August 2000 arXiv papers — page 15

Oswin Aichholzer, Carmen Cortes, Erik D. Demaine, Vida Dujmovic

A flipturn is an operation that transforms a nonconvex simple polygon into another simple polygon, by rotating a concavity 180 degrees around the midpoint of its bounding convex hull edge. Joss and Shannon proved in 1973 that a sequence of flipturns eventually transforms any simple polygon into a convex polygon. This paper describes several new results about

W. Hofstetter, S. Kehrein

We use the new method of infinitesimal unitary transformations to calculate zero temperature correlation functions in the strong-coupling phase of the anisotropic Kondo model. We find the dynamics on all energy scales including the crossover behaviour from weak to strong coupling. The integrable structure of the Hamiltonian is not used in our approach. Our m

Claudio Chamon, Christopher Mudry

A two-parameter field theoretical representation is given of a 2-dimensional dirty d-wave superconductor that interpolates between the Gaussian limit of uncorrelated weak disorder and the unitary limit of a dilute concentration of resonant scatterers. It is argued that a duality holds between these two regimes from which follows that a linearly vanishing den

G. -H. Gweon, J. D. Denlinger, J. W. Allen, C. G. Olson

A recent letter by Xue et al. (PRL v.83, 1235 ('99)) reports a Fermi-Liquid (FL) angle resolved photoemission (ARPES) lineshape for quasi one-dimensional Li0.9Mo6O17, contradicting our report (PRL v.82, 2540 ('99)) of a non-FL lineshape in this material. Xue et al. attributed the difference to the improved angle resolution. In this comment, we point

G. M. Wysin

Relaxation schemes for finding normal modes of nonlinear excitations are described, and applied to the vortex-spinwave scattering problem in classical two-dimensional easy-plane Heisenberg models. The schemes employ the square of an effective Hamiltonian to ensure positive eigenvalues, together with an evolution in time or a self-consistent Gauss-Seidel iter

E. Goldobin, A. Sterck, D. Koelle

We propose a new type of Josephson vortex ratchet. In this system a Josephson vortex moves in a periodic asymmetric potential under the action of a deterministic or random force with zero time average. For some implementations the amplitude of the potential can be controlled during the experiment, thus, allowing to tune the performance of the system and buil

P. Levy, L. Granja, E. Indelicato, D. Vega

The effect of Fe doping in the Mn site on the magnetic, transport and structural properties of polycrystalline La1/2Ca1/2MnO3 was studied. Doping with low Fe concentration (< 10%) strongly affects electrical transport and magnetization. Long range charge order is disrupted even for the lowest doping level studied (~2%). For Fe concentration up to 5% a ferrom

YounJoon Jung, Eli Barkai, Robert J. Silbey

Motivated by recent experiments we consider a stochastic lineshape theory for the case when the underlying process obeys power-law statistics, based on a generalized Anderson-Kubo oscillator model. We derive an analytical expression for the lineshape and find rich type of behaviors when compared with the standard theory, for example, new type of resonances a

Wolfgang Ketterle, Shin Inouye

We discuss the relationship between bosonic stimulation, density fluctuations, and matter wave gratings. It is shown that enhanced stimulated scattering, matter wave amplification and atomic four-wave mixing are in principle possible for fermionic or non-degenerate samples if they are prepared in a cooperative state. In practice, there are limitations by sho

Georg Goeppert, Bruno Huepper, Hermann Grabert

We study the temperature and gate voltage dependence of the conductance of the single electron transistor focusing on highly conducting devices. Electron tunneling is treated nonperturbatively by means of path integral Monte Carlo techniques and the conductance is determined from the Kubo formula. A regularized singular value decomposition scheme is employed

L. L. Goncalves, A. P. Vieira, L. P. S. Coutinho

The one-dimensional XXZ model (s=1/2, N sites) with uniform long-range interactions among the transverse components of the spins is considered. The Hamiltonian of the model is explicitly given by $H=J\sum_{j=1}^{N}(s_{j}^{x}s_{j+1}^{x}+s_{j}^{y}s_{j+1}^{y}) -(I/N)\sum_{j,k=1}^{N}s_{j}^{z}s_{k}^{z}-h\sum_{j=1}^{N}s_{j}^{z},$ where the $s^{x,y,z}$ are half the

E. Granato, T. Ala-Nissila, S. C. Ying

Recent experiments have revealed a giant &#34;peak effect&#34; in ultrapure high $T_c$ superconductors. Moreover, the new data show that the peak effect coincides exactly with the melting transition of the underlying flux lattice. In this work, we show using dynamical scaling arguments that the friction due to the pinning centers acting on the flux lattice d

