LINAC 2004 - List of Keywords

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

linac

Paper	Title	Other Keywords	Page
MO102	Accelerator Layout of the XFEL	electron, site, photon, undulator	2
	R. Brinkmann DESY, Hamburg
	The X-ray Free Electron Laser XFEL is a 4th generation synchrotron radiation facility based on the SASE FEL concept and the superconducting TESLA technology for the linear accelerator. In February 2003 the German government decided that the XFEL should be realized as a European project and located at DESY/Hamburg. The Ministry for Research and Eduation also announced that Germany is prepared to cover half of the investment and personnel costs of the project. This paper gives an overview of the overall layout and parameters of the facility, with emphasis on the accelerator design, technology and physics.
	Transparencies

MO201	Linac Coherent Light Source (LCLS) – Accelerator System Overview	damping, feedback, simulation, free-electron-laser	7
	P. Krejcik, Z. Huang, J. Wu SLAC, Menlo Park, California P. Emma SLAC/ARDA, Menlo Park, California
	The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL). Pulses of LCLS x-ray FEL will be several orders of magnitude brighter and shorter than most existing sources. These characteristics will enable frontier new science in several areas. To ensure the vitality of FEL lasing, it is critical to preserve the high quality of the electron beam during the acceleration and compression. We will give an overview of the LCLS accelerator system. We will address design essentials and technique challenges to satisfy the FEL requirements. We will report studies on the microbunching instability suppression via a Laser-Heater. The studies clearly prove the necessary of adding the Laser-Heater and show how effectively this Laser-Heater suppresses the instability by enhancing the Landau damping. We will report how to minimize the sensitivity of the final energy spread and the peak current to various system ‘jitters’. To minimize this sensitivity, a feedback system is required together with other diagnostics. With all these considerations, full start-to-end simulations show saturation at 1.5 Å, though the LCLS is expected to be a very challenging machine.
	Transparencies

MO203	Non-Interfering Beam Diagnostic Developments	electron, diagnostics, ion, proton	13
	A. Peters, P. Forck GSI, Darmstadt
	New high power proton and heavy ion linac projects are a big challenge for beam diagnostic developments. Due to the high inherent beam power mostly all destructive measurement techniques are not applicable. Thus a lot of beam diagnostic developments are under way from enhancements of well-known systems like beam position pick-ups or current transformers to new designs for profile or bunch length measurements using e.g. the interaction of the high power beams with the residual gas in the linacs. The latest progress in this field will be reviewed with descriptions of some remarkable solutions.
	Transparencies

MO204	Status of REX-ISOLDE	ion, emittance, injection, target	18
	O.K. Kester, S. Emhofer, D. Habs, K. Rudolph LMU, Garching F. Ames, P. Butler, P. Delahaye, M. Lindroos, T. Sieber, F.J.C. Wenander CERN, Geneva R. Repnow, H. Scheit, D. Schwalm, R. von Hahn MPI-K, Heidelberg
	After commissioning of the radioactive beam experiment at ISOLDE (REX-ISOLDE) first series of physics experiments in 2002 and 2003 have been performed. The REX-ISOLDE charge state breeder adjusts the charge-to-mass ratio of isotopes from all over the nuclear chart to the LINAC requirements. A variety of isotopes from different mass regions of the nuclear chart have been charge bred with REXEBIS to the required A/q < 4.5. A variety of tests with REXTRAP, REXEBIS and the LINAC structures have been done, in order to study the beam parameters, transmission efficiency and upgrade options. The LINAC now consists of six resonators and one re-buncher cavity. The beam energy, which can be delivered towards the target areas, can be varied between 0.8 and 2.2. An additional boost to 3 MeV/u is now possible because of the upgrade with a 202.56 MHz IH-cavity developed for the MAFF project. In addition experiment using beams from the RFQ at 0.3 MeV/u have been performed for solid state physics experiments. The present status of the projects and the commissioning measurements will be presented.
	Transparencies

