Properties Of Vacuum Research Articles

Lattice QCD in Background Fields

We review some recent results about the exploration of strong interactions in presence of external background fields by means of lattice QCD simulations. We discuss in particular studies concerning the influence of the external fields on the non-perturbative properties of the QCD vacuum and of the QCD phase diagram.

Effect of precursor sol pH on microstructural, optical and photocatalytic properties of vacuum annealed zinc tin oxide thin films on glass

Dip coated vacuum annealed zinc tin oxide thin films on soda lime silica glass have been deposited from the precursor sols containing zinc acetate dihydrate and tin (IV) chloride pentahydrate (Zn:Sn = 67:33, atomic ratio in percentage) in 2-methoxy ethanol by varying sol pH (0.85–5.5). Crystallinity, morphology, optical and photocatalytic properties of the films strongly depend on sol pH. Measurement of grazing incidence X-ray diffraction confirms the presence of hexagonal nano ZnO in the films derived from the sols of pH < 5.5. Film crystallinity deteriorates on increasing sol pH and the film deposited from the sol of pH 5.5 shows XRD amorphous but the selected area diffraction pattern and HRTEM image evidence the presence of nano Zn2SnO4 (size, 5–6 nm). Direct band gap energy of films increases on increasing sol pH. To visualize the film surface microstructure, FESEM study has been done and a rod-like surface feature is revealed in the film deposited from the sol of pH 2.85. A dependence of precursor sol pH on the photocatalytic activity of films towards degradation of Rhodamine 6G dye under UV (254 nm) irradiation is found and the highest decomposition rate constant, ‘k’ value is obtained from the film prepared from the sol of pH 5.5. The presence of zinc deficient nano Zn2SnO4 in the film may consider for generating the highest ‘k’ value. We also measure gelling time, viscosity of sols as well as UV and FTIR studies on the films and propose chemical reactions.

Computational Studies on SAMs of {Mn6} SMMs on Au(111): Do Properties Change upon Grafting?

Single molecule magnets (SMM) adsorbed on surfaces as magnetic building blocks represent a hot topic of research in the area of molecular magnetism. Indeed, the understanding the properties of molecules on surface is extremely challenging as atomistic structures are not readily available. In this regard, theoretical studies as reliable tool to reproduce and predict the structure and the magnetic ground state of SMMs in the bulk phase and adsorbed on a surface, should be considered very appealing. In this framework, we report a periodic density functional (DF) study on two {Mn6} SMM complexes of general formula [Mn(III)6O2(R-sao)6(O2C-th)2L], where HO2C-th=3-thiophene carboxylic acid, saoH2 = salicylaldoxime, R = H and L = (EtOH)4 (1) or R = Et and L = (EtOH)4(H2O)2 (2), performed to ascertain the structure of their self-assembled monolayers (SAM) on the Au(111) surface. Their magnetic properties in vacuum and in the adsorbed state have also been computed and our results clearly demonstrate that the grafti...

Compact Undulator for the Cornell High Energy Synchrotron Source: Design and Beam Test Results

We developed, built and beam tested a novel, compact, in-vacuum undulator magnet based on an adjustable phase (AP) scheme. The undulator is 1 m long with a 5mm gap. It has a pure permanent magnet structure with 24.4mm period and 1.1 Tesla maximum peak field. The device consists of two planar magnet arrays mounted on rails inside of a rectangular box-like frame with 156 mm × 146 mm dimensions. The undulator magnet is enclosed in a 273 mm (10.75") diameter cylindrical vacuum vessel with a driver mechanism placed outside. In May 2012 the CHESS Compact Undulator (CCU) was installed in Cornell Electron Storage Ring and beam tested. During four weeks of dedicated run we evaluated undulator radiation properties as well as magnetic, mechanical and vacuum properties of the undulator magnet. We also studied the effect of the CCU on storage ring beam. The spectral characteristics and intensity of radiation were found to be in very good agreement with expected. The magnet demonstrated reproducibility of undulator parameter K at 1.4 × 10−4 level. It was also found that the undulator K. parameter change does not affect electron beam orbit and betatron tunes.

Influence of doping with third group oxides on properties of zinc oxide thin films

The study of modifications in structural, optical and electrical properties of vacuum evaporated zinc oxide thin films on doping with III group oxides namely aluminum oxide, gallium oxide and indium oxide are reported. It was observed that all the films have transmittance ranging from 85 to 95%. The variation in optical properties with dopants is discussed. On doping the film with III group oxides, the conductivity of the films showed an excellent improvement of the order of 103 Ω−1 cm−1. The measurements of activation energy showed that all three oxide doped films have 2 donor levels below the conduction band.