Kazusumi Ino

We formulate a field theory for a class of spin-singlet quantum Hall states (the Haldane-Rezayi state and its variants) which have been proposed for the quantized Hall plateaus observed at the second lowest Landau level. A new essential ingredient is a class of super Chern-Simons field. We show that the known properties of the states are consistently describ

K. -I. Goh, H. Jeong, B. Kahng, D. Kim

We study the tilt dependence of the pinning-depinning transition for an interface described by the anisotropic quenched Kardar-Parisi-Zhang equation in 2+1 dimensions, where the two signs of the nonlinear terms are different from each other. When the substrate is tilted by m along the positive sign direction, the critical force F_c(m) depends on m as F_c(m)-

M. Trzeciecki, W. Hübner

The applicability of time-reversal symmetry to nonlinear optics is discussed, both from macroscopic (Maxwell equations) and microscopic (quantum theoretical) point of view. We find that only spatial operations can be applied for the symmetry classification of nonlinear optical processes in magnetic, in particular antiferromagnetic, materials. An example is g

Simon Johnston, B. Koribalski, J. M. Weisberg, W. Wilson

We have measured 21-cm absorption and emission spectra in the direction of a further 7 southern pulsars with the Parkes telescope to derive their kinematic distances and to study the interstellar medium. For the first time we have successfully obtained HI absorption measurements for PSRs J1602-5100, J1740-3015 and J1745-3040. We have also significantly impro

Simon Johnston, N. Wex, L. Nicastro, R. N. Manchester

We report here on multifrequency radio observations of the pulsed emission from PSR B1259-63 around the time of the closest approach to its B2e companion star. There was a general increase in the pulsar&#39;s dispersion measure and scatter broadening, and a decrease in the flux density towards periastron although changes in these parameters were seen on time

Ryan C. Bay

The photo-meson production of pions by shock-accelerated protons could generate a burst of ~10^14 eV neutrinos from gamma-ray bursts (GRBs) observable in the Antarctic Muon and Neutrino Detector Array (AMANDA) or its larger successors. Measurement of this flux can test the hypothesis that GRBs are the sources of the highest-energy cosmic rays, and GRB neutri

Alison Sills, Joshua A. Faber, James C. Lombardi,, Frederic A. Rasio

We continue our exploration of collisionally merged stars in the blue straggler region of the color-magnitude diagram. We report the results of new SPH calculations of parabolic collisions between two main-sequence stars, with the initial structure and composition profiles of the parent stars having been determined from stellar evolution calculations. Parall

Eric F. Bell, Carlton Baugh, Shaun Cole, Carlos Frenk

We examine the present-day galaxy disk colors and star formation rates (SFRs) in the semi-analytic model of Cole et al. (2000). We find that the fiducial model is a good match to Kennicutt&#39;s (1998) observed global star formation law, the color-based metallicity-magnitude correlation and the colors of low-luminosity galaxies. The main limitation of the mo

Gopal-Krishna, Judith A. Irwin

Taking a clue from the pair of HI supershells found in the Scd galaxy NGC 3556 (M 108), we propose a new mechanism for the origin of HI supershells in gas-rich massive galaxies. In this scenario, the two supershells were inflated out of the neutral hydrogen disk due to the localised flaring of a pair of radio lobes formed by the jets ejected from the nucleus

Eric F. Bell, Robert C. Kennicutt

We have used a sample of 43 star-forming galaxies imaged in the far-ultraviolet (FUV) by the UIT supplemented with 33 galaxies observed by FAUST, to explore the consistency of UV and H alpha derived star formation rates (SFRs). We find, even before correction for dust, that UV and H alpha SFRs are quantitatively consistent for low-luminosity galaxies, and th

Eva K. Grebel

Local Group galaxies such as the Milky Way, the Magellanic Clouds, and M31 are being used by a number of international collaborations to search for microlensing events. Type and number of detections place constraints on dark matter and the stellar populations within and along the line of sight to these galaxies. In this review I briefly discuss the stellar p

David Bacon, Alexandre Refregier, Richard Ellis

Gravitational lensing by large-scale structure induces weak coherent alignments in the shapes of background galaxies. Here we present evidence for the detection of this `cosmic shear&#39; at the 3.4 sigma significance level with the William Herschel Telescope. Analysis and removal of notable systematic effects, such as shear induced by telescope optics and s