MO301	SPIRAL2 at GANIL	ion, rfq, emittance, ion-source	23
	M.-H. Moscatello GANIL, Caen
	The detailed design study phase of the SPIRAL2 project has been launched since beginning of 2003. The aim of this facility is to produce rare ion beams, using a Uranium carbide target fission process, based on a fission rate of 10¹³ to 10¹⁴ fissions/s. The driver accelerator accelerates a 5 mA deuteron beam up to 20 MeV/u, impinging on a carbon converter to produce the neutrons necessary to the fission process. It has also to accelerate q/A=1/3 heavy ions, to energies between 0.75 and 14.5 MeV/A for different types of nuclear and non-nuclear physics experiments. The accelerator, based on a RFQ followed by an independently phased superconducting cavity linac with warm focusing sections, is under design. This paper presents the reference design chosen for SPIRAL2 driver accelerator and gives the design status of the different components: Sources, RFQ, Superconducting linac, RF Systems, Cryogenics, Mechanical layout.
	Transparencies

MO302	Development of Room Temperature and Superconducting CH-Structures	proton, impedance, ion, acceleration	28
	H. Podlech IAP, Frankfurt-am-Main
	H-mode cavities (IH-DTL, IH-RFQ, 4-Vane-RFQ) have been developed and operated successfully during the last decades for a large variety of applications in ion acceleration. At the IAP Frankfurt a new type of H-mode cavity, the CH-structure is under development. This multi cell drift tube cavity is operated in the H21 mode. Due to its mechanical stability, room temperature as well as superconducting cavities can be realized. The CH-structure is an excellent candidate for high power ion accelerators in the energy range from 5 to 100 MeV. The design status of the GSI 70 MeV, 70 mA proton injector DTL consisting of room temperature CH-structures is reported. Superconducting CH-structures can be used especially for cw operated linacs as designed for XADS, IFMIF or in nuclear physics projects. By using the KONUS beam dynamics and performing the particle simulations with the LORASR code it is possible to realize multi cell cavities without internal focusing lenses. A superconducting 352 MHz CH-structure (β=0.1) with 19 gaps has been built. We present the results of the first tests with this new cavity. The status of a PC version of the LORASR code will be reported.
	Transparencies

MOP01	Beam Intensity Adjustment in the RIA Driver Linac	target, ion, focusing, impedance	33
	P.N. Ostroumov, J.A. Nolen, I. Sharamentov ANL/Phys, Argonne, Illinois A.V. Novikov-Borodin RAS/INR, Moscow
	The Rare Isotope Accelerator Facility currently being designed in the U.S. will use both heavy ion and light ion beams to produce radionuclides via the fragmentation and spallation reactions, respectively. Driver beam power of up to 400 kW will be available so that beam sharing between target stations is a viable option to increase the number of simultaneous users. Using a combination of rf-sweepers and DC magnets the driver beams can be delivered to up to four targets simultaneously. With simultaneous beam delivery to more than one target independent adjustment of the relative beam intensities is essential. To enable such intensity adjustment we propose to use a fast chopper in the Medium Energy Beam Transport (MEBT) section. Several options of fast chopper design are discussed. The MEBT beam optics is being designed to accommodate and match the chopper technical specifications. Possible solutions and performance with the fast chopper are proposed.

MOP03	Proposal for Reduction of Transverse Emittance of BNL 200 MeV Linac	emittance, injection, rfq, proton	36
	J. Alessi, J. Beebe Wang, D. Raparia, W.-T. Weng BNL, Upton, Long Island, New York
	BNL plans to upgrade the AGS proton beam from the current 0.14 MW to higher than 1.0 MW and beyond for such a neutrino facility which consists of two major subsystems. First is a 1.2 GeV super-conducting linac (SCL) to replace the booster as injector for the AGS. Second is the performance upgrade for the AGS itself for the higher intensity and repetition rate. For high intensity proton accelerators, such as the upgraded AGS, there are very stringent limitations on uncontrolled beam losses. A direct effect of linac beam emittance is the halo/tail generation in the circulating beam. Studies show the estimated halo/tail generation in the beam for present normalized RMS emittance of linac beam is unacceptable. To reduce the transverse emittance of 200 MeV linac, the existing radio frequency quadrupole linac (RFQ) has to be relocated closer to drift tube linac (DTL) tank 1 to meet emittance requirement for the AGS injection with low loss. This paper will present the various options of matching between RFQ and DTL, and chopping options in the low energy beam transport (LEBT).

