/B₄C mirror improved the detection limit of boron using by a factor of 2 with respect to similar Mo/B₄C mirrors and by a factor of 4 with respect to a lead stearate crystal. Copyright © 2005 John Wiley & Sons, Ltd.     

Combined SIMS,AES, and XPS investigations of tantalum oxide layers

Thick layers of tantalum oxide prepared by thermal and anodic oxidation have been studied by combined SIMS, AES, and XPS during depth profiling by 3keV Ar⁺ ion sputtering. The chemical composition of these films is revealed by the OKLL and O 1s signals and by the “lattice valence” parameter determined from the TaO _n ^± intensities. Thus the anodic film consists of a contamination layer, an oxygen-rich reactive interface and a thick homogeneous oxide layer followed by an interface to the Ta metal. The thermal oxide shows an oxygen concentration decreasing with depth and a broad oxide-metal interface. In both cases, carbon contamination (carbide) prevents the application of the valence model to the clean Ta substrate. The sputtering yield of the oxides was found to be 0.6 Ta₂O₅/ion.     

Hole-phonon scattering in zinc doped GaSb

The phonon thermal conductivity values in Zn-doped GaSb are explained for hole concentrations ranging from 2 × 10¹⁷ to 4 × 10¹⁹ cm^-3. The concentration dependence of thermal conductivity above 3 × 10¹⁸ cm^-3 is similar to other doped materials and is explained by considering the scattering of phonons by free electrons (holes) given by Ziman and Kosarev and applying the screening effects suggested by Crossby and Grenier. The density-of-states effective mass is kept constant and the dilatation deformation potential is found to increase with hole concentration. For impurity concentrations less than 3 × 10¹⁸ cm^-3, the thermal conductivity is found to increase with hole concentration. Since this concentration region is below the metal-insulator transition, the theory of scattering of phonons by holes bound to the impurity atoms explains the conductivity results. The values of acceptor hole radius and deformation potential constants are in agreement with the experimental values.     

Assessing the discomfort of dual-axis whole-body vibration

This paper reports on an experiment designed to provide information fundamental to the prediction of the discomfort of multi-axis vibration. Seated subjects were exposed to various level and phase combinations of 3·15 Hz vertical (a_z) and 3·15 Hz lateral (a_y) sinusoidal vibration. One part of the experiment determined the levels of two single-axis vibrations (a_zanda_y separately) which produced similar discomfort to a selection of dual-axis vibrations. In another part of the experiment subjects adjusted the level of a 3·15 Hz motion in one of the two axes to produced similar discomfort to each of seven levels of the same frequency in the other axis.It was concluded that for dual-axis motions of the type investigated the discomfort is not greatly influenced by the phase between the two single-axis components producing the motion. Thus, the discomfort caused by the circular motion given by the combinations of the two sinusoidal components differing in phase by 90 degrees is similar to that caused by the translational motion produced by the same components combined with zero phase shift. The results confirm that a meaningful estimate of the relative discomfort produced by dual-axis stimuli can be determined from the levels of a single-axis reference motion appropriately adjusted by subjects. The level of a single-axis motion giving similar discomfort to each of the dual-axis conditions in the experiment was well approximated by the root-mean-square of the two levels of this single-axis motion equivalent to the two separate components of each dual-axis motion.     

Nitrogen bonding in aluminum oxynitride films

Assignment of oxidation states of N_1s in XPS spectra of aluminum oxynitride by curve fitting is difficult. The XPS curve fitting was previously discussed in the paper published in J. Non-Cryst. Solids, 224 (1998) 31, in which O_1s photoelectrons from GeO₂ glass were used to illustrate how to fit the XPS spectra. Three different ways were pointed out to eliminate the ambiguity caused by curve fitting such as comparing the data to data from standard samples, investigating the continuous surface modifications caused by slowly sputtering the surface, and monitoring the continuous surface modifications due to gradual increases in surface species under heating, cooling, or irradiation. Our recent work in aluminum oxynitride films provides another example of how to fit the XPS spectra of N_1s by three different oxidation states of N⁺, N²⁺, and N³⁺, by comparison of the measured data to data from previously published results, and by the gradual changes of spectra as functions of the oxygen contents in the films. Three oxidation states in different nitrogen bonding in the aluminum oxynitride, AlO₂N, Al₂O₅N₂, and AlO₃N, were clearly deduced.     

