A modified alignment method based on four-quadrant-grating moiré for proximity lithography

In this paper, we demonstrate a modified coarse-fine alignment scheme designed for proximity lithography. Both wafer alignment mark and mask alignment mark consists of linear grating arrays and “+” bar. Coarse alignment and fine alignment could work together to achieve the perfect alignment. Thereinto, coarse alignment, measured from two superposed “+” bars, guarantees the misalignment across wafer and mask within the measurement range of fine alignment, which is based on moiré fringes formed by the superposition of linear grating arrays. Then we conduct the experiments using a nanometer actuator to drive the wafer alignment mark meanwhile keeping the mask alignment mark motionless, which validates the feasibility and rationality of our designed scheme.     

A Big Horizontal Solar Telescope of the Main Astronomical Observatory of the Ukrainian National Academy of Sciences in the caucasus

This paper presents the Big Horizonal Solar Telescope of the Main Astronomical Observatory of the Ukrainian National Academy of Sciences installed at the Peak Terskol high-altitude station near Elbrus (the main mirror diameter is 650 mm and the focal length is 17.5 m). The telescope is equipped with a five-camera spectrograph intended for photographic spectral observations of active regions in the solar atmosphere and photoelectric measurements of the solar spectra with high spectral and spatial resolution. The observation procedure is described, and the results of the quality analysis of the recorded spectra and of the early measurements are presented.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 10, pp. 1326–1333, October, 1996.The authors wish to express their gratitude to C.I.Gandzha, V.V.Kul'beda, and Yu. M. Gavrilyuk from the Solar Physics Department of the PAO of the Ukrainian NAS and to the Board of Directors of the Observatory and of the High-Altitude Station for help in the development of the instrument.This paper is dedicated to the memory of E. A. Gurtovenko, D.Sc. in Phys. and Math., who initiated the installation of the telescope at Peak Terskol and who was the leader, an executor, and an observer in this project.     

The reciprocal of a Borel summable function is Borel summable

It is proven that if a functionF is Borel summable in some angular region and has a non-vanishing derivative at the origin, then its reciprocalF ^–1 is also Borel summable in a region which has essentially the same angular extent.Physique Mathématique et Théorique, Unité associée au CNRS No. 768     

In situ Video-STM study of the potential-induced (1 × 1) → “hex” transition on Au(1 0 0) electrode surfaces in Cl containing solution

The potential-induced (1 × 1) → “hex” transition on Au(1 0 0) electrodes in 0.01 M Na₂SO₄ + 1 mM HCl was studied by in situ scanning tunneling microscopy at high time resolution (Video-STM). According to these observations the elementary units of the “hex” surface reconstruction, hexagonally-ordered strings in the Au surface layer, are highly dynamic nanoscale objects. Isolated “hex” strings exhibit dynamic fluctuations in structure and position on the millisecond timescale. These fluctuations exceed the mobility of multistring “hex” domains by several orders of magnitude and can be explained by collective dynamic processes within the strings. Furthermore, the observations reveal a novel 1D mass transport mechanism along the strings, details on the nucleation and growth of “hex” strings and complex string restructuring processes, facilitating “hex” domain ripening.     

IceHEP high energy physics at the South Pole

With the solar and SN87 neutrino observations as proofs of concepts, the kilometer-scale neutrino experiment IceCube will scrutinize its data for new particle physics. In this paper, we review the prospects for the realization of such a program. We begin with a short overview of the detector response and discuss the reach of “beam” luminosity. After that we discuss the potential of IceCube to probe deviations of neutrino-nucleon cross-sections from the Standard Model predictions at center-of-mass energies well beyond those accessible in man-made accelerators. Then we review the prospects for extremely long-baseline analyses and discuss the sensitivity to measure tiny deviations of the flavor mixing angle, expected to be induced by quantum gravity effects. Finally, we discuss the potential to uncover annihilation of dark matter particles gravitationally trapped at the center of the Sun, as well as processes occurring in the early Universe at energies close to the Grand Unification scale.     