MOP06	A Dedicated 70 MeV Proton Linac for the Antiproton Physics Program of the Future Facility for Antiproton and Ion Research (FAIR) at Darmstadt	proton, rfq, ion, antiproton	42
	L. Groening, W. Barth, L. Dahl, R. Hollinger, P. Spädtke, W. Vinzenz, S. Yaramishev GSI, Darmstadt B. Hofmann, Z. Li, U. Ratzinger, A. Schempp, R. Tiede IAP, Frankfurt-am-Main
	The antiproton physics program of the future International Accelerator Facility at Darmstadt is based on a rate of 7·10¹⁰ cooled antiprotons per hour. To provide the primary proton intensities a proton linac is planned, which will be operated independently from the existing UNILAC for heavy ions. The proposed linac comprises a proton source, a RFQ, and a DTL. Its operation frequency of 352 MHz allows for an efficient acceleration to up to 70 MeV using normal conducting Crossed-bar H-cavities. These CH-cavities show high shunt impedances as known from IH-structures, but allow for much higher relative particle velocities of up to 40%. The beam pulses with a length of 25 μs, a current of 70 mA, and total transverse emittances of 7 μm will allow to fill the existing synchrotron SIS within one multi-turn-injection up to its space charge limit of 7·10¹² protons. The maximum SIS ramping rate limits the applied proton linac repetition rate to 5 Hz. This paper gives an overview of the proposed proton linac. The status of the design including beam dynamic studies will be reported.
	Transparencies

MOP09	Status of the 7 MeV/u, 217 MHz Injector Linac for the Heidelberg Cancer Therapy Facility	ion, quadrupole, rfq, ion-source	51
	B. Schlitt, K. Dermati, G. Hutter, F. Klos, C. Mühle, W. Vinzenz, C. Will, O. Zurkan GSI, Darmstadt A. Bechtold, U. Ratzinger, A. Schempp IAP, Frankfurt-am-Main Y.R. Lu PKU/IHIP, Beijing
	A clinical synchrotron facility for cancer therapy using energetic proton and ion beams (C, He and O) is under construction and will be installed at the Radiologische Universitätsklinik in Heidelberg, Germany, starting in 2005. The status of the ECR ion source systems, the beam line components of the low energy beam transport lines, the 400 keV/u RFQ and the 20 MV IH-cavity as well as the linac rf system will be reported. Two prototype magnets of the linac quadrupole magnets have been built at GSI and have been tested successfully. A test bench for the 1.4 MW, 217 MHz cavity amplifier built by industry has been installed at GSI including a 120 kW driver amplifier which will be used also for high power tests of the RFQ. A test bench for the RFQ using proton beams is presently being set up at the IAP. RF tuning of the 1:2 scaled IH-DTL model as well as Microwave Studio simulations of the model and the power cavity have been also performed at the IAP [1]. [1] Y.Lu, S.Minaev, U.Ratzinger, B.Schlitt, R.Tiede, this conference.
	Transparencies

MOP11	The Compact 20 MV IH-DTL for the Heidelberg Cancer Therapy Facility	simulation, rfq, ion, emittance	57
	Y.R. Lu, Y.R. Lu, B. Schlitt GSI, Darmstadt S. Minaev ITEP, Moscow U. Ratzinger, R. Tiede IAP, Frankfurt-am-Main
	A clinical synchrotron facility for cancer therapy using energetic proton and ion beams (C, He and O) is under construction and will be installed at the Radiologische Universitätsklinik in Heidelberg, Germany, starting in 2005. The different rf tuning concepts and tuning results for an 1:2 scaled IH-DTL model cavity are presented. Microwave Studio simulations have been carried out for the model and for the real power cavity. Results from the model measurements and the field simulations agree very well also for the higher order modes. The beam matching from the RFQ to the IH-DTL was optimised. Beam dynamics simulations using the LORASR code and starting with a particle distribution at the RFQ exit as calculated with PARMTEQ are presented. The IH drift tube array was matched with the gap voltage distribution resulting from rf model measurements.

