EPAC08 - List of Keywords (coupling)

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coupling

Paper	Title	Other Keywords	Page
MOPC117	Hybrid Snake Spin Resonance in RHIC	resonance, lattice, sextupole, betatron	337
	V. H. Ranjbar, D. T. Abell Tech-X, Boulder, Colorado M. Bai, A. U. Luccio BNL, Upton, Long Island, New York
	Simulations reveal a potential polarization loss during low beta squeeze. This depolarization appears to be driven by a spin tune modulation caused by spin precession through the strong low beta quads due to the vertical fields. The modulation of the spin tune introduces an additional snake resonance condition at ν_s0 ± n ν_x - ν_z l = integer which while the same numerology as the well known sextupole resonance, can operate in the absence of sextupole elements.

MOPD007	Waveguide Directional Couplers for High Vacuum Applications	vacuum, controls, ion	460
	H. Downs, P. G. Matthews, W. W. Sanborn Mega Industries, LLC, Gorham
	Directional couplers have always been critical elements in the RF feed systems for accelerator structures. Until now, however, such devices have been confined to areas outside of the high vacuum cavity feeds. The level control of the RF signal required at the cavity inputs is continually increasing and it has become apparent that a directional coupler design for the high vacuum side of the system is necessary. The following paper highlights a novel coupler design to allow high vacuum directional couplers to be realized. Results are presented for both electrical and mechanical characteristics for an L-band device.

MOPD033	The ALBA RF Amplifier System Based on Inductive Output Tubes (IOT)	controls, factory, power-supply, storage-ring	523
	P. Sanchez, D. Einfeld, M. L. Langlois, F. Pérez ALBA, Bellaterra J. Alex, A. Spichiger, J. Stahl Thomson Broadcast & Multimedia AG, Turgi C. Bel, G. Peillex-Delphe, P. Ponard TED, Thonon
	The ALBA accelerator RF systems include a complete new transmitter developed in collaboration between Thomson Broadcast & Multimedia (TBM), Thales Electron Devices (TED) and CELLS. A new IOT version, based on the previous TH793 has been developed by TED: the TH793-1, dedicated to scientific applications. It has demonstrated cw operation up to 90 kW at 500 MHz. In addition, a TH18973 LS cavity has also been developed, featuring a 6”1/8 coaxial RF output, an optimized cooling system and centred operation at 500 MHz, 7 MHz bandwidth and ± 5 MHz tuning range. TBM developed a new amplifier system to achieve high reliability and performance. Each IOT is powered by an individual power supply based on the Pulse Step Modulator technology. The amplifier control system was designed on a PLC controller with the possibility to interface with the Tango control system. The first amplifier was delivered to ALBA in summer 2007 and is already in use for the conditioning and testing of the first RF cavity. The remaining 13 amplifiers will be delivered in the second half of 2008. The paper gives an overview on the design and operation performance during commissioning and cavity testing.

MOPD034	Status of the High Power, Solid-State RF Amplifier Development at Laboratori Nazionali di Legnaro	controls, power-supply, synchrotron, extraction	526
	F. Scarpa, A. Facco, D. Zenere INFN/LNL, Legnaro, Padova
	The development of high power, unconditionally stable solid-state amplifiers for superconducting low-beta cavities, performed at Laboratori Nazionali di Legnaro in the framework of the EURISOL Design Study, has led to the construction and testing of two, newly designed 10 kW units that can be used both individually or coupled together to obtain a 20 kW source. Characteristic of this family of amplifiers, based on parallel assemblies of 300W modules equipped with mosfets and individual circulators, is their possibility of operating in any matching conditions and also, at a reduced power, in case of failure of one mosfet. Characteristics of the amplifiers and of the high power combiner will be described, and their performance and test results will be reported.

MOPP009	Copper Prototype Measurements of the HOM, LOM and SOM Couplers for the ILC Crab Cavity	dipole, simulation, polarization, damping	568
	G. Burt, P. K. Ambattu, A. C. Dexter Cockcroft Institute, Lancaster University, Lancaster L. Bellantoni Fermilab, Batavia, Illinois P. Goudket, P. A. McIntosh STFC/DL/ASTeC, Daresbury, Warrington, Cheshire Z. Li, L. Xiao SLAC, Menlo Park, California
	The ILC Crab Cavity is positioned close to the IP and hence is very sensitive to the wakefields induced by the beam. A set of couplers were designed to couple to and hence damp the spurious modes of the crab cavity. As the crab cavity is a deflecting mode cavity, it operates using a dipole mode and has different damping requirements than an accelerating mode cavity. A separate coupler is required for the monopole modes below the operating frequency of 3.9 GHz, known as the LOMs, the opposite polarization of the operating mode, the SOM, and the modes above the operating frequency, the HOMs. Each of these couplers have been manufactured out of copper and measured attached to an aluminium nine cell prototype of the cavity and their external Q factors were measured. The results were found to agree well with numerical simulations.

MOPP015	Continuously Adjustable Permanent Magnet Quadrupole for a Final Focus	quadrupole, permanent-magnet, multipole, dipole	583
	T. Sugimoto, M. Ichikawa, Y. Iwashita, M. Yamada Kyoto ICR, Uji, Kyoto M. Kumada NIRS, Chiba-shi S. Kuroda, T. Tauchi KEK, Ibaraki
	A permanent magnet quadrupole with continuous strength adjustability has been fabricated. It has a five-ring-singlet structure, which was proposed by R. L.Gluckstern. Its small overall diameter allows an outgoing beamline to pass closeby. Since the permanent magnet pieces do not have any vibration source in themselves, this magnet could be used as a quadrupole in a final focus doublet. Such a quadrupole system is described.

MOPP029	The First Measurement of Low-loss 9-cell Cavity in a Cryomodule at STF	feedback, klystron, superconducting-RF	610
	T. Saeki, M. Akemoto, S. Fukuda, F. Furuta, K. Hara, Y. Higashi, T. Higo, K. Hosoyama, H. Inoue, A. Kabe, H. Katagiri, S. Kazakov, Y. Kojima, H. Matsumoto, T. Matsumoto, S. Michizono, T. Miura, Y. Morozumi, H. Nakai, K. Nakanishi, N. Ohuchi, K. Saito, M. Satoh, T. Takenaka, K. Tsuchiya, H. Yamaoka, Y. Yano KEK, Ibaraki T. Kanekiyo Hitachi Technologies and Services Co., Ltd., Kandatsu, Tsuchiura J. Y. Zhai IHEP Beijing, Beijing
	We are constructing Superconducting RF Test Facility (STF) at KEK for the R&D of International Linear Collider (ILC) accelerator. In the beginning of year 2008, we installed one high-gradient Low-Loss (LL) type 9-cell cavity into a cryomodule at STF, where we assembled an input coupler and peripherals with the cavity in a clean room, and the assembled cavity packages were dressed with thermal shields and installed into a cryomodule. At the room-temperature, we performed the processing of capacitive-coupling input-coupler upto the RF power of 250 kW. At the temperature of 4 K, we measured the loaded Q of the cavity and the tuner was tested. At the temperature of 2 K, high-power RF was supplied from a klystron to the cavity and the performance of the cavity packeage was tested. This article presents the results of the first test of the Low-Loss (LL) 9-cell cavity package at 2 K in a cryomodule.

MOPP047	Simulation Studies on the Vertical Emittance Growth at the Existing ATF Extraction Beamline	emittance, extraction, multipole, damping	652
	F. Zhou, J. W. Amann, S. Seletskiy, A. Seryi, C. M. Spencer, M. Woodley SLAC, Menlo Park, California
	Significant dependence of the vertical emittance growth on the beam intensity was experimentally observed at the Accelerator Test Facility (ATF) at KEK extraction beamline. This technical note describes the simulations of possible vertical emittance growth sources, particularly in the extraction channel, where the magnets are shared by both the ATF extraction beamline and its damping ring. The vertical emittance growth is observed in the simulations by changing the beam orbit in the extraction channel, even with all optics corrections. The possible reasons for the experimentally observed dependence of the vertical emittance growth on the beam intensity are discussed. An experiment to measure the emittance versus beam orbit at the existing ATF extraction beamline is underway. M. Alabau et al. Study of Abnormal Vertical Emittance Growth in ATF Extraction Line, this proceeding.

MOPP051	Effect of Fill Patterns on Extraction Jitter in Damping Rings	damping, simulation, extraction, injection	664
	K. M. Hock, A. Wolski Cockcroft Institute, Warrington, Cheshire
	Injection of fresh bunches into a storage ring can induce jitter on stored bunches, as a result of wake field coupling. This transient effect can lead to an undesirable increase in the emittance of stored bunches; in the case of linear collider damping rings, there can also be jitter in the extracted bunches, which can adversely affect performance. We consider how the wake field coupling in a storage ring depends on the fill pattern, and, for the ILC damping rings, present the results of simulations of the transverse dynamics with a resistive wall wake field for a number of different fill patterns. We draw correlations between the extraction jitter and various machine parameters, including the fill pattern.

MOPP056	Beam Coupling Impedance in the ILC Damping Rings	impedance, insertion, damping, vacuum	670
	M. Korostelev, O. B. Malyshev, A. Wolski Cockcroft Institute, Warrington, Cheshire A. F. Grant, J. Lucas STFC/DL, Daresbury, Warrington, Cheshire
	The ILC damping rings have stringent specifications for beam quality and stability. To avoid instabilities, the various components in the vacuum chamber will need to be carefully designed to minimize the longitudinal and transverse wake fields. We present the results of impedance calculations for various components that are expected to make a significant contribution to the overall machine impedance.

MOPP060	Parameter Scan for the CLIC Damping Rings	emittance, damping, wiggler, target	679
	Y. Papaphilippou, H.-H. Braun, M. Korostelev CERN, Geneva
	Triggered by the RF frequency reduction of the CLIC main linac cavities, the damping ring parameters had to be reevaluated and the rings' performance adapted to the new luminosity requirements. In view of a staged approach for reaching the ultimate energy of the collider, the dependence of the rings output emittances under the influence of Intrabeam Scattering is evaluated with respect to different beam characteristics such as bunch population, beam energy, coupling and longitudinal beam characteristics.

MOPP086	A Novel Fabrication Technique for the Production of RF Photoinjectors	gun, electron, vacuum, controls	751
	P. Frigola, R. B. Agustsson, S. Boucher, A. Y. Murokh RadiaBeam, Los Angeles D. Cormier, T. Mahale NCSU, Raleigh L. Faillace Rome University La Sapienza, Roma J. B. Rosenzweig, G. Travish UCLA, Los Angeles, California
	Recent developments in Direct Metal Free Form Fabrication (DMFFF) technology may make it possible to design and produce near netshape copper structures for the next generation of very high duty factor, high gradient radio frequency (RF) photoinjectors. RF and thermal-management optimized geometries could be fully realized without the usual constraints and compromises of conventional machining techniques. A photoinjector design incorporating DMFFF and results from an initial material feasibility study will be reported.

MOPP088	The High Harmonics Cavity System for the New Experimental Storage Ring at FAIR	electron, impedance, bunching, emittance	757
	R. G. Heine, C. Dimopoulou, U. Laier GSI, Darmstadt
	The "Facility for Antiproton and Ion Research" (FAIR) will consist of several synchrotrons and storage rings dedicated to target experiments as well as in-situ experiments. One of the in-situ experiments is ELISe, a head-on collision of a heavy ion beam in the new experimental storage ring(NESR) with an electron beam prepared in the electron ring (ER). The vertex is placed in a bypass to the NESR where both rings have a common straight section. To prepare the heavy ion beam for collision with the bunched electron beam circulating at a fixed repetition rate a dedicated RF system called high harmonics cavity system (HHC) operating at a frequency of 44.7MHz is needed. The HHC will be realised as a disk loaded coaxial quarter wave resonator. This paper deals with the actual development status of this RF system, including analytically derived voltage demands, multipactor thresholds and considerations on input coupling and HOM damping.

MOPP091	Upgrade of Input Power Coupling System for the SNS RFQ	rfq, vacuum, linac, klystron	763
	Y. W. Kang, A. V. Aleksandrov, P. E. Gibson, T. W. Hardek, C. Luck, R. C. Peglow, A. V. Vassioutchenko ORNL, Oak Ridge, Tennessee
	A RF input power coupler system has been developed for upgrade of input coupling to the RFQ in the SNS linac front-end. The design employs two coaxial loop couplers for 402.5 MHz operation. Two couplers are used in parallel to power the accelerating structure with up to 800 kW total peak power at 8% duty cycle. Each coupler loop has a coaxial ceramic window that is connected to each output of a magic-T waveguide hybrid splitter through a coaxial to waveguide transition. The coaxial loop couplers have been designed, manufactured, and high power processed. This paper presents the following: RF and mechanical designs of the couplers and system, procedure and result of high power RF conditioning, and test and operation results of the upgraded system.

