bluuebunny/crossref_metadata_2025 huggingface dataset:
EVOLUTION OF THE QUARK MASS MATRIX
Authors: DE COSS MARITZA , HUERTA RODRIGO
Published: October 2002

Starting from a weak basis in which the up (or down) quark matrix is diagonal, we obtain an exact set of equations for the quark mass matrix elements in terms of known observables. We make a numerical analysis of the down (up) quark mass matrix. Using the data available for the quark masses and mixing angles at different energy scales, we found a numerical expression for these matrices. We also examine the most general case when the complex phases are introduced in the mass matrix. We find the numerical value for these phases as a function of δ, the CP-violating phase. The entire evolution of the mass matrix is found propagating the experimental errors to the final results.
EFFECTIVE STRING THEORIES AND FIELD THEORIES IN FOUR DIMENSIONS
Authors: NASIR SAZZAD , NIEMI ANTTI J.
Published: October 2002

We argue that in four dimensions bosonic strings can be bundled together in a manner which resembles the way how individual filaments become bundled together to form a cable. The energy of such a bundle of strings is described by its extrinsic geometry, and it involves both torsion and curvature contributions. This leads to ordinary four-dimensional field theories, that describe the bundles of strings in terms of closed knotted solitons. Examples of field theories that can be constructed in this manner include the Faddeev model and the Skyrme model.
MATRIX MODEL ON Z-ORBIFOLD
Authors: MIYAKE AKIKO , SUGAMOTO AKIO
Published: October 2002

Six-dimensional compactification of type IIA matrix model on the Z-orbifold is studied. Introducing a Z3 symmetry properly on the three mirror images of fields in the N-body system of the supersymmetric D0 particles, the action of the matrix model compactified on the Z-orbifold is obtained. In this matrix model [Formula: see text] supersymmetry is explicitly demonstrated.
A MODEL OF TWO-DIMENSIONAL TURBULENCE USING RANDOM MATRIX THEORY
Authors: IYER SAVITRI V. , RAJEEV S. G.
Published: October 2002

We derive a formula for the entropy of two-dimensional incompressible inviscid flow, by determining the volume of the space of vorticity distributions with fixed values for the moments Qk = ∫ ω(x)kd2x. This space is approximated by a sequence of spaces of finite volume, by using a regularization of the system that is geometrically natural and connected with the theory of random matrices. By taking the limit we get a simple formula for the entropy of a vortex field. We predict vorticity distributions of maximum entropy with given mean vorticity and enstrophy; we also predict the cylindrically symmetric vortex field with maximum entropy. This could be an approximate description of a hurricane.
OBSERVATIONS OF DARK SIDE OF THE UNIVERSE BY GRAVITATIONAL LENSING
Authors: FUTAMASE TOSHIFUMI
Published: October 2002

It is now widely recognized that strong and weak gravitational lensing both play important roles in the observational cosmology. We shall here report our proposal and recent observation on the determination of the dark energy using strong gravitational lensing, and our recent analysis of weak shear field around Cl1604+4304 where we found mass concentration with no optical counterparts. Our recent weak shear observation by Subaru/S-Cam is also briefly mentioned.
QUANTUM PERFECT FLUID COSMOLOGICAL MODEL AND ITS CLASSICAL ANALOGUE
Authors: BATISTA A. B. , FABRIS J. C. , GONCALVES S. V. B. , TOSSA J.
Published: October 2002

The quantization of gravity coupled to a perfect fluid model leads to a Schrödinger-like equation, where the matter variable plays the role of time. The wave function can be determined, in the flat case, for an arbitrary barotropic equation of state p = α ρ; solutions can also be found for the radiative non-flat case. The wave packets are constructed, from which the expectation value for the scale factor is determined. The quantum scenarios reveal a bouncing Universe, free from singularity. Such quantum cosmological perfect fluid models admit a universal classical analogue, represented by the addition, to the ordinary classical model, of a repulsive stiff matter fluid1,2. The existence of this universal classical analogue may imply that this perfect fluid coupled to gravity model is not a real quantum system. The quantum cosmological perfect fluid model is, for a flat spatial section, formally equivalent to a free particle in ordinary quantum mechanics, for any value of α, while the radiative non-flat case is equivalent to the harmonic oscillator. The repulsive fluid needed to reproduce the quantum results is the same in both cases.
Charmonium Production in Fermilab E789
Authors: Kaplan Daniel M.
Published: October 2002

Using a sample of > 105 J/ψ → μ+ μ- decays, Fermilab experiment 789 has studied production of J/ψ and ψ′ in 800 GeV proton-nucleon collisions. Differential cross sections and nuclear dependences have been measured for charmonium as well as for charm and beauty production. While charm and beauty production are consistent with perturbative QCD calculations, charmonium cross sections exceed the predictions of the color-singlet model by large factors, suggesting that additional mechanisms (such as color-octet production) may play important roles. Nuclear dependences of production cross sections may offer a new tool for the detailed understanding of charmonium production.
Charmonium Production with 300 GeV/c π+, π-, p and $\bar{p}$ Beams
Authors: Arenton Michael
Published: October 2002

Results of an experiment measuring the production of charmonium states with 300 GeV/c π+, π-, p and [Formula: see text] beams on a Li target are presented. Total and differential cross sections for production of J/ψ, ψ′ and χ states are presented. The separation of the χ signal into the χ1 and χ2 states is discussed. The fraction of J/ψ's that result from direct production is derived.
J/ψ Production at HERA
Authors: Brugnera Riccardo
Published: October 2002

In this report we summarize the experimental situation about J/ψ production at the HERA collider. Data will be shown on elastic, on proton diffractive dissociation and on inelastic production mechanisms. The experimental results will be compared with the existing theoretical models.
ISOTHERMAL RELAXATION OF RUBBED POLYSTYRENE THIN FILMS PROBED WITH OPTICAL BIREFRINGENCE MEASUREMENTS
Authors: SCHWAB ALEXANDER D. , ACHARYA BHARAT , KUMAR SATYENDRA , DHINOJWALA ALI
Published: October 2002

