EPAC 2006 - List of Keywords

A B C D E F G H I K L M O P Q R S T U V W X

LEFT

Paper	Title	Other Keywords	Page
MOPCH106	An Innovative Method to Observe RFQ Vanes Motion with Full-scale RF Power and Water Cooling	rfq, vacuum, SPIRAL2, optics	288
	A. France, O. Piquet CEA, Gif-sur-Yvette R. Ferdinand GANIL, Caen
	The design of high current RFQs is heavily strained by thermo-mechanical considerations, which eventually have an impact on machining costs, cooling systems, etc. A 1-meter long copper prototype of the SPIRAL2 RFQ has been specifically built to corroborate design options. An innovative method has been developed, allowing real-time observation of mechanical deformations of RFQ vanes, with full-scale RF power and water cooling. Digital images are acquired by a CCD camera, and processed by a dedicated software. Processing includes contrast stretching, low-pass filtering, and block-correlation followed by interpolation. Sub-pixel relative motions of RFQ electrode ends are clearly detected and measured, with RMS errors of the order of 0.6 microns.

MOPCH107	Tuning Procedure of the 6 Meter IPHI RFQ	rfq, dipole, coupling, quadrupole	291
	O. Piquet, M. Desmons, A. France CEA, Gif-sur-Yvette
	In the framework of the IPHI project (High Intensity Proton Injector), the RFQ cavity is divided into 6 sections of 1 meter each, and assembled in 3 segments separated by coupling plates. We will present the tuning procedure of the aluminium RFQ cold model to set the accelerating mode frequency, a flat voltage profile and to minimize the dipole components of the accelerating voltage. This tuning procedure can be divided in three steps. First, dipole mode frequencies are adjusted with rods for the 3 separated segments. Second, RFQ end cells and coupling cells are tuned by mechanical machining of tuning plates. Third, using a fully automated bead-pull for the measurement of the field distribution inside every RFQ quadrants, the RFQ is tuned with 96 plungers in a small number of iterations. Tuning this 6-meter long cold model is a comprehensive training in view of the future tuning of the copper RFQ with the variable voltage profile.

MOPCH135	Benchmarking Electron Cloud Data with Computer Simulation Codes	electron, simulation, RHIC, BNL	363
	U. Iriso CELLS, Bellaterra (Cerdanyola del Vallès) G. Rumolo CERN, Geneva
	Saturated electron flux and time decay of the electron cloud are experimentally inferred using many electron detector datasets at the Relativistic Heavy Ion Collider (RHIC). These results are compared with simulation results using two independent electron cloud computer codes, CSEC and ECLOUD. Simulation results are obtained over a range of different values for 1) the maximum Secondary Electron Yield (SEY), and 2) the electron reflection probability at zero energy. These results are used to validate parameterization models of the SEY as a function of the electron energy.

MOPCH169	High Pressure Rinsing Water Jet Characterization	TESLA, DIAMOND, linear-collider, collider	460
	D. Sertore, E. Cavaliere, M. Fusetti, P. Michelato, C. Pagani, P. Pierini INFN/LASA, Segrate (MI)
	High pressure rinsing is widely used as the final wet step in the high field superconducting cavities production. The interaction of an high speed ultra pure water jet with the niobium surface depends on various parameters such as water pressure, water throughput, treatment duration, cavity rotation speed, etc. In this paper we illustrate a simple technique for the characterization of water jet parameters based on the momentum transfer between the water jet and a load cell. The jet profile and its dependence on water pressure as well as the force exerted by the jet on the surface are easily measured. Moreover a portable apparatus has been set up and the information gathered in different laboratories will be used for a quantitative comparison of the different HPR systems. These measurements allow to study the correlation of the jet parameters with the effects (surface status, oxide formation, corrosion, etc) of the water interaction with the niobium surface. Furthermore a new analysis, based on the luminescence induced on transparent dielectric samples, is used for confirmation of the water jet structure.