MOP12	KONUS Beam Dynamics Design of a 70 mA, 70 MeV Proton CH-DTL for GSI-SIS12	proton, rfq, acceleration, quadrupole	60
	R. Tiede, G. Clemente, H. Podlech, U. Ratzinger IAP, Frankfurt-am-Main W. Barth, L. Groening GSI, Darmstadt Z. Li IMP, Lanzhou S. Minaev ITEP, Moscow
	The future scientific program at GSI needs a dedicated proton injector into the synchrotron SIS, in order to increase the proton intensity of the existing UNILAC/SIS12 combination by a factor of 70, resulting in 7· 10¹² protons in the synchrotron. A compact and efficient 352 MHz RFQ - CH-DTL combination based on novel structure developments for RFQ and DTL was worked out. For DTLs operated in an H-mode like CH-cavities (H210-mode), the shunt impedance is optimized by use of the KONUS beam dynamics. Beam dynamics simulation results of the CH-DTL section, covering the energy range from 3 to 70 MeV, with emphasis on the low energy front end are presented. Optimization aims are the reduction of emittance growth, of beam losses and of capital costs, by making use of the high acceleration gradients and shunt impedance values provided by the Crossbar H-Type (CH) structure. In addition, the beam dynamics design of the overall DTL layout has to be matched to the power limits of the available 352 MHz power klystrons. The aim is to power each cavity by one klystron with a peak rf power of around 1 MW.

MOP14	Development of Intense Beam Proton Linac in China	rfq, proton, dipole, vacuum	63
	S. Fu, S.X. Fang, H. Ouyang, S. Zhao IHEP Beijing, Beijing B. Cui, X. Guan CIAE, Beijing J. Fang, Z.Y. Guo PKU/IHIP, Beijing
	Study on intense beam proton linac was started about four years ago in a national program for the basic research on ADS in China. This ADS program is meant for the future development of the clean nuclear power generation. Another important application of HPPA for Chinese Spallation Neutron Source was also proposed recently in China, and it is financially supported by Chinese Academy of Sciences. In this paper, the research progress on intense beam proton linac in these two application fields will be outlined. It involves the test result of an high-current ECR proton source, construction status of a 3.5 MeV RFQ accelerator and the design of a DTL linac.

MOP15	TRASCO-RFQ as Injector for the SPES-1 Project	target, rfq, focusing, beam-losses	66
	P. Posocco, M. Comunian, A. Pisent INFN/LNL, Legnaro, Padova E. Fagotti INFN Milano, Milano
	The funded first phase of SPES foresees the realization at LNL of a facility able, on one hand, to accelerate a 10 mA protons beam up to 20 MeV for nuclear studies and, on the other hand, to accelerate a 30 mA protons beam up to 5 MeV for BNCT and preliminary ADS studies. In this two-way facility, the TRASCO RFQ will operate in two different current regimes. Moreover a specific MEBT has to be designed able to match the beam to the following superconducting linac and to deliver a beam with the correct characteristics to the neutron production target for the BNCT studies.

MOP18	Cold-Model Tests and Fabrication Status for J-PARC ACS	coupling, vacuum, alignment, simulation	75
	H. Ao, H. Akikawa JAERI/LINAC, Ibaraki-ken K. Hasegawa, A. Ueno JAERI, Ibaraki-ken N. Hayashizaki TIT, Tokyo M. Ikegami, S. Noguchi KEK, Ibaraki V.V. Paramonov RAS/INR, Moscow Y. Yamazaki J-PARC, Ibaraki-ken
	The J-PARC (Japan Proton Accelerator Research Complex) LINAC will be commissioned with energy of 181-MeV using 50 keV ion source, 3 MeV RFQ, 50 MeV DTL and 181 MeV SDTL (Separated DTL) on September 2006. It is planed to be upgraded by using 400 MeV ACS (Annular Coupled Structure), which is a high-beta structure most suitable for the J-PARC, in a few years from the commissioning. The first ACS cavity, which will be used as the first buncher between the SDTL and the ACS, is under fabrication. Detailed design and tuning procedure of ACS cavities has been studied with RF simulation analysis and cold-model measurements. The results of cold-model measurements, fabrication status, and related development items are described in this paper.

MOP19	Particle Distributions at the Exit of the J-PARC RFQ	simulation, rfq, beam-transport, injection	78
	Y. Kondo, A. Ueno JAERI, Ibaraki-ken K. Ikegami, M. Ikegami KEK, Ibaraki
	A 324 MHz, 3 MeV RFQ (Radio-Frequency Quadrupole) linac with 3.115 m vane length is used as the first RF linac of the J-PARC linac. The results of the J-PARC linac end-to-end (from the RFQ entrance to the injection point of the RCS) simulations significantly depend on the initial particle distributions. In the transverse phase spaces, Gaussian particle distributions, whose parameters were decided to reproduce the emittance measured in the LEBT (Low Energy Beam Transport), was used at the entrance of the RFQ. Two simulation codes, PARMTEQM and TOUTATIS, were used to produce the particle distributions at the exit of the RFQ. Since the simulated emittances showed good agreements with the emittances measured at downstream of the RFQ, they were confirmed to have the validity to be used as the initial distribution of the end-to-end simulation.