Optical birefringence measurements were used to observe the isothermal relaxation of rubbed polystyrene films on silica substrates below the glass transition temperature. The relaxation dynamics were described by the Kohlrausch–Williams–Watts relaxation function with Arrhenius temperature dependence on relaxation time. The isothermal results were in good agreement with results obtained using a 1 K min -1 heating rate.
SHORT-TIME DECOHERENCE AND DEVIATION FROM PURE QUANTUM STATES
Authors: PRIVMAN VLADIMIR
Published: October 2002

In systems considered for quantum computing, i.e., for control of quantum dynamics with the goal of processing information coherently, decoherence and deviation from pure quantum states, are the main obstacles to error correction. At low temperatures, usually assumed in quantum computing designs, some of the accepted approaches to evaluation of relaxation mechanisms break down. We develop a new formalism for the estimation of decoherence at short times, appropriate for evaluation of quantum computing architectures.
ALFVÉN BOUNDARY CRISIS
Authors: CHIAN A. C.-L. , BOROTTO F. A. , REMPEL E. L.
Published: October 2002

A new transition mechanism to Alfvén chaos via boundary crisis is reported. This crisis appears in a complex plasma region in the presence of a large number of coexisting attractors. We characterize an example of double boundary crises using the unstable periodic orbit determined from the numerical solution of the driven-dissipative derivative nonlinear Schrödinger equation, and demonstrate how the same unstable periodic orbit causes the appearance/disappearance of two chaotic attractors due to two successive homoclinic tangencies.
ASCENDING CHAIN CONDITIONS IN FREE BAXTER ALGEBRAS
Authors: GUO LI
Published: October 2002

In this paper we study ascending chain conditions in a free Baxter algebra by making use of explicit constructions of free Baxter algebras that were obtained recently. We investigate ascending chain conditions both for ideals and for Baxter ideals. The free Baxter algebras under consideration include free Baxter algebras on sets and free Baxter algebras on algebras. We also consider complete free Baxter algebras.
BRANS–DICKE COSMOLOGY IN AN ANISOTROPIC MODEL WHEN VELOCITY OF LIGHT VARIES
Authors: CHAKRABORTY SUBENOY , CHAKRABORTY NARAYAN CHANDRA , DEBNATH UJJAL
Published: October 2002

In this paper, we have studied Brans–Dicke (BD) Cosmology in an anisotropic Kantowski–Sachs space–time model; considering variation of the velocity of light. We have addressed the flatness problem considering both cases namely (i) when the Brans–Dicke scalar field φ is constant (ii) when φ varies, specially for radiation dominated era perturbatively and non-perturbatively and asymptotic behaviour have been studied.
HIGH RESOLUTION NEAR-EDGE SPECTROSCOPY OF MOLECULES AND MOLECULAR VAN DER WAALS CLUSTERS
Authors: FLESCH R. , TAPPE W. , RÜHL E. , PAVLYCHEV A. A.
Published: October 2002

High resolution near-edge excitation of isolated molecules and homogeneous molecular van der Waals clusters is reported. Resonant excitation near the element K-edges of isolated and clustered carbon monoxide and nitrogen gives rise to small spectral shifts that can only be detected by high spectral resolution. The experimental results indicate for the vibrationally resolved 1s → π* transitions of isolated molecules that symmetric line shapes cannot be used rather than the lifetime-broadened rotational fine structure. Clustered molecules exhibit characteristic redshifts of the order of a few meV relative to the corresponding isolated molecules. Changes in Franck–Condon factors and changes in spectral line shape are observed, as well. The experimental results are discussed in the framework of the quasiatomic approach with respect to intermolecular interactions and dynamic localization of resonant core-to-valence excitations.
PHOTOEMISSION MICROSCOPY INVESTIGATION OF BURIED p–n GaAs HOMOJUNCTIONS AND Al/n-GaAs SCHOTTKY BARRIERS
Authors: BARBO F. , BERTOLO M. , BIANCO A. , CAUTERO G. , FONTANA S. , JOHAL T. K. , LA ROSA S. , PURANDARE R. C. , SVETCHNIKOV N. , FRANCIOSI A. , ORANI D. , PICCIN M. , RUBINI S. , CIMINO R.
Published: October 2002

A natural application of the emerging technique of photoemission microscopy to the study of semiconductor interfaces involves measuring a device in cross section to directly determine heterojunction parameters. We present here results on p–n GaAs homojunctions, which served as a prototype system to demonstrate the applicability of this technique to buried semiconductor interfaces. We also describe preliminary measurements of the electrostatic potential profile across Al/GaAs Schottky junctions.
SPACE-RESOLVING VUV AND SOFT X-RAY SPECTROSCOPY IN THE TANDEM MIRROR GAMMA 10 PLASMA
Authors: YOSHIKAWA M. , OKAMOTO Y. , KAWAMORI E. , WATANABE Y. , WATABE C. , FURUKAWA T. , KUBOTA Y. , SEDO K. , CHO T. , YATSU K. , YAMAGUCHI N.
Published: October 2002