Minimizing vehicle noise passing the street bumps using Genetic Algorithm

The purpose of this paper is to optimize noise emission level associated with two types of speed reducers for different speeds of a vehicle (20, 40, 60 km/h) by Genetic Algorithm and Artificial Neural Network. The optimization shows that the maximum level of noise is sensitive to speed reducer dimensions. It is reduced by 24 dB(A) by changing the width from 0.6 m to 0.3 m for the height 0.04 m whereas, it is reduced by 32 dB(A) by changing from the height 0.055 m and the width 0.9 m to the height 0.04 m and the width 0.3 m.     

A measurement of the τ lifetime

We have reconstructed 695 three-track τ decay vertices using a high resolution drift chamber close to the interaction point. From the distribution of decay lengths we measure the lifetime to be (3.06 ±0.20±0.14)×10⁻¹³ s. Using this result we find that the ratio of charged weak coupling constant for the τ to that of the μ,G _τ/G _μ=0.967±0.040 consistent with the concept of lepton universality. On leave from Warsaw University, Poland Now at Hasylab, DESY Supported by Bundesministerium für Forschung und Technologie Supported by UK Science and Engineering Research Council Supported by CAICYT Supported by the Minerva Gesellschaft für Forschung GmbH Supported by US Dept. of Energy, contract DE-AC02-76ER000881 and by US Nat. Sci. Foundation Grant no INT-8313994 for travel Partially supported by grant CPBP 01.06     

The application of some beam-foil measurements for Co I and Co II to the cobalt photospheric abundance

The mean lives of a number of energy levels in Co I and Co II have been measured. Particular attention has been paid to the energy loss incurred by the ions in the foil, which was found to be somewhat larger than the loss forecast by Lindhard's theory.A-values derived for Co I (using relativegA-values from the literature) are found to be significantly lower than those reported previously by other authors. Fair agreement is obtained for Co II with theA-values forecast by Warner. The Co IA-values indicate that the cobalt solar abundance given by Goldberget al. (LogN _Co=4.64) should be increased to about 4.9.     

Combinatorial synthesis and high throughput evaluation of thermoelectric power factor in Mg-Si-Ge ternary compounds

Discrete phase libraries of thermoelectric compounds, Mg_xSi_yGe_1−y, were fabricated by a combinatorial pulsed laser deposition followed by annealing as a thin film form on an integrated ceramic substrate. In the substrate are embedded four probe electrical contacts to each sample, lead wires and pads to be accessed by needle probes. Resistivity and Seebeck coefficient were evaluated electrically, while temperature difference was locally given to each sample by a local heater also embedded in the substrate. The sample temperature (300-673 K) was controlled by a heating stage and temperature difference at the two contact points for each sample was evaluated by an infrared camera. The dependences of polarity and absolute values of Seebeck coefficient on the composition agree well with the data in literature.     

Small-polaron mobility in nonstoichiometric cerium dioxide

The high temperature drift mobility (μ_d) of charge carriers in nonstoichiometric cerium dioxide (CeO_2?x) has been calculated by combining the electrical conductivity and nonstoichiometry data on the basis of the oxygen vacancy model with correct ionization state. The electrical conductivity was measured by a four-probe d.c. technique and the nonstoichiometry by thermogravimetric analysis. The dilute solution model of the point defects is valid up to x = 0.03. From the magnitude of μ_d and its temperature dependence, the charge carriers in CeO_2?x, are proposed to be small-polarons formed by localization of electrons at cerium sites and the charge transport process is proposed to occur by a hopping mechanism. The observed temperature dependence of μ_d is in accord with that derived by Holstein and Friedman for small-polaron transport by the hopping mechanism. The activation energy of mobility is found to increase with increasing x as expected for the hopping model.     

Induced nuclear fission accompanied by pion emission

Basic features of the nuclear-fission process induced by protons of incident energy in the range 150<E _p<600 MeV and accompanied by pion emission are predicted on the basis of the cascade-evaporation-fission model. Specific calculations are performed for the total cross section; and the angular and double-differential distributions of pions; excitation-energy,mass number, and charge-number distributions of compound nuclei; and the mass-energy distributions of fission fragments. Various lines of possible experimental investigations into this fission channel are discussed, including searches for the pionic channel of nuclear decay induced by protons of energy close to the meson-production threshold, advancements to the energy region E _p<100 MeV in order to study of new mechanisms of pion production in nuclear fission, and an extension of investigations to the case of nuclear fission accompanied by kaon emission.     