MOP20	Design of the R.T. CH-Cavity and Perspectives for a New GSI Proton Linac	impedance, simulation, proton, resonance	81
	Z. Li IMP, Lanzhou W. Barth, K. Dermati, L. Groening GSI, Darmstadt G. Clemente, H. Podlech, U. Ratzinger, R. Tiede IAP, Frankfurt-am-Main
	The CH-Structure has been studied at the IAP Frankfurt and at GSI for several years. Compared with the IH structure (H110-mode), the CH structure (H210-mode) can work at higher frequency (700 MHz) and can accelerate ions to higher energy (up to 150 AMeV). Detailed Microwave Studio (MWS) simulations were performed for this structure. Since a multi-gap cavity can be approximated as a quasi-periodic structure, it is possible to analyze one βλ/2-cell at an energy corresponding to the cavity center. Additionally, a reduced copper conductivity of 85% was assumed. Geometry variations with respect to rf frequency and shunt impedance can be performed rapidly by that method in the first stage of optimization. Effective shunt impedances from 100 MΩ/m down to 25 MΩ/m were obtained for the energy range from 5 AMeV to 150 AMeV by this method. The rf frequency was 350 MHz up to 70 MeV and 700 MHz above. A systematic analysis of the influence of the cell number in long CH cavities on the effective shunt impedance is presented. The possibility to apply this structure to a 70 mA, 70 MeV, 352 MHz proton linac for GSI is discussed.

MOP21	The Pre-Injector Linac for the Diamond Light Source	gun, diagnostics, electron, booster	84
	C. Christou, V. Kempson DIAMOND, Chilton, Didcot, Oxon K. Dunkel, C. Piel ACCEL, Bergisch Gladbach
	The Diamond Light Source is a new medium-energy high brightness synchrotron light facility which is under construction on the Rutherford Appleton Laboratory site in the U.K. The accelerator facility can be divided into three major components; a 3 GeV 561 m circumference storage ring, a full-energy booster synchrotron and a 100 MeV pre-injector linac. This paper describes the linac design and plans for operation. The linac is supplied by ACCEL Instruments GmbH under a turn-key contract, with Diamond Light Source Ltd. providing linac beam diagnostics, control system hardware and standard vacuum components. Commissioning of the linac will take place in early 2005 and user operation of the facility will commence in 2007.

MOP24	Using a Solid State Switch for a 60kV Bouncer to Control Energy Spread during the Beam Pulse*	coupling, synchrotron, impedance, power-supply	87
	L. Donley, J.C. Dooling, G.E. McMichael, V. F. Stipp ANL, Argonne, Illinois
	The beam injected into the IPNS Linac is from a column utilizing a Cockcroft-Walton voltage source. The accelerating column consists of a single high gradient gap. To lessen the likelihood of gap voltage breakdown, we pulse (“bounce”) the column voltage up during the beam pulse allowing the column DC voltage to be lower. The accelerating voltage is supplied through a 5 MΩ resistor and has only small capacitance to hold the voltage constant during the beam pulse. A capacitor is connected between the high voltage end of the column and the bouncer pulse generator. The bouncer pulse increases the column voltage to the proper level just microseconds before the beam pulse. A slope on the top of the bouncer pulse allows for correction to be added, compensating for the voltage droop that results from beam loading. The bouncer that has served this purpose in the past utilized a tube amplifier. In searching for a suitable replacement system it was decided that the system should be able to deliver a 60 kV pulse and the slope on the top of the pulse could be controlled by an RC rise. A solid state switch was purchased for this application. Switch protection and other design decisions will be discussed.