Vacuum ultraviolet (VUV) and soft X-ray (SX) spectroscopic measurements are important means to diagnose radiation power loss, impurity ion densities and effective charge of confined plasma, Z eff , in magnetically confined plasmas such as fusion plasmas. We have constructed space- and time-resolving flat-field VUV (150–1050Å) and SX (20–350Å) spectrographs by using aberration-corrected concave gratings with varied line spacing. Absolute calibration experiments have been conducted at the Photon Factory in the High Energy Accelerator Research Organization. Absolute sensitivities of the VUV and SX spectrographs have been obtained for the two (S and P) polarization geometries. Thus, absolute intensities of emission spectra from impurity ions can be measured together with their radial distributions in plasmas. The total radiation power was determined to be less than 6 kW within ±20% of error in our normal plasma operation. Density profiles of impurity ions were reduced by using absolute emissivities of impurity lines and a collisional-radiative model. Moreover, the value of Z eff is estimated to be 1.00 in the tandem mirror GAMMA 10 plasma.
SOFT X-RAY REFLECTIVITY AND THERMAL STABILITY OF CoCr/C MULTILAYER X-RAY MIRRORS
Authors: TAKENAKA H. , NAGAI K. , ITO H. , ICHIMARU S. , SAKUMA T. , NAMIKAWA K. , MURAMATSU Y. , GULLIKSON E. , PERERA C. C.
Published: October 2002

The development of highly reflective multilayer mirrors for use in the wavelength region around 6 nm is desired for X-ray photoemission spectroscopy for inner-shell excitation using a Schwarzschild objective. For this application, reflectivity is the most critical parameter determining the performance of multilayer mirrors, because the reflectivity of multilayers in the 6 nm region is generally very low. We have designed CoCr/C multilayer mirrors with a comparatively high reflectivity at around normal incidence and have fabricated them by magnetron sputtering. The measured peak reflectivity is about 16% at a wavelength of around 6 nm and an incident angle of 88°. The reflectivity remains almost constant for 4 h under 300°C in an Ar atmosphere.
TEMPERATURE DEPENDENCE OF LASER-INDUCED HOT LUMINESCENCE OF SELF-TRAPPED EXCITONS IN SOLID XENON
Authors: SELG M. , KINK M. , KINK R. , MAKSIMOV J. , MARTINSON I.
Published: October 2002

Hot luminescence of self-trapped excitons in solid xenon has been investigated in a wide temperature range (from LHeT to 100 K), using X-ray and two-photon excimer laser (ArF and KrF) excitation. Hot luminescence of bulk Xe crystals of volume 2 cm 3 appears to be very sensitive to both the temperature and the quality of the samples, while its highest intensity has been registered under KrF laser excitation. The experimental results are in good accordance with a recent nonperturbative quantum relaxation theory of strong local vibrational excitations.
TEMPERATURE AND TIME DEPENDENCE OF EMISSION PROPERTIES OF ZnO FILMS DEPOSITED ON Si SUBSTRATES
Authors: ZHANG G. B. , ZHOU H. J. , SHI C. S. , SHI J. Y. , ZHOU Y. X. , ZHANG X. Y. , FU Z. X. , KIRM M. , ZIMMERER G.
Published: October 2002

The emission properties of ZnO films deposited on Si substrates by reactive dc sputtering have been studied using synchrotron radiation (SR). The integrated luminescence spectra as well as the spectra at a fast time window from about 4 ns to 8 ns and a slow time window from about 20 ns to 160 ns were measured simultaneously, at a temperature range from several K to 300 K. Apart from the bound-exciton radiation recombination (peaked at 369.5 nm) and ultraviolet emission band (peaked at 380 nm), a new emission band peaked at 290 nm was found for the first time under SR vacuum ultraviolet excitation. The mechanisms of these photoluminescence emissions are discussed.
XAS AND MCD STUDIES OF CrFe2O4
Authors: MIZUMAKI MASAICHIRO , AGUI AKANE , SAITOH YUJI , NAKAZAWA MAKOTO , MATSUSHITA TOMOHIRO , KOTANI AKIO
Published: October 2002

Magnetic circular dichroism (MCD) spectra of CrFe 2 O 4 have been measured by using the helicity switching method. The method achieves a high signal-to-noise ratio and resolved the fine structure in these spectra. The theoretical spectra, which were calculated by the charge transfer model, reproduced the experimental spectra. The origin of three negative peaks around the L3 edge in Cr 2p-MCD is attributed to the [Formula: see text] electron configuration in the initial state.
MAGNETIC CIRCULAR DICHROISM IN THE SOFT X-RAY ABSORPTION SPECTRA OF Co-BASED HEUSLER ALLOYS
Authors: YAMASAKI A. , IMADA S. , SUGA S. , KANOMATA T. , ISHIDA S.
Published: October 2002

Magnetic circular dichroism (MCD) of core-level absorption spectra (XAS) in the soft X-ray region has been measured for the ferromagnetic Heusler alloys Co 2 TiSn , Co 2 ZrSn , and Co 2 NbSn . The Co 2p → 3d XAS–MCD spectra show an obvious contribution of the orbital angular momentum component to the magnetic moment in these alloys. The ratio between the orbital and the spin magnetic moments derived from the MCD spectra varies by more than a factor of 2 within these alloys. The mechanism of this variation is discussed in comparison with the band structure calculation.
EXPERIMENTAL AND THEORETICAL STUDIES OF THE ELECTRONIC STRUCTURES OF AuAl2 AND PtGa2
Authors: HSU L.-S. , GUO G. Y. , DENLINGER J. D. , ALLEN J. W.
Published: October 2002

Synchrotron-radiation-excited angle-resolved photoemission spectra for the (100) and (111) faces of AuAl 2 and the (111) face of PtGa 2 are presented, along with derived experimental dispersion relations. These bands are compared with those obtained from the first-principles theoretical band-structure calculations. The total densities of states at the Fermi energy for these two materials are compared with those obtained from the specific-heat measurements. The energy variations of Au and Pt 5d bands for AuAl 2 and PtGa 2, respectively, show atomic-like behavior in the photon-energy range of 80–220 eV.
ELECTRONIC STRUCTURES OF LINEAR CARBON CHAIN MOLECULES
Authors: HINO S. , OKADA Y. , IWASAKI K. , KIJIMA M. , SHIRAKAWA H.
Published: October 2002