Jonathan P. Gardner, Thomas M. Brown, Henry C. Ferguson

We present galaxy counts in the near-ultraviolet (NUV; 2365Å) and far-ultraviolet (FUV; 1595Å) obtained from Space Telescope Imaging Spectrograph (STIS) observations of portions of the Hubble Deep Field North (HDFN), the Hubble Deep Field South (HDFS), and a parallel field near the HDFN. All three fields have deep (AB$>$29) optical imaging, and we determine

A. P. Schoenmakers, K. -H. Mack, A. G. de Bruyn, H. J. A. Rottgering

We have formed a complete sample of 26 low redshift (z < 0.3) giant radio galaxies (GRGs) from the WENSS survey, selected at flux densities above 1 Jy at 325 MHz. We present 10.5-GHz observations with the 100-m Effelsberg telescope of 18 sources in this sample. These observations, together with similar data of the remaining eight sources, are combined with d

C. A. Collins, L. Guzzo, H. Boehringer, P. Schuecker

We report the results of the spatial two-point correlation function xi(r) for the new X-ray galaxy cluster survey REFLEX, which comprises of 452 X-ray selected clusters (449 with redshifts) detected by the ROSAT satellite during the ROSAT All-Sky-Survey. The REFLEX cluster sample is flux limited to 3x10^{-12} erg s^{-1} cm^{-2} in the ROSAT energy band (0.1-

Fabien Casse, Jonathan Ferreira

In this paper, steady-state MHD calculations of non-relativistic magnetized accretion discs driving jets are presented. For the first time, an energy equation describing the effects of entropy generation along streamlines is included. Using a simplified approach, we showed that thermal effects have a tremendous influence on the disc capability to feed jets w

Shantanu Basu

We make the hypothesis that molecular cloud fragments are triaxial bodies with a large scale magnetic field oriented along the short axis. While consistent with theoretical expectations, this idea is supported by magnetic field strength data, which show strong evidence for flattening along the direction of the mean magnetic field. It is also consistent with

Chip Kobulnicky, David Koo

This study presents Keck optical and infrared spectroscopy of the rest-frame ultraviolet and optical emission lines in two Lyman alpha emitting galaxies at z>2. These data provide insight on the evolution of fundamental galaxy scaling relations at early epochs, especially the luminosity-velocity and luminosity-metallicity relations. Lynx 2-9691 exhibits exte

Nadya A. Smirnova, Alain Coc

Classical novae are potential sources of gamma-rays, like the 1.275 MeV gamma emission following 22Na beta decay, that could be detected by appropriate instruments on board of future satellites like INTEGRAL. It has been shown that the production of 22Na by novae is affected by the uncertainty on the 21Na(p,gamma)22Mg rate and in particular by the unknown pa

Jun Pan, Peter Coles

We investigate the behaviour of galaxy clustering on large scales using the PSCz catalogue. In particular, we ask whether there is any evidence of large-scale fractal behaviour in this catalogue. We find the correlation dimension in this survey varies with scale, consistent with other analyses. For example, our results on small and intermediate scales are co

Amir Leshem, Alle-Jan van der Veen

Radio-astronomical observations are increasingly contaminated by interference, and suppression techniques become essential. A powerful candidate for interference mitigation is adaptive spatial filtering. We study the effect of spatial filtering techniques on radio astronomical imaging. Current deconvolution procedures such as CLEAN are shown to be unsuitable

T. Morel, R. Doyon, N. St-Louis

We report on the first near-IR [Fe II] line imaging survey of extragalactic SNRs. Observations of a sample of 42 objects drawn from an optically-selected catalogue of SNRs in M33 provide evidence for a wide range in the [Fe II] 1.644 microns luminosities. This can be understood as being primarily due to variations in the chemical abundances and density of th

Ian Smail, Rob Ivison, Andrew Blain, Jean-Paul Kneib

We summarise the main results on the faint submillimeter (submm) galaxy population which have come from the SCUBA Cluster Lens Survey. We detail our current understanding of the characteristics of these submm-selected galaxies across wavebands from X-rays to radio. After presenting the main observational properties of this population we conclude by discussin

Horst R. Beyer

The reduced (in the angular coordinate $ϕ$) wave equation and Klein-Gordon equation are considered on a Kerr background and in the framework of $C^{0}$-semigroup theory. Each equation is shown to have a well-posed initial value problem,i.e., to have a unique solution depending continuously on the data. Further, it is shown that the spectrum of the semigroup&

