MedWorm: Physics

A capillary absorption spectrometer for stable carbon isotope ratio (C/C) analysis in very small samples

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

J. F. Kelly, R. L. Sams, T. A. Blake, M. Newburn, J. Moran et al. A capillary absorption spectrometer (CAS) suitable for IR laser isotope analysis of small CO samples is presented. The system employs a continuous-wave (cw) quantum cascade laser to study nearly adjacent rovibrational transitions of different isotopologues of CO near 2307 cm (4.34 [mu]m). This initi ... [Rev. Sci. Instrum. 83, 023101 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

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Improved chopping of a lithium beam for plasma edge diagnostic at ASDEX Upgrade

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

M. Willensdorfer, E. Wolfrum, R. Fischer, J. Schweinzer, M. Sertoli et al. The lithium beam diagnostic at ASDEX Upgrade routinely delivers electron density profiles in the plasma edge by lithium beam impact excitation spectroscopy. An accurate background subtraction requires a periodically chopped lithium beam. A new, improved chopping system was developed and installed. I ... [Rev. Sci. Instrum. 83, 023501 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

Effectiveness of frequency mapping on 28 nm device broken scan chain failures

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

S. H. Goh, Yan Pan, G. F. You, Y. H. Chan, He ran et al. Frequency mapping methodology is an effective diagnostic tool for detection of manufacturing defects in scan chains. It analyses reflected laser modulations from toggling scan cells to localize defective scan path or scan cell. In this paper, we demonstrate experimentally that the use of solid immer ... [Rev. Sci. Instrum. 83, 023702 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

Pilot-scale cooling tower to evaluate corrosion, scaling, and biofouling control strategies for cooling system makeup water

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

S. H. Chien, M. K. Hsieh, H. Li, J. Monnell, D. Dzombak et al. Pilot-scale cooling towers can be used to evaluate corrosion, scaling, and biofouling control strategies when using particular cooling system makeup water and particular operating conditions. To study the potential for using a number of different impaired waters as makeup water, a pilot-scale system ... [Rev. Sci. Instrum. 83, 024101 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

An explosively driven high-power microwave pulsed power system

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

M. A. Elsayed, A. A. Neuber, J. C. Dickens, J. W. Walter, M. Kristiansen et al. The increased popularity of high power microwave systems and the various sources to drive them is the motivation behind the work to be presented. A stand-alone, self-contained explosively driven high power microwave pulsed power system has been designed, built, and tested at Texas Tech University's ... [Rev. Sci. Instrum. 83, 024705 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

Application of length vernier in phase coincidence detection and precision frequency measurement

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

Miao Miao, Zhou Wei, and Wang Bin For comparison of arbitrary frequency signals, the paper proposed two levels of length vernier based on the time-space relationship are used in three levels of phase coincidence detecting circuits to extract the phase coincidence information by proper logic calculation. The length/phase of each vern ... [Rev. Sci. Instrum. 83, 024706 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

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Recent progress on the superconducting ion source VENUS

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

J. Y. Benitez, K. Y. Franzen, A. Hodgkinson, T. Loew, C. M. Lyneis et al. The 28 GHz Ion Source VENUS (versatile ECR for nuclear science) is back in operation after the superconducting sextupole leads were repaired and a fourth cryocooler was added. VENUS serves as an R&D device to explore the limits of electron cyclotron resonance source performance at 28 GHz with its 10 ... [Rev. Sci. Instrum. 83, 02A311 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

The electron cyclotron resonance ion source with arc-shaped coils concept (invited)

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

H. Koivisto, P. Suominen, O. Tarvainen, and P. Spadtke The main limitation to further improve the performance of ECR ion sources is set by the magnet technology related to the multipole magnet field used for the closed minimum-B structure. The JYFL ion source group has sought different approaches to improve the strength of the minimum-B structure requir ... [Rev. Sci. Instrum. 83, 02A312 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

Matrix of small-radius radio-frequency discharges as a volume-production based source of negative hydrogen ions

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

St. Lishev, Ts. Paunska, A. Shivarova, and Kh. Tarnev Based on experience from a workboth theoretical and experimental oneon negative hydrogen ion beam sources studied regarding fusion applications, a novel design of a rf source with volume production of the ions is proposed. The suggestion is for a source constructed as a matrix of small-radius tandem ... [Rev. Sci. Instrum. 83, 02A702 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

