August 2000 arXiv papers — page 11

Ilia Gogoladze, Mirian Tsulaia

We suggest a new mechanism for electroweak symmetry breaking in the supersymmetric Standard Model. Our suggestion is based on the presence of an anomalous U(1)_A gauge symmetry, which naturally arises in the four dimensional superstring theory, and heavily relies on the value of the corresponding Fayet-Illiopoulos ξ-term.

Felipe J. Llanes-Estrada, Stephen R. Cotanch, Pedro J. de A. Bicudo, J. Emilio F. T. Ribeiro

We report a glueball Regge trajectory emerging from diagonalizing a confining Coulomb gauge Hamiltonian for constituent gluons. Using a BCS vacuum ansatz and gap equation, the dressed gluons acquire a mass, of order 800 $MeV$, providing the quasiparticle degrees of freedom for a TDA glueball formulation. The TDA eigenstates for two constituent gluons have or

Mark Alford, Jeffrey Bowers, Krishna Rajagopal

In any context in which color superconductivity arises in nature, it is likely to involve pairing between species of quarks with differing chemical potentials. For suitable values of the differences between chemical potentials, Cooper pairs with nonzero total momentum are favored, as was first realized by Larkin, Ovchinnikov, Fulde and Ferrell (LOFF). Conden

Eric R. Sharpe

In this article we explain discrete torsion. Put simply, discrete torsion is the choice of orbifold group action on the B field. We derive the classification H^2(G, U(1)), we derive the twisted sector phases appearing in string loop partition functions, we derive M. Douglas's description of discrete torsion for D-branes in terms of a projective represent

F. Naito, K. Yoshino, C. Kubota, T. Kato

An Alvaretz-type DTL, to accelerate the H- ion beam from 3 to 50 MeV, is being constructed as the injector for the JAERI/KEK Joint Project. The following components of the DTL have been developed: (1) a cylindrical tank, made by copper electroforming; (2) rf contactors; (3) a pulse-excited quadrupole magnet with a hollow coil made by copper electroforming; (

Jorge Villavicencio

We derive an exact analytic solution to a Klein-Gordon equation for a step potential barrier with cutoff plane wave initial conditions, in order to explore wave evolution in a classical forbidden region. We find that the relativistic solution rapidly evanesces within a depth $2x_p$ inside the potential, where $x_p$ is the penetration length of the stationary

A. Seryi, L. Hendrickson, P. Raimondi, T. Raubenheimer

The performance of various systems of the Next Linear Collider (NLC) have been studied in terms of ground motion using recently developed models. In particular, the performance of the beam delivery system is discussed. Plans to evaluate the operation of the main linac beam-based alignment and feedback systems are also outlined.

Andrei Seryi, Tor Raubenheimer

We present a ground motion model for the SLAC site. This model is based on recent ground motion studies performed at SLAC as well as on historical data. The model includes wave-like, diffusive and systematic types of motion. An attempt is made to relate measurable secondary properties of the ground motion with more basic characteristics such as the layered g

A. Seryi, M. Breidenbach, J. Frisch

Ground motion may be a limiting factor in the performance of future linear colliders. Cultural noise sources, an important component of ground motion, are discussed here, with data from the SLD region at SLAC.

E. G. Cook

Solid-state modulators for pulsed power applications have been a goal since the first fast high-power semiconductor devices became available. Recent improvements in both the speed and peak power capabilities of semiconductor devices developed for the power conditioning and traction industries have led to a new generation of solid-state switched high power mo

E. G. Cook, B. S. Lee, S. A. Hawkins, F. V. Allen

An all solid-state kicker modulator for the Dual-Axis Radiographic Hydrodynamic Test facility (DARHT-2) has been designed and tested. This kicker modulator uses multiple solid-state modules stacked in an inductive-adder configuration where the energy is switched into each section of the adder by a parallel array of MOSFETs. The modulator features very fast r

M. Sugimoto, M. Kinsho, H. Takeuchi

The intense neutron source for development of fusion materials planned by international collaboration makes a new step to clarify the technical issues for realizing the 40 MeV, 250 mA deuteron beam facility. The baseline concept employs two identical 125 mA linac modules whose beams are combined at the flowing lithium target. Recent work for reducing the cos

W. P. Lysenko, J. D. Gilpatrick, L. J. Rybarcyk, J. D. Schneider

Quadrupole scans were used to characterize the LEDA RFQ beam. Experimental data were fit to computer simulation models for the rms beam size. The codes were found to be inadequate in accurately reproducing details of the wire scanner data. When this discrepancy is resolved, we plan to fit using all the data in wire scanner profiles, not just the rms values,