Molecular precursor-mediated methanol dissociation on Si(1 1 1)7 × 7: ab initio study

We present an ab initio study of methanol interaction with the Si(1 1 1)7 × 7 surface using a Si(1 1 1)4 × 2 model. The study of the methanol dissociation on Si(1 1 1)4 × 2 shows that pair dissociation on adatom-restatom dangling bonds is largely favoured, in agreement with the experimental observations. The “center” type adatom is slightly more reactive than the “corner” type one, although the difference is weak. Similar behaviour is observed in both adatom types. Our results for a direct CH₃OH dissociation favouring a basic cleavage (adsorption of OH and CH₃ fragments) rather than an acidic one (adsorption of H and OCH₃ fragments), we are finally led to take a kinetic effect into consideration to reconcile theory with experiment. We show that the presence of molecular precursor states is possible. Different orientations with respect to the silicon dangling bonds of these molecular precursors are investigated. However, the corresponding energies are very close and, considering their relative energies, it is finally difficult to discriminate between acidic and basic cleavages.     

Fractional motions

Brownian motion is the archetypal model for random transport processes in science and engineering. Brownian motion displays neither wild fluctuations (the “Noah effect”), nor long-range correlations (the “Joseph effect”). The quintessential model for processes displaying the Noah effect is Lévy motion, the quintessential model for processes displaying the Joseph effect is fractional Brownian motion, and the prototypical model for processes displaying both the Noah and Joseph effects is fractional Lévy motion. In this paper we review these four random-motion models–henceforth termed “fractional motions” –via a unified physical setting that is based on Langevin’s equation, the Einstein–Smoluchowski paradigm, and stochastic scaling limits. The unified setting explains the universal macroscopic emergence of fractional motions, and predicts–according to microscopic-level details–which of the four fractional motions will emerge on the macroscopic level. The statistical properties of fractional motions are classified and parametrized by two exponents—a “Noah exponent” governing their fluctuations, and a “Joseph exponent” governing their dispersions and correlations. This self-contained review provides a concise and cohesive introduction to fractional motions.     

Characteristics of Radio Telescopes with Multielement Microstrip Focal Arrays

We calculate beam patterns (BPs) and power characteristics of radio telescopes in the multibeam regime with the use of different types of microstrip focal arrays. A terrace design of focal array for illumination of the asymmetric secondary mirror of the RATAN-600 radio telescope and a symmetric paraboloid dish is proposed. Ways for optimization of this type of array are considered. Characteristics of a radio telescope with a millimeter-wave planar circularly polarized focal array are calculated. Some applications of multibeam microstrip focal arrays are considered.__________Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika,Vol.48, No. 2, pp. 95–109, February 2005     

Observation of the 2005 January 20 GLE Event Using Yangbajing Solar Neutron Telescope & Neutron Monitor

A solar cosmic rays Ground Level Enhancement(GLE) event associated with a X7.1/2b solar flare in 2005 January 20 was observed by the Yangbajing solar neutron telescope(SNT) and neutron monitor(NM), located at Yangbajing Tibet(90.53°E, 30.11°N, 4310m a.s.l) with the highest vertical geomagnetic cut-off rigidity of 14.1GV in NM network. The statistical significance of the counting rate enhancement recorded by solar neutron telescope in >40MeV channel was 3.7σ in the time window of 07:00—07:05UT and 6.0σ in the time window of 07:00—07:20UT, respectively. The onset time of 06:51—06:52UT for this GLE event was clearly observed by the Yangbajing NM. Our observation indicates that solar protons have been accelerated up to energies of >10GeV during this solar event.     

Zero-level problem of solar magnetographs and observations of large-scale magnetic fields

This paper discusses some aspects of the zero-level problem of solar magnetographs which is particularly important for observations of large-scale magnetic fields on the Sun. Experiments at the STOP telescope of the Sayan Solar Observatory (SSO) showed that in addition to the adjustment errors of the polarization analyzer, the focusing errors of the spectrograph, and the linear polarization of the light (these mechanisms were known previously [5]), spurious signals of the magnetograph are brought about by polarization effects in the optical details preceding the polarization analyzer (coelostat mirrors and the objective) and aberration errors of the spectrograph. Disadvantages of the method of monitoring the zero level from the nonmagnetic line 512.37 nm FeI are pointed out. A correlation was made between the observations of the solar mean magnetic field in the SSO and WSO (Wilcox Solar Observatory, Stanford, USA) — the observatories which use the different methods of zero-level monitoring.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 10, pp. 1306–1314, October, 1996.In closing, the author wishes to express his gratitude to V. M. Grigoryeva and V. A. Kotov (the Crimean Observatory) for discussing some problems in this study, S. Chuprakov (Institute of Solar-Terrestrial Physics, Siberian Branch of the RAS) for consultations on how to operate the DEMOS software, and P. Scherrer (SSO) for providing original Stanford observations of the solar MMF and allowing us to use them in this paper.The results presented in this paper were supported in part by the International Science Foundation under Grant No. NN3000 and the Russian Foundation for Fundamental Research under Grant No. 96-02-16638.     