MOPP092	Efficient Fan-out RF Vector Control Algorithm	controls, impedance, proton	766
	Y. W. Kang ORNL, Oak Ridge, Tennessee
	A new RF vector control algorithm for fan-out power distribution using reactive transmission line circuit parameters for maximum power efficiency is presented. This control with fan-out power distribution system is considered valuable for large scale SRF accelerator systems to reduce construction costs and save on operating costs. Other fixed power splitting systems with individual cavity voltage control at each cavity input may not deliver the power efficiency since excessive power needs to be maintained at each cavity input. In a fan-out RF power distribution system, feeding multiple accelerating cavities with a single RF power generator can be accomplished by adjusting phase delays between the load cavities and reactive loads at the cavity inputs for independent control of cavity RF voltage vectors. In this approach, the RF control parameters for a set of specified cavity RF voltage vectors is determined for a whole fan-out system. The reactive loads and phase shifts can be realized using high power RF phase shifters.

MOPP096	C-band Linac Optimization for a Race-track Microtron	linac, simulation, impedance, resonance	778
	Yu. A. Kubyshin UPC, Barcelona D. Carrillo, L. García-Tabarés, F. Toral CIEMAT, Madrid A. V. Poseryaev, V. I. Shvedunov MSU, Moscow
	Optimization results of a C-band standing wave on-axis coupled linac for a miniature race-track microtron (RTM) are presented. The optimization procedure includes three steps: choice of the linac cells lengths and field strength following requirements of the RTM beam dynamics, 2D cells geometry optimization to maximize the shunt impedance and minimize the surface field strength and, finally, full scale 3D optimization. The 3D calculations were done independently with two codes: ANSYS and HFSS. Various methods of calculation of the coupling slots dimensions, including the waveguide-linac coupling slot, are described in detail.

MOPP097	Measurements on the Rf Cavity for the ALBA Storage Ring	impedance, storage-ring, vacuum, pick-up	781
	M. L. Langlois, M. Cornelis, F. Pérez, P. Sanchez ALBA, Bellaterra
	ALBA storage ring will use 6 ambient temperature nose cone HOM damped cavities tuned at 500 MHz, designed at BESSY and known as the EU cavity. A first one, manufactured by ACCEL, was delivered in 2007 to investigate on its behaviour. This paper describes the data collected during investigation. First, bead-pull measurements were performed to assess impedance, both on fundamental and high order modes. Emphasis was put on E011, due to the discrepancy between expected values and results for this mode. The vacuum bake-out and related pressure are shown. Then, the cavity was conditioned and observations were made on multipacting levels, conditioning time and surface temperatures. The latter were found inhomogeneous and leads are detailed to avoid local overheating.

MOPP098	A 201-MHz Normal Conducting RF Cavity for the International MICE Experiment	vacuum, impedance, emittance, focusing	784
	D. Li, A. J. DeMello, S. P. Virostek, M. S. Zisman LBNL, Berkeley, California R. A. Rimmer Jefferson Lab, Newport News, Virginia
	MICE is a demonstration experiment for the ionization cooling of muon beams. Eight RF cavities are proposed to be used in the MICE cooling channel. These cavities will be operated in a strong magnetic field; therefore, they must be normal conducting. The cavity design and construction are based on the successful experience and techniques developed for a 201-MHz prototype cavity for the US MUCOOL program. Taking advantage of a muon beam’s penetration property, the cavity employs a pair of curved thin beryllium windows to terminate conventional beam irises and achieve higher cavity shunt impedance. The cavity resembles a round, closed pillbox cavity. Two half-shells spun from copper sheets are joined by e-beam welding to form the cavity body. There are four ports on the cavity equator for RF couplers, vacuum pumping and field probes. The ports are formed by means of an extruding technique.

MOPP100	Performance of Compact Electron Injector on Evanescent Oscillations	electron, gun, cathode, resonance	790
	V. V. Mytrochenko, M. I. Ayzatskiy, I. V. Khodak, K. Kramarenko, V. A. Kushnir, A. Opanasenko, S. A. Perezhogin, D. L. Stepin, Z. V. Zhiglo NSC/KIPT, Kharkov
	An injector on the basis of a resonator structure with exponentially increasing amplitude of the electric field along an axis was developed at NSC KIPT. The injector is supplied with RF power through a rectangular-to-coaxial waveguide transition to provide axial symmetry of the accelerating field. The injector was designed to provide the output current up to 1 A at particle energy up to 1 MeV. Results of the injector test are presented in the work. Results obtained are compared with calculated ones.

MOPP108	Status of HOM Damped Room-temperature Cavities for the ESRF Storage Ring	impedance, simulation, storage-ring, damping	808
	V. Serriere, A. K. Bandyopadhyay, L. Goirand, J. Jacob, D. Jalas, B. Ogier, A. Triantafyllou ESRF, Grenoble N. Guillotin SOLEIL, Gif-sur-Yvette
	At the ESRF, longitudinal coupled bunch instabilities driven by cavity HOM are currently avoided up to the nominal current of 200 mA by precisely controlling the temperatures of the six five-cell cavities installed on the storage ring. A longitudinal bunch by bunch feedback has recently allowed to overcome the remaining HOM and thereby increase the current in the storage ring to 300 mA. In parallel, HOM damped room-temperature cavities are being developed for highly reliable passive operation at 300 mA. They are designed for a possible later upgrade to higher currents.

MOPP131	Cryomodule Tests of the STF Baseline 9-cell Cavities at KEK	radiation, electron, superconducting-RF, linac	868
	E. Kako, H. Hayano, S. Noguchi, N. Ohuchi, M. Sato, T. Shishido, K. Watanabe, Y. Yamamoto KEK, Ibaraki
	The STF-Baseline superconducting cavity system, which includes four TESLA-type 9-cell cavities, input couplers and frequency tuners, has been developed for the future ILC project. A 6m-cryomodule including one of four STF-Baseline cavities was assembled for the initial test called the STF Phase -0.5. The first cool-down of the cryomodule and high power tests of the STF-Baseline cavity had been successfully carried at 2 K. The maximum accelerating gradient (Eacc,max) of 19.3 MV/m was achieved in a specific pulse width of 1.5 msec and a repetition of 5 Hz, (23.4 MV/m in a shorter pulse of 0.6 msec). The onset of x-rays radiation was observed at higher field than 15 MV/m, and the measured Qo value was about 5 x 10⁹ at 18 MV/m in accompanied with field emission. The detuning angle of about -13 degrees at 18 MV/m was successfully compensated to nearly zero by a combined operation with both an offset detuning and an optimised applied voltage in the piezo element. String assembly of four STF-Baseline cavities has been stated in Jan. 2008. The second cryomodule test for 4 cavities, called the STF Phase -1.0, is scheduled in this early summer.

MOPP132	Progress Towards Development of an L-Band SC Traveling Wave Accelerating Structure with Feedback	feedback, acceleration, resonance, linac	871
	A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio P. V. Avrakhov LPI, Moscow S. Kazakov KEK, Ibaraki N. Solyak, V. P. Yakovlev Fermilab, Batavia, Illinois
	We describe an ongoing experimental program and progress towards development of a conceptual design for a superconducting traveling wave accelerating structure for the ILC. The accelerating gradient can be significantly improved by the use of an RF feedback system redirecting the accelerating wave that passed through the superconducting traveling wave accelerator (STWA) section back to the input of the accelerating structure. The conceptual design of the SC traveling wave accelerator has been considered by P. Avrakhov et al. [PAC07, pp.2538], where shape optimization, coupler cell design and tuning issues in the feedback loop were presented. The proposed TW structure design gives an overall 24% increase in gradient over the 1 m long standing wave structure and potentially can reach 46% if a longer structure is employed. Experimental investigation of the TW SC structure considers tests of a single cavity having the same shape as the regular cell of the full-sized STWA structure, and the same ratio of the RF fields. The details of the individual parts, joint configurations along with some developments on forming and welding of the proposed cavity shapes are discussed.

MOPP155	Superconducting RF Deflecting Cavity Design and Prototype for Short X-ray Pulse Generation	damping, simulation, collider, dipole	913
	J. Shi, H. Chen, C.-X. Tang TUB, Beijing G. Cheng, G. Ciovati, P. Kneisel, R. A. Rimmer, G. Slack, L. Turlington, H. Wang Jefferson Lab, Newport News, Virginia D. Li LBNL, Berkeley, California A. Nassiri, G. J. Waldschmidt ANL, Argonne, Illinois
	Deflecting RF cavities are proposed to be used in generating short x-ray pulses (on ~1-picosecond order) at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL)* using a novel scheme by Zholents*. To meet the required deflecting voltage, impedance budget from higher order, lower order and the same order modes (HOM, LOM and SOM) of the APS storage ring, extensive deflecting cavity design studies have been conducted with numerical simulations and cavity prototypes. In this paper, we report recent progress on a single cell S-band (2.8-GHz) superconducting deflecting cavity design with waveguide damping. A copper and a niobium prototype cavity were fabricated and tested, respectively to benchmark the cavity and damping designs. A new damping scheme has been proposed which provides stronger damping to both HOM and LOM by directly coupling to a damping waveguide on the cavity equator. A. Nassiri, private communication, 2007 ** A. Zholents et al. NIM, 1999, A425:385-389.

MOPP156	Fabrication and Low Power Testing of an L-band Deflecting Cavity for Emittance-exchange at ANL	simulation, polarization, vacuum, emittance	916
	J. Shi, H. Chen, W.-H. Huang, C.-X. Tang, D. Tong TUB, Beijing W. Gai, C.-J. Jing, K.-J. Kim, J. G. Power ANL, Argonne, Illinois D. Li LBNL, Berkeley, California
	An L-Band RF deflecting cavity has been built at Tsinghua University for a planned transverse-to-longitudinal emittance exchange experiment at Argonne National Laboratory (ANL). The deflector is a 1.3-GHz, 3-cell cavity operated in a TM110-like mode that delivers a deflecting voltage of 3.4 MV. In this paper, we review the cavity design and present detail of the fabrication, cold testing and tuning progress. Cell radii were left undercut to account for simulation errors, which yielded a higher frequency in the first bench measurement but removed by the final tuning on the lathe. Field distribution on axis was measured using the ‘‘bead-pull'' method and tuned to balance in the 3 cells.

MOPP157	Critical Magnetic Field Determination of Superconducting Materials	pick-up, pulsed-power, klystron, electromagnetic-fields	919
	A. Canabal, T. Tajima LANL, Los Alamos, New Mexico V. A. Dolgashev, S. G. Tantawi SLAC, Menlo Park, California T. Yamamoto UTNL, Ibaraki
	Using a 11.4 GHz, 50-MW, <1 μs, pulsed power source and a TE013-like mode copper cavity, we have been measuring critical magnetic fields of superconductors for accelerator cavity applications. This device can eliminate both thermal and field emission effects due to a short pulse and no electric field at the sample surface. A model of the system is presented in this paper along with a discussion of preliminary experimental data.

MOPP165	FZJ Smallest SC Triple-Spoke Cavity	vacuum, cryogenics, simulation, site	937
	E. Zaplatin, W. Braeutigam, M. Pap, M. Skrobucha FZJ, Jülich P. Kneisel Jefferson Lab, Newport News, Virginia
	The paper describes the design, fabrication and test results of the smallest triple-spoke cavity (resonant frequency 760 MHz, β=0.2) developed at Forschungszentrum Juelich.

TUPC021	High Bandwidth Wall Current Monitor for CTF3	resonance, impedance, shielding, electromagnetic-fields	1092
	A. D'Elia, R. Fandos, L. Soby CERN, Geneva
	Wall Current Monitors (WCM) are commonly used to observe the time profile and spectra of a particle beam by detecting its image current. For the 3rd CLIC Test Facility (CTF3), a WCM having a very large bandwidth (100kHz-20GHz) is in principle required. This very stringent request was critically reviewed because the low cut-off frequency of 100 kHz is quite outstanding. It was initially chosen because of the bunch train length but, in reality, because of the high frequency cut-off of 20GHz, the low frequency cut-off should rather be related to the maximum expected Missing Bunch Ratio (MBR). The solution that we propose has a low frequency cut-off of 2GHz corresponding to an MBR of 1/6 for 83ps bunch spacing. If needed, it could be lowered to 400MHz (MBR equal to 1/30). That solution has been fully characterized both from an electromagnetic and from a mechanical point of view. The first tests of a prototype are foreseen in February 2008.