MOPCH171	ILC Coaxial Blade Tuner	TTF, DESY, electron, linear-collider	466
	C. Pagani, A. Bosotti, P. Michelato, N. Panzeri, R. Paparella, P. Pierini INFN/LASA, Segrate (MI)
	A coaxial (blade) tuner solution has been developed for the compensation of the Lorentz force detuning of the superconducting cavities under the high gradient pulsed operation foreseen for ILC operation. The device is based on prototypes successfully tested at DESY in 2002 both on CHECHIA and on the superstructures inserted in the TTF string. During both tests the blade tuner performed as expected in terms of stiffness, frequency sensitivity and tuning capabilities. An improvement of the tuner characteristics has been designed by the integration of fast tuning capabilities by means of piezo-ceramic element. Two prototipes of the new INFN coaxial piezo blade tuner have just been manufactured and they will be tested at DESY and BESSY after the cavity integration. In this paper the blade tuner design and main characteristics are presented, together with the early interpretation of the cold test results.

MOPCH174	Optimization of the BCP Processing of Elliptical Nb SRF Cavities	simulation, extraction, insertion, DESY	469
	C. Boffo, C. A. Cooper, A.M. Rowe Fermilab, Batavia, Illinois G. Galasso University of Udine, Udine
	Bulk niobium (Nb) electropolished SRF cavities performing at or above 35 MV/m is an aggressive goal recently put forth by the International Linear Collider (ILC) collaboration. Buffered chemical polishing (BCP) is still the most cost effective and least complex processing technique known today to optimize the surface properties of high gradient single crystal and relatively low gradient polycrystalline SRF cavities. BCP will be the preferred chemical process in the production of the nine-cell third harmonic 3.9 GHz cavities at Fermilab. The internal shape of these cavities will result in uneven material removal rates between iris and equator of the cells. We will describe a thermal-fluid finite element model adopted to simulate the etching process, and thus revealing the issues at hand. Experimental work, such as flow visualization tests performed to verify the simulation, will also be discussed. Finally we are presenting results obtained with a novel device, which allows to homogenize the flow pattern and to resolve the problem.

MOPLS068	Beam Impact of the ILC Collimators	simulation, electron, monitoring, positron	703
	G. Ellwood, R.J.S. Greenhalgh CCLRC/RAL, Chilton, Didcot, Oxon
	Spoilers in the ILC Beam Delivery System are required to survive a minimum of 1-2 direct impacts from each energetic electron or positron bunch of charged particles without failure, in addition to maintaining low geometric and resistive wall wakefields. The transient shock wave resulting from rapid localised beam heating and its implications for spoiler design are studied using ANSYS. The realistic patterns of energy deposition are taken from FLUKA.The results presented quantify uncertainties in the predictions and consider possible options for spoiler jaws for the ILC.

TUPCH060	Beam Collimator System in the J-PARC 3-50BT Line	emittance, synchrotron, injection, quadrupole	1148
	M.J. Shirakata, H. Oki, T. Oogoe, Y. Takeuchi, M. Yoshioka KEK, Ibaraki
	For the J-PARC 50 GeV Main Ring Synchrotron (MR), the design beam emittance is 54 pi mm mrad. On the other hand, the 3 GeV beam from the Rapid Cycling Booster Synchrotron (RCS) may have a large halo component upto 216 pi mm mrad. In order to absorb the halo component, a beam collimator system will be installed in the beam transport line called as the 3-50BT, which connects the RCS and the MR. From the view of the hands-on maintenance, high endurance structure is adopted. The beam collimator design including the beam optics is reported in this paper.

TUPCH084	Expected Signal for the TBID and the Ionization Chambers Downstream of the CNGS Target Station	target, proton, secondary-beams, instrumentation	1208
	L. Sarchiapone, A. Ferrari, E. Gschwendtner, M. Lorenzo Sentis CERN, Geneva
	Downstream the carbon graphite target of the CNGS (CERN Neutrinos to Gran Sasso) facility at CERN it has been decided to install a secondary emission monitor called TBID (Target Beam Instrumentation Downstream) monitor to measure the multiplicities and the left/right as well as up/down asymmetries of secondary particles from target. Calculations show that the titanium windows used to close off the TBID vacuum tank might not withstand the highest beam intensities with small spot sizes expected at CNGS, in case the proton beam accidentally misses the 4-5 mm diameter target rods. Therefore it has been suggested to place two ionisation chambers as a backup for the TBID located left and right of the TBID monitors. Monte Carlo simulations with the particle transport code FLUKA were performed firstly to obtain the fluence of charged particles in the region of interest and secondly to estimate the induced radioactivity (noise) in this area. This allows to assess the actual signal/noise situation and thus to determine the optimal position (lateral displacement with respect to the beamline) of the ionisation chambers. This document presents the results of these calculations.