P. N. Ostroumov, R. C. Pardo, G. P. Zinkann, K. W. Shepard

A test of the acceleration of multiple charge-state uranium beams was performed at the ATLAS accelerator. A 238U+26 beam was accelerated in the ATLAS PII linac to 286 MeV (~1.2 MeV/u) and stripped in a carbon foil located 0.5 m from the entrance of the ATLAS Booster section. A 58Ni9+ 'guide' beam from the tandem injector was used to tune the Booster

P. N. Ostroumov, K. W. Shepard, V. N. Aseev, A. A. Kolomiets

This paper describes a design for the front end of a superconducting (SC) ion linac which can accept and simultaneously accelerate two charge states of uranium from an ECR ion source. This mode of operation increases the beam current available for the heaviest ions by a factor of two. We discuss the 12 MeV/u prestripper section of the Rare Isotope Accelerato

P. N. Ostroumov, J. A. Nolen, K. W. Shepard

There is demand for the construction of a medium-energy ion linear accelerator based on superconducting rf (SRF) technology. It must be capable of producing several hundred kilowatts of CW beams ranging from protons to uranium. A considerable amount of power is required in order to generate intense beams of rare isotopes for subsequent acceleration. At prese

L. A. Day, M. Pieck, D. Barr, K. U. Kasemir

Measurement of high-power proton beam-halo formation is the ongoing scientific experiment for the Low Energy Demonstration Accelerator (LEDA) facility. To attain this measurement goal, a 52-magnet beam line containing several types of beam diagnostic instrumentation is being installed. The Experimental Physics and Industrial Control System (EPICS) and commer

M. Mizumoto, N. Ouchi, J. Kusano, E. Chishiro

The JAERI/KEK Joint Project for the high-intensity proton accelerator facility has been proposed with a superconducting (SC) linac option from 400 MeV to 600MeV. System design of the SC linac has been carried out based on the equipartitioning concept. The SC linac is planned to use as an injector to a 3GeV rapid cycling synchrotron (RCS) for spallation neutr

K. Yoshino, E. Takasaki, F. Naito, T. Kato

Quadrupole electromagnets have been developed with a hollow coil produced using an improved periodic reverse electroforming. These will be installed in each of the drift tubes of the DTL (324 MHz) as part of the JAERI/KEK Joint Project at the high-intensity proton accelerator facility. Measurements of the magnets' properties were found to be consistent w

M. Popovic, L. Allen, A. Moretti, E. McCrory

The peak current limit for the Fermilab Linac was recently studied. The purpose was to learn what components of the present Linac can be used for the first stage of a proposed proton driver[1]. For this application the Linac must provide a H- beam in excess of 5000 mA-msec per pulse. The original Fermilab Linac was designed for protons with a peak current of

Z. Igarashi, K. Nanmo, T. Takenaka, E. Takasaki

The new method to stabilize the beam energy of the KEK 40MeV proton linac, is developed now. In this method, the signal of the velocity monitor installed upstream the debuncher in the 40MeV beam line, is processed and then fed to the phase shifter of the debuncher rf system so as to cancel the fluctuation of the beam energy. In this article, the beam tests t

Milorad Popovic

A muon collider as well as a neutrino factory requires a large number of muons with a kinetic energy of 50GeV or more. Muon survival demands a high gradient linac. The large transverse and longitudinal emittance of the muon beam coming from a muon cooling system implies the need for a large acceptance, acceleration system. These two requirements point clearl

Milorad Popovic, Todd Sullivan

We report the results of observations of H- beam instabilities at the Fermilab Linac. By intentionally creating "high" background pressure with different gases in the 750 keV transport line we observed coherent transverse beam oscillations. The minimal pulse length required to observe oscillations and the frequency of oscillations are functions of pr

N. Toge

The JLC is a linear collider project pursued in Japan by researchers centered around KEK. The R&D status for the JLC project is presented, with emphasis on recent results from ATF concerning studies of production of ultra-low emittance beams and from manufacturing research on X-band accelerator structures.