TUPC023	Design of the Transverse C-band Deflecting Structure for Measurement of Bunch Length in X-FEL	resonance, RF-structure, simulation, klystron	1098
	H. Ego JASRI/SPring-8, Hyogo-ken Y. Otake RIKEN/SPring-8, Hyogo
	In SPring-8, the 8 GeV X-FEL with a short length of about 700 m is under construction. An electron beam with a bunch length in duration of less than 200 fs is indispensable for stable and brilliant X-ray radiation. We planned to measure the short bunch length with a transverse RF deflector. A bunch measuring system including the deflector must be located within 15 m of a bunch compressor at a beam energy of 1.45 GeV. To install the system in the restricted space, we need a deflector generating a transverse deflecting voltage over 40 MV. Therefore a new C-band deflecting structure was designed. It is a periodic disk-loaded structure with a racetrack-shaped iris in the center of each disk. The deflecting resonant mode is the HEM11-5π/6 mode of a backward traveling-wave and its transverse shunt impedance is more than 12 MΩ/m. The racetrack-shaped iris serves both as a cell-to-cell coupler and a beam passing hole, prevents rotation of the deflection plane of the HEM11 mode and makes the deflecting mode resonant stably. We represent the details and merits of the C-band structure with the demanded performance in this paper.

TUPC026	Simulating a UMER Beam Position Monitor	simulation, dipole, electron, quadrupole	1104
	K. Fiuza IF-UFRGS, Porto Alegre S. Bernal, I. Haber, R. A. Kishek UMD, College Park, Maryland
	We have investigated numerically and experimentally a beam position monitor (BPM), using the WARP code* to study image charge effects for an off-axis beam. In order to apply the theory of image charge, we calibrated the BPM response for the University of Maryland Electron Ring*. We studied the BPM linearity using several WARP simulations with different transverse offsets. The simulations were also compared with offsets measured employing a phosphor screen. In this paper we report the methodology used and results of this work. D. P. Grote et. all "New Developments in WARP Progress Toward End-to-End Simulation", Fus. Eng. & Des. 32-33 (1996) 193. ** J. Harris et. all "A fast beam position monitor for UMER", PAC'01, p 1387.

TUPC042	Limitations of Electro-optic Longitudinal Electron Bunch Length Measurements	simulation, laser, resonance, diagnostics	1149
	S. P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Berden FOM Rijnhuizen, Nieuwegein W. A. Gillespie, P. J. Phillips University of Dundee, Nethergate, Dundee, Scotland A. MacLeod UAD, Dundee
	Electro-optic (EO) techniques are becoming increasingly important in ultrafast electron bunch longitudinal diagnostics and have been implemented at various accelerator labs. A crucial aspect of any implementation is a robust assessment of its resolution capabilities. However the assessments of the temporal limitations often differ between groups and the assumptions employed in deriving these limitations are frequently not addressed. With EO measurements of intense CTR pulses and ultrafast Coulomb fields, it may also be necessary to reconsider the validity of the usual interpretation of the EO effect as a phase retardation proportional to the Coulomb field. From a generic analysis of various sources of the temporal limitations we present a summary of the capability of various EO techniques which can be applied to specific implementations with differing laser and bunch parameters. As well as specifying the quantitative limitations and their scaling with experimental parameters, the qualitative effects of distortion in the measured profile are also summarised. Additional limitations, which arise from a breakdown of the phase-retardation interpretation of the EO effect, are discussed.

TUPC043	Towards Sub-micrometer Resolution of Single Bunch Strip Line BPM	pick-up, feedback, vacuum, simulation	1152
	A. Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
	A high resolution single bunch BPM set-up is designed based on a strip line pickup. One of the BPM modifications developed is a Difference-Sum BPM. In this BPM, each strip line signal is converted into a three 600MHz square wave burst in a cascaded irregular strip line coupler. The Difference and Sum bursts produced by a hybrid junction are detected in a pair of synchronous detectors. The synchronous detector reference signals, and single-sample ADC triggers are manufactured from the Sum burst. The set-up and features of this BPM are presented. The BPM resolution was measured using a KEK ATF beam. For a bunch intensity above 10⁹ electrons the resolution is about 1 μm (for BPM effective aperture 1/5). With appropriate ADCs, this BPM can measure individual bunches at a rate of up to 50 MHz. The BPM latency to the ADC inputs is as low as 10 ns. High resolution and low latency together, make this BPM suitable for beam-based fast feedback/feed-forward systems.

TUPC080	Fermi Low-energy Transverse RF Deflector Cavity	emittance, electron, linac, RF-structure	1239
	P. Craievich, S. Biedron, C. Bontoiu, S. Di Mitri, M. Ferianis, M. Veronese ELETTRA, Basovizza, Trieste D. Alesini, L. Palumbo INFN/LNF, Frascati (Roma) L. Ficcadenti Rome University La Sapienza, Roma M. Petronio DEEI, Trieste
	The layout of FERMI@Elettra will include a transverse S-band RF deflector that will be located after the first bunch compressor (BC1) at 250 MeV. The deflector will operate in a vertical deflecting mode and coupled to a downstream dipole will be used to measure the electron bunch length and in particular to allow time-resolved beam quality measurements such as horizontal slice emittance and slice energy spread. In this paper we discuss the electron bunch deflection at 250 MeV taking into account the principal elements that dominate the selection of the transverse peak voltage specification: the finite transverse emittance, the resolution of OTR screens and the desired number of the slice divisions along the bunch that we wish to observe. The RF deflector proposed here is a frequency scaled version of the 5-cell standing wave SPARC structure.

TUPC086	Pinhole Camera Resolution and Emittance Measurement	emittance, synchrotron, synchrotron-radiation, radiation	1254
	C. A. Thomas, G. Rehm Diamond, Oxfordshire
	Third generation synchrotron light source are characterised by a low emittance and a low emittance coupling. Some light sources are already proposing to operate with extremely low coupling close to 0.1% and thus vertical emittance approaching 1pm. We derive the limits for the emittance coupling measurement due to the resolution of the X-ray pinhole camera. We also show that it is possible to design a pinhole camera in order to push the limit resolution beyond 0.1% emittance coupling. We then illustrate our calculations with the example of Diamond and compare them with experimental data.

TUPC087	4D Emittance Measurements Using Multiple Wire and Waist Scan Methods in the ATF Extraction Line	emittance, extraction, quadrupole, simulation	1257
	C. Rimbault, P. Bambade, J. Brossard LAL, Orsay M. Alabau IFIC, Valencia S. Kuroda KEK, Ibaraki A. Scarfe UMAN, Manchester M. Woodley SLAC, Menlo Park, California
	Emittance measurements performed in the diagnostic section of the ATF extraction line since 1998 lead to vertical emittances three times larger than the expected ones, with a strong dependence on intensity. An experimental program is pursued to investigate potential sources of emittance growth and find possible remedies. This requires efficient and reliable emittance measurement techniques. In the past, several phase-space reconstruction methods developed at SLAC and KEK have been used to estimate the vertical emittance, based on multiple location beam-size measurements and dedicated quadrupole scans. These methods have been shown to be very sensitive to measurement errors and other fluctuations in beam conditions. In this context new emittance measurements have been performed revisiting these methods and newly developed ones with a systematic approach to compare and characterise their performance in the ATF EXT line.

TUPC088	Statistical Weighting of the MICE Beam	emittance, target, simulation, lattice	1260
	C. T. Rogers STFC/RAL/ASTeC, Chilton, Didcot, Oxon
	Conventionally only average properties such as means and variances of charged particle beams are measured. Such a technique is limited in that it is challenging to measure moments beyond the second and certain correlations are difficult to measure. In the Muon Ionisation Cooling Experiment (MICE), the beam rate is sufficiently low that particles pass singly through the accelerator and measurements can be made of the position, time (relative to RF phase) and momentum of individual particles. This makes a number of new analysis tools available. In this paper two particular tools are studied: the analysis of third and higher beam moments and the ability to select an input beam based on such moments.

TUPC098	Results of the LHC Prototype Chromaticity Measurement System Studies in the CERN-SPS	controls, feedback, betatron, emittance	1290
	R. J. Steinhagen, A. Boccardi, T. Bohl, M. Gasior, O. R. Jones, J. Wenninger CERN, Geneva K. K. Kasinski AGH, Cracow
	Tune and chromaticity control is an integral part of safe and reliable LHC operation. Tight tolerances on the maximum transverse beam excursions allow oscillation amplitudes of less than 30 um. This leaves only a small margin for transverse beam and momentum excitations required for measuring tune and chromaticity. This contribution discusses the baseline LHC continuous chromaticity measurement with results from tests at the CERN-SPS. The system is based on continuous tracking of the tune using a phase-locked-loop (PLL) while modulating the beam momentum. The high PLL tune resolution achieved ( ~1·10^-6 ) made it possible to detect chromaticity changes well below the nominally required 1 unit for relative momentum modulations of only 2·10^-5. The sensitive tune measurement front-end employed allowed the PLL excitation and radial amplitudes to be kept below a few tens of micrometers. These results show that this type of measurement can be considered as practically non-perturbative permitting its use even during nominal LHC operation.

TUPC122	Feedback Corrections for Ground Motion Effects at ATF2	sextupole, feedback, quadrupole, optics	1353
	Y. Renier, P. Bambade LAL, Orsay
	Ground motion will over time produce beam misalignments and size increases at the IP of the ATF2 beam line. The spatial and temporal characteristics of the vibrations measured on the site have been studied and model parameters have been fitted to allow reliably simulating the effects induced on the beam. A feedback loop to minimise the residual beam motion at the IP is considered, based on optimising the coefficients of a PID controller on both short and long time-scales.

TUPC150	Ensemble Cavity Control System Simulation Using Pulse-to-pulse Calibration	controls, simulation, klystron, alignment	1422
	C. Serrano, L. R. Doolittle, A. Ratti, A. Vaccaro LBNL, Berkeley, California
	For cost reasons one klystron will supply RF power to multiple cavities in recent projects. Individual cavity field stability and optimal drive needs to be achieved considering beam propagation, cavity tuning, cavity coupling, and cable lengths. External environmental factors continuously modify physical properties of the accelerating structures and waveguides. Therefore a calibration system has been designed to adapt individual drive signals and vector-sum alignment in a pulse-to-pulse basis. An eight-cavity model and a calibration system have been tested in simulation using the hardware-software simulation tool developed at LBNL.

TUPD024	Results of ELBE Window and Coupler Tests with a Resonant Ring	vacuum, klystron, controls, resonance	1479
	A. Buechner, H. Buettig, R. Schurig, G. Staats, A. Winter FZD, Dresden
	A new test bench based on a resonant ring has been built at ELBE to run window as well as coupler tests. The resonant ring is driven by a 10 kW klystron and allows tests with RF power up to 100 kW in CW mode and about 200 kW in pulsed mode. Coupler tests are done with liquid Nitrogen cooling under almost real conditions. The results of warm window and coupler tests in pulsed and CW mode are presented. Also details about the ring and a special designed coupler tip to rectangular waveguide transition are given.

TUPD041	The Design of a 5 MeV Accelerator Based on Multipactor Electron Gun	electron, cathode, gun, emittance	1520
	M. Zhong, C.-X. Tang, S. Zheng TUB, Beijing
	The Multipactor Electron Gun (MPG) based on the multipactor effect can produce short duration, high current and self-bunching electron beams. This paper presents our work on the design of an S-band accelerator based on MPG and the result of preliminary experiment. The mechanical structure was designed with ability of replacing secondary electron emitters. Pd-Ba alloy and Pt were used as the secondary electron emitters of the MPG. The distance between electrodes and the resonant frequency of the MPG can be adjusted separately by step motors. The parameter of the accelerator tube was optimized using numerical simulation with the design outlet energy of the electron is 5MeV and an average current of 100mA.

TUPP015	Investigations into Cost Reductions of X-band Instrumentation	resonance, instrumentation, klystron, controls	1559
	D. Van Winkle, V. A. Dolgashev, J. D. Fox, S. G. Tantawi SLAC, Menlo Park, California
	The prohibitive costs of commercial test equipment for making fast and accurate pulsed phase and amplitude measurements at X-band result in decreased productivity due to shortages of shared equipment across the test laboratory. In addition, most current set-ups rely on the use of pulsed power heads which do not allow for the measurement of phase thereby limiting the flexibility of available measurements. In this paper, we investigate less expensive in-house designed instrumentation based upon commercial satellite down converters and widely available logarithmic detector amplifiers and phase detectors. The techniques are used to measure X-band pulses with widths of 50 ns to 10’s of usec. We expect a dynamic range of 30-40 dB with accuracies of less than ± 0.1 dB. We show results of the built and tested systems with particular attention focused on temperature performance and accuracy. Block diagrams of the down conversion scheme, and the architecture of a multi-signal X-band RF monitor and measurement system is illustrated. Measured results, and possible modifications and upgrades are presented.