Upgrade of the resonance ionization laser ion source at ISOLDE on-line isotope separation facility: New lasers and new ion beams

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

V. N. Fedosseev, L.-E. Berg, D. V. Fedorov, D. Fink, O. J. Launila et al. The resonance ionization laser ion source (RILIS) produces beams for the majority of experiments at the ISOLDE on-line isotope separator. A substantial improvement in RILIS performance has been achieved through a series of upgrade steps: replacement of the copper vapor lasers by a Nd:YAG laser; repl ... [Rev. Sci. Instrum. 83, 02A903 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

Laser ion source development at Holifield Radioactive Ion Beam Facility

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

This report describes the efforts made to develop a resonant-ionization laser ion source based on tunable Ti:sapphire lasers for nuclear physics and astrophysics research at Holifield Radioactive Ion Beam Facility. Three Ti:sapphire lasers have been upgraded with individual pump lasers to eliminate ... [Rev. Sci. Instrum. 83, 02A904 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

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Diagnostics of the ITER neutral beam test facility

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

R. Pasqualotto, G. Serianni, P. Sonato, M. Agostini, M. Brombin et al. The ITER heating neutral beam (HNB) injector, based on negative ions accelerated at 1 MV, will be tested and optimized in the SPIDER source and MITICA full injector prototypes, using a set of diagnostics not available on the ITER HNB. The RF source, where the H/D production is enhanced by cesium eva ... [Rev. Sci. Instrum. 83, 02B103 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

Comparison between off-resonance and electron Bernstein waves heating regime in a microwave discharge ion source

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

G. Castro, D. Mascali, F. P. Romano, L. Celona, S. Gammino et al. A microwave discharge ion source (MDIS) operating at the Laboratori Nazionali del Sud of INFN, Catania has been used to compare the traditional electron cyclotron resonance (ECR) heating with an innovative mechanisms of plasma ignition based on the electrostatic Bernstein waves (EBW). EBW are obtain ... [Rev. Sci. Instrum. 83, 02B501 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

Laser and focused ion beam combined machining for micro dies

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

Y. Yoshida, W. Okazaki, and T. Uchida We have developed a laser and focused ion beam (FIB) compound process for press mold dies of a micro lens array (MLA) and a micro needle array (MNA) in a glassy carbon (GC). The press mold die of the MLA was roughly fabricated by UV-YAG laser. After this process, we finished this surface by scanning ... [Rev. Sci. Instrum. 83, 02B901 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

The second generation Singapore high resolution proton beam writing facility

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

J. A. van Kan, P. Malar, and Armin Baysic de Vera A new proton beam focusing facility, designed for proton beam writing (PBW) applications has been tested. PBW allows for proximity free structuring of high aspect ratio, high-density 3D nanostructures. The new facility is designed around OM52 compact quadrupole lenses capable of operating in a varie ... [Rev. Sci. Instrum. 83, 02B902 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

A Tandetron as proton injector for the eye tumor therapy in Berlin

Review of Scientific Instruments — Tue, 07 Feb 2012 01:08:28 +0100

J. Rohrich, T. Damerow, W. Hahn, U. Muller, U. Reinholz et al. The therapy of eye tumors with fast protons is an excellent tool giving very high local control rates. At the Helmholtz-Zentrum Berlin (HZB) almost 1800 patients were treated since 1998. A 2 MV Tandetron was installed as injector for the k = 132 HZB cyclotron. Using the standard 358 duoplasmatron io ... [Rev. Sci. Instrum. 83, 02B903 (2012)] published Mon Feb 6, 2012. (Source: Review of Scientific Instruments)

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Dynamic mitigation of instabilities

Physics of Plasmas — Tue, 07 Feb 2012 01:08:28 +0100

S. Kawata In the paper Phys. Plasmas 18, 092705 (2011), dynamic stabilization mechanism for the Rayleigh-Taylor instability was discussed together with another dynamic migration mechanism, which we proposed and is discussed further in a more general way in this paper. In general, a perturbation of physical qu ... [Phys. Plasmas 19, 024503 (2012)] published Mon Feb 6, 2012. (Source: Physics of Plasmas)