How much can one break chiral symmetry in the linear sigma model?

We show that the hedgehog soliton solution describing the nucleon in theSU(3) ×SU(3) linear sigma model breaks down when the pion mass becomes too large.On leave of absence from the Laboratoire de Physique Théorique, Université de Nice, parc Valrose, F-06034 Nice Cedex, France     

Quasi-free states of the C.C.R.—Algebra and Bogoliubov transformations

We give a complete characterization of quasi-free states (generalized free states) of the C.C.R. algebra. We prove that the pure quasi-free states areall Fock states and that any two Fock states are related through a symplectic automorphism (Bogoliubov transformation). We make an explicit construction of these representations which correspond to primary quasi-free states.Work under contract D.G.R.S.T.Attaché de Recherches au C.N.R.S. This work is part of a Thèse de Doctorat d'Etat presented to the Faculté des Sciences de Marseille in May 1968, under the number A.O.2.323.Aangesteld Navorser van het Belgisch N.F.W.O. On leave from University of Louvain (Belgium).     

Discrete Painlevé equations and their appearance in quantum gravity

We discuss an algorithmic approach for both deriving discrete analogues of Painlevé equations as well as using such equations to characterize similarity reductions of spatially discrete integrable evolution equations. As a concrete example we show that a discrete analogue of Painlevé I can be used to characterize similarity solutions of the Kac-Moerbeke equation. It turns out that these similarity solutions also satisfy a special case of Painlevé IV equation. In addition we discuss a methodology for obtaining the relevant continuous limits not only at the level of equations but also at the level of solutions. As an example we use the WKB method in the presence of two turning points of the third order to parametrize (at the continuous limit) the solution of Painlevé I in terms of the solution of discrete Painlevé I. Finally we show that these results are useful for investigating the partition function of the matrix model in 2D quantum gravity associated with the measure exp [–t ₁ z ² –t ₂ z ⁴ –t ₃ z ⁶].     

A case of subdominant/suppressed “high energy” contribution to the baryon asymmetry of the Universe in flavoured leptogenesis

The CP-violation necessary for the generation of the baryon asymmetry of the Universe YB$Y_B$ in the “flavoured” leptogenesis scenario can arise from the “low energy” PMNS neutrino mixing matrix U   and/or from the “high energy” part of neutrino Yukawa couplings, which can mediate CP-violating phenomena only at some high energy scale. The possible interplay between these two types of CP-violation is analysed. The type I see-saw model with three heavy right-handed Majorana neutrinos having hierarchical spectrum is considered. We show that in the case of inverted hierarchical light neutrino mass spectrum, there exist regions in the corresponding leptogenesis parameter space where the relevant “high energy” phases have large CP-violating values, but the purely “high energy” contribution in YB$Y_B$ plays a subdominant role in the production of baryon asymmetry compatible with the observations. In some of these regions the purely “high energy” contribution in YB$Y_B$ is so strongly suppressed that one can have successful leptogenesis only if the requisite CP-violation is provided by the Majorana phase(s) in the neutrino mixing matrix.     

Borel summability for a nonpolynomial potential

We consider the energy levels of a one-dimensional quantum system in the rational potential 1/2x ²±gx ⁴/(1+gx ²). Their perturbation expansions ing are shown to be Borel summable. The proof is flexible enough to allow simple extensions to other nonpolynomial interactions.Physique Mathématique et Théorique, Equipe de Recherche associée au CNRS     

A Multibeam SIS Mixer Module for a Focal Plane Array Receiver

The integration of many receiver units into a receiver array is a common method of improvement of imaging systems. This approach, well known in the mm band for Schottky mixer arrays, has not so far been developed for Superconductor - Insulator - Superconductor (SIS) junction mixers, which give the best sensitivity in the short mm wave range and in the submm range.We demonstrate for the first time a practical low noise multibeam receiver module using SIS mixer technology. The basis for the integration of several SIS mixers with a common local oscillator source is given by the saturation of the SIS receiver noise dependence upon local oscillator power. The module comprises three identical SIS mixers integrated with a common local oscillator, coupled through a three branch waveguide directional coupler. The multibeam module has been developed for a focal plane array receiver of the 30 meter radio telescope of the Institut de Radioastronomie Millimétrique (IRAM).     