TUPP019	Wakefield and RF Kicks due to Coupler Asymmetry in TESLA-type Accelerating Cavities	emittance, linac, impedance, collider	1571
	K. L.F. Bane, C. Adolphsen, Z. Li SLAC, Menlo Park, California M. Dohlus, I. Zagorodnov DESY, Hamburg E. Gjonaj, T. Weiland TEMF, Darmstadt I. G. Gonin, A. Lunin, N. Solyak, V. P. Yakovlev Fermilab, Batavia, Illinois
	In a future linear collider, such as the International Linear Collider (ILC), trains of high current, low emittance bunches will be accelerated in a linac before colliding at the interaction point. Asymmetries in the accelerating cavities of the linac will generate asymmetries in the fields that will kick the beam and tend to degrade the beam emittance and thus the collider performance. In the main linac of the ILC, which is filled with TESLA-type superconducting cavities, it is the fundamental and higher mode couplers that are asymmetric and thus the source of such kicks. The kicks are of two types: one, due to (the asymmetries in) the fundamental RF fields and the other, due to transverse wakefields that are generated even when the beam is on axis. For the ILC configuration we numerically and analytically study both types of kicks and their effect on beam emittance. For the wakefield effect this is quite challenging since the bunches are very short (rms length of 300 microns), the cavity is very long (~1 m), and the distance to steady-state is even longer (~6 m). Finally, we study changes in the coupler design that can greatly reduce the effect.

TUPP025	Preliminary Impedance Budget for the TPS Storage Ring	impedance, storage-ring, single-bunch, vacuum	1586
	A. Rusanov NSRRC, Hsinchu
	Taiwan Photon Source (TPS) is a new third generation low-emittance synchrotron storage ring which will be built at the present site of the NSRRC in Hsinchu, Taiwan. Preliminary results of the ongoing impedance studies of the TPS are presented in this paper. The overall impedance of the vacuum chamber has been evaluated with focus on the longitudinal broad-band impedance, which can lead to bunch lengthening and microwave instability. Wakepotentials and impedances produced by each component of the storage ring have been evaluated by using 3D electromagnetic code GdfidL. Then longitudinal loss factor, longitudinal broad-band impedance and transverse kick factors were computed. Results are summarized in the table. Numerically obtained data is compared to analytical results for simplified geometries of the vacuum chamber components.

TUPP028	Bunch Length and Impedance Measurements at SPEAR3	impedance, single-bunch, lattice, storage-ring	1595
	W. J. Corbett, W. X. Cheng, A. S. Fisher, X. Huang SLAC, Menlo Park, California
	A series of bunch length measurements have been made for different lattice configurations in SPEAR3 as a function of single-bunch current. The lattices include achromatic optics, low-emittance optics and short-bunch, low-momentum compaction optics (low-alpha). The streak-camera data clearly demonstrates effects of both resistive and reactive chamber impedance and shows levels of microwave instability threshold. In the low-alpha mode, signs of bunch length ‘bursting’ were observed. Fitted bunch-profile data, impedance calculations and bursting data are presented.

TUPP029	Beam Coupling Impedance Measurement and Mitigation for a TOTEM Roman Pot	impedance, resonance, insertion, vacuum	1598
	M. Deile, F. Caspers, T. Kroyer, M. Oriunno, E. Radermacher, A. Soter CERN, Geneva F. Roncarolo UMAN, Manchester
	The longitudinal and transverse beam coupling impedance of the first final TOTEM Roman Pot unit has been measured in the laboratory with the wire method. For the evaluation of transverse impedance the wire position has been kept constant, and the insertions of the RP were moved asymmetrically. With the original configuration of the RP, resonances with fairly high Q values were observed. In order to mitigate this problem, RF-absorbing ferrite plates were mounted in appropriate locations. As a result, all resonances were sufficiently damped to meet the stringent LHC beam coupling impedance requirements.

TUPP035	Analysis of Intensity Instability Threshold at Transition in RHIC	octupole, impedance, emittance, electron	1616
	W. Fischer, I. Blackler, M. Blaskiewicz, P. Cameron, C. Montag, V. Ptitsyn, T. Roser BNL, Upton, Long Island, New York
	The beam intensity of ion beams in RHIC is limited by a fast transverse instability at transition, driven by the machine impedance and electron clouds. For gold and deuteron beams we analyze the dependence of the instability threshold on beam and machine parameters from recent operational data and dedicated experiments. We fit the machine impedance to the experimental data.

TUPP038	On the Longitudinal Coupling Impedance and Transmission Coefficient from Uniform and Hollow Ring Sources	impedance, space-charge, synchrotron, electromagnetic-fields	1625
	A. M. Al-Khateeb, O. Boine-Frankenheim, R. W. Hasse GSI, Darmstadt J. M. Shobaki Yarmouk, Irbid
	The longitudinal coupling impedance and the transmission coefficient resulting from a thin ring and from a uniform disk are obtained analytically for a resistive cylindrical beam-pipe of finite wall thickness. The impedances are derived and then compared with the well known corresponding expression for perturbations on a uniform, coasting beam. The transmission coefficients from both sources are found to be exactly the same. Differences do appear in the expressions for the electromagnetic fields within the beam region, and therefore leading to different coupling impedances. By applying the results to parameters relevant for the SIS-18 synchrotron at GSI, it is found that the formula from the ring source underestimates the space-charge impedance at all beam energies and it shows a noticeable deviation from the disk formula for all frequencies. Although their mathematical expressions are different, resistive-wall impedances from the two sources are found to be numerically equal. The space-charge impedances become equal asymptotically only in the so called ultra-relativistic limit. A. Al-Khateeb is on leave from Yarmouk University, Irbid, Jordan

TUPP051	Coupling Impedance of DAΦNE Upgraded Vacuum Chamber	impedance, vacuum, electron, simulation	1661
	F. Marcellini, D. Alesini, P. Raimondi, G. Sensolini, B. Spataro, A. Stella, S. Tomassini, M. Zobov INFN/LNF, Frascati (Roma)
	The DAΦNE Phi-factory at INFN LNF has been ugraded in the second half of 2007 with a scope to test a recently proposed scheme of crab waist collisions. The vacuum chamber of the collider has been substantially modified: two new low impedance interaction regions have been designed and installed, the new stripline injection kickers have been implemented, the old bellows have been substituted by the new ones and all ion clearing electrodes have been removed. In the paper we present the machine impedance study of these new vacuum chamber components and compare bunch lengthening measurements in the modified DAΦNE with simulation results.

TUPP053	Radiolocation of a HOM Source in the PEP-II Rings	vacuum, single-bunch, impedance, luminosity	1664
	A. Novokhatski, J. Seeman, M. K. Sullivan SLAC, Menlo Park, California
	A signal from the antenna situated in the LER (Low Energy Ring) helped to find a broken shielded bellows in the HER (High Energy Ring) during a single HER bunch operation.

TUPP061	Comparison between Laboratory Measurements, Simulations and Analytical Predictions of the Resistive Wall Transverse Beam Impedance at Low Frequencies	impedance, simulation, damping, luminosity	1679
	F. Roncarolo UMAN, Manchester F. Caspers, T. Kroyer, E. Métral CERN, Geneva B. Salvant EPFL, Lausanne
	The prediction of the resistive wall transverse beam impedance at the first unstable betatron line (8 kHz) of the CERN Large Hadron Collider (LHC) is of paramount importance for understanding and controlling the related coupled-bunch instability. Until now only novel analytical formulas were available at this frequency. Recently, laboratory measurements and numerical simulations were performed to crosscheck the analytical predictions. The experimental results based on the measurement of the variation of a probe coil inductance in the presence of i) sample graphite plates, ii) stand-alone LHC collimator jaws and iii) a full LHC collimator assembly are presented in detail. The measurement results are compared to both analytical theories and simulations. In addition, the consequences for the understanding of the LHC impedance are discussed.

TUPP062	Beam Coupling Impedance Studies on LHC FP420 Multi-pocket Beam Pipe Prototype	impedance, simulation, resonance, scattering	1682
	F. Roncarolo, R. Appleby, R. M. Jones UMAN, Manchester
	The LHC FP420 collaboration is assessing the feasibility of installing forward proton detectors 420m from the ATLAS and/or CMS interaction points. The latest prototype of a FP420 station consists of a modified LHC beam pipe in which two pockets hosting the detectors introduce an abrupt cross-section variation of the pipe. During the FP420 proposed operation, each station is moved towards the beam as close as 3 mm (~ 10 σx). The impact on the LHC beam coupling impedance has been evaluated with a laboratory wire measurement and a suite of numerical simulations. In addition, we describe a proposed modification of the beam pipe design which minimizes the impedance of the resonances without compromising the FP420 detector signal to background ratio.

TUPP063	Characterization of the ATLAS Roman Pots Beam Coupling Impedance and Mechanics	impedance, vacuum, simulation, resonance	1685
	F. Roncarolo, R. M. Jones UMAN, Manchester F. Caspers, B. Di Girolamo, T. Kroyer CERN, Geneva
	At the LHC, four Roman Pot (RP) type detectors will be installed on both sides of the ATLAS experiment with the aim of measuring elastic scattering at very small angles and determining the absolute luminosity at the interaction point. During dedicated LHC runs, the detectors will be positioned at about 1 mm from the nominal beam orbit. Numerical simulations and laboratory measurements were carried out to characterize the RP impact on the total LHC beam coupling impedance. The measurement results assess the effectiveness of RF-absorbing ferrite plates that have been mounted in convenient locations in order to damp high Q resonances of the RP structure. In addition, we review the RP mechanics emphasizing the accuracy and reproducibility of the positioning system.

TUPP067	Transverse Mode-coupling Instability in the CERN SPS: Comparing MOSES Analytical Calculations and HEADTAIL Simulations with Experiments in the SPS	simulation, impedance, kicker, injection	1694
	B. Salvant EPFL, Lausanne G. Arduini, E. Métral, G. Papotti, G. Rumolo, R. J. Steinhagen, R. Tomas CERN, Geneva R. Calaga BNL, Upton, Long Island, New York
	Since 2003, single bunches of protons with high intensity (1.2·10¹¹ protons) and low longitudinal emittance (0.2 eVs) have been observed to suffer from heavy losses in less than one synchrotron period after injection at 26 GeV/c in the CERN Super Proton Synchrotron (SPS) when the vertical chromaticity is corrected. Understanding the mechanisms underlying this instability is crucial to assess the feasibility of an anticipated upgrade of the SPS, which requires bunches of 4·10¹¹ protons. Analytical calculations from MOSES and macroparticle tracking simulations using HEADTAIL with an SPS transverse impedance modelled as a broadband resonator had already qualitatively and quantitatively agreed in predicting the intensity threshold of a fast instability. A sensitive frequency analysis of the HEADTAIL simulations output was then done using SUSSIX, and brought to light the fine structure of the mode spectrum of the bunch coherent motion. A coupling between the azimuthal modes -2 and -3 was clearly observed to be the reason for this fast instability. The aim of the present paper is to compare the HEADTAIL simulations with dedicated measurements performed in the SPS in 2007.

TUPP068	Bench Measurements of the Low Frequency Transverse Impedance of the CERN LHC Beam Vacuum Interconnects with RF Contacts	impedance, vacuum, cryogenics, betatron	1697
	B. Salvant EPFL, Lausanne F. Caspers, E. Métral CERN, Geneva F. Roncarolo UMAN, Manchester
	The low frequency longitudinal and transverse impedances of the CERN Large Hadron Collider (LHC) have to be specifically minimized to prevent the onset of coherent instabilities. The LHC beam vacuum interconnects were designed as Plug In Modules (PIMs) with RF contacts to reduce their coupling impedances, but the resulting contact resistance is a concern, as this effect is difficult to estimate. High sensitivity measurements of the transverse impedance of a PIM at low frequency using a coil probe are presented. In particular, the increase of the transverse impedance of the PIM when it is elongated to its operating position is discussed in detail. Finally, the issue of non-conforming contact resistance is also addressed.