R. Akre, V. Bharadwaj, P. Emma, P. Krejcik

The Linac Coherent Light Source (LCLS) project at SLAC uses a dense 15 GeV electron beam passing through a long undulator to generate extremely bright x-rays at 1.5 angstroms. The project requires electron bunches with a nominal peak current of 3.5kA and bunch lengths of 0.020mm (70fs). The bunch compression techniques used to achieve the high brightness imp

H. Vernon Smith,, J. David Schneider

The 75-keV injector and 6.7-MeV RFQ that comprise the first portion of the cw, 100-mA proton linac for the accelerator production of tritium (APT) project have been built and operated. The LEDA RFQ has been extensively tested for pulsed and cw output-beam currents <=100 mA. Up to 2.2 MW of cw rf power from the 350-MHz rf system is coupled into the RFQ, inclu

S. Virostek, J. Staples

The Spallation Neutron Source (SNS) Front-End Systems Group at Lawrence Berkeley National Lab (LBNL) is developing a Radio Frequency Quadrupole (RFQ) to accelerate an H- beam from 65 keV to 2.5 MeV at the operating frequency of 402.5 MHz. The 4 section, 3.7 meter long RFQ is a 4 vane structure operating at 6% duty factor. The cavity walls are made from OFE C

K. L. F. Bane, Z. Li

The injector linacs of the JLC/NLC comprise the e+ booster, the e- drive linac, the e+ booster, and the two prelinacs. These four systems together transport the two types of beams from the 80 MeV point at the end of their respective bunchers up to the storage rings, and then from the storage rings to the 10 GeV point at the beginning of the bunch compressors

L. Ya. Glozman

The conceptual issues of low-energy baryon physics are discussed. In particular, a comparison between the naive one gluon exchange model for the interaction between constituent quarks in hadrons and the Goldstone boson exchange picture is made. The &#34;defects&#34; of the Goldstone boson exchange model for baryons, indicated by Isgur are examined in detail.

A. Ludu, R. F. O&#39;Connell, J. P. Draayer

We use a one-scale similarity analysis which gives specific relations between the velocity, amplitude and width of localized solutions of nonlinear differential equations, whose exact solutions are generally difficult to obtain. We also introduce kink-antikink compact solutions for the nonlinear-nonlinear dispersion K(2,2) equation, and we construct a basis

G. Pappas, M. Rapoport

Local models are schemes defined in linear algebra terms that describe the &#39;etale local structure of integral models for Shimura varieties and other moduli spaces. We point out that the flatness conjecture of Rapoport-Zink on local models fails in the presence of ramification and that in that case one has to modify their definition. We study in detail ce

Eric R. Sharpe

In a previous paper we outlined how discrete torsion can be understood geometrically as an analogue of orbifold U(1) Wilson lines. In this paper we shall prove the remaining details. More precisely, in this paper we describe gerbes in terms of objects known as stacks (essentially, sheaves of categories), and develop much of the basic theory of gerbes in such

Eric R. Sharpe

In this technical note we give a purely geometric understanding of discrete torsion, as an analogue of orbifold Wilson lines for two-form tensor field potentials. In order to introduce discrete torsion in this context, we describe gerbes and the description of certain type II supergravity tensor field potentials as connections on gerbes. Discrete torsion the

Maulik K. Parikh

We review the thermodynamics of the confined and unconfined phases of superconformal Yang-Mills at large N on a three-sphere, focussing especially on the confinement-deconfinement transition. We determine an N-dependent phase boundary and point out some directions for future work.

Wung-Hong Huang

The thermodynamic potential of ideal gases described by the simplest non-abelian statistics is investigated. I show that the potential is the linear function of the element of the abelian-part statistics matrix. Thus, the factorizable property in the Haldane (abelian) fractional exclusion shown by the author [W. H. Huang, Phys. Rev. Lett. 81, 2392 (1998)] is

Wung-Hong Huang

The microcanonical statistics of the Schwarzschild black holes as well as the Reissner-Nordstr$\sf \ddot{o}$m black holes are analyzed. In both cases we set up the inequalities in the microcanonical density of states. These are then used to show that the most probable configuration in the gases of black holes is that one black hole acquires all of the mass a

D. Chruscinski

We show that the requirement of the relativistic invariance for any self-interacting, abelian p-form theory uniquely determines the form of the corresponding quantization condition.