Nonlinear Optical Properties in Vacuum Induced by Intense Laser Light with Axially Symmetric Polarization

Nonlinear Optical Properties in Vacuum Induced by Intense Laser Light with Axially Symmetric Polarization

Optical and Electrical Properties of Thin Films of CuS Nanodisks Ensembles Annealed in a Vacuum and Their Photocatalytic Activity

Effects on the optical, electrical, and photocatalytic properties of undoped CuS thin films nanodisks vacuum annealed at different temperatures were investigated. The chemical bath prepared CuS thin films were obtained at 40°C on glass substrates. The grain size of13.5±3.5 nm was computed directly from high-resolution transmission electron microscopy (HRTEM) images. The electrical properties were measured by means of both Hall effect at room temperature and dark resistivity as a function of the absolute temperature 100–330 K. The activation energy values were calculated as 0.007, 0.013, and 0.013 eV for 100, 150, and 200°C, respectively. The energy band gap of the films varied in the range of 1.98 up to 2.34 eV. The photocatalytic activity of the CuS thin film was evaluated by employing the degradation of aqueous methylene blue solution in the presence of hydrogen peroxide. The CuS sample thin film annealed in vacuum at 150°C exhibited the highest photocatalytic activity in presence of hydrogen peroxide.

Electron Irradiation of Graphene Field Effect Transistor Devices

ABSTRACTWe report the effects of electron irradiation on graphene Field Effect Transistor (FET) devices. We irradiated the graphene devices with 30keV electrons and measured the electrical transport properties in high vacuum in-situ. Upon electron irradiation, a Raman ‘D’ band appears. In addition, we observed that the doping behavior of the graphene devices changed from P to N type as a result of the irradiation. We also observed a shift of the Dirac point while the graphene FET device stays in vacuum and after it interacted with environmental molecules under ambient conditions.

Compositional Dependence of the Optical Properties of Vacuum Evaporated Thin GeSe2-GeTe-PbTe Films

Abstract Chalcogenide glasses from the GeSe 2 -GeTe-PbTe system were synthesized by taking preliminary prepared GeSe 2 , GeTe and PbTe in their molecular percentages and melting them in an evacuated quartz ampoule. Thin films were deposited on optical glass substrates BK-7 and Si-wafer substrates by thermal evaporation. Using X-ray microanalysis it was found that the film composition differs to a certain degree from the bulk composition. The changes in the optical properties of thin GeSe 2 -GeTe-PbTe films were studied as a function of their composition, exposure to light and annealing. It is shown by XRD analysis that the thin films are amorphous up to layers with composition of Ge 27 Se 51 Te 14 Pb 8 . The optical constants (refractive index, n and absorption coefficient, α), the thickness, d as well as the optical band gap, E g , depending on the film composition were determined by spectrophotometric measurements in the region 450-2500 nm applying the Swanepoel's envelop method and Tauc's procedure. With the increase of the Te content in the layers, the absorption edge is shifted to the higher wavelengths, the refractive index increases from 2.54 for Ge 31 Se 66 Te 3 up to 3.37 for Ge 32 Se 55 Te 13 while the optical band gap decreases from 1.86 eV for to 1.30 eV for the same compositions. Similar dependence was observed with the increase of the PbTe content in the layers. After annealing of thin films, the values of n decrease, the optical band gap increases and a shift of the absorption edge to the shorter wavelengths is observed.

The Oscillating Universe Theory (To the Unified Field Theory)

This paper represents model of oscillating universe theory. We try to realize model of both electromagnetic waves and spectrum of elementary particles from the unified point of view. Consideration of problems of the gravitational optics and dark matter is developing from the solid crystal model for the vacuum. The vacuum is represented as a three-dimensional crystal lattice matter with a very small lattice period, much less than 10-26 cm. The oscillators are located at the nodes of an infinite lattice. It is shown that an infinite set of equations to describe the coupled oscillations of moving oscillators converges to a system of twelve equations. We have obtained the combined equations for a multicomponent order parameter in the form of the electric and magnetic vacuum polarization, which defines the spectrum and symmetry of normal oscillations in the form of elementary particles. Two order parameters—a polar vector and an axial vector— had to be introduced as electrical and magnetic polarization, correspondingly, in order to describe dynamic properties of vacuum. Vacuum susceptibility has been determined to be equal to the fine structure constant a. Unified interaction constant g for all particles equal to the double charge of Dirac monopole has been found (g = e/a, where e—electron charge). The fundamental vacuum constants are: g, a, parameters of length and parameters of time for electron and nucleon oscillations, correspondingly. Energy of elementary particles has been expressed in terms of the fundamental vacuum parameters, light velocity being equal to . The term mass of particle has been shown to have no independent meaning. Particle energy does have physical sense as wave packet energy related to vacuum excitation. Exact equation for particle movement in the gravitational field has been derived, the equation being applied to any relatively compact object: planet, satellite, electron, proton, photon and neutrino. The situation has been examined according to the cosmological principle when galaxies are distributed around an infinite space. In this case the recession of galaxies is impossible, so the red shift of far galaxies’ radiation has to be interpreted as the blue time shift of atomic spectra; it follows that zero-energy, and consequently electron mass are being increased at the time. Since physical vacuum has existed eternally, vacuum parameters can be either constant, or oscillating with time. It is the time oscillation of the parameters that leads to the growth of electron mass within the last 15 billion years and that is displayed in the red shift; the proton mass being decreased that is displayed in planet radiation.