Nonlinear entropy transfer via zonal flows in gyrokinetic plasma turbulence

Physics of Plasmas — Tue, 07 Feb 2012 01:08:28 +0100

M. Nakata, T.-H. Watanabe, and H. Sugama Nonlinear entropy transfer processes in toroidal ion temperature gradient (ITG) and electron temperature gradient (ETG) driven turbulence are investigated based on the gyrokinetic entropy balance relations for zonal and non-zonal modes, which are coupled through the entropy transfer function regarde ... [Phys. Plasmas 19, 022303 (2012)] published Mon Feb 6, 2012. (Source: Physics of Plasmas)

Strain-vorticity induced secondary motion in shallow flows

Physics of Fluids — Tue, 07 Feb 2012 01:08:28 +0100

Leon P. J. Kamp Deviations from two-dimensionality of a shallow flow that is dominated by bottom friction are quantified in terms of the spatial distribution of strain and vorticity as described by the Okubo-Weiss function. This result is based on a Poisson equation for the pressure in a quasi-horizontal (primary) ... [Phys. Fluids 24, 023601 (2012)] published Mon Feb 6, 2012. (Source: Physics of Fluids)

Trajectory-guided configuration interaction simulations of multidimensional quantum dynamics

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Scott Habershon We propose an approach to modelling multidimensional quantum systems which uses direct-dynamics trajectories to guide wavefunction propagation. First, trajectory simulations are used to generate a sample of dynamically relevant configurations on the potential energy surface (PES). Second, the sample ... [J. Chem. Phys. 136, 054109 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

The sign problem and population dynamics in the full configuration interaction quantum Monte Carlo method

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

J. S. Spencer, N. S. Blunt, and W. M.C. Foulkes The recently proposed full configuration interaction quantum Monte Carlo method allows access to essentially exact ground-state energies of systems of interacting fermions substantially larger than previously tractable without knowledge of the nodal structure of the ground-state wave function. We in ... [J. Chem. Phys. 136, 054110 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

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The multi-configuration electron-nuclear dynamics method applied to LiH

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Inga S. Ulusoy and Mathias Nest The multi-configuration electron-nuclear dynamics (MCEND) method is a nonadiabatic quantum dynamics approach to the description of molecular processes. MCEND is a combination of the multi-configuration time-dependent Hartree (MCTDH) method for atoms and its antisymmetrized equivalent MCTDHF for elec ... [J. Chem. Phys. 136, 054112 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Quasi-variational coupled cluster theory

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

James B. Robinson and Peter J. Knowles We extend our previous work on the construction of new approximations of the variational coupled cluster method. By combining several linked pair functional transformations in such a way as to give appropriately balanced infinite-order contributions, in order to approximate well at all orders, we f ... [J. Chem. Phys. 136, 054114 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Stochastic mapping of the Michaelis-Menten mechanism

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Eva Doka and Gabor Lente The Michaelis-Menten mechanism is an extremely important tool for understanding enzyme-catalyzed transformation of substrates into final products. In this work, a computationally viable, full stochastic description of the Michaelis-Menten kinetic scheme is introduced based on a stochastic equivalent ... [J. Chem. Phys. 136, 054111 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Exploring the competition between localization and delocalization of the neutral soliton defect in polyenyl chains with the orbital optimized second order opposite spin method

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Westin Kurlancheek, Rohini Lochan, Keith Lawler, and Martin Head-Gordon Theory and implementation of the analytical nuclear gradient is presented for orbital optimized scaled opposite-spin perturbation theory (O2). Evaluation of the O2 analytical gradient scales with the 4th power of molecular size, like the O2 energy. Since the O2 method permits optimization of the orb ... [J. Chem. Phys. 136, 054113 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

The electronic spectrum of the C-CH radical

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Dongfeng Zhao (赵东锋), Harold Linnartz, and Wim Ubachs The electronic gas-phase absorption spectrum of the bent carbon-chain radical, HCCHCH with C symmetry, is recorded in the 595 nm region by cavity ring-down spectroscopy through an expanding hydrogen plasma. An unambiguous spectroscopic identification becomes possible from a systematic deuterium labe ... [J. Chem. Phys. 136, 054307 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

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Surface area controlled heterogeneous nucleation