S. Tokumoto, Y. H. Chin, H. Mizuno, K. Ohya

In this paper, we summarize the high power testing results of the X-band mixed-mode RF windows at KEK and SLAC for linear colliders. The main feature of these windows is that the combination of modes on the surface of the ceramic significantly decreases the electric and magnetic fields in the junction between the ceramic and the metal. So far two types of hi

E. Jongewaard, G. Caryotakis, C. Pearson, R. M. Phillips

Klystrons capable of 75 MW output power at 11.4 GHz have been under development at SLAC for the last decade. The work has been part of the program to realize all the components necessary for the construction of the Next Linear Collider (NLC). The effort has produced a family of solenoid-focused 50 MW klystrons, which are currently powering a 0.5 GeV test acc

J. A. Hernando, L. Blum

Density functional theory, when applied to systems with $T\neq 0$, is based on the grand canonical extension of the Hohenberg-Kohn-Sham theorem due to Mermin (HKSM theorem). While a straightforward canonical ensemble generalization fails, work in nanopore systems could certainly benefit from such extension. We show that, if the asymptotic behaviour of the ca

V. Bortolani, V. Celli, A. M. Marvin

We present the theory for Multiple Energy X-ray Holography (MEXH), using a multipole expansion for the scattered field. We find that light polarization plays a crucial role in the reconstruction of the image, and we suggest how to use it in order to eliminate aberration effects. The method we propose is alternative to the SWIFT method (scattered-wave--includ

E. Akkermans, D. M. Gangardt, K. Mallick

We present a study of the behaviour of metastable vortex states in mesoscopic superconductors. Our analysis relies on the London limit within which it is possible to derive closed analytical expressions for the magnetic field and the Gibbs free energy. We consider in particular the situation where the vortices are symmetrically distributed along a closed rin

H. Hong, M. Y. Choi

We study synchronization and noise-induced resonance phenomena in systems of globally coupled oscillators, each possessing finite inertia. The behavior of the order parameter, which measures collective synchronization of the system, is investigated as the noise level and the coupling strength are varied, and hysteretic behavior is manifested. The power spect

Jacco van Loon

The DENIS/ISOGAL near/mid-IR survey of the Milky Way for the first time probes stellar populations in the innermost obscured regions of our galaxy. Ages, metallicities and extinction-corrected luminosities are derived for these stars individually. An old metal-rich population dominates in the inner galactic Bulge, but there are also indications for the prese

Kirk D. Borne

The knowledge discovery potential of the new large astronomical databases is vast. When these are used in conjunction with the rich legacy data archives, the opportunities for scientific discovery multiply rapidly. A Virtual Observatory (VO) framework will enable transparent and efficient access, search, retrieval, and visualization of data across multiple d

Pierre Astier

Distance measurements to Type Ia supernovae (SNe Ia) at cosmological distances indicate that the Universe is accelerating and that a large fraction of the critical energy density exists in a component with negative pressure. Various hypotheses on the nature of this ``dark energy&#39;&#39; can be tested via their prediction for the equation of state of this c

Andreas A. Berlind, Vijay K. Narayanan, David H. Weinberg

Measurements of the cosmological density parameter Omega using techniques that exploit the gravity-induced motions of galaxies constrain, in linear perturbation theory, the degenerate parameter combination beta = Omega^{0.6}/b, where the linear bias parameter b is the ratio of the fluctuation amplitudes of the galaxy and mass distributions. However, the rela

F. Krüger, E. Lunghi

The CP-violating asymmetries in the exclusive decay B->K^*l^+l^- (l=e,mu,tau) are predicted to be exceedingly small in the standard model (SM), thereby offering an opportunity to assess various new-physics scenarios. We derive quantitative predictions for various integrated observables in B->K^*mu^+mu^- decay in the presence of physics beyond the SM with add

M. S. Oey

A rudimentary, one-zone, closed-box model for inhomogeneous chemical evolution is offered as an alternative reference than the Simple model in the limit of no mixing. The metallicity distribution functions (MDFs) of Galactic halo and bulge stars can be matched by varying a single evolutionary parameter, nQ. Q is the filling factor of contaminating regions an

Thomas Papenbrock, George F. Bertsch

We study a class of interacting, harmonically trapped boson systems at angular momentum L. The Hamiltonian leaves a L-dimensional subspace invariant, and this permits an explicit solution of several eigenstates and energies for a wide class of two-body interactions

Csaba Csaki, Michael L. Graesser, Graham D. Kribs

The dynamics of a stabilized radion in the Randall-Sundrum model (RS) with two branes is investigated, and the effects of the radion on electroweak precision observables are evaluated. The radius is assumed to be stabilized using a bulk scalar field as suggested by Goldberger and Wise. First the mass and the wavefunction of the radion is determined including