Photoelectron spectra of compounds having a linear carbon chain terminated by phenyl groups to stabilize the chain have been measured. The spectra consist of the contribution of phenyl groups and that of the chain part, which indicates small interaction between them. The highest occupied molecular orbital (HOMO) of these compounds derives from the carbon chain part. The longer the chain length becomes, the lower the binding energy of the HOMO. This fact implies the instability of a very long linear carbon chain. The spectra are well explained with the aid of semiempirical molecular orbital calculations.
THREE-DIMENSIONAL BAND MAPPING BY COMBINED VERY-LOW-ENERGY ELECTRON DIFFRACTION AND PHOTOEMISSION
Authors: STROCOV V. N. , CLAESSEN R. , STARNBERG H. I. , NILSSON P. O. , NICOLAY G. , HÜFNER S. , BLAHA P. , KIMURA A. , HARASAWA A. , SHIN S. , KAKIZAKI A.
Published: October 2002

Resolving the 3D wave vector k in photoemission mapping of the band structure E( k ) requires knowledge of the unoccupied final states. Both dispersions and lifetimes of these states can be achieved by very-low-energy electron diffraction (VLEED). By incorporating the non-free-electron and excited-state effects in the final states, combining VLEED with photoemission provides accurate mapping of the valence E( k ) resolved in the 3D wave vector and under control of the intrinsic accuracy. We here concentrate on the most accurate combined method which uses angle-dependent VLEED and photoemission measurements. It provides access to many Brillouin-zone lines using one crystal surface, and benefits from an intensity gain and a better intrinsic accuracy near the Fermi level.
Outsourcing at Fatima Memorial Hospital
Authors: Qureshi Zafar Iqbal
Published: October 2002

Fatima Memorial Hospital is the first charitable Trust Hospital in Pakistan, and its sponsoring body is Ferozesons Trust. In order to continue to provide services to the needy, the Trust needed to continuously improve its financial resources. When Dr. Qureshi took over the charge of the Hospital as its ACEC, he was asked to streamline the management systems to build a lean organization. He decided to outsource the janitorial services as a pilot project to achieve a number of objectives. If the janitorial services experiment proved successful, then the project would extend to laundry work as well. After the janitorial services were outsourced, concerns regarding cleanliness of the Hospital were brought up by patients and the management. They felt that the quality of service being provided by the contractor was not up to desired quality standards. In view of this, ACEC had two concerns: not to de-motivate the contractor; and not to compromise on the quality of service being provided by the contractor.
The Korean IPO Market: Initial Returns
Authors: Kim Byung-Ju , Kish Richard J. , Vasconcellos Geraldo M.
Published: October 2002

Most Korean IPOs show significant initial underpricing which accounts for high initial returns. Our study explores the institutional and regulatory factors that have affected both the offering and after-market pricing mechanisms to test several hypotheses that might explain this underpricing in the Korean IPO market. We find a systematic difference in the initial stock price performance of new issues in an environment where firms have different motives for going public. We also find that in less regulated periods, the explanatory power of the variables relating to both the signaling and ex ante uncertainty hypotheses increase.
COORDINATION GAMES WITH VANISHING ACTIONS
Authors: SCHOENMAKERS G. , FLESCH J. , THUIJSMAN F.
Published: October 2002

We deal with n-player coordination games with vanishing actions, which are repeated games where all non-diagonal entries yield zero-payoffs, and where, moreover, at any stage beyond ri any player i loses any action that she has not used during the previous ri stages of play. For these games we examine the set of equilibrium rewards, where we treat the two-player case and the more player case separately. Folk-theorem like results are established.
STABILITY OF THE CORE IN A CLASS OF NTU GAMES: A CHARACTERIZATION
Authors: BHATTACHARYA ANINDYA , BISWAS AMIT K.
Published: October 2002

The core and the stable set are possibly the two most crucially important solution concepts for cooperative games. The relation between the two has been investigated in the context of symmetric transferable utility games and this has been related to the notion of large core. In this paper the relation between the von-Neumann–Morgenstern stability of the core and the largeness of it is investigated in the case of non-transferable utility (NTU) games. The main findings are that under certain regularity conditions, if the core of an NTU game is large then it is a stable set and for symmetric NTU games the core is a stable set if and only if it is large.
RADIAL SOLUTIONS FOR WEIGHTED SEMILINEAR EQUATIONS
Authors: CATRINA FLORIN , LAVINE RICHARD
Published: October 2002

In this paper we prove the exact cut-off between existence and nonexistence of radial solutions in a class of problems of the Brezis–Nirenberg type. We obtain this by studying the existence/nonexistence of positive solutions in [Formula: see text] for -vtt+¼v=vp-1 +λe-ctv, for different values of the parameters c>0 and λ, for p≥2.
AN INTEGRATED MULTI-AGENT CSCW SYSTEM FOR CONCURRENT PRODUCT DEVELOPMENT
Authors: CAO JIAN , ZHANG SHENSHENG
Published: October 2002

Product development capability is more and more important for an enterprise in a knowledge-based economic era. In the philosophy of concurrent engineering, product development should be carried out in a concurrent way. Computer support is necessary for Concurrent Product Development (CPD). As an excellent tool to meet complex needs, CSCW has been used in CPD. But nearly all CSCW systems that have been developed so far concentrate on a more or less narrow sub-field of cooperative work. Thus, the need of integrated CSCW applications are apparent. The agent is a suitable programming paradigm that can be used to meet the complex needs. In this paper, a P-PROCE (Process, Product, Resource, Organization, Control & Evaluation) model is introduced for CPD firstly. By categorizing the agents of the multi-agent system (MAS) into different types of agent according to P-PROCE model and offering a structure of MAS, the CPD is mapped to MAS. The cooperation among agents is very important for MAS. In the paper, a two-layer cooperation structure of MAS is proposed. In the macro layer, agent based workflow control the CPD process and in the micro layer the entity agents interact with each other directly to fulfill the task. The key issues of these two cooperation layers are discussed in the paper. Component based structure of agent and an implemented case are also provided in the paper.
A REVIEW ON THE INTERACTION ISSUES IN AGENT-BASED MARKETPLACES
Authors: KONING JEAN-LUC
Published: October 2002