TUPP074	A New RF Shielded Bellows for the DAΦNE Upgrade	shielding, impedance, simulation, storage-ring	1706
	S. Tomassini, F. Marcellini, P. Raimondi, G. Sensolini INFN/LNF, Frascati (Roma)
	A new RF shielded bellows, using the technology of omega shaped strip of beryllium copper material, has been developed and tested on the DAΦNE Upgrade. The RF omega shield is composed by many Be-Cu strips held by an external floating ring. Thermal power loss on strips can be easily extracted and dissipated allowing high beam current operation. Leakage of beam induced e.m. fields through the RF shield is almost suppressed. Twenty omega bellows were manufactured and installed in the DAΦNE storage rings and showed good properties up to a stored beam current of 700 mA. DAΦNE upgrade: A New magnetic and mechanical layout. PAC07. pp. 1466-1468, Albuquerque. **Design and E. M. Analysis of the New DAΦNE Interaction Region. PAC07, Albuquerque, pp 3988.

TUPP093	Crystalline Beam Simulations	ion, storage-ring, simulation, laser	1747
	D. A. Krestnikov JINR/DLNP, Dubna, Moscow region M. Grieser MPI-K, Heidelberg M. Ikegami JAEA/Kansai, Kizu-machi Souraku-gun Kyoto-fu I. N. Meshkov, A. O. Sidorin, A. V. Smirnov, G. V. Trubnikov JINR, Dubna, Moscow Region M. Nakao, A. Noda, H. Souda, H. Tongu Kyoto ICR, Uji, Kyoto K. Noda, T. Shirai NIRS, Chiba-shi
	A new program code was elaborated for the simulation of crystalline beams on the S-LSR storage ring (Kyoto Univ., Japan) under action of the cooling system. For the investigation of ordered proton beams, which recently were observed in first time on S-LSR, a special molecular dynamics technique was used. This article presents results of the numerical simulation and comparison with experimental data.

TUPP117	Review of Energy Variation Approaches in Medical Accelerators	linac, electron, radiation, photon	1797
	S. M. Hanna MINA, Danville, California
	Most of cancer Radiation Therapy (RT) machines rely on a linac as the source of the treatment beam which can be an electron beam or an X-ray beam. In either case, an approach to vary the energy of the linac’s output beam may be needed to target cancer tumors of different depths. Over the last two decades, multiple approaches for medical linac energy variation were proposed and some of them have been developed and implemented clinically. The most direct and conventional technique is to vary the amount of the RF power delivered to the linac and hence the energy output as required by the treatment plan. A second approach involves keeping the RF power delivered to the linac fixed but varying the power delivered to different sections of the linac by utilizing a mechanical or an electronic switch that controls the power distribution inside the linac. A third approach is to use two separate linac sections. The first section receives a fixed amount of RF power while the RF power delivered to second section is controlled using conventional microwave power splitting techniques. In this paper we will review the above approaches and discuss the advantages and disadvantage of each technique.

TUPP132	Design, Construction and Low Power RF Tests of the First Module of the ACLIP Linac	linac, proton, cyclotron, booster	1836
	V. G. Vaccaro Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli C. De Martinis Universita' degli Studi di Milano & INFN, Segrate D. Giove INFN/LASA, Segrate (MI) M. R. Masullo INFN-Napoli, Napoli S. J. Mathot CERN, Geneva A. C. Rainò, V. Variale INFN-Bari, Bari R. J. Rush e2v, Chelmsford, Essex
	ACLIP is a 3 GHz proton SCL linac designed as a booster for a 30 MeV commercial cyclotron. The final energy is 62 MeV well suitable for the therapy of ocular tumours or for further acceleration (up to 230 MeV) by a second linac in order to treat deep seated tumours. The possibility of using magnetrons as the source of RF power, to reduce the overall cost of the machine, is under investigation within a collaboration with the company e2v (Chelmsford, UK). ACLIP is a 5 modules structure coupled together. The first one (able to accelerate proton from 30 to 35 MeV) has been machined and completely the brazed. We plan to have the high power test by early fall 2008. In this paper we will review the main features of the linac and discuss the results of the RF measurements carried out on this prototype.

WEXG01	Performance of KEKB with Crab Cavities	luminosity, simulation, resonance, collider	1893
	Y. Funakoshi KEK, Ibaraki
	20 years after they were initially proposed, in February 2007 crab cavities are for the first time installed in an operating collider, KEKB. The commissioning of KEKB with crab cavities is presented, and the performance of the collider is compared to the performance without crab cavities. Lessons learned from the operation with such cavities for future projects are discussed.
	Slides

WEOBM01	R&D Activities Aimed at Developing a Curved Fast Ramped Superconducting Dipole for FAIR SIS300	dipole, synchrotron, ion, antiproton	1950
	P. Fabbricatore, S. Farinon, R. Musenich INFN Genova, Genova F. Alessandria, G. Bellomo, G. Volpini INFN/LASA, Segrate (MI) U. Gambardella INFN/LNF, Frascati (Roma) J. E. Kaugerts, G. Moritz GSI, Darmstadt R. Marabotto ASG, Genova M. Sorbi Universita' degli Studi di Milano & INFN, Segrate
	One of the basic components of the FAIR facility, under development at GSI, is the synchrotron SIS300 (300 Tm rigidity). In order to reach the required high intensities of proton and heavy ion beams, the magnets of this synchrotron have to be pulsed from the injection magnetic field of 1.5 T up to 4.5 T maximum field at the rate of 1 T/s. These 7.8 m long, cos-teta shaped coils with a 100 mm bore have the particular characteristic to be curved (the sagitta is 114 mm). All these aspects demand for a challenging R&D, aimed at the development of a low loss conductor and of a suitable winding technology for curved coil. Further design issues are related to the optimization of the stress distribution involving materials able to hold 10⁷ cycles and to the maximization of the heat transfer to coolant (supercritical helium at 4.7 K). At the present time, design activities are going on with the aim to design, construct and test a 3.8 m long prototype within 2009. In order to achieve this objective, several intermediate milestones are included in the R&D program. One of the most challenging is the industrial development of a method for winding a curved cos-teta dipole.
	Slides

WEPC003	Coupling Control at the SLS	quadrupole, emittance, betatron, sextupole	1983
	A. Streun, Å. Andersson, M. Böge, A. Luedeke PSI, Villigen
	The vertical beam size measurement at the Swiss Light Source (SLS) is based on vertically polarized visual light and allows to verify a vertical emittance of a few pm rad, resp. an emittance ratio in the 10^-4 range obtained in 400 mA top-up user operation mode by tuning the lattice by means of 24 skew quadrupoles. Suppression of betatron coupling by local and global coupling correction prevents losses of Touschek scattered particles at the narrow vertical gaps of the in-vacuum undulators and thus protects these devices and increases beam lifetime, resp. the top-up interval. We will report on our experience with the beam size monitor, on the method of coupling control and on the achievements in vertical emittance and beam lifetime.

WEPC014	Beam Lifetime Studies of Hefei Advanced Light Source (HALS) Storage Ring	emittance, lattice, scattering, storage-ring	2016
	G. Feng, W. Li, L. Liu, L. Wang, C.-F. Wu, H. Xu, S. C. Zhang USTC/NSRL, Hefei, Anhui
	Hefei Advanced Light Source (HALS) will be a high brightness light source with about 0.2nmrad emittance at 1.5GeV. Ultra low beam emittance and relatively low beam energy of HALS would result in poor beam lifetime. Comparing the beam-gas scattering and Touschek scattering effects, a conclusion can be drawn that Beam lifetime will be affected strongly by Touschek scattering. Touschek lifetime has been studied considering linear and nonlinear effects for the lattice structure. Relations between lifetime and RF cavity voltage, lifetime and emittance coupling, lifetime and gap heights of insertion devices have been calculated respectively. After the optimization, proper cavity voltage and emittance coupling are chosen to get about 1.06 hours of total lifetime including gas scattering losses effect. Installing a third harmonic RF cavity can lengthen the beam bunch to increase the total lifetime to about 3.85 hours. Top up injection operation will be applied to keep bunch current within the required value.

WEPC048	Experimental Characterization of the Insertion Device Effects on Beam Dynamics at SOLEIL	undulator, focusing, injection, insertion	2097
	P. Brunelle, C. Benabderrahmane, F. Briquez, O. V. Chubar, O. Marcouillé, F. Marteau, A. Nadji, L. S. Nadolski SOLEIL, Gif-sur-Yvette
	SOLEIL, the French 2.75 GeV third generation light source, has been delivering photons to beam lines in routine operation since January 2007. The storage ring is presently equipped with eleven insertion devices: 3 in-vacuum 20mm period undulators (U20), 1 Apple-II type 52mm period undulator (HU52), 3 Apple-II type 80mm period undulators (HU80), 3 electromagnetic 256mm period undulators (HU256) and 1 electromagnetic 640mm period 10m long undulator (HU640). Commissioning of insertion devices consists of characterizing all the effects on beam dynamics in terms of focussing, injection efficiency, beam lifetime and sensitivity to working point, and also in optimizing feedforward tables in order to compensate for closed orbit distortions during field variations (this last point is detailed in other papers). We will focus here on the significant effects observed with some undulators. Measurements, using electron beam, of the transverse variation of field integrals, were helpful to understand bad effects impacting the daily operation. The introduction of real magnetic characteristics in the lattice model is in progress in order to further optimize the working point.

WEPC066	The Transport Line Upgrade Proposal of Hefei Light Source	quadrupole, injection, storage-ring, dipole	2145
	L. Wang, G. Feng, W.-W. Gao, W. Li, L. Liu, H. Xu, S. C. Zhang USTC/NSRL, Hefei, Anhui
	The injector of Hefei Light Source is a 200 MeV linac. A 55m transport line transfer beam to injection point of storage ring. At current stage, the mismatch of phase space is a potential source limiting the injection efficiency and stable operation of light source. A new focusing configuration of transport line was put forward, where the Twiss parameters matching was implemented. A skew quadrupole was introduced to make horizontal dispersion function matching. This matching between transport line and storage ring would be helpful to improve injection efficiency of HLS storage ring.

WEPC076	Remote Tilt-control System of Injection Bump Magnet in the SPring-8 Storage Ring	injection, synchrotron, synchrotron-radiation, radiation	2172
	K. Fukami, C. Mitsuda, M. Oishi, M. Shoji, K. Soutome, H. Yonehara, C. Zhang JASRI/SPring-8, Hyogo-ken M. Hasegawa, T. Nakanishi SES, Hyogo-pref. T. Ohshima RIKEN/SPring-8, Hyogo
	The SPring-8 storage ring has four pulse-bump magnets to generate bump orbit for beam injection. Rotational error of the bump magnets around a beam-axis (tilt) induces the stored-beam oscillation in vertical direction due to horizontal error field. In the top-up operation, vertical perturbation of the stored-beam during beam injection is mainly produced by the tilt. We evaluated the tilt angle by measuring of the perturbation turn-by-turn using a single-pass BPM system and realigned bump magnets manually inside the accelerator tunnel. It was required to repeat the measurement and realignment processes two or three times for convergence. To correct the tilts smoothly, we developed a remote tilt-control system. The system consists of two fixed and one movable supports in vertical direction under each bump magnets. The movable support is driven by a stepper motor through 1/30 worm gear in the range of ±4 mrad with the accuracy of less than 0.1 mrad. By using this system, we succeeded complete on-beam reduction of the perturbation.

WEPC160	Eddy-current Effect on Field Multipoles Arising in Dipole Magnets with Elliptic and Rectangular Beam Pipe	multipole, dipole, vacuum, quadrupole	2383
	E. Perevedentsev, A. L. Romanov BINP SB RAS, Novosibirsk
	We present an analytical evaluation of the field-distortion effect from eddy currents induced by variation of magnetic field of dipole magnets with elliptic or rectangular beam pipe of finite conductivity. The pipe sizes and aspect are arbitrary except that for practical reasons we assume the pipe wall thickness is small as compared to the skin depth. Handy formulas are presented for the field multipoles arising from non-round shape of the beam pipe.