J. E. Cieza Montalvo, M. D. Tonasse

One of the versions of the SU(3)$_L\otimesU(1)_N$ electroweak model predicts charged heavy-leptons which do not belong to any class of heavy-leptons proposed up to now. We investigate the production and signatures of pairs of these heavy-leptons {\it via} the Drell-Yan process and the gluon-gluon fusion at the CERN Large Hadron Collider (LHC). As an example

D. Marsden, R. E. Lingenfelter, R. E. Rothschild

Radio pulsars are thought to spin-down primarily due to torque from magnetic dipole radiation (MDR) emitted by the time-varying stellar magnetic field as the star rotates. This assumption yields a `characteristic age&#39; for a pulsar which has generally been assumed to be comparable to the actual age. Recent observational limits on the proper motion of puls

R. Mankin, T. Laas, R. Tammelo

We present an alternative method for constructing the exact and approximate solutions of electromagnetic wave equations whose source terms are arbitrary order multipoles on a curved spacetime. The developed method is based on the higher-order Green&#39;s functions for wave equations which are defined as distributions that satisfy wave equations with the corr

Daniel Ashery

Diffractive dissociation of particles can be used to study their light-cone wave function. Results from Fermilab experiment E791 for diffractive dissociation of 500 GeV/c $π^-$ mesons into di-jets are presented. The results show that the $|q\bar {q}>$ light-cone asymptotic wave function describes the data well for $Q^2 \sim 10 ~{\rm (GeV/c)^2}$ or more. Evid

J. J. Halliwell

Inspired by Mott&#39;s (1929) analysis of particle tracks in a cloud chamber, we consider a simple model for quantum cosmology which includes, in the total Hamiltonian, model detectors registering whether or not the system, at any stage in its entire history, passes through a series of regions in configuration space. We thus derive a variety of well-defined

S. Blawid, A. J. Millis

We use the dynamical mean-field method to calculate the charge density wave transition temperature of the half-filled Holstein model as function of typical phonon frequency in the physically relevant adiabatic limit of phonon frequency Omega much less than electron bandwidth t. Our work is the first systematic expansion of the charge density wave problem in

A. Hebecker, C. Wetterich

We formulate conditions for the naturalness of cosmological quintessence scenarios. The quintessence lagrangian is taken to be the sum of a simple exponential potential and a non-canonical kinetic term. This parameterization covers most variants of quintessence and makes the naturalness conditions particularly transparent. Several ``natural&#39;&#39; scalar

A. H. Barnett, M. Blaauboer, A. Mody, E. J. Heller

We model the 2-probe conductance of a quantum point contact (QPC), in linear response. If the QPC is highly non-adiabatic or near to scatterers in the open reservoir regions, then the usual distinction between leads and reservoirs breaks down and a technique based on scattering theory in the full two-dimensional half-plane is more appropriate. Therefore we r

Z. Fodor, S. D. Katz

The spectrum of ultrahigh energy (above \approx 10^{9} GeV) cosmic rays is consistent with the decay of GUT scale particles. The predicted mass is m_X=10^b GeV, where b=14.6_{-1.7}^{+1.6}.

Cristiano Porciani, Piero Madau

Recent evidence appears to link gamma-ray bursts (GRBs) to star-forming regions in galaxies at cosmological distances. If short-lived massive stars are the progenitors of GRBs, the rate of events per unit cosmological volume should be an unbiased tracer (i.e. unaffected by dust obscuration and surface brightness limits) of the cosmic history of star formatio

F. M. L. Almeida, Y. A. Coutinho, J. A. Martins Simoes, M. A. B. do Vale

The discovery potential for detecting new heavy Majorana and Dirac neutrinos at some recently proposed high energy $e^+e^-$ colliders is discussed. These new particles are suggested by grand unified theories and superstring-inspired models. For these models the production of a single heavy neutrino is shown to be more relevant than pair production when compa

T. G. Wang, W. Brinkmann, W. Yuan, J. X. Wang

Recent observations of Broad Absorption Line (BAL) quasars demonstrated that the soft X-ray emission of these objects is extremely weak and convincing evidence for very strong absorption by a high column density (~ 10^23.5 cm^-2) was obtained for PG 1411+442, even though it is one of the few BAL QSOs strongly detected in soft X-rays. This paper examines the

T. Gollisch, C. Wetterich

A careful treatment of the discretization errors in the path integral formulation of quantum mechanics leads to a unique prescription for the translation from the Hamiltonian to the action in the functional integral. An example is given by an interaction quadratic in the occupation number, characteristic for manybody bosonic systems. As a result, the term li