MOP25	The LEBRA 125 MeV Electron Linac for FEL And PXR Generation	electron, klystron, laser, undulator	90
	K. Hayakawa, Y. Hayakawa, K. Ishiwata, K. Kanno, K. Nakao, T. Sakai, I. Sato, T. Tanaka LEBRA, Funabashi K. Yokoyama KEK, Ibaraki
	A 125 MeV electron linac has been constructed at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University for Free Electron Laser (FEL) and Parametric X-ray (PXR) generation. Two klystrons feed rf power of approximately 20 MW peak and 20 μsec pulse duration each to an injector and three 4 m accelerating structures. Phase of the rf fed to each component is controlled independently. Two accelerating structures connected with the second klystron and a ninety degrees bending system as a momentum analyzer constitute a magnetic bunching system. Electron bunches of 3 to 4 psec width formed at the injector are compressed to within 1 psec during passing through the magnetic bunching system. Peak current of the electron beam injected to the FEL system installed downstream of the momentum analyzer is expected to be about 50 A. FEL lasing has been achieved at the wavelength range from 1 to 6 mm. Estimated peak power of the extracted FEL light pulse is about 2 MW. Applied researches using the FEL started last autumn. Preliminary experiment for the PXR generation has been continued.

MOP27	Commissioning of a 6 MeV X-Band SW Accelerating Guide	electron, vacuum, gun, injection	96
	Q. Jin, Y. Lin, X. Sun, X. Tao, D. Tong TSINGHUA, Beijing B. Chen, B. Sun, Y. Zou BIEVT, Beijing 100016
	A 6 MeV, X-band on-axis SW electron linear accelerating guide is being developed in Accelerator laboratory of Tsinghua University. It can be suitable for portable radiation therapy and radiography. The design, manufacture and high power test of the guide are given in this paper. The guide is 38 cm long and contains 25 accelerating cells with 24 coupling cells, operated in the π/2 mode. The RF power source is a pulsed magnetron at 9300 MHz with 1.5 MW peak power. The results of beam tests are following: the electron energy is more than 6 MeV at 50 mA and focal spot size is less than φ 1.5 mm without any focusing solenoid.

MOP28	A Study of Higher-Band Dipole Wakefields in X-Band Accelerating Structures for the G/NLC	dipole, emittance, simulation, impedance	99
	R.M. Jones SLAC/ARDA, Menlo Park, California
	The X-band linacs for the GLC/NLC (Global Linear Collider/Next Linear Collider) have evolved from the DDS (Damped Detuned Structure) series [1,2]. The present series of accelerating structures are each 60 cm in length and incorporate both damping and detuning of the dipole modes which comprise the wakefield. In order to adequately damp the wakefield the dipole frequencies of adjacent structures are interleaved. The properties of the first dipole band have been extensively studied. However, limited analysis has been done on the higher order dipole bands. Here, we calculate the contribution of the higher order bands of the interleaved structures to the wakefield using a mode matching computer code [3]. Beam dynamics issues are also studied by tracking the beam through the complete linac using the particle beam tracking code LIAR [4]. [1] R.M Jones et al,1996,Proc. EPAC96 (also SLAC-PUB-7187) [2] J.W. Wang et al, 2000, Proc. LINAC2000 (also SLAC-PUB-8583) [3] V.A. Dolgashev, Ph.D. thesis, Budker INP, Novosibirsk, 2002.[4] R. Assman et al, LIAR, SLAC-PUB AP-103

MOP29	RHIC Electron Cooler	electron, cathode, gun, emittance	102
	J. Kewisch, I. Ben-Zvi, R. Calaga, X.Y. Chang, A. Jain, V. Litvinenko, C. Montag, V. Yakimenko BNL, Upton, Long Island, New York
	Electron cooling has been applied in many accelerators with low energies where cooling times are short. Electron cooling is now considered for RHIC, where gold ions are stored at 100 GeV/u. For a cooling time of one hour an electron beam with 55 MeV and 10 nC/bunch is necessary. The transverse normalized emittance must be 50 mm·mrad, the energy spread 10^-4. Only a Photo-cathode Energy Recovery LINAC (PERL) promises such quality. For a minimum electron temperature inside the 1 Tesla cooling solenoid it is necessary to have a "magnetized beam", i.e. a beam from a cathode immersed in a longitudinal magnetic field. The emittance compensation scheme used in RF guns was adapted so that the magnetization does not lead to strong emittance growth. A super-conducting cavity was developed for the RHIC electron cooler, optimized for high current operation. Simulations with the TBBU computer code show a multi-bunch beam breakup threshold of 3 Amperes. After acceleration the bunches are lengthened and the energy spread is reduced by rotation in the longitudinal phase space. The original bunch length must be restored by a second rotation before deceleration and energy recovery.