N. Ryde, B. Gustafsson, K. Eriksson, K. H. Hinkle

We have observed the intermediate regions of the circumstellar envelope of Mira (o Ceti) in photospheric light scattered by three vibration-rotation transitions of the fundamental band of CO, from low-excited rotational levels of the ground vibrational state, at an angular distance of beta = 2&#34;-7&#34; away from the star. The data were obtained with the P

S. Aalto, S. Huettemeister

High resolution OVRO aperture synthesis maps of the 12CO 1-0 emission in the `Medusa&#39; galaxy merger (NGC4194) reveal the molecular emission being surprisingly extended. It is distributed on a total scale of 25$&#39;&#39;$ (4.7 kpc) - despite the apparent advanced stage of the merger. The complex, striking CO morphology occupies mainly the center and the

E. Daddi

The results of a 700 arcmin^2 survey for EROs are presented. The sky distribution of EROs is very inhomogeneous and their two point correlation function shows a very high amplitude, a factor of 10 larger than that of the field galaxy population. Such a clustering can explain the strong variance found in previous works, and provides evidence that ERO are most

H. Takahashi, H. Matsuhara, H. Watarai, T. Matsumoto

We present the results of ground-based imaging spectroscopy of the [Ne II] 12.8 micron line emitted from the ultracompact (UC) H II regions; W51d, G45.12+0.13, G35.20-1.74 and Monoceros R2, with 2arcsec spatial resolution. We found that the overall distribution of the [Ne II] emission is generally in good agreement with the radio (5 or 15 GHz) VLA distributi

Brad M. S. Hansen

I describe models for the formation of planetary systems surrounding the remnants of stellar mergers and collisions. I focus primarily on models for the viscous evolution of disks suitable for the formation of the planets surrounding the pulsar B1257+12. I show that the adaptation of models for traditional protoplanetary disks which invoke quiescent or `dead

Keith R. Dienes, Ina Sarcevic

We demonstrate that sizable neutrino flavor oscillations can be generated in a model with large extra spacetime dimensions even if the physics on the brane is flavor-diagonal, the bulk neutrino theory is flavor-neutral, and the brane/bulk couplings are flavor-blind. This is thus a compact model for addressing neutrino flavor oscillations in higher dimensions

Oleg Yakovlev, Stefan Groote

We suggest an infrared-insensitive quark mass, defined by subtracting the soft part of the quark self energy from the pole mass. We demonstrate the deep relation of this definition with the static quark-antiquark potential. At leading order in 1/m this mass coincides with the PS mass which is defined in a completely different manner. Going beyond static limi

Niclas Wyllard

We study derivative corrections to the effective action for a single D-brane in type II superstring theory coupled to constant background fields. In particular, within this setting we determine the complete expression for the (disk level) four-derivative corrections to the Born-Infeld part of the action. We also determine 2n-form 2n-derivative corrections to

J. I. Kapusta

Microscopic black holes explode with their temperature varying inversely as their mass. Such explosions would lead to the highest temperatures in the present universe, all the way to the Planck energy. Whether or not a quasi-stationary shell of matter undergoing radial hydrodynamic expansion surrounds such black holes is been controversial. In this paper rel

Paul B. Slater

We compute, using a formula of Dittmann, the Bures metric tensor (g) for the eight-dimensional convex set of three-level quantum systems, employing a newly-developed Euler angle-based parameterization of the 3 x 3 density matrices. Most of the individual metric elements (g_{ij}) are found to be expressible in relatively compact form, many of them in fact bei

C. P. Martin

We discuss both the UV and IR origin of the one-loop triangle gauge anomalies for noncommutative nonabelian chiral gauge theories with fundamental, adjoint and bi-fundamental fermions for U(N) groups. We find that gauge anomalies only come from planar triangle diagrams, the non-planar triangle contributions giving rise to no breaking of the Ward identies. Ge

P. Raimondi, A. Seryi

The length, complexity and cost of the present Final Focus designs for linear colliders grows very quickly with the beam energy. In the paper, a novel final focus system is presented and compared with the one proposed for NLC. This new design is simpler, shorter and cheaper, with comparable bandwidth, tolerances and tunability. Moreover, the length scales sl

M. E. Schulze, J. D. Gilpatrick, W. P. Lysenko, L. J. Rybarcyk

The Low-Energy Demonstration Accelerator (LEDA) radio-frequency quadrupole (RFQ) is a 100% duty factor (CW) linac that delivers >100 mA of H+ beam at 6.7 MeV. The 8-m-long, 350-MHz RFQ structure accelerates a dc, 75-keV, 110-mA H+ beam from the LEDA injector with >90% transmission. LEDA [1,2] consists of a 75-keV proton injector, 6.7-MeV, 350-MHz CW RFQ with