While there are already literature surveys upon agent-mediated electronic commerce applications, none have specifically tackled the issue from an interaction perspective or looked at how the control is distributed among the agents. This state-of-the-art survey focuses on how agent interactions are handled. First, it deeply looks at how methods for enforcing the actions taken by agents have been dealt with, namely protocols, negotiation and auction. Second, it defines the various types of communication languages used in multi-agent market architectures. The three main alternatives are KQML, ACL and FLBC. A comparison is then made between them and shows how much they suite their purpose. Third, this paper highlights how the current electronic commerce applications provide explicit and integrated support for complex agent interactions and present several virtual institutions where agents are engaged in multiple bilateral negotiations. Finally, it discusses some related research perspectives and identify some limitations.
AN XML-CENTRED SYSTEM ARCHITECTURE FOR FLEXIBLE ELECTRONIC SERVICES
Authors: WESKE MATHIAS , SCHNEIDER BERND
Published: October 2002

Derived from a set of business models for electronic commerce, a system architecture based on XML is introduced, which supports the proposed business models adequately. The modular design of the architecture and its flexibility is demonstrated by a sample application, which implements an online supermarket based on a franchising business model. To show the flexibility of the architecture, personalization components are designed and implemented in the sample application.
QUANTITATIVE QUANTUM DYNAMICS CALCULATION OF H2 + CH3 → H + CH4 REACTION
Authors: LI YI M. , ZHANG JOHN Z. H.
Published: October 2002

We report in this paper quantum dynamics calculation of state-selected reaction probabilities for a benchmark chemical reaction H 2 + CH 3 → H + CH 4 on an ab initio potential energy surface. The quantum dynamics calculation is based on the recently developed semirigid vibrating rotor target (SVRT) model and involves six degrees of freedom. The present result is the first such high-level quantum dynamics calculation of microscopic reaction probability for a chemical reaction between two molecules with at least one of the reagents being larger than a diatomic molecule.
FURTHER GENERALIZATION AND NUMERICAL IMPLEMENTATION OF PSEUDO-TIME SCHRÖDINGER EQUATIONS FOR QUANTUM SCATTERING CALCULATIONS
Authors: MANDELSHTAM VLADIMIR A. , NEUMAIER ARNOLD
Published: October 2002

We review and further develop the recently introduced numerical approach [Phys. Rev. Lett. 86, 5031, (2001)] for scattering calculations based on a so called pseudo-time Schrödinger equation, which is in turn a modification of the damped Chebyshev polynomial expansion scheme [J. Chem. Phys. 103, 2903, (1995)]. The method utilizes a special energy-dependent form for the absorbing potential in the time-independent Schrödinger equation, in which the complex energy spectrum is mapped inside the unit disk Ek → uk, where uk are the eigenvalues of some explicitly known sparse matrix U. Most importantly for the numerical implementation, all the physical eigenvalues uk are the extreme eigenvalues of U (i.e. |uk| ≈ 1 for resonances and |uk| = 1 for the bound states), which allows one to extract these eigenvalues very efficiently by harmonic inversion of a pseudo-time autocorrelation function y(t) = ϕ T Ut ϕ using the filter diagonalization method. The computation of y(t) up to time t = 2T requires only T sparse real matrix-vector multiplications. We describe and compare different schemes, effectively corresponding to different choices of the energy-dependent absorbing potential, and test them numerically by calculating resonances of the HCO molecule. Our numerical tests suggest an optimal scheme that provide accurate estimates for most resonance states using a single autocorrelation function.
Positron Annihilation in Proton Irradiated Czochralski-Grown Si
Authors: Uedono Akira , Cho Yang-Koo , Ikari Shoichiro Tanigawa
Published: October 2002

Defects introduced by 65 MeV proton irradiation into Czochralski-grown Si were investigated by the positron annihilation technique. Doppler broadening profiles of the annihilation radiation and lifetime spectra of positrons were measured as a function of isochronal annealing temperature. Divacancies introduced by the irradiation were found to migrate above 200° C and they formed stable vacancy-oxygen complexes such asV3On(n=1–3). These defects annealed out at ∼500° C. After the recovery of vacancy-oxygen complexes, oxygen clusters were found to be the predominant defect. The aggregation of the oxygen clusters started above 800° C.
NMR Study of Magnetic and Compositional Inhomogeneities in Co–Cr Thin Films
Authors: Takei Koji , David J. Rogers David J. Rogers , Yasushi Maeda Yasushi Maeda
Published: October 2002

Spin-echo 59Co NMR is employed to detect magnetically distinct components in a Co–Cr thin film. Magnetic components with different values of the anisotropy field can be detected by measuring spin-echo intensity as a function of rf pulse field applied to the sample. For a film deposited at 400°C, two magnetic components are observed. The chemical composition is estimated for each component from the NMR frequency spectra.
Excitation Processes of a Dye Doped into an Amorphous Material Investigated by Photochemical Hole-Burning
Authors: Horie Norio Murase
Published: October 2002

This paper discusses the excitation processes of a dye doped into an amorphous material as studied by using the photochemical hole-burning (PHB) technique. Our system is sulfonated tetraphenylporphin doped into poly(vinyl alcohol). The observed data were the extents of laser-induced hole filling (LIHF) in PHB at 20 K for wavelengths longer than the wavelength of the newly burned hole. Quantitative analysis using the least-squares method showed that the measured extents of LIHF can be explained by system parameters expressing non-site-selective excitations: the Debye-Waller factor, the energy of lattice vibrational excitation accompanied by the purely electronic excitation, and other parameters related to two kinds of vibronic excitations.
Partial Discharges in Gaseous Voids for DC Voltage
Authors: Frederik H. Kreuger Frederik H. Kreuger , Udo Fromm Udo Fromm
Published: October 2002