WEPD037	Nb3Sn Quadrupoles in the LHC IR Phase I Upgrade	quadrupole, optics, luminosity, dipole	2491
	A. V. Zlobin, J. A. Johnstone, V. Kashikhin, N. V. Mokhov, I. L. Rakhno Fermilab, Batavia, Illinois S. Peggs, G. Robert-Demolaize, P. Wanderer, R. de Maria BNL, Upton, Long Island, New York
	After some years of operation at nominal parameters, the LHC will be upgraded for higher luminosity. At the present time it is planned to perform the IR upgrade in two phases with the target luminosity for Phase I of ~2.5· 10³⁴ cm^-2s^-1 and up to 10³⁵ cm^-2s^-1 for Phase II. In Phase I the baseline 70-mm NbTi low-beta quadrupoles will nominally be replaced with larger aperture NbTi magnets and in Phase II with higher performance Nb3Sn magnets. U. S.-LARP is working on the development of large aperture high-performance Nb3Sn magnet technologies for the LHC Phase II luminosity upgrade. Recent progress also suggests the possibility of using Nb3Sn quadrupoles in the Phase I upgrade, improving the luminosity through an early demonstration of Nb3Sn magnet technology in a real accelerator environment. This paper discusses the possible hybrid optics layouts for Phase I upgrades with both NbTi and Nb3Sn quadrupoles, introducing magnet parameters and issues related to using Nb3Sn quadrupoles including magnet length and aperture limitations, field quality, operation margin, etc. Possible transition scenarios to Phase II are also discussed.

WEPP035	Study of Beam-beam Issue for KEKB Crab Crossing	luminosity, lattice, resonance, simulation	2596
	K. Ohmi, J. W. Flanagan, Y. Funakoshi, N. Iida, H. Koiso, A. Morita, Y. Ohnishi, K. Oide, Y. Seimiya KEK, Ibaraki
	A short lifetime at collision is one of the limits on luminosity performance at KEKB in crab crossing mode. The beam-beam halo was evaluated via simulation. The beam lifetime and profile were measured for various beam conditions, vertical emittances, tunes and collision offsets. We discuss why the lifetime is shortened by the beam-beam interaction.

WEPP085	RF Coupler Kicks and Wake-fields in SC Accelerating Cavities	simulation, dipole, linac, higher-order-mode	2719
	N. Juntong, R. M. Jones, I. R.R. Shinton UMAN, Manchester C. D. Beard STFC/DL/ASTeC, Daresbury, Warrington, Cheshire G. Burt Cockcroft Institute, Warrington, Cheshire
	The main accelerating cavities of the ILC provide acceleration of both positron and electron beams to 250 GeV per beam and 500 GeV per beam in a proposed upgrade. The wake-field excited by each ultra-relativistic beam in the accelerating cavities can seriously dilute the emittance of the particles within the beams. Each cavity is supplied with both fundamental and higher order mode couplers. The geometrical configuration of these RF couplers results in an asymmetrical field and this gives rise to both an RF kick being applied to the beam and transverse wake-field. Detailed e.m. fields are simulated in the vicinity of the couplers in order to assess the impact on the beam dynamics. We investigate modified geometries with a view to alleviating the emittance dilution resulting from the e.m. field associated with the RF couplers.

WEPP089	Wake-field Suppression in the CLIC Main Linac	damping, dipole, emittance, positron	2725
	V. F. Khan, R. M. Jones UMAN, Manchester
	The CLIC linear collider aims at accelerating multiple bunches of electrons and positrons and colliding at a centre of mass energy of 3 TeV. These bunches are accelerated through X-band linacs operating at an accelerating frequency of 12 GHz. Each beam readily excites wake-fields in the accelerating cavities of each linac. The transverse components of the wake-fields, if left unchecked, can dilute the beam emittance. The present CLIC design relies on heavy damping of these wake-fields in order to ameliorate the effects of the wake-field on the beam emittance. Here we present initial results on a modified design which combines both damping and detuning of the cell frequencies of each cavity structure in order to enhance the overall decay of the wake-field. Interleaving of cell frequencies is explored as a means to improve the damping.

WEPP091	Injector Upgrade for the S-DALINAC	vacuum, linac, acceleration, electron	2731
	T. Kuerzeder, A. Araz, M. Brunken, J. Conrad, R. Eichhorn, H.-D. Gräf, M. Hertling, F. Hug, M. Konrad, M. Platz, A. Richter, S. Sievers, T. Weilbach TU Darmstadt, Darmstadt W. Ackermann, W. F.O. Müller, B. Steiner, T. Weiland TEMF, Darmstadt J. D. Fuerst ANL, Argonne, Illinois
	Since 1991 the superconducting Darmstadt linear accelerator S-DALINAC provides an electron beam of up to 130 MeV for nuclear and astrophysical experiments. Currently its injector delivers beams of up to 10 MeV with a current of up to 60 μA. The upgrade aims to increase both parameters to 14 MeV and 150 μA in order to allow more demanding astrophysical experiments. Therefore, a modified cryostat module equipped with two new cavities is required. Due to an increase in RF power to 2 kW the old coaxial RF input couplers, being designed for a maximum power of 500 W, have to be replaced by new waveguide couplers. We review the design principles and report on the fabrication of the coupler and the whole module.

WEPP092	Tuning of Waveguide to Cavity Coupling Coefficient Beta for a PWT Linac and a Photocathode Gun	gun, linac, simulation, electromagnetic-fields	2734
	S. Krishnagopal BARC, Mumbai U. Kale, S. Lal, K. K. Pant RRCAT, Indore (M. P.)
	The waveguide to cavity coupling coefficient beta for two types of accelerating structures: a Plane Wave Transformer (PWT) linac and a 1.6 cell photocathode gun has been tuned to obtain critical coupling in both. Analytical calculation of the dimensions of slot required for critical coupling have been done using Gao’s formulation based on Bethe’s theory for hole coupling. While the PWT linac structure, with high inter-cell coupling, shows good agreement between measured and predicted slot dimensions for different values of beta, the agreement is not so good in the photocathode gun on account of poor inter-cell coupling. This paper discusses details of the analytical calculation of slot dimensions for the two structures, their comparison with experimentally measured results, and the procedure adopted for tuning the two structures to critical coupling.

WEPP093	Prototype of Parallel Coupled Accelerating Structure	focusing, resonance, controls, linac	2737
	A. E. Levichev, V. M. Pavlov BINP SB RAS, Novosibirsk Y. D. Chernousov ICKC, Novosibirsk V. Ivannikov, I. V. Shebolaev ICKC SB RAS, Novosibirsk
	The prototype of parallel coupled accelerating structure is developed. It consists of five accelerating cavities, common excitation cavity and RF power waveguide feeder. The excitation cavity is a segment of rectangular waveguide loaded by cupper pins. The excitation cavity operate mode is TE₁₀₅. Connection between excitation cavity and accelerating cavities is performed by magnetic field. The expressions for coupled factor excitation cavity to accelerating cavities and coefficient of efficiency for RF power transmission from generator to accelerating cavities are obtained using coupled cavities theory. The parallel coupled accelerating structure electrodynamic characteristics are measured.

WEPP098	Efficient Traveling-wave Accelerating Structure for Linear Accelerators	electron, bunching, acceleration, linac	2746
	V. M. Pirozhenko MRTI RAS, Moscow
	The shaped traveling-wave (STW) structure contains periodic structure of cavities with optimal shape and magnetic coupling operating in the forward traveling-wave mode. The structure combines the advantages of conventional standing-wave (SW) and traveling-wave (TW) structures. It ensures high efficiency of the use of radio-frequency (RF) power for the particle acceleration inherent in the SW structures. Also it gives a possibility to vary output energy of the particles by changing the beam loading and provides for good matching with RF generator without application of special matching devices that is inherent in the TW structures. The STW structure is well suited for compact variable-energy electron linear accelerators used for radiation technologies.

WEPP099	Results from Atomic Layer Deposition and Tunneling Spectroscopy for Superconducting RF Cavities	scattering, superconductivity, vacuum, electron	2749
	J. Norem, J. W. Elam, M. J. Pellin ANL, Argonne, Illinois C. Z. Antoine CEA, Gif-sur-Yvette L. Cooley Fermilab, Batavia, Illinois J. F. Moore MassThink LLC, Naperville, IL Th. Proslier, J. Zasadzinski IIT, Chicago, Illinois
	Atomic Layer Deposition is a process that synthesizes materials in successive monolayers, at rates on the order of 1 micron/hour. We have been using this technique at Argonne as a possible way to improve both superconducting rf (SCRF) and normal rf structure performance. Initial experiments have led to a new model of high field Q-slope and new ways of controlling SCRF surfaces, as well as suggesting ways to significantly improve the operating gradients of both superconducting and normal structures. We have also been testing this technique in superconducting structures. Initial measurements show significant improvement over “cavity-grade” Nb samples.

WEPP132	Efficiency Enhancement of Active High-Power Pulse Compressors	extraction, controls, plasma	2803
	S. V. Kuzikov, Yu. Danilov, A. A. Vikharev IAP/RAS, Nizhny Novgorod
	High power microwaves needed to accelerate particles in multi-TeV colliders can be produced using active pulse compressors. An active compressor has a storage cavity whose Q-factor is modulated by means of RF switch. An efficiency of such compressor is limited due to diffraction losses at power accumulation regime and in conventional case does not exceed 81.4%. A new microwave pulse compressor operated with a superposition of quasi-degenerated modes is suggested. A proper choice of eigen frequencies and Q-factors of these modes allows essential enhancement of efficiency (asymptotically up to 100%). A 30 GHz project of multi-megawatt compressor based on dual-mode circular cross-section cavity is considered.

WEPP133	High-gradient Multi-mode Two-beam Accelerating Structure	acceleration, simulation, collider, linear-collider	2806
	S. V. Kuzikov, M. E. Plotkin IAP/RAS, Nizhny Novgorod J. L. Hirshfield Yale University, Physics Department, New Haven, CT S. Kazakov Omega-P, Inc., New Haven, Connecticut
	A new accelerating structure which is aimed to provide gradient >150 MV/m for next generation of multi-TeV linear colliders is suggested. The structure is based on periodic system of quasi-optical cavities. Each of these cavities is excited in several equidistantly-spaced eigen modes by the drive beam in such a way that the RF fields reach peak values only during the short time intervals when an accelerating bunch is resident in the cavities, thus exposing the cavity surfaces to strong fields for only a small fraction of time. This feature is expected to raise the breakdown and pulse heating thresholds. The proposed structure embodies most of additional attractive properties: the cavity is an all metallic structure, no transfer or coupling structures are needed between the drive and acceleration channels, the cavity fields are symmetric around the axes of the drive beam and the accelerated beam, the cavity can exhibit high transformer ratio. Calculations of single quasi-optical rectangular cavity with parameters of drive and accelerating beams close to ones adopted for the CLIC project show that high gradient as well as high efficiency are achievable. S. V. Kuzikov et al. "Quasi-optical accelerating structure operated with a superposition of synchronized modes," Conf. Digest of Joint 32nd IRMMW Conf., Cardiff, UK, 2007, Vol.2, p.797-798.

WEPP142	Simulation of and Progress towards a Micron-scale Laser-powered Dielectric Electron Source	simulation, laser, vacuum, resonance	2827
	G. Travish, J. B. Rosenzweig, J. Xu UCLA, Los Angeles, California S. Boucher RadiaBeam, Marina del Rey R. B. Yoder Manhattan College, Riverdale, New York
	A dielectric, slab-symmetric structure for generating and accelerating low-energy electrons has been under study for the past two years. The resonant device is driven by a side-coupled laser and is configured to maintain field provide necessary for synchronous acceleration and focusing of nonrelativistic particles. Intended applications of the structure include the production of radiation for medical treatments, imaging, and industrial uses. The details of the structure geometry and its resonant properties have been studied with 2D and 3D electromagnetic codes, the results of which are present here.

WEPP149	Advances in Parametric-resonance Ionization Cooling	resonance, emittance, space-charge, betatron	2838
	Y. S. Derbenev Jefferson Lab, Newport News, Virginia R. P. Johnson Muons, Inc, Batavia
	Parametric-resonance ionization cooling (PIC) is a muon-cooling technique that is useful for low-emittance muon colliders. This method requires a well-tuned focusing channel that is free of chromatic and spherical aberrations. The dispersion function of the channel must be large where the correction magnets are placed for aberration control but small and non-zero where the ionization cooling beryllium wedges are located to provide emittance exchange to maintain small momentum spread. In order to be of practical use in a muon collider, it also necessary that the focusing channel be as short as possible to minimize muon loss due to decay. A compact PIC focusing channel is described in which new magnet concepts are used to generate the required lattice functions.