M. Post, S. Leupold, U. Mosel

We calculate the spectral function $A_ρ$ of the $ρ$ meson in nuclear matter. The calculation is performed in the {\it low density} approximation, where the in-medium self energy $Σ_{med}$ is completely determined by the vacuum $ρN$ forward scattering amplitude. This amplitude is derived from a relativistic resonance model. In comparison to previous non-relat

D. de Florian, M. Grazzini

We study the region of small transverse momenta in qqbar- and gg-initiated processes with no colored particle detected in the final state. We present the universal expression of the O(alpha_s^2) logarithmically enhanced contributions up to next-to-next-to-leading logarithmic accuracy. From there we extract the coefficients that allow the resummation of the l

Ana Lopez, Eduardo Fradkin

We present an effective theory for the bulk Fractional Quantum Hall states in spin-polarized bilayer and spin-1/2 single layer two-dimensional electron gases (2DEG) in high magnetic fields consistent with the requirement of global gauge invariance on systems with periodic boundary conditions. We derive the theory for the edge states that follows naturally fr

Amir Masoud Ghezelbash, Shahrokh Parvizi

We investigate the Kac-Moody algebra of noncommutative Wess-Zumino-Witten model and find its structure to be the same as the commutative case. Various kinds of gauged noncommutative WZW models are constructed. In particular, noncommutative $U(2)/U(1)$ WZW model is studied and by integrating out the gauge fields, we obtain a noncommutative non-linear $σ$-mode

E. Churazov, M. Brüggen, C. R. Kaiser, H. Böhringer

The morphology of the X-ray and radio emitting features in the central $\sim$ 50 kpc region around the galaxy M87 strongly suggests that buoyant bubbles of cosmic rays (inflated by an earlier nuclear active phase of the galaxy) rise through the cooling gas at roughly half the sound speed. In the absence of strong surface tension, initially spherical bubbles

Jose I. Latorre, Tim R. Morris

Scheme independence of exact renormalization group equations, including independence of the choice of cutoff function, is shown to follow from general field redefinitions, which remains an inherent redundancy in quantum field theories. Renormalization group equations and their solutions are amenable to a simple formulation which is manifestly covariant under

J. Douari, M. Daoud

We give the realizations of the extended Weyl-Heisenberg (WH) algebra and the Rubakov-Spiridonov (RS) superalgebra in terms of anyons, characterized by the statistical parameter $ν\in[0,1]$, on two-dimensional lattice. The construction uses anyons defined from usual fermionic oscillators (Lerda-Sciuto construction). The anyonic realization of the superalgebr

Hartmut Wittig

The status of lattice calculations in the light hadron sector is reviewed. Special emphasis is given to recent lattice determinations of the mass of the strange quark. The impact of non-perturbative renormalization and control over lattice artefacts on the attainable precision is discussed in detail. Furthermore the influence of dynamical quark effects is as

Rong-Gen Cai, Nobuyoshi Ohta

We show that combining the spatial noncommutative SYM limit and Lorentz transformation, one can obtain a well-behaved light-like noncommutative SYM limit. The light-like noncommutative SYM is unitary. When the boost velocity is finite, the resulting theory with space-time noncommutativity is unitary as well. The light-like noncommutative SYM limit can also b

Ph. de Forcrand, M. Pepe

We construct a smooth gauge for the adjoint field which is free of ambiguities on the lattice. In this Laplacian Center Gauge, center vortices and monopoles appear together as local gauge defects. A numerical study of center vortices in SU(2) and SU(3) supports equality of the $Z_N$ and SU(N) string tensions in the continuum limit, and only then.

K. Kobayakawa, Y. S. Honda, T. Samura

We examine the first order Fermi acceleration on the presumption that supernova remnant shocks cross ambient magnetic fields with various angles. These oblique shocks accelerate particles more efficiently than the parallel shocks and elevate the maximum energies achievable by the particles. The primary cosmic ray spectrum is strongly dependent upon these ene

Sze Kui Ng

A new quantum gauge model is proposed. From this quantum gauge model we derive a quantum invariant of 3-manifolds. We show that this quantum invariant of 3-manifolds gives a classification of closed (orientable and connected) 3-manifolds. From this classification we then prove the Poincaré conjecture.