Morphology, Structural and Dielectric Properties of Vacuum Evaporated V2O5 Thin Films

Vanadium pentoxide (V2O5) thin films were deposited on well cleaned glass substrate using evaporation technique under the pressure of 10-5 Torr. The thickness of the films was measured by the multiple beam interferometry technique and cross checked by using capacitance method. Metal-Insulator-Metal (MIM) structure was fabricated by using suitable masks to study dielectric properties. The dielectric properties were studied by employing LCR meter in the frequency range 12 Hz to 100 kHz for various temperatures. The temperature co- efficient of permittivity (TCP), temperature co-efficient of capacitance (TCC) and dielectric constant (ɛ) were calculated. The activation energy was calculated and found to be very low. The activation energy was found to be increasing with increase in frequency. The obtained low value of activation energy suggested that the hopping conduction may be due to electrons rather than ions.

Vacuum properties of TARLA

The Turkish Accelerator and Radiation Laboratory at Ankara (TARLA) is a part of the Turkish Accelerator Center project, which was designed to produce an infrared free electron laser in the wavelength band of 2-250 mu m. The beamline of TARLA consists of 4 major sections: injector, beam transport line with linacs, optical cavities, and dump. All system components must be kept under ultrahigh vacuum standards to prevent beam scattering with residual gas. In the present study, the vacuum requirements of the beamline are defined and simulation vacuum and gas flow in the accelerator are presented.

Effects of substrate temperatures and deposition rates on properties of aluminum fluoride thin films in deep-ultraviolet region

Aluminum fluoride (AlF(3)) is a low-refractive-index material widely used in coatings for deep-ultraviolet (DUV) optical systems, especially 193 nm laser systems. Low optical loss and stability are essential for film application. In this study, AlF(3)> thin films were prepared by thermal evaporation with a resistive heating boat. The effects of substrate temperatures and deposition rates on the optical properties in vacuum and in air, composition, and microstructures were discussed respectively. In vacuum the deposition parameters directly influenced the microstructures that determined the refractive index. When the films were exposed to air, aluminum oxide (Al(2)O(3)) formed in the films with water adsorption. Thus the refractive index increased and a nonmonotonic changing trend of the refractive index with substrate temperature was observed. The Al(2)O(3) was also found to be conductive to reducing absorption loss. AlF(3) films prepared at a high substrate temperature and deposition rate could yield stable structures with large optical loss.

Influence of substrate temperature and post deposition annealing on the properties of vacuum deposited ZnSe thin films

The effects of substrate temperature and post deposition annealing on the structural, optical and electrical properties of vacuum deposited ZnSe thin films are presented here. The chemical composition of the films varied drastically with substrate temperature which in turn caused changes in various properties of the films. The grain size of the films increased with substrate temperature and also after annealing. The electrical properties of the films were found to be varying as a function of chemical composition and grain size.

Can observations inside the Solar System reveal the gravitational properties of the quantum vacuum?

The understanding of the gravitational properties of the quantum vacuum might be the next scientific revolution. It was recently proposed that the quantum vacuum contains the virtual gravitational dipoles; we argue that this hypothesis might be tested within the Solar System. The key point is that the quantum vacuum (“enriched” with the gravitational dipoles) induces a retrograde precession of the perihelion. It is obvious that this phenomenon might eventually be revealed by more accurate studies of orbits of planets and orbits of the artificial Earth satellites. However, we suggest that potentially the best “laboratory” for the study of the gravitational properties of the quantum vacuum is the recently discovered dwarf planet Eris with its satellite named Dysnomia; the distance of nearly 100 AU from the Sun makes it the unique system in which the precession of the perihelion of Dysnomia (around Eris) is strongly dominated by the quantum vacuum.