TUPCH124	Improvement of Co-based Amorphous Core for Untuned Broadband RF Cavity	impedance, acceleration, heavy-ion, synchrotron	1304
	A. Sugiura, M. Kanazawa, T. Misu, S. Yamada NIRS, Chiba-shi K. Katsuki, T. Kusaka, K. Sato Toshiba, Yokohama
	We have developed a cobalt-based amorphous core as a new magnetic-alloy (MA) core for the loaded RF cavity. Because of its permeability found to be approximately twice as high as that of FINEMET, this MA core is an excellent candidate for constructing a compact broadband RF cavity with less power consumption. In this report, we present our recent studies of the Co-based amorphous core's physical properties and performance. Improvement of the new core coated by new materials surface of ribbon is also described.

TUPCH126	Outgassing Rate of Highly Pure Copper Electroplating Applied to RF Cavities	vacuum, linac, KEK, simulation	1307
	T. Abe, T. Kageyama, Y. Saito, H. Sakai, Y. Sato, Y. Takeuchi KEK, Ibaraki Z. Kabeya, T. Kawasumi MHI, Nagoya T. Nakamura, S. Nishihashi, K. Tsujimoto Asahi Kinzoku Co., Ltd., Gifu K. Tajiri Churyo Engineering Co., Ltd., Nagoya
	We plan to apply a new copper electroplating with a high purity and a high electric conductivity to normal-conducting RF cavities for electron or positron storage rings with a high current beam. As reported in 2005 Particle Accelerator Conference, our first test cavity, made of iron, with the electroplated copper surface finished up by electropolishing showed an excellent electric performance compared with the case of cavities made of oxygen free copper. Our next step is to examine the vacuum performance. This paper reports results of the outgassing-rate measurements on our second test cavity together with its fabrication process.

TUPCH143	High Gradient Tests of an 88 MHZ RF Cavity for Muon Cooling	CERN, factory, linac, simulation	1352
	C. Rossi, R. Garoby, F. Gerigk, J. Marques Balula, M. Vretenar CERN, Geneva
	The scheme for a Muon Cooling channel developed at CERN in the frame of Neutrino Factory studies foresees the use of 44 and 88 MHz cavities operating at a real-estate gradient as high as 4 MV/m. To assess the feasibility of this scheme, including high-gradient operation at relatively low frequency and the production and handling of high RF peak powers, a test stand was assembled at CERN. It included an 88 MHz resonator reconstructed from a 114 MHz cavity previously used for lepton acceleration in the PS, a 2.5 MW final amplifier made out of an old linac unit improved and down-scaled in frequency, and a PS spare amplifier used as driver stage. After only 160 hours of conditioning the cavity passed the 4 MV/m level, with local peak surface field in the gap exceeding 25 MV/m (2.4 times the Kilpatrick limit). The gradient was limited by the amplifier power, the maximum RF peak output power achieved during the tests being 2.65 MW. This paper presents the results of the tests, including an analysis of field emission from the test cavity, and compares the results with the experience in conditioning ion linac RF cavities at CERN.

TUPCH165	Compact Single-channel Ka-band SLED-II Pulse Compressor	coupling, scattering, CLIC, linac	1411
	S.V. Kuzikov, S.V. Kuzikov, M.E. Plotkin, A.A. Vikharev Omega-P, Inc., New Haven, Connecticut J.L. Hirshfield Yale University, Physics Department, New Haven, CT
	Basic studies of factors that limit RF fields in warm accelerator structures require experiments at RF power levels that can only be produced from an intense drive beam, as with CLIC studies, or using pulse compression of output pulses from the RF source. This latter approach is being implemented to compress output pulses from the Yale/Omega-P 34-GHz magnicon to produce ~100-200 MW, 100 ns pulses. A new approach for passive pulse compression is described that uses a SLED-II-type circuit operating with axisymmetrical modes of the TE0n type that requires only a single channel instead of the usual double channel scheme. This allows avoidance of a 3-dB coupler and need for simultaneous fine tuning of two channels. Calculations show that with this device at 34 GHz one can anticipate a power gain of 3.3:1, and an efficiency of 66% for a 100 ns wide output pulse, taking into account losses and a realistic 50-ns long 180 degrees phase flip.