THPPGM01	A Control and Systems Theory Approach to the High Gradient Cavity Detuning Compensation	controls, feedback, resonance	2952
	R. Paparella INFN/LASA, Segrate (MI)
	The compensation of dynamic detuning is of primary importance in order to operate TESLA type cavities at the high accelerating gradient foreseen for the ILC (31.5 MV/m). This article firstly resumes recent successful experiences of open loop compensation of the Lorentz force detuning, repetitive and synchronous to the RF pulse, using fast piezoelectric actuators with different fast tuning systems. Possible strategies and results for the closed loop compensation of the stochastic microphonic detuning are also presented. Lastly, a deep characterization of the system under control is given, exploiting the system transfer functions acquired through both installed piezo actuators/sensors and phase locked measurements. This ultimately allows the analytical modeling of the behavior of cavity detuning and of its active compensation with piezoelectric actuators.
	Slides

THPPGM04	SLIM - An Early Work Revisited	radiation, closed-orbit, damping, lattice	2963
	A. Chao SLAC, Menlo Park, California
	An early, but at the time illuminating, piece of work on how to deal with a general, linearly coupled accelerator lattice is revisited. This work is based on the SLIM formalism developed in 1979-1981.
	Slides

THPC003	Sum of Emittance in the Presence of a Linear Coupling	emittance, betatron, quadrupole, focusing	2975
	M. Aslaninejad, H. Ghasem IPM, Tehran
	In this article, the influence of linear coupling due to skew quadrupoles on the transverse equations of motion and emittances in accelerators is studied. We first introduce the definition of the transverse single particle emittances using the Floquet transformation in alternating gradient as well as the constant focusing rings, then in the presence of the linear coupling, due to skew quadrupoles we introduce the coupled differential equations governing the particles motion and try to solve them by a direct method and also using the normal modes of motion to find the relation between the two transverse emittances. Based on smooth approximation and using the normal modes* we solve the equations of motion of a test charged particle and derive two new formulas for the sum of the emittances, and the conditions under which this sum is invariant. P. J.Bryant, CERN Acclerator School, CERN, PROCEEDINGS, 94-01, Vol. I. *E. Metral, CERN/PS 2001-066(AE).

THPC006	Applications of a BPM-based Technique for Measuring Real Space Distributions in the Spallation Neutron Source Ring and Transport Lines	target, injection, simulation, diagnostics	2984
	S. M. Cousineau, T. A. Pelaia, M. A. Plum ORNL, Oak Ridge, Tennessee
	The SNS accumulator ring and associated transport lines are designed to accumulate and transport up to 1.5·10¹⁴ ppp to a liquid mercury target for neutron spallation. Since commissioning, a dedicated effort has been put forth to characterize the lattice and beam dynamics at low intensity. Toward this goal, a BPM-based technique for measuring real space beam distributions at low beam intensities was developed. Recently, this technique has been used to diagnose and localize a strong source of coupling in the lattice, to verify and troubleshoot complementary diagnostics devices, and to provide data for code benchmarking. Other potential applications of this technique include investigations of single particle dynamics and resonances, studies of injection painting techniques, and possibly measurement of quadrupole power supply errors in the ring. In this paper we present the results of applying this technique to various situations in the SNS ring and transport lines, including the first ORBIT benchmarks of the SNS ring and RTBT. T. Pelaia et al, Nucl. Instr. And Methods, in progress.

THPC007	Permanent Magnet Skew Quadrupoles for the Low Emittance LER Lattice of PEP-II	quadrupole, permanent-magnet, emittance, lattice	2987
	F.-J. Decker, S. D. Anderson, D. Kharakh, M. K. Sullivan SLAC, Menlo Park, California
	The vertical emittance of the low energy ring (LER) in the PEP-II B-Factory was reduced by using skew quadrupoles consisting of permanent magnet material. The advantages over electric quadrupoles or rotating existing normal quadrupoles are discussed. To assure a high field quality a Biot Savart calculation was used to cancel the natural 12-pole component by using different size poles over a few layers. A magnetic measurement confirmed the high quality of the magnets. After installation and adjusting the original 12 skew and 16 normal quadrupoles the emittance contribution from the region close to the interaction point, which was the biggest part in the original design, was considerably reduced.

THPC008	Constants and Pseudo-constants of Coupled Beam Motion in the PEP-II Rings	betatron, sextupole, quadrupole, lattice	2990
	F.-J. Decker, W. S. Colocho, M.-H. Wang, Y. T. Yan, G. Yocky SLAC, Menlo Park, California
	Constants of beam motion help as cross checks to analyze beam diagnostics and the modeling procedure. Pseudo-constants, like the betatron mismatch parameter or the coupling parameter det C, are constant till certain elements in the beam line change then. This can be used to visually find the non-desired changes, pinpointing errors compared with the model.

THPC015	Computational Beam Dynamics Studies for Improving the Ring Injection and Extraction Systems in SNS	scattering, injection, quadrupole, septum	3008
	J. A. Holmes, S. M. Cousineau, M. A. Plum, J. G. Wang ORNL, Oak Ridge, Tennessee
	The ring injection and extraction systems must function as designed in order for the Spallation Neutron Source (SNS) to achieve its specified performance. In commissioning and early operations we have encountered problems that have been traced to these systems. We experienced high beam losses in and around the injection dump, the rectification of which has necessitated significant study and development by a multidisciplinary team. The results include a number of enhancements of existing features and the addition of new elements and diagnostics. The problem in the extraction region stems from tilted beam distributions observed in the ring-to-target beam transport line (RTBT) and on the target, thus complicating the control of the beam-on-target distribution. This indicates the inadvertant introdution of x-y beam coupling somewhere upstream of the RTBT. The present paper describes computational studies, using the ORBIT Code, addressed at the detailed understanding and solution of these problems.

THPC024	Closed Orbit Correction at the LNLS UVX Storage Ring	sextupole, storage-ring, optics, feedback	3029
	L. Liu, R. H.A. Farias, X. R. Resende, P. F. Tavares LNLS, Campinas
	The orbit correction of stored electrons in the LNLS storage ring often needs a few iterations to converge to the smallest distortion. This is caused in part by the residual coupling between transverse planes. This coupling effect can be included in the correction algorithm leading to the best orbit in just one iteration. However, in the LNLS ring, the number of monitors equals the number of vertical correctors but surpasses the number of horizontal correctors. This means that the vertical orbit can be corrected to zero at the position monitors in the decoupled situation but the horizontal orbit cannot. For the coupled case, the incapacity of zeroing the horizontal orbit leaks into the vertical plane. This problem can be addressed by the eigenvector method with constraints.

THPC025	Further Advances in Understanding and Optimising Beam Dynamics in the Diamond Storage Ring	dynamic-aperture, quadrupole, lattice, storage-ring	3032
	I. P.S. Martin, R. T. Fielder, E. C. Longhi, B. Singh Diamond, Oxfordshire R. Bartolini JAI, Oxford
	We report the results of recent beam dynamics studies of the Diamond storage ring. These studies were aimed at both improving our understanding of the machine operation as well as establishing a reliable, well corrected lattice with long lifetime and high injection efficiency suitable for later top-up operation. Particular attention has been given to measuring and controlling the linear optics of the lattice, to determining the various contributions to the overall beam lifetime and to optimising the sextupole strengths for good on and off momentum dynamic aperture. For each topic, detailed comparisons with model predictions are also described.

THPC026	Measurement of Complex Coupling Driving Term of Linear Difference Resonance Using Turn-by-turn Beam Position Monitors	betatron, quadrupole, resonance, storage-ring	3035
	M. Masaki, K. Soutome, S. Takano, M. Takao JASRI/SPring-8, Hyogo-ken
	X-Y emittance coupling is one of the important measures of beam quality in an electron storage ring for high brilliant light source. We have developed a method of measuring complex coupling driving term C of linear difference resonance using turn-by-turn beam position monitors (BPMs), assuming the perturbation theory with the single resonance approximation. Since both amplitude and phase of the driving term are derived, we can uniquely determine the strength of two-degree-of-freedom skew quadrupole magnets for correction of the linear resonance coupling. Before the correction, the driving term was measured by the developed method at the SPring-8 storage ring where small skew quadrupole components are distributed as error magnetic fields. On the other hand, the linear resonance coupling was corrected using the counter skew quadrupole magnets, the strength of which was adjusted to minimize vertical beam size near the linear difference resonance. The measured driving term C was broadly consistent with the counter term calculated from the adjusted strength of skew quadrupole magnets for the coupling correction.

THPC032	Vertical Beam Size Reduction via Compensation of Residual Transverse Coupling	wiggler, optics, simulation, closed-orbit	3047
	T. F. Roque, X. R. Resende, P. F. Tavares LNLS, Campinas
	The Brazilian Synchrotron Light Source (LNLS) is currently constructing a beamline which will make use of the radiation produced by the EPU installed in the storage ring (SR) in 2007. Various force tasks have been triggered by this new beamline in order to achieve required beam properties and stability. One of these tasks has to do with reducing the SR's vertical beam size at the straight section where the EPU is located, hence improving the radiation brilliance from the EPU. This report will describe our recent efforts in understanding and controlling what residual effects there are in the ring that dominate the ring's vertical beam size. In particular, we study the effects of residual coupling perturbations on the beam size through the transfer matrix formalism which, we argue, is the most appropriate. A beam model including transverse linear coupling is validated with measured closed orbit response functions. By Analyzing this model we are able to propose new skew quadrupole elements to the SR that might reduce the vertical beam size at the EPU section and we can infer the validity of results with a pinhole beam imaging system which we have available in our diagnostic beamline.

THPC037	Studies of Orthogonal Bumps for ILC Main Linac	emittance, linac, alignment, simulation	3059
	N. Solyak Fermilab, Batavia, Illinois S. A. Glukhov BINP SB RAS, Novosibirsk
	To preserve small vertical emittance of the beam in ILC main linac a few beam-based alignment techniques were proposed and studied in recent years. Dispersion and wakefield bumps are one of the effective tool for final tuning of the machine. One of the modifications of bumps is so called orthogonal (or SVD) bumps, proposed for CLIC. In paper we present study of orthogonal bumps performances for final alignment of the ILC main linac.

THPC042	Uncoupled Achromatic Tilted S-bend	quadrupole, dipole, electron, controls	3071
	N. Tsoupas, A. Kayran, V. Litvinenko, W. W. MacKay BNL, Upton, Long Island, New York
	A particular section of one of the electron beam transport lines, to be used in the e-cooling project* of the Relativistic Heavy Ion Collider (RHIC), is constrained to bend the beam simultaneously in both the horizontal and vertically planes and also be achromatic in both planes. The simultaneous horizontal and vertical achromatic bend is accomplished by rotating, about the longitudinal axis of the beam, the dipole and quadrupole elements of this section of the line. However such a rotation of the magnetic elements may couple the transported beam through the first order beam transfer matrix (linear coupling). In this paper we investigate for a sufficient condition, that the first order transport matrix (R-matrix) can satisfy, under which such a section of a beam transfer line is both achromatic and also constrains the beam at the exit of the line to emerge linearly uncoupled. We also provide a complete solution for the beam optics, of this part of the beam transfer line, which satisfies achromaticity and no first order beam coupling. *htpp://www.bnl.gov/cad/eRhic/Documents/AD_Position_Paper_2007.pdf

THPC051	Adiabaticity and Reversibility Studies for Beam Splitting Using Stable Resonances	resonance, synchrotron, emittance, proton	3095
	S. S. Gilardoni, F. Franchi, M. Giovannozzi CERN, Geneva
	At the CERN Proton Synchrotron, a series of beam experiments proved beam splitting by crossing the one-fourth resonance. Depending on the speed at which the horizontal resonance is crossed, the splitting process is more or less adiabatic, and a different fraction of the initial beam is trapped in the islands. Experiments prove that when the trapping process is reversed and the islands merged together, the final distribution features thick tails. The beam population in such tails is correlated to the speed of the resonance crossing and to the fraction of the beam trapped in the stable islands. Experiments, simulations, and possible theoretical explanations are discussed.

THPC064	Use of LOCO at Synchrotron SOLEIL	lattice, storage-ring, quadrupole, optics	3131
	L. S. Nadolski SOLEIL, Gif-sur-Yvette
	SOLEIL is a 354 m long 2.75 GeV third generation synchrotron light source delivering photons to beam-lines since January 2007. This paper will discuss in details the first attempts using LOCO code and problems encountered due to the storage ring lattice compactness. The introduction into the code of constraints on the quadrupole gradient variations gave tremendous improvements. The convergence is satisfactory, beta –beatings are reduced from 5% to below 1% RMS in both planes. Restoring the symmetry of the lattice enhanced the performances of the storage ring. In the last part, different ways of using LOCO as a powerful diagnostics tool will be given.