Vacuum structure and string tension in Yang-Mills dimeron ensembles

We numerically simulate ensembles of SU(2) Yang-Mills dimeron solutions with a statistical weight determined by the classical action and perform a comprehensive analysis of their properties as a function of the bare coupling. In particular, we examine the extent to which these ensembles and their classical gauge interactions capture topological and confinement properties of the Yang-Mills vacuum. This also allows us to put the classic picture of meron-induced quark confinement, with the confinement-deconfinement transition triggered by dimeron dissociation, to stringent tests. In the first part of our analysis we study spacial, topological-charge and color correlations at the level of both the dimerons and their meron constituents. At small to moderate couplings, the dependence of the interactions between the dimerons on their relative color orientations is found to generate a strong attraction (repulsion) between nearest neighbors of opposite (equal) topological charge. Hence, the emerging short- to mid-range order in the gauge-field configurations screens topological charges. With increasing coupling this order weakens rapidly, however, in part because the dimerons gradually dissociate into their less localized meron constituents. Monitoring confinement properties by evaluating Wilson-loop expectation values, we find the growing disorder due to the long-range tails of these progressively liberated merons to generate a finite and (with the coupling) increasing string tension. The short-distance behavior of the static quark-antiquark potential, on the other hand, is dominated by small, ``instantonlike'' dimerons. String tension, action density and topological susceptibility of the dimeron ensembles in the physical coupling region turn out to be of the order of standard values. Hence, the above results demonstrate without reliance on weak-coupling or low-density approximations that the dissociating dimeron component in the Yang-Mills vacuum can indeed produce a meron-populated confining phase. The density of coexisting, hardly dissociated and thus instantonlike dimerons seems to remain large enough, on the other hand, to reproduce much of the additional phenomenology successfully accounted for by nonconfining instanton vacuum models. Hence, dimeron ensembles should provide an efficient basis for a more complete description of the Yang-Mills vacuum.

Swaging of liquid phase sintered 90W–7Ni–3Fe tungsten heavy alloy

The aim of this study was to investigate the effect of swaging on the microstructure and mechanical properties of vacuum sintered 90W–7Ni–3Fe alloys. Cold isostatically pressed samples were sintered under vacuum at 1510°C, for 30min. Samples were then 15% cold rotary swaged. The study has shown that, mechanical properties of relatively low density (<98% theoretical) liquid phase sintered 90W–7Ni–3Fe alloy can be considerably improved by swaging due to increase in density and strain hardening.

Wheeler-DeWitt equation in2+1dimensions

The infrared structure of quantum gravity is explored by solving a lattice version of the Wheeler-DeWitt equations. In the present paper only the case of 2+1 dimensions is considered. The nature of the wavefunction solutions is such that a finite correlation length emerges and naturally cuts off any infrared divergences. Properties of the lattice vacuum are consistent with the existence of an ultraviolet fixed point in $G$ located at the origin, thus precluding the existence of a weak coupling perturbative phase. The correlation length exponent is determined exactly and found to be $\nu=6/11$. The results obtained so far lend support to the claim that the Lorentzian and Euclidean formulations belong to the same field-theoretic universality class.

Supersymmetric extension of technicolor & fermion mass generation

We provide a complete extension of Minimal Walking Technicolor able to account for the Standard Model fermion masses. The model is supersymmetric at energies greater or equal to the technicolor compositeness scale. We integrate out, at the supersymmetry breaking scale, the elementary Higgses. We use the resulting four-fermion operators to derive the low energy effective theory. We then determine the associated tree-level vacuum and low energy spectrum properties. Furthermore we investigate the phenomenological viability of the model by comparing its predictions with electroweak precision tests and experimental bounds on the mass spectrum. We then turn to the composite Higgs phenomenology at the LHC and show that current data are already constraining the parameter space of the model.

Studies on phase transformation and molecular orientation in nanostructured zinc phthalocyanine thin films annealed at different temperatures

Studies on the electronic and optical properties of thin films of organometallic compounds such as phthalocyanine are very important for the development of devices based on these compounds. The nucleation and grain growth mechanism play an important role for the final electronic as well as optoelectronic properties of the organic and organometallic thin films. The present article deals with the change in the film morphology, grain orientation of nanocrystallites and optical properties of zinc phthalocyanines (ZnPc) thin films as a function of the post deposition annealing temperature. The effect of annealing temperature on the optical and structural property of vacuum evaporated ZnPc thin films deposited at room temperature (30°C) on quartz glass and Si(100) substrates has been investigated. The thin films have been characterized by the UV–vis optical absorption spectra, X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy. From the studies of UV–vis absorption spectra and XRD data, a metastable α to β-phase transformation has been observed when the thin films were annealed at a temperature greater than about 250°C. The FESEM images have shown the particlelike structure at room temperature and the structure became rodlike when the films were annealed at high temperatures. TEM image of ZnPc film dissolved in ethanol has shown spectacular rod-shaped crystallites. High resolution transmission electron microscopy image of a single nanorod has shown beautiful “honey-comb” like structure. Particle size and root mean square roughness were calculated from AFM images. The changes in band gap energy with increase in annealing temperature have been evaluated.