TUPLS012	Dynamic Stresses in the LHC TCDS Diluter from 7 TeV Beam Loading	simulation, LHC, septum, extraction	1511
	B. Goddard, A. Presland, W.J.M. Weterings CERN, Geneva L. Massidda CRS4, PULA
	In the event of an unsynchronised beam abort, the MSD extraction septum of the LHC beam dumping system is protected from damage by the TCDS diluter. The simultaneous constraints of obtaining sufficient beam dilution while ensuring the survival of the TCDS make the design difficult, with high thermally induced dynamic stresses occurring in the material needed to attenuate the particle showers induced by the primary beam impact. In this paper, full 3D simulations are described where the worst-case beam loading has been used to generate the local temperature rise and to follow the resulting time evolution of the mechanical stresses. The results and the accompanying design changes for the TCDS, to provide an adequate performance margin, are detailed.

TUPLS070	Chromaticity Control in Linear-field Nonscaling FFAGs by Sextapoles	quadrupole, focusing, lattice, betatron	1657
	S.R. Koscielniak TRIUMF, Vancouver
	Because of their high repetition rate and large apertures, FFAGs are proposed for high-current medical accelerators suitable for cancer therapy. The linear-field nonscaling FFAG is made from repeating cells containing D and F combined function magnets. The betatron tune profiles decrease with momentum; this leads to the crossing of resonances. We examine how sextapole magnets may be used to flatten the tune profile; in particular (i) whether it is better to place them at the D or F; (ii) what strength is required; and (iii) what is their effect on the closed orbits and path length? The orbit geometry is derived from a thin-element model and the tunes from power series in the quadrupole strength. Chromaticity is corrected by coupling focusing strength to dispersion, which is far stronger in the F element. The zeros of the orbit dispersion become the poles of the "sextapole strength to flatten the tune at some particular momentum". We demonstrate that a weak F sextapole can produce a substantial horizontal tune flattening, and has little impact on other optical properties. Contrarily, placing the sextapole at the D element may destroy the dynamic aperture and or vertical focusing.

TUPLS071	Minimum Cost Lattices for Nonscaling FFAGs	lattice, closed-orbit, acceleration, quadrupole	1660
	S.R. Koscielniak TRIUMF, Vancouver
	Previously, linear-field FFAG lattices for muon acceleration have been optimized under the condition of minimum path length variation. For non-relativistic particles, as are employed in the hadron therapy of cancer, that constraint is removed allowing a wider range of design choices. We adopt the thin-element kick model for a degenerate F0D0 cell composed of D and F combined function magnets. The dipole field components are parametrised in terms of the bending at the reference momentum and the reverse bend angle. The split between positive and negative bending sets the shape of the closed orbits. The cost function, based on stored magnetic energy, is explored in terms of the split. Two cost minima are found, one corresponding to minimum peak magnet field in the F element, and another to minimum radial aperture in the D element. Analytic formulae are given for the minimization conditions. The minimum field lattice is similar to existing designs based on minimizing the path length variation, but the minimum aperture lattice presents a new direction for future detailed design studies.

TUPLS110	Measurement of the Extraction Kicker System in J-PARC RCS	kicker, vacuum, extraction, proton	1759
	J. Kamiya, M. Kinsho, M. Kuramochi, T. Takayanagi, O. Takeda, T. Ueno, M. Watanabe, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken
	Kicker magnet system in the J-PARC RCS is now under construction at JAEA (Japan Atomic Energy Agency). Their role in RCS is to kick the accelerated 3 GeV proton beam to the following extraction line at a repetition rate of 25 Hz. There are three kinds of kicker magnets (S, M, L), distinguished by the difference in the size of their apertures. The specification of 2 % is required on the magnetic field in terms of homogeneity in time and space from the beam optical point of view. The required flatness of the temporal uniformity was accomplished by superposing the waveforms of the two kicker magnet. The required specification to the special uniformity is also very severe to achieve because our kicker magnet is designed with a large aperture in order to accept a maximum beam power of 1 MW. We established the search coil as a detector and 3-axes stage to perform magnetic field mapping. In order to reduce the signal noises and detect the stable output signals, matching register and integrated circuit were carefully selected. The 3-axes stage was precisely aligned. The distribution of the magnetic field (By) and integrated BL were systematically measured for the three types of kickers. J. Kamiya et al. “Magnetic field measurement of the extraction kicker magnet in J-PARC RCS,” submitted for publication to the proceedings of the 19th International Conference on Magnet Technology.