K. Furukawa, Linac Commissioning Group

KEK electron linac was upgraded to 8 GeV for the KEK B-Factory (KEKB) project. During the commissioning of the upgraded linac, even continuing SOR ring injections, we had achieved a primary electron beam with 10-nC (6.24 x 10^10) per bunch up to 3.7-GeV for positron generation. This could be classified as one of the brightest S-band linac&#39;s. Since the KE

K. Furukawa, A. Enomoto, N. Kamikubota, T. Kamitani

The KEK 8-GeV electron / 3.5-GeV positron linac has been operated with very different beam specifications for downstream rings, KEKB, PF and PF-AR. For the reliable operation among these beam modes intelligent beam switching and beam feedback systems have been developed and used since its commissioning. A software panel is used to choose one of four beam mod

Jan Wiersig

We show that wave functions in planar rational polygonal billiards (all angles rationally related to Pi) can be expanded in a basis of quasi-stationary and spatially regular states. Unlike the energy eigenstates, these states are directly related to the classical invariant surfaces in the semiclassical limit. This is illustrated for the barrier billiard. We

M. Rooman, Ph. Spindel

Using the Chern-Simon formulation of (2+1) gravity, we derive, for the general asymptotic metrics given by the Fefferman-Graham-Lee theorems, the emergence of the Liouville mode associated to the boundary degrees of freedom of (2+1) dimensional anti de Sitter geometries. Holonomies are described through multi-valued gauge and Liouville fields and are found t

M. V. Foursa, D. A. Murashev, S. R. Slabospitsky

We investigate the charged Higgs boson contribution into $t\bar b$-pair production in pp-collisions at LHC. It is shown that due to the $\cz$-boson exchange the total yield of $t\bar b$ is modified significantly for small and large values of $\tanβ$. However, for the small values of $\tanβ$ one should expect also the production of right-polarized top quark c

Forough Nasseri, Sohrab Rahvar

Assuming the space dimension is not constant but decreases during the expansion of the Universe, we study chaotic inflation with the potential $m^2ϕ^2/2$. Our investigations are based on a model Universe with variable space dimensions. We write down field equations in the slow-roll approximation, and define slow-roll parameters by assuming the number of spac

K. Langfeld, E. -M. Ilgenfritz, H. Reinhardt

For SU(2) lattice gauge theory, a new SO(3) cooling procedure is proposed which removes the SU(2)/Z(2) coset fields from the lattice configurations and reveals a Z(2) vortex vacuum texture different from the P-vortex content obtained in the maximal center gauge. Cooling can be restricted in a renormalization group invariant way by a parameter controlling the

Z. Fang, S. Fukuda, S. Yamaguchi, S. Anami

Spurious oscillations in klystrons due to returning electrons from the collector into the drift tube were observed and studied at KEK. Simulations of returning electrons using EGS4 Monte Carlo method have been performed. And the oscillation conditions are described in this paper.

Shozo Uehara, Satoshi Yamada

We study the issue of defining the discrete light-cone quantization (DLCQ) in perturbative string theory as a light-like limit. While this limit is unproblematic at the classical level, it is non-trivial at the quantum level due to the divergences by the zero-mode loops. We reconsider this problem in bosonic string theory. We construct the multi-loop scatter

A. I. Dzergatch, S. V. Vinogradov

The proposed linear accelerator (&#34;scanator&#34;) consists of a terawatt table-top laser and a set of passive elements - beam splitters, dispersion elements for stretching of the laser pulse and chirping of the splitted beams, and dispersion elements for angle scanning of crossed frequency-modulated laser beams. Ions are trapped and accelerated in RF well

G. Guethlein, T. Houck, J. McCarrick, S. Sampayan

The next generation of radiographic machines based on induction accelerators is expected to generate multiple, small diameter x-ray spots of high intensity. Experiments to study the interaction of the electron beam with plasmas generated at the x-ray converter and at beamline septa are being performed at the Lawrence Livermore National Laboratory (LLNL) usin

Y. Jung, R. J. Silbey, J. Cao

The electron transfer kinetics of mixed-valence systems is studied via solving the eigen-structure of the two-state non-adiabatic diffusion operator for a wide range of electronic coupling constants and energy bias constants. The calculated spectral structure consists of three branches in the eigen-diagram, a real branch corresponding to exponential or multi