When designing ac insulation systems much knowledge and experience is available concerning partial discharges. However, for dc insulation there is a lack of knowledge of partial discharges and their effect on reliability and lifetime. For this reason we conducted a study on the distribution functions of the discharge magnitude and the time between two discharges. A model has been developed to describe the discharge behavior for dc voltage. The measurement results are in agreement with the proposed model. The extinction voltage of the discharges is close to the ignition voltage. The discharge frequency is mainly determined by the statistical time lag (period between reaching a voltage sufficient to cause breakdown and the breakdown itself). The statistical time lag depends strongly on the test voltage.
Ferroelectric Liquid Crystal Mixtures Containing Chiral Pyranose Compounds for Response-Voltage Minimum Mode
Authors: Koden Mitsuhiro , Kaneko Takashi , Tamai Kazuhiko , Takeda Hitoshi , Miyoshi Shuji , Wada Tomio , Takeda Mitsunori , Itoh Keizou , Yamazaki Takashi , Kitazume Tomoya
Published: October 2002

Ferroelectric liquid crystal (FLC) materials for the response-voltage minimum (τ–V
min
) mode were developed by doping novel chiral pyranose compounds into achiral host materials with negative dielectric anisotropy. The chiral pyranose derivatives, wherein three chiral centers and a trifluoromethyl group were fixed in the 6-membered ring, induced short τmin
in the τ–V
min
characteristic. The developed FLC materials were driven by drive schemes for the τ–V
min
mode, giving short line address times.
Far-Infrared Properties of Bi2Sr2Ca2Cu3Oxin Pulsed High Magnetic Fields
Authors: Yasuhiro Shimamoto Yasuhiro Shimamoto , Tadashi Takamasu Tadashi Takamasu , Noboru Miura Noboru Miura , Nobuhiko Kubota Nobuhiko Kubota , Yuh Shiohara Yuh Shiohara
Published: October 2002

Far-infrared (FIR) transmission measurements have been performed in Bi2Sr2Ca2Cu3Oxsuperconducting thin films in high pulsed magnetic field. We have observed a marked difference in the field dependence of FIR transmission between photon energies above and below the energy gap 2Δ (B=0). That is, the transmission increases below 2Δ and decreases above 2Δ with increasing field. We found that the magnetic field dependence of the transmission for various wavelengths in the FIR region can be explained by the flux flow model under the assumption that the effects of flux pinning are negligible.
Photoinduced Current of a CuO/ZnO Thin-Film Heterojunction in Humid Atmosphere
Authors: Ushio Yoshijiro , Miyayama Masaru , Yanagida Hiroaki
Published: October 2002

The effects of the light illumination on the humidity sensing properties of a CuO/ZnO thin-film heterojunction where the interface is partly exposed to atmosphere were investigated. When ultraviolet light ( ∼400 nm) was applied to the heterojunction, a very large photoinduced current, about two orders of magnitude larger than that in dry air, was observed under humid conditions at the forward bias of the p-n junction above about 1 V. The increase of photoinduced current is assumed to be due to desorption of adsorbed oxygen species on ZnO promoted by the adsorption of water molecules and the application of the forward bias, which caused the changes of interface states.
Electrical Properties of Pyrolyzed and Electrochemically Lithium-Doped Poly(hydrazocarbonyl-1,4-phenylenecarbonyl) Film
Authors: Roh Young Bae , Araki Hisashi , Yoshino Katsumi , Takase Masaaki , Banjyo Takashi
Published: October 2002

The carrier transport and detailed carbonization processes of pristine (poly (hydrazocarbonyl-1,4-phenylenecarbonyl):PHP) film have been investigated as a function of heat-treatment temperature (HTT). Formation of (poly(1,3,4-oxadiazole-2,5-diyl-1,4-phenylene):POP) at HTT=400°C is confirmed and explained by the dehydration reaction of PHP molecular structure. Conductivity (σ) increases by 20 orders of magnitude from 10-18 S/cm with HTT of 1000°C. The enhancement of σ with HTT up to 600°C has been interpreted by the increase of localized charge carrier and the most prominent effect of the enhancement of σ by HTT above 800°C has been explained by not only the increase of carrier density but also the increase of mobility. Even in the sample of low HTT ( <500°C), σ is enhanced and its activation energy decreases upon electrochemical Li doping. On the other hand, in the sample of high HTT ( 800–1000°C) σ decreases slightly and its activation energy increases. Electrical conduction in the sample of low HTT ( <600°C) is explained by three-dimensional variable range hopping (3D-VRH). On the other hand, in the nondoped and Li-doped sample of high HTT ( ≥600°C), the conduction process is explained by taking both 3D-VRH and metallic conduction processes into consideration.
Characteristics of Ablation Plasma Produced by Intense, Pulsed, Ion Beam
Authors: Kang Xiangdong , Katsumi Masugata Katsumi Masugata , Kiyoshi Yatsui Kiyoshi Yatsui
Published: October 2002

Characteristics of ablation plasma produced by the irradiation of an intense, pulsed, ion beam on targets, which has been known to be very effective in preparing thin films and is known as ion-beam evaporation (IBE), have been investigated experimentally by time-of-flight of ion-flux density measured by biased ion collector (BIC). With ion-beam power density of ∼109 W/cm2, the velocity and the kinetic energy of the ablation plasma were measured at various positions from the substrate using a titanium or aluminum target. An analytic solution derived from one-dimensional hydrodynamic expansion into a vacuum has been developed for the IBE process. Using such a model, it is possible to deduce the temperature in IBE from the signals of BICs. This method is also applicable to other intense pulsed energy sources such as lasers or electron beams.
Depth Profiling of Hg1-xCdxTe by Secondary Ion Mass Spectrometry: Detecting CsX+ with Cs+ Ion Beam
Authors: Hayashi Shun-ichi , Hashiguchi Yoshihiro , Fujii Satoshi , Kitazima Hideo
Published: October 2002