WEIFI02	Can the Accelerator Control System be Bought from Industry?	controls, target, vacuum, instrumentation	1916
	M. Plesko Cosylab, Ljubljana
	This presentation is intended for project leaders and specialists, whose components depend on the control system, which is nearly everybody apart from control experts. The presentation will explain the basic concepts of an accelerator control system, illustrate the similarities and differences among the most popular packages, which are nicely disguised in acronyms such as EPICS, TANGO, TINE, DOOCS, COACK, XAL, CDEV, etc. and compare them to commercial control systems (DCS and SCADA) and LabView. The second part of the presentation will analyse whether a control system is in principle a component as any other and whether therefore in principle it should be bought eventually from a competent supplier like all the other components. It will identify the reasons why many people are reluctant to outsource control systems and illustrate this with some personal experiences and suggestions how to overcome these problems. The talk will conclude by showing how naively we have started a spin-off company* to commercialize the accelerator control system that we have developed, how we have found sustainable sources of business, and how we see the future in this and related markets. * Cosylab - Control System Laboratory, www.cosylab.com
	Transparencies

WEPCH068	6-D Beam Dynamics Studies in EMMA FFAG	acceleration, dipole, electron, quadrupole	2080
	F. Meot CEA, Gif-sur-Yvette
	Extensive simulations of 6-D transmission simulations in linear, non-scaling FFAGs, based on gutter rapid acceleration, are reported. They concern two different on-going projects: the 20~GeV muon accelerators in the Neutrino Factory (NuFact) with ISS parameters* and a 20~MeV electron model of these machines, EMMA*. http://www.hep.ph.ic.ac.uk/iss/**http://hepunx.rl.ac.uk/uknf/wp1/emodel/

WEPCH077	Particle Tracking in a Sextupole Field using the Euler Method Approximation	sextupole, lattice, dynamic-aperture, ELETTRA	2098
	S. Di Mitri, E. Karantzoulis ELETTRA, Basovizza, Trieste
	The purpose of this paper is to evaluate any differences in the single particle tracking through a magnetic lattice when sextupoles are treated either like sliced or single-kick elements. Only on-energy transverse motion is considered. Convergence and symplecticity of the method of sliced sextupoles are discussed. Dynamic apertures and transverse phase spaces applied to the Elettra synchrotron lattice are compared for the two cases.

WEPCH122	2D Wake Field Calculations of Tapered Structures with Different FDTD Discretization Schemes	vacuum, simulation, impedance	2206
	C. Schmidt Rostock University, Institute for General Electrical Engn., Rostock H.-W. Glock, U. van Rienen Rostock University, Faculty of Engineering, Rostock
	The continual performance improvement of particle accelerators requires advanced prediction of parasitic wake field effects, even in structures of comparatively weak influence like tapers. In the case of smooth tapered components, even well established codes like MAFIA* demonstrate strong discretization dependency of the results or solver instabilities, making them not reliable in such applications. Grid dispersion is assumed to generate this failure. In Ref.** an alternative discretization scheme is described, using a homogeneous rotated mesh intended to eliminate such grid dispersion effects. In order to study the dependence on the discretization applied, we use this scheme to calculate wake fields in prototype taper structures of rotational symmetry. Furthermore a comparison is provided with the results of a non-rotated mesh, MAFIA runs and - so far applicable - analytical approaches. MAFIA V4.107: CST GmbH, Bad Nauheimer Str. 19, D-64289 Darmstadt*R. Hampel et al. New discretization scheme for wake field computation in cylindrically symmetric structure. Proc. EPAC'04, pp 2559

WEPCH137	FAKTOR2: A Code to Simulate the Collective Effects of Electrons and Ions	electron, ion, simulation, CLIC	2242
	W. Bruns, D. Schulte, F. Zimmermann CERN, Geneva
	A new code for computing the multiple effects of slowly moving charges is being developed. The basic method is electrostatic particle in cell. The underlying grid is rectangular and locally homogeneous. At regions of interest, e.g., where the beam is, or near material boundaries, the mesh is refined recursively. The motion of the macroparticles is integrated with an adapted timestep. Fast particles are treated with a smaller timestep, and particles in regions of fine grids are also treated with a fine timestep. The position of collision of particles with material boundaries is accurately resolved. Secondary particles are then created according to user-specified yield functions.

