Microstructure and Optical Properties of Tantalum Modified TiO2 Thin Films Prepared by the Sol-Gel Process

Tantalum doped TiO2 thin films ((TiO2)(1-x) (Ta2O5)(x), x = 0, 0.1%, 0.3%, 0.5%, 0.8%) were prepared on ITO-coated substrates by means of the sol gel method and spin coating technology followed by rapid thermal annealing treatment (RTA). The effects of various processing parameters, including Ta content (x = 0-0.8%) and annealing temperature, on the growth and properties of thin films were investigated. Structural characteristics by X-ray diffraction analysis indicated that the doping of Ta2O5 in the TiO2 without change the anatase structure of TiO2 thin films. The optical transmittance of (TiO2)(1-x) (Ta2O5) thin films decrease from 50% down to 20% with increasing the Ta2O5 concentrations from x = 0.00 to x = 0.8%. The absorption coefficient shows energy gap were decreased with increasing Ta2O5 content from 2.932 eV for x = 0.00 to 2.717 eV for x = 0.8%. Doping TiO2 with Ta2O5 can lower its band gap and shift its optical response to the visible region

Three-Particle Correlations from Parton Cascades in Au+Au Collisions

We present a study of three-particle correlations among a trigger particle and two associated particles in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV using a multi-phase transport model (AMPT) with both partonic and hadronic interactions. We found that three-particle correlation densities in different angular directions with respect to the triggered particle (`center', `cone', `deflected', `near' and `near-away') increase with the number of participants. The ratio of `deflected' to `cone' density approaches to 1.0 with the increasing of number of participants, which indicates that partonic Mach-like shock waves can be produced by strong parton cascades in central Au+Au collisions.Comment: 9 pages, 6 figures; Final version to appear in Physics Letters

Di-hadron azimuthal correlation and Mach-like cone structure in parton/hadron transport model

In the framework of a multi-phase transport model (AMPT) with both partonic and hadronic interactions, azimuthal correlations between trigger particles and associated scattering particles have been studied by the mixing-event technique. The momentum ranges of these particles are $3< p^{trig}_T< 6$ GeV/$c$ and $0.15< p_{T}^{assoc} < 3$ GeV/$c$ (soft), or $2.5<p^{trig}_T<$ 4 GeV/$c$ and $1< p_{T}^{assoc} < 2.5$ GeV/$c$ (hard) in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. A Mach-like structure has been observed in correlation functions for central collisions. By comparing scenarios with and without parton cascade and hadronic rescattering, we show that both partonic and hadronic dynamical mechanisms contribute to the Mach-like structure of the associated particle azimuthal correlations. The contribution of hadronic dynamical process can not be ignored in the emergence of Mach-like correlations of the soft scattered associated hadrons. However, hadronic rescattering alone cannot reproduce experimental amplitude of Mach-like cone on away-side, and the parton cascade process is essential to describe experimental amplitude of Mach-like cone on away-side. In addition, both the associated multiplicity and the sum of $p_{T}$ decrease, whileas the $$ increases, with the impact parameter in the AMPT model including partonic dynamics from string melting scenario.Comment: 9 pages, 5 figures; Physics Letters B 641, 362-367 (2006

Photoluminescence Properties of the Zn1-x Y (x) O Tubes Prepared by Polycarbonate Templates

We have prepared Zn1-x Y (x) O (x=0 and 0.01) tubes to study its structural and photoluminescent properties. A pore wetting process of porous polycarbonate templates with the liquid precursor and following thermal treatment were utilized for preparing the Zn1-x Y (x) O tube structure. Using the polycarbonate template with pore size of about 2 mu m diameter, the Zn1-x Y (x) O tubes were obtained. Photoluminescence (PL) spectroscopy was used to measure optical emissions from 350 to 650 nm with a He-Cd laser. The results of the PL spectra show that the Zn1-x Y (x) O tubes have evident emission peaks at the UV (about 380 nm) and visible (around 500 to 650 nm) region. The emission peak at the UV region was slightly shifted to higher wavelengths with increasing Y content. Meanwhile, the green and yellow emission peaks intensity increases as Y content increases. These results are explained by the structure tuning and oxygen deficiency with the introduction of Y