Y. M. Wang, S. I. Kwon, A. H. Regan

The RF system for the SNS superconducting linac consists of a superconducting cavity, a klystron, and a low-level RF (LLRF) control system. For a proton linac like SNS, the field in each individual cavity needs to be controlled to meet the overall system requirements. The purpose of the LLRF control system is to maintain the RF cavity field to a desired magn

R. A. Kishek, P. G. O&#39;Shea, M. Reiser

A process of energy transfer is demonstrated in non-equilibrium charged particle beams with anisotropy and space charge. Equipartitioning of energy between available degrees of freedom occurs in just a few betatron wavelengths, without halo formation. Collective space charge modes similar to those observed in recent experiments provide the underlying couplin

Sung-il Kwon, Yi-Ming Wang, Amy Regan, Tony Rohlev

The SNS SRF system is operated with a pulsed beam. For the SRF system to track the repetitive reference trajectory, a feedback and a feedforward controllers has been proposed. The feedback controller is to guarantee the closed loop system stability and the feedforward controller is to improve the tracking performance for the repetitive reference trajectory a

A. V. Titov, N. S. Mosyagin

In calculations of heavy-atom molecules with the shape-consistent Relativistic Effective Core Potential (RECP), only valence and some outer-core shells are treated explicitly, the shapes of spinors are smoothed in the atomic core regions and the small components of four-component spinors are excluded from calculations. Therefore, the computational efforts ca

P. L. Colestock, T. Wangler, C. K. Allen, R. L. Sheffield

Due to the potentially adverse effects of the generation of halo particles in intense proton beams, it is imperative to have a clear understanding of the mechanisms that can lead to halo formation for current and proposed high- intensity linacs. To this end a theoretical model has been developed, which indicates that protons under the combined influence of s

L. M. Young, L. J. Rybarcyk, J. D. Schneider, M. E. Schulze

The LEDA RFQ, a 350-MHz continuous wave (CW) radio-frequency quadrupole (RFQ), successfully accelerated a 100-mA CW proton beam from 75 keV to 6.7 MeV. We have accumulated 111 hr of beam on time with at least 90 mA of CW output beam current. The 8-m-long RFQ accelerates a dc, 75-keV, ~106-mA H+ beam from the LEDA injector with ~94% transmission. When operati

J. -F. Ostiguy, K. -Y. Ng

During the course of the last decade, traveling wave accelerating structures for a future Linear Collider have been the object of intense R&D efforts. An important problem is the efficient computation of the long range wakefield with the ability to include small alignment and tuning errors. To that end, SLAC has developed an RF circuit model with a demonstra

HL Rutkowski, LL Reginato, WL Waldron, KP Chow

The second phase accelerator for the Dual Axis Hydrodynamic Test facility (DARHT) is designed to provide an electron beam pulse that is 2 microsec long, 2kA, and 20 MeV in particle energy. The injector provides 3.2 MeV so that the linac need only provide 16.8 MeV. The linac is made with two types of induction accelerator cells. The first block of 8 cells hav

A. E. Grelick, N. Arnold, S. Berg, D. Dohan

An S-band linear accelerator is the source of particles and the front end of the Advanced Photon Source injector. In addition, it supports a low-energy undulator test line (LEUTL) and drives a free-electron laser (FEL). A waveguide-switching and distribution system is now under construction. The system configuration was revised to be consistent with the rece

L. I. Donley, V. F. Stipp, F. R. Brumwell, G. E. McMichael

The H- Accelerator consists of a 750 keV Cockcroft Walton preaccelerator and an Alvarez type 50 MeV linac. The accelerator has been in operation since 1961. Since 1981, it has been used as the injector for the Intense Pulsed Neutron Source (IPNS), a national user facility for neutron scattering. The linac delivers about 3.5x1012 H- ions per pulse, 30 times p

A. Moretti, N. Holtkamp, T. Jurgens, Z. Qian

A multi-laboratory collaboration is studying the feasibility of building a muon collider, the first phase of which maybe a neutrino factory. The phase space occupied by the muons is very large and needs to be cooled several orders of magnitude for either machine, 100,000 to 1 million for the collider and ten to 100 for the factory. Ionization cooling is the

J. S. Oh, J. S. Bak, M. H. Cho, W. Namkung

An e+e- linear collider at 500-GeV C.M. (center of mass) has been proposed as a future accelerator. The C-band linear collider has more than a thousand klystrons and matching modulators. The linear colliders require smart modulators with high reliability, compact and simple configuration, and good power efficiency. This study suggests solutions to problems e