WEPCH144	CSR Effects in a Bunch Compressor: Influence of the Transverse Force and Shielding	shielding, CSR, simulation, radiation	2260
	G. Bassi, J.A. Ellison, K.A. Heinemann UNM, Albuquerque, New Mexico
	We study the influence of CSR on particle bunches traveling on arbitrary planar orbits between parallel conducting plates with a fixed "vertical" charge distribution. Our goal is a numerical solution of the 2 degree-of-freedom Vlasov-Maxwell equations. This provides simulations with lower numerical noise than the macroparticle method and allows the study of emittance degradation and microbunching. As reported, we calculate the fields excited by the bunch in the lab frame using a new formula that leads to a simplification. The Vlasov equation is integrated in the beam frame interaction picture using the method of local characteristics. The transformation between traditional beam frame and lab frame coordinates is carefully treated. Here we report on our implementation of the algorithm in the context of a chicane bunch compressor, where the strong correlation between phase space variables requires an adaptive grid. In particular, we present a complete analysis (moments + reduced densities) of the bunch evolution under the fields produced by the unperturbed bunch density. Finally, our progress on the fully self-consistent case is discussed. Vlasov treatment of coherent synchrotron radiation from arbitrary planar orbits, Nucl. Instr. Meth. Phys. Res. A, in press.** ICFA Beam Dynamics Mini-Workshop on CSR, Berlin-Zeuthen, 2002. See http://www.desy.de/csr.

WEPCH148	Computing TRANSPORT/TURTLE Transfer Matrices from MARYLIE/MAD Lie Maps	optics, beam-transport, accelerator-theory, CERN	2272
	G.H. Gillespie G.H. Gillespie Associates, Inc., Del Mar, California
	Modern optics codes often utilize a Lie algebraic formulation of single particle dynamics. Lie algebra codes such as MARYLIE and MAD offer a number of advantages that makes them particularly suitable for certain applications, such as the study of higher order optics and for particle tracking. Many of the older more traditional optics codes use a matrix formulation of the equations of motion. Matrix codes such as TRANSPORT and TURTLE continue to find useful applications in many areas where the power of the Lie algebra approach is not necessary. Arguably the majority of practical optics applications can be addressed successfully with either Lie algebra or matrix codes, but it is often a tedious exercise to compare results from the two types of codes in any detail. Differences in the choice of dynamic variables, between Lie algebra and matrix codes, compounds the comparison difficulties already inherent in the different formulations of the equations of motion. This paper summarizes key relationships and methods that permit that direct numerical comparison of results from MARYLIE and MAD with those from TRANSPORT and TURTLE.

WEPLS006	Requirements for Accelerator-based Neutrino Facilities	factory, CERN, alignment, monitoring	2406
	A.P. Blondel DPNC, Genève
	Classification: 1-A18, 3-A09, 4-A15, 6-T03 (non exhaustive). The study of neutrino oscillations offers promises of great discoveries including leptonic CP violation. The experimental programs that are under discussion pose considerable challenges to accelerator builders. Extremely high intensities are needed for classical on- and off-axis pion decay beams; novel ideas such as beta-beams and muon decay beams have been invented and are being studied. The experiments to be performed require outstanding predictability and monitoring of the neutrino flux. The challenges will be reviewed and a list of requirements will be proposed.

WEPLS051	Dark Current Investigation of TTF and PITZ RF Guns	cathode, gun, PITZ, DESY	2493
	L. Monaco, P. Michelato, C. Pagani, P. Pierini, D. Sertore INFN/LASA, Segrate (MI) J.H. Han, S. Schreiber DESY, Hamburg M. Krasilnikov, F. Stephan DESY Zeuthen, Zeuthen
	The dark current is one of the limiting factor in the operation of RF guns at high gradient. The continuous request of higher brilliance sources and further emittance minimization, leads to apply higher gradients in the RF gun cavity, with the consequence of a significant dark current production. In this context we set up a collaborative effort to identify the dark current sources in the gun, in order to discriminate between the gun and cathode contribution. A critical analysis and organization of dark current measurements, taken during the operation of TTF and PITZ guns, with several cathodes operated at different accelerating fields and solenoids focusing, is presented. Potential areas of improvement are also discussed, together with a possible associated program.