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Brian Steer, Boris Gorbunov, Jonathan Rowles, and David Green Heterogeneous nucleation of liquid from a gas phase on nanoparticles has been studied under various saturation ratios and nuclei size. The probability of liquid droplet nucleation, especially at a low degree of deviation from equilibrium, was measured for both atmospheric aerosol particles and engin ... [J. Chem. Phys. 136, 054704 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Nonadiabatic dynamics of O(D) + N(XSigma)-->O(P) + N(XSigma) on three coupled potential surfaces: Symmetry, Coriolis, spin-orbit, and Renner-Teller effects

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

We present the spin-orbit (SO) and Renner-Teller (RT) quantum dynamics of the spin-forbidden quenching O(D) + N(XSigma)-->O(P) + N(XSigma) on the NO X-tildeA, aA, and b-tildeA coupled PESs. We use the permutation-inversion symmetry, propagate coupled-channel (CC) real wavepackets, and compute initia ... [J. Chem. Phys. 136, 054308 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Mobility matrix of a spherical particle translating and rotating in a viscous fluid confined in a spherical cell, and the rate of escape from the cell

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

B. U. Felderhof and A. Sellier The mobility matrix of a spherical particle moving in a spherical cavity, filled with a viscous incompressible fluid, and with no-slip boundary condition at the wall of the cavity, is evaluated from the Oseen tensor for the cavity by the method used by Lorentz for a particle near a planar wall. For ... [J. Chem. Phys. 136, 054703 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Correlated intermolecular coupling fluctuations in photosynthetic complexes

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Sebastiaan M. Vlaming and Robert J. Silbey The functioning and efficiency of natural photosynthetic complexes is strongly influenced by their embedding in a noisy protein environment, which can even serve to enhance the transport efficiency. Interactions with the environment induce fluctuations of the transition energies and couplings betwee ... [J. Chem. Phys. 136, 055102 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Effects of particles on stability of flow-induced precursors

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Peng-Wei Zhu, Andrew W. Phillips, and Graham Edward The effect of two colorant particles with different surface geometries on the stability of shear-induced precursors in isotactic polypropylene was studied after the cessation of shear flow at 140 degrees C. In the absence of particles, the shear-induced precursors survived for at least 100 s after ... [J. Chem. Phys. 136, 054903 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

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Methyl group rotation, H spin-lattice relaxation in an organic solid, and the analysis of nonexponential relaxation

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

We report H spin-lattice relaxation measurements in polycrystalline 4,4-dimethoxybiphenyl at temperatures between 80 and 300 K at NMR frequencies of omega/2pi = 8.50, 22.5, and 53.0 MHz. The data are interpreted in terms of the simplest possible Bloch-Wangsness-Redfield methyl group hopping model. D ... [J. Chem. Phys. 136, 054508 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Formation of dodecagonal quasicrystals in two-dimensional systems of patchy particles

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Marjolein N. van der Linden, Jonathan P. K. Doye, and Ard A. Louis The behaviour of two-dimensional patchy particles with five and seven regularly arranged patches is investigated by computer simulation. For higher pressures and wider patch widths, hexagonal crystals have the lowest enthalpy, whereas at lower pressures and for narrower patches, lower density crysta ... [J. Chem. Phys. 136, 054904 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Conformational properties of macromolecular pyramoids and their potential use as nano-containers

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

M. Kosmas and P. Efthymiopoulos We study the macroscopic behavior of a pyramid-like nano-construct made of linear macromolecular chains. The average mean square end-to-end distances of the six edges of the pyramoid are evaluated by means of the Gaussian chain model and are found smaller than those of free chains because of archite ... [J. Chem. Phys. 136, 054905 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Cold collisions of complex polyatomic molecules

Journal of Chemical Physics — Tue, 07 Feb 2012 01:08:27 +0100

Zhiying Li and Eric J. Heller We introduce a method for classical trajectory calculations to simulate collisions between atoms and large rigid asymmetric-top molecules. We investigate the formation of molecule-helium complexes in buffer-gas cooling experiments at a temperature of 6.5 K for molecules as large as naphthalene. Our ... [J. Chem. Phys. 136, 054306 (2012)] published Mon Feb 6, 2012. (Source: Journal of Chemical Physics)

Effect of P addition on nanocrystallization and high temperature magnetic properties of low B and Nb containing FeCo nanocomposites