THPC073	Measurement of Resonance Driving Terms in the ATF Damping Ring	resonance, sextupole, simulation, kicker	3155
	R. Tomas, F. Zimmermann CERN, Geneva K. Kubo, S. Kuroda, T. Naito, T. Okugi, J. Urakawa KEK, Ibaraki
	The measurement of resonance driving terms in the Damping Ring of the Accelerator Test Facility in KEK could help finding possible machine imperfections and even to optimize single particle stability through the minimization of non-linearities. The first experimental attempts of this enterprise are reported in this note.

THPC081	RF Wire Compensator of Long-range Beam-beam Effects	emittance, dynamic-aperture, simulation, beam-beam-effects	3173
	U. Dorda, F. Caspers, T. Kroyer, F. Zimmermann CERN, Geneva
	The dynamic aperture of the proton beam circulating in the Large Hadron Collider (LHC) is expected to be limited by up to 120 long-range beam-beam encounters. In order to perfectly compensate the LHC long-range beam-beam effect for nominal as well as for so-called 'PACMAN' bunches, i.e. bunches at the start or end of a bunch train, the wire compensator strength should be adjusted for each bunch individually. Here an RF-based compensator is proposed as a practical solution for the PACMAN compensation. We show that this approach also allows relaxing the power and precision requirements compared with those of a pulsed DC device, to a level within the state-of-the-art of RF technology. Furthermore it allows the use of a passive circulator in the tunnel close to the beam and thus a significantly reduction of the transmission line length and of the resulting multiple reflection issues. Simulations, issues related to RF phase noise and first experimental results from laboratory models as well as from a wire-compensator prototype installed in the CERN Super Proton Synchrotron (SPS) are presented.

THPC082	Wire Excitation Experiments in the CERN SPS	simulation, beam-losses, optics, resonance	3176
	U. Dorda, J.-P. Koutchouk, R. Tomas, J. Wenninger, F. Zimmermann CERN, Geneva R. Calaga, W. Fischer BNL, Upton, Long Island, New York
	In order to study the effect of long range interaction and its wire compensation experimentally, current carrying wires are installed in the CERN Super Proton Synchrotron (SPS). In this paper we summarize the main results of the 2007 wire excitation results at 26, 37 and 55 GeV including wire-current-, beam-wire distance and chromaticity scans. A strong dependence on the chromaticity and indications of a threshold effect at 37 and 55 GeV was found. The results are compared to simulation, to a simple analytic scaling law and to experimental results from RHIC. Wire-driven resonances have been observed through the Fourier spectrum of experimental BPM data and compared to simulations.

THPC097	A Full Analytical Method to Determine Equilibrium Quantities of Mismatched Charged Particle Beams evolving in Linear Channels	emittance, simulation, focusing, resonance	3203
	R. P. Nunes, F. B. Rizzato IF-UFRGS, Porto Alegre
	The focus of this work is to show a full analytical expression to determine relevant equilibrium quantities of a magnetically focused and high-intensity charged particle beam when evolving in a linear channel. Through the current approach, some intermediate steps of our original hybrid model which have to be solved numerically now can be eliminated, leading to the obtainment of a full analytical expression. This expression relates initial beam parameters with those obtained at equilibrium, allowing that the fraction of halo particles f can be evaluated. As a consequence, through the developed model, beam quantities like the envelope and emittance can be naturally determined. This is important in the accelerator engineering, since halo characteristics is a factor to be considered in the design of its confinement structure. For validation, full self-consistent N-particle beam numerical simulations have been carried out and its results compared with the predictions supplied by the full analytical model. The agreement is shown to be nice as with the simulations as with the hybrid numerical-analytical version of the model.

THPC098	Halo characterization of initially mismatched beams through phase-space modeling	emittance, simulation, focusing, plasma	3206
	R. P. Nunes, F. B. Rizzato IF-UFRGS, Porto Alegre
	This work discusses a method of characterizing the beam particles with just some assumptions about the entire beam phase-space topology. At equilibrium, the beam phase-space can be recognized as composed by almost two distinct regions: a thin horizontal branch over the r axis that is populated by the core particles and a curve branch in the dr/ds x r plane, which is populated by the halo particles. Since these regions have a regular shape, then it is readily possible to convert them to an analytical expression. Two distinct shapes have been employed (circular and elliptical) to model the beam halo branch. With this, all usual initial beam mismatch values are covered with accuracy to determine the beam envelope and emittance at equilibrium. Full self-consistent N-particle beam simulations have been carried out and its results compared with the ones obtained with the model. Results agreed nice for all analyzed mismatch cases.

THPC110	Investigation of Helical Cooling Channel	emittance, simulation, superconductivity, quadrupole	3233
	K. Yonehara, V. Balbekov Fermilab, Batavia, Illinois
	A helical cooling channel (HCC) has been proposed to quickly reduce phase space of muon beams. It is composed of solenoidal and helical coils to provide focusing and dispersion needed for the six-dimension cooling. A comprehensive investigation of the HCC is performed in presented work including theoretical analysis, particle tracking and Monte Carlo simulation. These results are also compared with the past simulation results* to confirm the helical cooling theory. Optimization of the channel and estimation of its ultimate performances are presented. Y. Derbenev and R. P. Johnson. PRSTAB 8, 041002 (2005). *K. Yonehara et al. TPPP052, Particle Accelerator Conference 2005.

THPC129	Coupling Correction in NSLS X-ray Ring	quadrupole, electron, storage-ring, insertion	3290
	M. G. Fedurin, I. Pinayev BNL, Upton, Long Island, New York
	In this paper we describe MATLAB script for reduction of the transverse coupling in the NSLS X-ray storage ring. The algorithm is based on varying strength of the skew quadrupoles and observation of the vertical beam size. The details of the iterative procedure are also discussed.

THPC135	Vertical Emittance Measurements and Optimisation at the Australian Synchrotron	emittance, quadrupole, lattice, storage-ring	3303
	M. J. Spencer, R. T. Dowd, G. LeBlanc ASP, Clayton, Victoria
	Adjustment to the vertical emittance of the Australian Synchrotron storage ring was made using 28 skew quadrupoles. The skew quadrupole settings were calculated using the LOCO method which uses measurements of vertical dispersion as well as transverse coupling. The vertical emittance was monitored indirectly through lifetime, tune crossing, x-ray pinhole camera and calibrated model calculations. The paper outlines the results of these studies.

THPP003	RF System Design for the EMMA FFAG	controls, power-supply, acceleration, linac	3377
	C. D. Beard, S. A. Griffiths, C. Hill, P. A. McIntosh, A. E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire N. Bliss, A. J. Moss, C. J. White STFC/DL, Daresbury, Warrington, Cheshire D. Teytelman Dimtel, San Jose
	In this report the RF system design for EMMA is described. The power source options, power supplies, waveguide distribution scheme and control system is discussed. The architecture necessary to meet the operation specifications requires a large degree of adjustment. To simplify commissioning and enhance the versatility of the machine a complex RF system is desired. This report details the RF "knobs" included to meet this.

THPP024	Detailed Study of the RF Properties of the FETS RFQ Cold Model	rfq, simulation, quadrupole, ion-source	3422
	S. Jolly, A. Kurup, D. A. Lee, J. K. Pozimski, P. Savage Imperial College of Science and Technology, Department of Physics, London Y. Cheng IHEP Beijing, Beijing A. P. Letchford STFC/RAL, Chilton, Didcot, Oxon
	A 324MHz four vane RFQ cold model has been built, as part of the development of a proton driver Front End Test Stand (FETS) at the Rutherford Appleton Laboratory (RAL) in the UK. Previous measurements to determine the electric field profile were made using the bead-pull perturbation method: these measurements have been refined and expanded. New measurements of the electric field profile, Q-value and resonant modes are presented. Measurements of the fundamental frequency and Q-value of the RFQ as a result of modifications to the profile of the end flange inserts are also given. Finally, an experiment is outlined to determine the beam transmission properties of the cold model based on beam transport simulations with the General Particle Tracer package (GPT).

THPP027	Heating and Stress in the LANSCE Side-coupled Linac RF Cavities	linac, impedance	3431
	S. S. Kurennoy, S. Konecni, J. F. O'Hara, L. Rybarcyk LANL, Los Alamos, New Mexico
	RF heating and related temperature distribution and stress are important problems in room-temperature accelerating cavities operating at high duty factors. To evaluate feasibility of higher duty operations of the Los Alamos Neutron Science Center (LANSCE) side-coupled linac (SCL), we have performed a combined 3-D electromagnetic (EM) and thermal-stress analysis of the SCL RF cavities. In the process, we have developed a procedure and interface for data exchange between the electromagnetic (MicroWave Studio) and engineering (COSMOS) codes for the combined EM-engineering analysis. This interface can be useful for other applications involving room-temperature accelerating cavities.

THPP050	Recent Status of Laser Cooling for Mg Realized at S-LSR	laser, ion, synchrotron, electron	3476
	A. Noda, M. Ikegami, T. Ishikawa, M. Nakao, T. Shirai, H. Souda, M. Tanabe, H. Tongu, A. Wakita Kyoto ICR, Uji, Kyoto M. Grieser MPI-K, Heidelberg I. N. Meshkov, A. V. Smirnov JINR, Dubna, Moscow Region K. Noda NIRS, Chiba-shi
	At an ion storage and cooler ring, S-LSR, a laser cooling has been applied to the 40 keV ²⁴Mg⁺ ion beam guiding a laser with the wave length of 280nm parallel to the ion beam together with the deceleration by an induction voltage. Up to now, the longitudinal temperature has been cooled down to 3.6 Kelvin for the ion number of 3x10⁴ although the transverse one still remains around 500 Kelvin. The longitudinal temperature is limited by the heat transfer from the transverse degree of freedom through intra-beam scattering, which becomes stronger according to increase of ion number. It is found that the equilibrium longitudinal temperature is linearly coupled with the transverse one* for our experimental condition up to now. In the present paper, recent experimental data will be presented together with the procedure of beam diagnosis with the use of optical methods using a spontaneous emission of the Mg ions. Possible approach to realize the resonant coupling through synchro-betatron coupling** is also to be presented. * M. Tanabe et al., To be published in Applied Physics Express (APEX). ** Okamoto, A. M. Sessler, D Möhl, Phys. Rev. Lett. 72 (1994)3977.

THPP078	IFMIF-EVEDA RFQ Design	rfq, simulation, vacuum, beam-losses	3542
	A. Pisent, M. Comunian, E. Fagotti, A. Palmieri, P. A. Posocco, C. Roncolato INFN/LNL, Legnaro, Padova F. Grespan Università degli Studi di Milano, Milano A. Pepato INFN- Sez. di Padova, Padova
	The RFQ of IFMIF-EVEDA project is characterized by very challenging specifications, with 125 mA of deuteron accelerated up to 5 MeV. After the long period of conceptual and comprehensive design of IFMIF accelerator, the decision of the construction of its low energy part has implied a new analysis of the RFQ design. In particular the beam dynamics design has been optimized, with a consistent reduction of the structure length and power consumption, and improvement of the performances in terms of beam losses. The resonator, of four vanes kind, has been designed taking advantage of the theoretical background and experimental experience gained in Europe with IPHI and TRASCO projects. The mechanical design has been analysed considering different approaches, involving vacuum brazing, laser or e'beam welding.

THPP136	The Replacement of the Isis White-circuit Choke	synchrotron, factory, proton, power-supply	3679
	S. West, M. G. Glover, J. W. Gray STFC/RAL/ISIS, Chilton, Didcot, Oxon K. Papp, K. Pointner TA, Leonding L. A.E. Van Lieshout Imtech Vonk, Coevorden
	ISIS, located at the Rutherford Appleton Laboratory is the world’s leading pulsed neutron source. It produces intense bursts of neutrons every 20mS when 800MeV protons are fired into a heavy metal target by an accelerating synchrotron. The ISIS synchrotron is based on a resonant “White Circuit”* allowing superimposed DC and AC currents to circulate in the ring of dipole and quadrupole magnets. The magnets themselves resonate with tuned capacitor banks at 50Hz and a large ten-winding choke allows both a path for the DC component of the current and a means to inject the AC power which maintains the 50Hz AC oscillation. This choke, which dates from the 1960’s, was a veteran of the “NINA” synchrotron in Daresbury before it began service at ISIS. Should it fail it could take at years to repair and a scheme is now well under way to replace it with ten individual chokes with in-situ spares so that the system will gain redundancy and robustness. This paper covers progress to date and the problems that have been encountered and their solutions. *M. G. White et al. "A 3-BeV High Intensity Proton Synchrotron," The Princeton-Pennsylvania Accelerator, CERN Symp.1956 Proc., p525.