Bernard L. G. Bakker, Ho-Meoyng Choi, Chueng-Ryong Ji

The divergences appearing in the 3+1 dimensional fermion-loop calculations are often regulated by smearing the vertices in a covariant manner. Performing a parallel light-front calculation, we corroborate the similarity between the vertex-smearing-technique and the Pauli-Villars regularization. In the light-front calculation of the electromagnetic meson curr

A. M. Fedotov, N. B. Narozhny, Yu. E. Lozovik

We consider an atom interacting with a quantized electromagnetic field inside a cavity with variable parameters. The atom in the ground state located in the initially empty cavity can be excited by variation of cavity parameters. We have discovered two mechanisms of atomic excitation. The first arises due to the interaction of the atom with the non-stationar

DZero Collaboration, B. Abbott

We present a search for electroweak production of single top quarks in the electron+jets and muon+jets decay channels. The measurements use ~90 pb^-1 of data from Run 1 of the Fermilab Tevatron collider, collected at 1.8 TeV with the DZero detector between 1992 and 1995. We use events that include a tagging muon, implying the presence of a b jet, to set an u

Hiroko Koyama, Tetsuro Konishi

A new phase of temporal evolution of the one-dimensional self-gravitating system is numerically discovered. Fractal structure is dynamically created from non-fractal initial conditions. Implication to astrophysics and mathematical physics is discussed.

Asher Peres, Daniel Terno

A hybrid formalism is proposed for interacting classical and quantum sytems. This formalism is mathematically consistent and reduces to standard classical and quantum mechanics in the case of no interaction. However, in the presence of interaction, the correspondence principle is violated.

A. V. Taichenachev, A. M. Tumaikin, V. I. Yudin, L. Hollberg

A method of sideband Raman cooling to the vibrational ground state of the $m=0$ Zeeman sublevel in a far-detuned two-dimensional optical lattice is proposed. In our scheme, the Raman coupling between vibrational manifolds of the adjacent Zeeman sublevels is shifted to the red sideband due to the ac Stark effect induced by a weak pump field. Thus, cooling and

E. N. Schmierer, K. C. D. Chan, D. C. Gautier, J. G. Gioia

For the baseline APT (Accelerator Production of Tritium) linac design, power couplers are required to transmit 210-kW of CW RF power to the superconducting cavities. These APT couplers operate at 700 MHz, have a coaxial design and an adjustable coupling to the superconducting cavities. Since May 1999, we have been testing couplers of this design on a room-te

Peter D. Smith

The CCT (Coupled Cavity Tuning) code automates the RF calculations and sizing of RF cavities for the CCL (Coupled Cavity Linac) structures of APT. It is planned to extend the code to the CCDTL (Coupled Cavity Drift Tube Linac). The CCT code controls the CCLFISH code, a member of the Poisson Superfish series of codes [1]. CCLFISH performs RF calculations and

Michael Lynch, William Reass, Daniel Rees, Amy Regan

The SNS linac accelerates an average beam current of 2 mA to an energy of 968 MeV. The linac is pulsed at 60 Hz with an H- beam pulse of 1 ms. The first 185 Mev of the linac uses normal conducting cavities, and the remaining length of the linac uses superconducting cavities. The linac operates at 402.5 MHz up to 87 MeV and then changes to 805 MHz for the rem

D. Rees, W. Roybal, J. Bradley

We are currently operating the front end of the accelerator production of tritium (APT) accelerator, a 7 MeV radio frequency quadrapole (RFQ) using three, 1.2 MW CW klystrons. These klystrons are required and designed to dissipate the full beam power in the collector. The klystrons have less than 1500 operational hours. One collector has failed and all colle

G. N. Kim, H. S. Kang, Y. S. Lee, M. H. Cho

The Pohang Accelerator Laboratory operates an electron linac for the pulsed neutron source as one of the long-term nuclear R&D programs at the Korea Atomic Energy Research Institute. The designed beam parameters are as follows; The nominal beam energy is 100 MeV, the maximum beam power is 10 kW, and the beam current is varied from 300 mA to 5A depends on the

L. Rinolfi, H. Braun, R. Pittin, F. Zhou

The CLIC Test Facility (CTF3) is an intermediate step to demonstrate the technical feasibility of the key concepts of the new RF power source for CLIC. CTF3 will use electron beams with an energy range adjustable from 170 MeV (3.5 A) to 380 MeV (with low current). The injector is based on a thermionic gun followed by a classical bunching system embedded in a

R. Eichhorn, U. Ratzinger

Room temperature IH-type drift tube structures are used at different places now for the acceleration of ions with mass over charge ratios up to 65 and velocities between 0.016 c and 0.1 c. These structures have a high shunt impedance and allow the acceleration of very intense beams at high accelerating gradients. The overall power consumption of room tempera