Hg1-
x

Cd

x

Te (MCT) multilayers grown by photoassisted metal organic chemical vapor deposition (MOCVD) utilizing the interdiffused multilayer process (IMP) have been investigated by secondary ion mass spectrometry (SIMS). The SIMS measurement used a primary ion beam of Cs and the detected secondary ions were of the form CsX+ (X=Cd, Te and Hg). The secondary ion intensity of CsHg+ was higher than that of Hg+ by about two orders of magnitude. CsX+ detection was shown to achieve excellent linearity with the content of Hg in a series of Hg1-
x

Cd

x

Te samples (x=0, 0.2, 0.3, 0.375 and 1.0). CsX+ detection by SIMS was proven to be a very useful technique for the evaluation of the thin multilayers in the MCT samples whose layers have 180 nm to 360 nm in thickness.
Rare-Earth Barium Niobates:*A New Class of Potential Substrates for YBa2Cu3O7-δSuperconductor
Authors: Koshy Jacob , Kurian Jose , Thomas Jijimon K. , Yogendra P. Yadava Yogendra P. Yadava , Alathoor D. Damodaran Alathoor D. Damodaran
Published: October 2002

A class of complex perovskites REBa2NbO6(where RE=Pr, Nd, Sm and Eu) have been sintered as single phase materials having a high sintered density and stability, for their use as substrates for YBa2Cu3O7-δsuperconductors. The structure of these materials was studied by X-ray diffraction technique and all of them were found to be isostructural having a cubic perovskite structure. These newly developed materials do not react with YBa2Cu3O7-δsuperconductors even after annealing 1:1 volume mixture at 950° C for 15 h. The presence of REBa2NbO6upto 20 vol% in the YBa2Cu3O7-δ–REBa2NbO6composite did not show any deterimental effect on the superconducting transition temperature of YBa2Cu3O7-δ. Dielectric constant and loss factor of REBa2NbO6were found to be in the range suitable for their use as substrates for microwave applications. Superconducting YBa2Cu3O7-δthick films screen-printed on these new substrates gave a zero transition temperatureTc0≈92 K and current density≈2×105A/cm2at 77 K.
Microstructure and Magnetic Properties of Mechanically Alloyed Fe–Zn
Authors: Pan Chi-Wen , Chang Yen-Hwei , Chin-Chuan Hsu Chin-Chuan Hsu , Ming-Pan Hung Ming-Pan Hung
Published: October 2002

The coercivity of the as-milled samples had a maximum value of 90 Oe for 33.9 wt%Zn. When annealed at 400° C for 10 days, the metastableεphase, and Γ and Γ1phases appeared with 9.75 wt%Zn, and 33.7 wt%Zn, respectively. The α-Fe phase disappeared at 73.3 wt%Zn, causing the saturation magnetization to decrease drastically to 2 emu/g. The precipitation of the metastableεphase in the annealed samples containing 24.2 wt%Zn had a maximum coercivity of 175 Oe. A single α-Fe phase is obtained upon solution treatment at 800° C for 1 h. After aging, precipitation of theεphase occurred for Zn content above 6.74 wt%. The saturation magnetisation and the coercivity of aged samples were larger than those of solution-treated samples.
Effects of Electron Beam Damage on the Electrical Characteristics of n-type Metal-Oxide-Semiconductor Field-Effect-Transistors
Authors: Jeon Young Jin , Chun Sin-Chong Park
Published: October 2002

The effects of electron beam damage on the degradations of n-type metal-oxide-semiconductor field-effect-transistors (n-MOSFETs) due to the creation of interface traps were investigated using charge-pumping and subthreshold slope measurement methods. The in situ device characteristics such as threshold voltage were not changed much by the electron beam damage as compared with those of virgin ones if the devices were annealed properly. The long-term reliability characteristics, however, were significantly degraded even with a small dose of electron beam irradiation. Moreover, device lifetimes were shown to decrease at a fast rate as the electron beam irradiation dose was increased even after annealing. It was also observed that the interface trap density dependency on electron beam irradiation dose investigated by the charge-pumping method was highly consistent with that by the subthreshold slope measurement technique.
Diffusion Behavior of Point Defects in Si Crystal during Melt Growth IV: Numerical Analysis
Authors: Habu Ryuichi , Iwasaki Toshio , Harada Hirohumi , Tomiura Azusa
Published: October 2002

This paper describes a numerical analysis technique for the solution of the phenomenological diffusion equations of point defects in silicon single crystals during melt growth. The calculation, which assumes an entropy barrier against the pair annihilation reaction between point defects (self-interstitials and vacancies), gives a distribution of point defects which closely agrees with the distribution of grown-in crystal defects observed in CZ-crystals.
Surface Passivation of In0.52Al0.48As Using (NH4)2Sxand P2S5/(NH4)2S
Authors: Yoshida Nobuhide , Totsuka Masahiro , Junsuke Ino Junsuke Ino , Satoru Matsumoto Satoru Matsumoto
Published: October 2002

(NH4)2Sxand P2S5/(NH4)2S treatments were applied on In0.52Al0.48As surfaces. From X-ray photoelectron spectroscopy measurements, residual sulful atoms on the surface were found to form In–S, Al–S, and As–S bonds. The performance of Schottky diodes was improved by (NH4)2Sxand P2S5/(NH4)2S treatments in terms of the reverse leakage current and barrier height. In addition, the advantage of using P2S5/(NH4)2S was revealed compared with (NH4)2Sx.
Defect Equilibration and Intrinsic Stress in Undoped Hydrogenated Amorphous Silicon
Authors: Kitsuno Yu , Cho Gyuseong , Drewery John , Wan-Shick Hong Wan-Shick Hong , Victor Perez-Mendez Victor Perez-Mendez
Published: October 2002