C. Vermare, D. C. Moir, G. J. Seitz

We present the first time resolved OTR angular distribution measurements of an intense pulsed electron beam (1.7 kA, 60 ns). These initial experiments on the first axis of the Dual Axis Radiographic Hydro-Testing (DARHT) facility and subsequent analysis, demonstrate the possibility to extract, from the data, the energy and the divergence angle of a 3.8 and 2

J. C. Dooling, F. R. Brumwell, M. K. Lien, G. E. McMichael

Injected beam energy and energy spread are critical parameters affecting the performance of our rapid cycling synchrotron (RCS). A real-time energy monitoring system is being installed to examine the H- beam out of the Intense Pulsed Neutron Source (IPNS) 50 MeV linac. The 200 MHz Alvarez linac serves as the injector for the 450 MeV IPNS RCS. The linac provi

B. Schlitt, A. Bechtold, U. Ratzinger, A. Schempp

A dedicated clinical synchrotron facility for cancer therapy using energetic proton and ion beams (C, He and O) has been designed at GSI for the Radiologische Universitaetsklinik at Heidelberg, Germany. The design of the injector linac is presented. Suitable ion sources are discussed and results of ion source test measurements are reported. The LEBT allows f

E. McCrory, T. Kroc, A. Moretti, M. Popovic

We have reported previously on the conditioning of the high-gradient accelerating cavities in the Fermilab Linac. Automated measurements of the sparking rate have been recorded since 1994 and are reported here. The sparking rate has declined since the beginning, but there are indications that this rate may have leveled off now. The X-rays emitted by the cavi

R. Ferdinand, P-Y. Beauvais, R. Duperrier, A. France

A 5-MeV RFQ designed for a proton current up to 100-mA CW is now under construction as part of the High Intensity Proton Injector project (IPHI). Its computed transmission is greater than 99 %. The main goals of the project are to verify the accuracy of the design codes, to gain the know-how on fabrication, tuning procedures and operations, to measure the ou

R. Duperrier, R. Ferdinand, P. Gros, J-M. Lagniel

The chopping line is a critical part of the ESS linac in term of technical realisation of the choppers and preservation of the beam qualities. A new optimised design of the ESS RFQs and chopping lines is reported. The beam dynamics has been optimised with H- beam currents up to 100-mA to have safety margin with respect to the ESS goals. The first RFQ transmi

R. Gobin, P-Y. Beauvais, O. Delferriere, R. Ferdinand

The development of a high intensity negative ion source is part of a considerably larger activity presently undergoing at CEA Saclay in the field of high intensity linear accelerators. Preliminary studies toward the construction of a 2.45 GHz ECR H- ion source have been performed for few months. This new test bench takes advantage of our experience on the Fr

M. Vretenar

In view of a possible evolution of the CERN accelerator complex towards higher proton intensities, a 2.2 GeV H- linac with 4 MW beam power has been designed, for use in connection with an accumulator and compressor ring as proton driver of a muon-based Neutrino Factory. The high-energy part of this linac can use most of the RF equipment (superconducting cavi

B. H. Choi

KAERI (Korea Atomic Energy Research Institute) has been performing the project named KOMAC (Korea Multi-purpose Accelerator Complex) within the frame work of national mid and long term nuclear research plan. The final objectives of KOMAC is to build a 20-MW (1 GeV and 20 mA) cw (100% duty factor) proton linear accelerator. As the first stage, the low energy

J. M. Han

The Radio-Frequency Quadrupole (RFQ) linac that will accelerate a 20mA proton beam from 50keV to 3MeV has been designed and is being fabricated as the first phase, KOMAC Test Facility (KTF), of the Korea Multipurpose Accelerator Complex (KOMAC) project at the Korea Atomic Energy Research Institute (KAERI). The physical, engineering designs and fabrication st

Arup Banerjee, Manoj K. Harbola

Using the orbitals generated by the van Leeuwen-Baerends potential, we calculate frequency dependent response properties of noble gas atoms of He, Ne and Ar and alkaline earth atoms Be and Mg, with particlar emphasis on their nonlinear polarizabilities. For this we employ time-dependent Kohn-Sham formalism with adiabatic local-density aproximation (ALDA) for

J. S. T. Ng, P. Chen, W. Craddock, F. J. Decker

We present results from the SLAC E-150 experiment on plasma focusing of high energy density electron and, for the first time, positron beams. We also discuss measurements on plasma lens-induced synchrotron radiation, longitudinal dynamics of plasma focusing, and laser- and beam-plasma interactions.