Partial Wave Analysis of J/ψ→γ(K+K−π+π−)J/\psi \to \gamma (K^+K^-\pi^+\pi^-)

BES data on $J/\psi \to \gamma (K^+K^-\pi^+\pi^-)$ are presented. The $K^*\bar K^*$ contribution peaks strongly near threshold. It is fitted with a broad $0^{-+}$ resonance with mass $M = 1800 \pm 100$ MeV, width $\Gamma = 500 \pm 200$ MeV. A broad $2^{++}$ resonance peaking at 2020 MeV is also required with width $\sim 500$ MeV. There is further evidence for a $2^{-+}$ component peaking at 2.55 GeV. The non-$K^*\bar K^*$ contribution is close to phase space; it peaks at 2.6 GeV and is very different from $K^{*}\bar{K^{*}}$.Comment: 15 pages, 6 figures, 1 table, Submitted to PL

Multiple-path Quantum Interference Effects in a Double-Aharonov-Bohm Interferometer

We investigate quantum interference effects in a double-Aharonov-Bohm (AB) interferometer consisting of five quantum dots sandwiched between two metallic electrodes in the case of symmetric dot-electrode couplings by the use of the Green’s function equation of motion method. The analytical expression for the linear conductance at zero temperature is derived to interpret numerical results. A three-peak structure in the linear conductance spectrum may evolve into a double-peak structure, and two Fano dips (zero conductance points) may appear in the quantum system when the energy levels of quantum dots in arms are not aligned with one another. The AB oscillation for the magnetic flux threading the double-AB interferometer is also investigated in this paper. Our results show the period of AB oscillation can be converted from 2π to π by controlling the difference of the magnetic fluxes threading the two quantum rings

Single Spin Asymmetry ANA_N in Polarized Proton-Proton Elastic Scattering at s=200\sqrt{s}=200 GeV

We report a high precision measurement of the transverse single spin asymmetry $A_N$ at the center of mass energy $\sqrt{s}=200$ GeV in elastic proton-proton scattering by the STAR experiment at RHIC. The $A_N$ was measured in the four-momentum transfer squared $t$ range $0.003 \leqslant |t| \leqslant 0.035$ \GeVcSq, the region of a significant interference between the electromagnetic and hadronic scattering amplitudes. The measured values of $A_N$ and its $t$-dependence are consistent with a vanishing hadronic spin-flip amplitude, thus providing strong constraints on the ratio of the single spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated by the Pomeron amplitude at this $\sqrt{s}$, we conclude that this measurement addresses the question about the presence of a hadronic spin flip due to the Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

The cyclic deformation behavior of cryomilled (CM) AA5083 alloys was compared to that of conventional AA5083-H131. The materials studied were a 100 pct CM alloy with a Gaussian grain size average of 315 nm and an alloy created by mixing 85 pct CM powder with 15 pct unmilled powder before consolidation to fabricate a plate with a bimodal grain size distribution with peak averages at 240 nm and 1.8 μm. Although the ultra-fine-grain (UFG) alloys exhibited considerably higher tensile strengths than those of the conventional material, the results from plastic-strain-controlled low-cycle fatigue tests demonstrate that all three materials exhibit identical fatigue lives across a range of plastic strain amplitudes. The CM materials exhibited softening during the first cycle, similar to other alloys produced by conventional powder metallurgy, followed by continual hardening to saturation before failure. The results reported in this study show that fatigue deformation in the CM material is accompanied by slight grain growth, pinning of dislocations at the grain boundaries, and grain rotation to produce macroscopic slip bands that localize strain, creating a single dominant fatigue crack. In contrast, the conventional alloy exhibits a cell structure and more diffuse fatigue damage accumulation