Relaxation data for the thermal equilibrium defect densities in undoped a-Si:H are obtained by time-of-flight (TOF) measurement in the temperature range of 160° to 250° C. The internal stress in the material is also measured. The mobility-lifetime product of electrons (µτ) increases from 0.50×10-7 to its equilibrium value of 2.24×10-7 cm2/V during the 160° C annealing. The equilibrium value of µτ is equivalent to the spin density (N
s) of 1.12×1015 cm-3. The N
s curves have a minimun value just before their equilibrium. The time dependence of the N
s relaxation follows a two-term stretched exponential form which corresponds to two metastable states, and each relaxation time is activated with activation energies of 1.10 to 1.20 eV. The thermal equilibrium N
s increases with temperature with an activation energy of 0.20 to 0.30 eV. The data for the second annealing at 160° C after the first long annealings at 200° and 250° C also follows the two-term stretched exponential form derived from the first annealing data. The result suggests the presence of a multivalley energy configuration diagram at metastable states. The drift mobility of electrons (µ) increases slightly compared with the µτ changes, and no stress change is observed during the various annealing steps. It is concluded that the structural change is much smaller than the change in metastable-state densities during annealing in the temperature range of 160° to 250° C.
Magnetostatic Uniaxial Anisotropy in Metal Magnetic Tape
Authors: Masuda Morio , Maeda Kohji , Tadashi Kobayashi Tadashi Kobayashi , Shigeru Shiomi Shigeru Shiomi
Published: October 2002

The magnetostatic uniaxial anisotropy observed in metal magnetic films has been investigated theoretically and experimentally. The theoretical calculation has been carried out, assuming, for an assembly of magnetic particles, a simplified model where ellipsoidal magnetic particles form a three-dimensional periodic array and the direction of their major axes fluctuates from the longitudinal direction. The theoretical calculation has been found to be successful in interpreting the experimental results of the samples prepared in this work as well as those supplied by a few magnetic tape manufacturers.
Time Dependent Resistance Increase in Poly-Si Load Resistor due to Hydrogen Diffusion from Plasma-Enhanced Chemical Vapor Deposition Silicon Nitride Film in High Density Static Random Access Memories
Authors: Hideki Shibata Hideki Shibata , Kazuhiko Hashimoto Kazuhiko Hashimoto
Published: October 2002

A study has been done on hydrogen diffusion into poly-Si load resistors in high density static random access memories (SRAMs) from plasma-enhanced chemical vapor deposition (CVD) silicon nitride film. For the first time, it was found that the resistance of load resistors in 1 Mbit SRAMs increases in proportion to the time during high temperature duration testing, resulting in time dependent retention current decrease. This phenomenon is due to the decrease in trap density at the poly-Si grain boundaries, which in turn is caused by continual hydrogen diffusion from plasma-CVD nitride film. It was also confirmed that hydrogen diffuses through not only upper-side dielectrics but also back-side dielectrics and/or the poly-Si/dielectric interface. Furthermore, from these experimental results, a empirical equation is proposed for the resistance change, and the increase in resistance over 10 years is predicted to be 20% at 125° C.
Magnetoresistance and Preferred Orientation in Fe–Mn/Ni–Fe/Cu/Ni–Fe Sandwiches with Various Buffer Layer Materials
Authors: Nakatani Ryoichi , Hoshino Katsumi , Shin Noguchi Shin Noguchi , Yutaka Sugita Yutaka Sugita
Published: October 2002

Magnetoresistance effects and film structures have been investigated in [Fe–Mn/Ni–Fe/Cu/Ni–Fe/buffer layer/Si] sandwiches with various buffer layer materials. The sandwich with Nb, Ta, Ti, Zr or Hf buffer layer has strong (111) texture. Cu, Ag, Au and Cr buffer layers do not cause strong (111) texture. When the sandwich has strong (111) texture, the Ni–Fe layer neighboring the Fe–Mn antiferromagnetic layer is strongly exchange-biased by the Fe–Mn layer, and thus the sandwich shows a high magnetoresistance ratio.
A New Kinetic Model for Assessing the Performance of Advanced CO2 Gasdynamic Lasers
Authors: Ebina Kosuke , Yokozawa Takeshi , Yamaguchi Shigeru , Kanazawa Hirotaka , Hara Hiroshi , Mine Yasuharu , Komatsu Katsuhiko , Saito Hideaki
Published: October 2002

A theoretical analysis of CO2 gasdynamic laser ( CO2-GDL) performance using a six-temperature model is described in this paper. This model has specifically included vibrational transfer processes associated with vibrational non equilibrium of O2 and H2O so that the kinetic behaviors of these species in an active laser medium can be properly assessed. The calculation carried out with this model showed that presence of O2 in the laser medium together with H2O reduces the population inversion. Consequently, under the condition where the concentration of H2O was ∼4 mol%, every additional percent of O2 was found to be about one percent reduction in the small signal gain of a CO2-GDL. The calculation resulted in good agreement with experimental studies in the variation of the small signal gains as well as vibrational temperatures for various laser gas composition.
Ferroelectric Behavior in Aliphatic Polyurethanes
Authors: Tasaka Shigeru , Shouko Toshikatu , Kei-ichi Asami Kei-ichi Asami , Norihiro Inagaki Norihiro Inagaki
Published: October 2002

Ferroelectric behavior was first found in aliphatic polyurethanes, poly(trimethylene-heptamethylene dicarbamate) (3,7-polyurethane) and poly(pentamethylene-hexamethylene dicarbamate) (5,6-polyurethane). From a displacement-field (D-E) hysteresis loop, remanent polarization was estimated as 50–60 mC/m2 for both polymers. The remanent polarization in annealed 3,7-polyurethane was stable over the glass transition temperature (30° C) up to 115° C, from which the reorientation of hydrogen bondings takes place in crystal. These polyurethanes with not only an odd-odd number but also an even-odd number of CH2 groups are likely to form a ferroelectric crystal. No Curie point was found up to their melting points.