G. Franchetti, S. Gilardoni, P. Gruber, K. Hanke

Experimental and theoretical activities are underway at CERN with the aim of examining the feasibility of a very-high-flux neutrino source. In the present scheme, a high-power proton beam (some 4 MW) bombards a target where pions are produced. The pions are collected and decay to muons under controlled optical condition. The muons are cooled and accelerated

Jean-Pierre Delahaye, Ian Wilson

The CLIC study of a high-energy (0.5 - 5 TeV), high-luminosity (1034 - 1035 cm-2 sec-1) e+e- linear collider is presented. Beam acceleration using high frequency (30 GHz) normal-conducting structures operating at high accelerating fields (150 MV/m) significantly reduces the length and, in consequence, the cost of the linac. Using parameters derived from gene

B. G. Sidharth

We consider the recent description of elementary particles in terms of Quantum Mechanical Kerr-Newman Black Holes, a description which provides a rationale for and at the same time reconciles the Bohm-hydrodynamical formulation on the one hand and the Nelsonian stochastiic formulation on the other. The Boson-Fermion divide is discussed, and it is pointed out

B. Yu. Bogdanovich, A. V. Nesterovich

It is known, that at high energies of ions (more than 10 MeV for light ions) the focusing by magnetic quadrupole fields is most effective, whereas at small energies (less than 1 MeV) - the focusing by electrical quadrupole fields. At intermediate energies of ions (from 1 to 10 MeV) the efficiency of each of these types of a focusing is reduced. The authors o

E. Chevallay, S. Hutchins, P. Legros, G. Suberlucq

For short, high-intensity electron bunches, alkali-tellurides have proved to be a reliable photo-cathode material. Measurements of lifetimes in an RF gun of the CLIC Test Facility II at field strengths greater than 100 MV/m are presented. Before and after using them in this gun, the spectral response of the Cs-Te and Rb-Te cathodes were determined with the h

Y. Y Sharon, M. S. Fayache, Y. Durga Devi, L. Zamick

The spin-orbit splittings in the spectra of nuclei with mass numbers 5, 15 and 17 are studied within the framework of shell-model configuration mixing calculations including 2$\hbar ω$ excitations. The contributions of the two-body spin-orbit and tensor components of the nucleon-nucleon interaction are studied in various model spaces. It is found that the ef

Simon Capstick, W. Roberts

The application of quark models to the spectra and strong and electromagnetic couplings of baryons is reviewed. This review focuses on calculations which attempt a global description of the masses and decay properties of baryons, although recent developments in applying large N_c QCD and lattice QCD to the baryon spectrum are described. After outlining the c

Vadim Kostrykin, Robert Schrader

In this article we continue our analysis of Schrödinger operators on arbitrary graphs given as certain Laplace operators. In the present paper we give the proof of the composition rule for the scattering matrices. This composition rule gives the scattering matrix of a graph as a generalized star product of the scattering matrices corresponding to its subgrap

M. S. Baouendi, P. Ebenfelt, Linda Preiss Rothschild

Iterated Segre mappings of real analytic generic submanifolds in complex space have been an essential tool in the study of holomorphic, formal, and CR mappings between such manifolds. In this paper we present a theory of iterated Segre mappings for smooth or formal submanifolds. In particular, we characterize finite type in terms of the rank of the iterated

Pavel Stovicek

A possible generalization of the method of orbits to SLq(2,R) is discussed.

L. G. S. Duarte, S. E. S. Duarte, L. A. C. P. da Mota, J. E. F. Skea

A set of MapleV R5 software routines for solving first order ordinary differential equations (1ODEs) is presented. The package implements the Prelle-Singer Method in its original form plus its extension to include elementary functions (ELFs) on the integrating factor . The package also presents a theoretical extension to deal with all 1ODEs presenting liouvi

Shun-Jen Cheng, Weiqiang Wang

We establish a new Howe duality between a pair of two queer Lie superalgebras (q(m),q(n)). This gives a representation theoretic interpretation of a well-known combinatorial identity for Schur Q-functions. We further establish the equivalence between this new Howe duality and the Schur-Sergeev duality between q(n) and a central extension $\Hy_k$ of the hyper

Eduardo Esteves, Nivaldo Medeiros

In the 80&#39;s D. Eisenbud and J. Harris considered the following problem: ``What are the limits of Weierstrass points in families of curves degenerating to stable curves?&#39;&#39; But for the case of stable curves of compact type, treated by them, this problem remained wide open since then. In the present article, we propose a concrete approach to this pr

Aleksandar Mijatovic

In this paper we describe a procedure to simplify any given triangulation of the 3-sphere using Pachner moves. We obtain an explicit exponential-type bound on the number of Pachner moves needed for this process. This leads to a new recognition algorithm for the 3-sphere.