WEPLS089	Feasibility Study of a Permanent Magnet Made from High-Tc Bulk Superconductor	dipole, permanent-magnet, superconductivity, shielding	2580
	M. Masuzawa, K. Egawa, K. Tsuchiya KEK, Ibaraki
	A field trapping experiment using a magnetic field up to ~1.5 T was performed using high-Tc bulk superconductors. Applications of bulk high-Tc superconductors have been investigated in various fields. High-Tc superconductors are attractive since they can trap higher magnetic fields than conventional permanent magnets. The trapping experiment was done with a field of above 1 T, which can be easily produced by conventional magnets. However, achieving the desired field distribution and understanding the characteristics of the trapped field and its decay process would open up the possibility of high-Tc bulk superconductor applications in the design of magnets for particle accelerators The distribution of the trapped field and its decay process was monitored by an array of Hall sensors for different shapes of the bulk superconductors. The observations are reported on in this paper.

WEPLS110	New Measurements of Sextupole Field Decay and Snapback Effect on Tevatron Dipole Magnets	dipole, injection, sextupole, LHC	2640
	G. Velev, P. Bauer, R.H. Carcagno, J. DiMarco, M.J. Lamm, D.F. Orris, P. Schlabach, C. Sylvester, M. Tartaglia, J. Tompkins Fermilab, Batavia, Illinois
	To perform detailed studies of the dynamic effects in superconducting accelerator magnets, a fast continuous harmonics measurement system based on the application of a digital signal processor (DSP) has been built at Fermilab. Using this new system the dynamic effects in the sextupole field, such as the field decay during the dwell at injection and the rapid subsequent "snapback" during the first few seconds of the energy ramp, are evaluated for more than ten Tevatron dipoles from the spares pool. The results confirm the previously observed fast drift in the first several seconds of the sextupole decay and provided additional information on a scaling law for predicting snapback duration. The presented information can be used for an optimization of the Tevatron and for future LHC operations.

THESPA01	Before the Big Bang: An Outrageous New Perspective and its Implications for Particle Physics	background, radiation, LANL, electron	2759
	R. Penrose Mathematical Institute, Oxford
	The second law of thermodynaics implies that big bang must have been an extraordinarily precisely organized state. What was the geometrical nature of this state? How can we resolve, in any scientific way, the mystery of how such precision came about? In this talk, a novel (and perhaps outrageous) solution is suggested, which involves an examination of what is to be expected of the very remote future of our universe, with its observed accelerated expansion. Some possible observational consequences of the proposal will be indicated, together with some apparent implications for particle physics, some of which are non-standard.

THPCH005	Considerations for the High-intensity Working Point of the SIS100	resonance, beam-losses, dipole, synchrotron	2793
	G. Franchetti, O. Boine-Frankenheim, I. Hofmann, V. Kornilov, P.J. Spiller, J. Stadlmann GSI, Darmstadt
	In the FAIR project the SIS100 synchrotron is foreseen to provide high-intensity beams of U 28+, including slow extraction to the radioactive beam experimental area, as well as high-intensity p beams for the production of antiprotons. In this paper we discuss the proposal of three different working points, which should serve the different needs: (1) a high intensity working point for U²⁸⁺; (2) a slow extraction working point (also U²⁸⁺); (3) a proton operation working point to avoid transition crossing. The challenging beam loss control for all three applications requires a careful account of the effects of space charge, lattice nonlinearities and chromaticity, which will be discussed in detail in this paper. Since tunes are not split by an integer and the injected emittances are different, the Montague stop-band needs to be avoided. Moreover, final bunch compression for the U beam requires a sufficiently small momentum spread, and the risk of transverse resisitive wall instabilities poses further limitations on our choice of working points.