Time-Resolved and Pulse EPR Study of Triplet States of Alkylketones in β-Cyclodextrin

The triplet states of deoxybenzoin (DOB) and benzophenone (BP) molecules in randomly methylated β-cyclodextrin (CD) cavity are studied by time-resolved (TR) and pulse electron paramagnetic resonance (EPR). The observed TR EPR spectrum of DOB in β-CD at 30 K is close to the spectrum measured in polar solvent trifluoroethanol, revealing strong hydration by water molecules. At the same time, TR EPR spectrum of BP in β-CD corresponds to nonpolar surrounding of the CO-group. The electron spin relaxation times T ₁ and T ₂ of triplet BP at 30 K measured by pulse EPR are found to be different in β-CD compared to nonpolar toluene glass. The observed increase of T ₂ by up to a factor of four in β-CD is caused by the lower vibration amplitude of CO-bond of BP due to the confinement in β-CD. The influence of β-CD with covalently attached nitroxide on the triplet states of DOB and BP is principally different: the excited triplet states could not be observed by TR EPR due to the efficient quenching of the excited states by nitroxide.     

Luminescence characteristics of K2Ca2(SO4)3:Eu,Tb micro- and nanocrystalline phosphor

K₂Ca₂(SO₄)₃ microcrystalline pure, doped with Eu, Tb and co-doped with Eu, Tb was prepared by solid-state diffusion method. Nanoparticles of these phosphors were also prepared by the chemical co-precipitation method. The formation of the compounds was confirmed by XRD. The particle size was calculated by broadening of the XRD peaks using Scherrer's formula. The particle size of nanocrystalline powder material was approximately found to be around 20 nm. Thermoluminescence and photoluminescence were studied to see the effect of co-doping and particle size. Tb³⁺ co-doping decreases the intensity in the Eu²⁺ doped phosphor due to the energy transfer and multiple de-excitations through various radiative and non-radiative processes. The sensitivity of K₂Ca₂(SO₄)₃:Eu,Tb microcrystalline phosphor was around 15 times more than LiF-TLD 100 and 7 times more than CaSO₄:Dy. A high temperature peak (615 K) was observed in case of the nanoparticles, which was attributed to a particle size induced phase transition. This was confirmed by differential scanning calormetry measurements. The decrease in the sensitivity in case of nanoparticles is attributed to the particle size effect i.e. volume to surface ratio. Theoretical analysis of the glow curves was done by glow curve convolution deconvolution method to calculate trapping parameters of various peaks.     

Reduction properties of perovskite-related rare earth orthoferrites

Perovskite-related materials of composition LaFe_1?x Co _x O₃ have been prepared by conventional calcination methods and by mechanical milling methods. The reduction properties in a flowing mixture of hydrogen and nitrogen have been monitored by temperature programmed reduction techniques and the nature of the reduced phases characterised by X-ray powder diffraction, X-ray absorption spectroscopy and⁵⁷Fe Mössbauer spectroscopy. The smaller particle materials made by mechanical milling methods are more susceptible to reduction than their counterparts made by conventional solid state methods. The presence of cobalt enhances the reducibility of iron in the perovskite-related structures. In iron-rich systems more limited reduction of iron and cobalt leads to the segregation of discrete metallic phases without destruction of the perovskite-related structure at temperatures up to 1200°C whereas in cobalt-rich systems the reduction of Fe³⁺ and Co³⁺ leads to significant segregation of alloy and metallic phases and is accompanied by destruction of the perovskite-related structure.     

Enhanced shape anisotropy and magneto-optical birefringence by high energy ball milling in NixFe1−xFe2O4 ferrofluids

Ferrofluids belonging to the series Ni_xFe_1−xFe₂O₄ were synthesised by two different procedures—one by standard co-precipitation techniques, the other by co-precipitation for synthesis of particles and dispersion aided by high-energy ball milling with a view to understand the effect of strain and size anisotropy on the magneto-optical properties of ferrofluids. The birefringence measurements were carried out using a standard ellipsometer. The birefringence signal obtained for chemically synthesised samples was satisfactorily fitted to the standard second Langevin function. The ball-milled ferrofluids showed a deviation and their birefringence was enhanced by an order. This large enhancement in the birefringence value cannot be attributed to the increase in grain size of the samples, considering that the grain sizes of sample synthesised by both modes are comparable; instead, it can be attributed to the lattice strain-induced shape anisotropy(oblation) arising from the high-energy ball-milling process. Thus magnetic-optical (MO) signals can be tuned by ball-milling process, which can find potential applications.