S. Dimiev, R. Lazov, N. Milev

Almost-complex and hyper-complex manifolds are considered in this paper from the point of view of complex analysis and potential theory. The idea of holomorphic coordinates on an almost-complex manifold $(M,\mathbf{J}%)$ is suggested by D. Spencer. For hypercomplex manifolds we introduce the notion of hyper-holomorphic function and develop some analogous sta

David Iglesias, Juan C. Marrero

The notion of a generalized Lie bialgebroid (a generalization of the notion of a Lie bialgebroid) is introduced in such a way that a Jacobi manifold has associated a canonical generalized Lie bialgebroid. As a kind of converse, we prove that a Jacobi structure can be defined on the base space of a generalized Lie bialgebroid. We also show that it is possible

Palle E. T. Jorgensen

A theorem of Glimm states that representation theory of an NGCR C*-algebra is always intractable, and the Cuntz algebra O_N is a case in point. The equivalence classes of irreducible representations under unitary equivalence cannot be captured with a Borel cross section. Nonetheless, we prove here that wavelet representations correspond to equivalence classe

S. J. Dilworth, David Mitra

We show that the Lindenstrauss basic sequence in l_1 may be used to construct a conditional quasi-greedy basis of l_1, thus answering a question of Wojtaszczyk. We further show that the sequence of coefficient functionals for this basis is not quasi-greedy.

Anders Skovsted Buch

We prove an explicit combinatorial formula for the structure constants of the Grothendieck ring of a Grassmann variety with respect to its basis of Schubert structure sheaves. We furthermore relate K-theory of Grassmannians to a bialgebra of stable Grothendieck polynomials, which is a K-theory parallel of the ring of symmetric functions.

Amer Iqbal, Asad Naqvi

We use level truncated superstring field theory to obtain the effective potential for the Wilson line marginal deformation parameter which corresponds to the constant vacuum expectation value of the U(1) gauge field on the D-brane in a particular direction. We present results for both the BPS and the non-BPS D-brane. In the case of non-BPS D-brane the effect

E. I. Guendelman

The consequences of considering the measure of integration in the action to be defined by degrees of freedom independent of the metric are studied. Models without the cosmological constant problem, new ways of spontaneously breaking scale symmetry which have an interesting cosmology and theories of extended objects (string, branes) without a fundamental scal

R. N. Mohapatra, A. Perez-Lorenzana, C. A. de S. Pires

A new economical model for neutrino masses is proposed in the context of brane bulk scenarios for particle physics, where global B-L symmetry of the standard model is broken spontaneously by a gauge singlet Higgs field in the bulk. This leads to a bulk majoron whose KK excitations may make it visible if neutrinoless double beta decay if the string scale is c

Stephen Godfrey, Pat Kalyniak, Basim Kamal, M. A. Doncheski

We examine the sensitivity of the process e gamma to nu q +X to W&#39; bosons which arise in various extensions of the standard model. We consider photon spectra from both the Weizsacker Williams process and from a backscattered laser. The process is found to be sensitive to W&#39; masses up to several TeV, depending on the model, the center of mass energy,

Steve Geer

The recent evidence for neutrino oscillations opens a new and exciting era in neutrino physics. The next generation of accelerator based neutrino oscillation experiments are expected to confirm the nature of the oscillations, and begin to measure some of the associated oscillation parameters. However, these experiments will not be able to completely determin

Robert Blair, Günter Grindhammer, Michael Klasen, Michael Krämer

This summary of the working group 2 of DIS 2000 encompasses experimental and theoretical results of jet physics, open and bound state heavy flavour production, prompt photon production, next-to-leading order QCD calculations and beyond, instantons, fragmentation, event shapes, and power corrections, primarily from deep-inelastic scattering and photoproductio

John P. Ralston, P. Jain, Douglas W. McKay, S. Panda

Cosmic ray events above 10^19 eV have posed a fundamental problem for more than thirty years. Recent measurements indicate that these events do not show the features predicted by the GZK bound. The events may, in addition, display angular correlations with point sources. If these observations are confirmed for point sources further than 50 - 100 Mpc, then st