THPCH033	Recent Studies of Geometric and Resistive-wall Impedance at SOLEIL	impedance, SOLEIL, vacuum, single-bunch	2850
	R. Nagaoka, J.-C. Denard, M.-P. Level SOLEIL, Gif-sur-Yvette
	Coupling impedance studies are of great importance for SOLEIL not only to avoid beam instability, but also to ensure protection of a concerned chamber from EM fields excited by the beam. This paper deals with components that required particularly such efforts, which include BPMs, ceramic chambers, and a vertical scraper. The heat deposited in the BPM buttons is investigated as a function of the gap between a button and an electrode, button diameter and thickness. High temperatures on a vacuum tight feed-through would be a problem, affecting the measurement stability at high currents. Coupling of a trapped mode among successively passing bunches is also investigated. To evaluate the heat deposited in a titanium coated ceramic chamber, its impedance is analytically solved using the field matching technique. The solution obtained justifies the image current model that assumes a constant image current density across the coating when the skin depth is greater than the coating thickness. The azimuthal image current distribution is pursued with Piwinski's formalism for flat chambers. The paper also deals with components not treated earlier such as a stripline.

THPCH036	Wakefield Calculations for 3D Collimators	SLAC, simulation, impedance, DESY	2859
	I. Zagorodnov DESY, Hamburg K.L.F. Bane SLAC, Menlo Park, California
	The wakefield effects of the collimators is of concern for future projects. To relax the wakefield effects a gradual transition from a large to a small aperture is used. The impedance of a smooth round collimator is understood well and a good agreement between measurements, theory and simulations is achieved. However, for rectangular flat collimators there is noticeable difference between theory and experiment. Using recently developed time domain numerical approach, which is able to model curved boundaries and does not suffer from dispersion in longitudinal direction, we calculate the short-range geometric wakefields of 3D collimators. This method together with developed by us recently indirect 3D integration algorithm allows to obtain accurate numerical estimations, which are compared to measurements and to analytical results. The applicability range for the analytical formulas is highlighted.

THPCH059	Kicker Impedance Measurements for the Future Multi-turn Extraction of the CERN Proton Synchrotron	kicker, impedance, extraction, resonance	2919
	E. Métral, F. Caspers, M. Giovannozzi, A. Grudiev, T. Kroyer, L. Sermeus CERN, Geneva
	In the context of the novel multi-turn extraction, where charged particles are trapped into stable islands in transverse phase space, the ejection of five beamlets will be performed by means of a set of three new kickers. Before installing them into the machine, a measurement campaign has been launched to evaluate the impedance of such devices. Two measurement techniques were used to try to disentangle the driving and detuning impedances. The first consists in measuring the longitudinal impedance for different transverse offsets using a single displaced wire. The sum of the transverse driving and detuning impedances is then deduced applying Panofsky-Wenzel theorem. The second uses two wires excited in opposite phase and yields the driving transverse impedance only. Finally, the consequences on the beam dynamics are also analyzed.

THPCH128	Portable SDA (Sequenced Data Acquisition) with a Native XML Database	collider, controls, injection, proton	3101
	T.B. Bolshakov, E.S. McCrory Fermilab, Batavia, Illinois
	SDA is a general logging system for a repeated, complex process. It has been used as one of the main logging facility for the Tevatron Collider during Run II. It creates a time abstraction in terms understood by everyone and allows for common time tick across different subsystems. In this article we discuss a plan to re-implement this highly successful FNAL system in a more general way so it can be used elsewhere. Latest technologies, namely a native XML database and AJAX, are used in the project and discussed in the article.

THPCH130	Design and Implementation of Analog Feedback Damper System for an Electron-proton Instability at the Los Alamos Proton Storage Ring	feedback, kicker, storage-ring, impedance	3104
	C. Deibele, S. Assadi, V.V. Danilov, S. Henderson, M.A. Plum, C. Sibley III ORNL, Oak Ridge, Tennessee S. Breitzmann, S.-Y. Lee IUCF, Bloomington, Indiana J.M. Byrd LBNL, Berkeley, California J.D. Gilpatrick, R.J. Macek, R.C. McCrady, J.F. Power, J. Zaugg LANL, Los Alamos, New Mexico
	The PSR (Proton Storage Ring) at LANSCE has observed an E-P (electron-proton) instability. A wideband analog feedback damper system was designed and implemented that has shown it is possible to correct this instability. The damper system consists of two 180 degree hybrids, low level amplifiers, a delay line, comb filter, power amplifiers, and adjustable delay lines. The system bandwidth is about between 10^-300 MHz, and was developed and implemented in stages showing improvement in the e-p threshold of the buncher voltage. The system takes advantage of fiber optic technology for delays as well as for the comb filter. A system description and some measurement results are presented.