Peculiar acceleration

It has been proposed recently to observe the change in cosmological redshift of distant galaxies or quasars with the next generation of large telescope and ultra-stable spectrographs (the so-called Sandage–Loeb test). Here we investigate the possibility of observing the change in peculiar velocity in nearby clusters and galaxies. This “peculiar acceleration” could help reconstructing the gravitational potential without assuming virialization. We show that the expected effect is of the same order of magnitude of the cosmological velocity shift. Finally, we discuss how to convert the theoretical predictions into quantities directly related to observations.     

Magneto-optical effects of the antiferromagnetic semiconductor EuTe

The Faraday rotation and the absorption of EuTe have been measured on thin films in the fundamental absorption region from 2·0 to 4·3 eV. Above the Néel temperature,T _N =9·6 °K, we observe in the energy range of the 4f ⁷–4f ⁶ 5dt _2g transition, one minimum and two main maxima of rotation. The temperature dependence of the maxima is found to be different: for one extremum the rotation resembles the magnetization curve of an antiferromagnet with a maximum at the Néel temperature; for the second, however, the rotation shows a ferromagnetic dependence on temperature with a point of inflexion at the Néel temperature and saturation for lower temperatures.This ferromagnetic behaviour within the antiferromagnetic structure of EuTe can be explained by assuming a ferromagnetic superlattice which gives rise to a magnetic Brillouin zone. Thus the ferromagnetic peak is attributed to transitions from the localized 4f ground state to the new zone boundaries.We wish to thank Mr. H. P. Staub for technical assistance, Dr. E. Kaldis for supplying the substances and Dr. J. Muheim for the mass spectroscopic analysis. Financial support by the Schweizerische Nationalfonds zur Förderung der wissenschaftlichen Forschung is gratefully acknowledged.     

Gamma-ray astronomy by the air shower technique: Performance and perspectives

Summary The techniques for γ-ray astronomy at energies ≥10 TeV using air shower detectors are discussed. The results, based on a number of large arrays, are negative, with no point sources being identified. While the contributions to γ-ray astronomy so far have been only upper limits, these arrays in the future will make significant progress in the understanding of cosmic rays in the energy range 10¹³ eV to 10¹⁶ eV. Also, contributions to solar physics are being made by observations of shape and time dependence of the shadow of the Sun as observed in cosmic rays. For the advancement of γ-ray astronomy a greater sensitivity is required in the energy region of 10 TeV. A number of promising techniques to accomplish a greater sensitivity are discussed. They include the enlargement of the Tibet array at 4300 meters altitude, the array of open photomultipliers at La Palma (AIROBICC), which views the shower by the Cherenkov photons produced in the atmosphere, and the instrumentation of a pond at Los Alamos with photomultipliers (Milagro). Invited talk given at the XXIV International Cosmic-Ray Conference, Rome, August 28–September 8, 1995.     

Improved beamforming using curved sparse 2D arrays in ultrasound

In this work we have investigated the effect of curving phase-steered sparse periodic two-dimensional arrays in one direction, and relate this effect to the geometry of the arrays. We have shown that curving is equivalent to removing some of the element periodicity, thus adding some “randomness” to the layout. Compared to flat phase-steered periodically sparse two-dimensional arrays, curving offers an even greater suppression of grating lobes located at directions along the curvature. The class of arrays yielding improved performance due to this suppression of grating lobes has been characterized.The point spread functions of some previously proposed array layouts, shown to be promising for ultrasonic imaging, have been simulated. The arrays have been simulated with various number of elements as well as various focal points, with array and field parameters typical to those in volumetric cardiac imaging. On a 48 × 48 element grid with a transducer center frequency of 3 MHz and the target at 40 mm, reductions in the peak sidelobe level of up to 12 dB were recorded for some critical steering directions, without significant differences in the beamwidth. The integrated sidelobe ratio was also examined, showing an almost equivalent performance as the flat array. This study shows that, without adding any complexity to the system, the overall image quality of a volumetric imaging system can be improved significantly by curving the array in one direction.