MOP30	Linear Accelerator LINAC-800 of the DELSY Project	electron, acceleration, gun, radiation	105
	V.V. Kobets, N. Balalykin, I.N. Meshkov, I.A. Seleznev, G. Shirkov JINR, Dubna, Moscow Region
	In the report the modernization of electron linear accelerator MEA (Medium Energy Accelerator) is discussed. The goal of the work is to create on the base of MEA a complex of free electron lasers overlaying a range of radiation waves from infrared to ultraviolet. Status of the work is reported.

MOP31	Development of a C-band Accelerating Module for SUPERKEKB	positron, klystron, acceleration, electron	108
	S. Ohsawa, M. Ikeda, K. Kakihara, T. Kamitani, T. Oogoe, T. Sugimura, S. Yamaguchi, K. Yokoyama KEK, Ibaraki
	High power rf processing of 1 m C-band accelerating section for Super KEKB was successfully performed and power corresponding to 42 MV/m was achieved. Processing data were accumulated including acoustic sensor to find the arcing position. No structural damage was observed from the phase shift measurement performed after the processing. Processed accelerator was installed in the beam line of KEKB linac and being re-processed. The beam acceleration of 40 MV/m was successfully achieved in October 2003. Present status of C-band accelerator development is reported.

MOP34	Injector Linac Upgrade for the BEPCII Project	positron, electron, target, gun	111
	S.H. Wang IHEP Beijing, Beijing
	BEPCII- an upgrade project of Beijing Electron Positron Collider (BEPC) is a factory type of e⁺e^- collider. It requests its injector linac to have the higher beam energy (1.89 GeV) for on-energy injection and the higher beam current (40 mA e⁺ beam) for higher injection rate (≥50 mA/min). The low beam emittance (1.6 π·mm·mrad for e⁺ beam, and 0.2 π·mm·mrad for 300 mA e^- beam) and low beam energy spread (±0.5%) are also requested to meet the storage ring acceptance. Hence the original BEPC injector linac must be upgraded to have a new electron gun with its complete tuning system, a new positron source with a flux concentrator, a new RF power system with its phasing loops and a new beam tuning system with orbit correction and optics tuning devices. These new components have been designed, fabricated, tested and now being installed in their final positions, which are described in this paper. The beam commissioning is expected to start from the October of 2004.
	Transparencies

MOP40	A Study Of Coupler-Trapped Modes In X-Band Linacs for the GLC/NLC	simulation, emittance, linear-collider, collider	129
	R.M. Jones, V.A. Dolgashev SLAC/ARDA, Menlo Park, California Z. Li SLAC, Menlo Park, California J. Wang SLAC/ARDB, Menlo Park, California
	Each of the X-band accelerating structures for the GLC/NLC consist of 55 cells which accelerate a train of charged particles. The cells are carefully designed to ensure that the transverse wakefield left behind each bunch does not disrupt the trailing bunches. However, unless attention is paid to the design of the fundamental mode coupler, then a dipole mode is trapped in the region of the coupler and cells. This mode can give rise to severe emittance dilution if care is not taken to avoid a region of resonant growth in the emittance. Here, we present results on HFSS simulations, cold test experimental measurements and beam dynamics simulations arising as a consequence of the mode trapped in the coupler. The region in which the trapped mode has little influence on the beam is delineated.

MOP41	Emittance-Imposed Alignment and Frequency Tolerances for the TESLA Linear Collider	emittance, collider, dipole, luminosity	132
	N. Baboi DESY, Hamburg R.M. Jones SLAC/ARDA, Menlo Park, California
	One option in building a future 500 GeV c.m. collider is to use superconducting 1.3 GHz 9-cell cavities. Wakefields excited by the bunch train in the TESLA linac can resonantly drive the beam into unstable operation such that a BBU (Beam Break Up) mode results or at the very least significant emittance dilution occurs. The largest kick factors (proportional to the transverse fields which transversely kick the beam off axis) are found in the first three dipole bands and hence multi-bunch emittance growth is mainly determined from these bands. These higher order dipole modes are damped by carefully orientating higher order mode couplers at the downstream end of the cavities. We investigate the dilution in the emittance of a beam injected with an initial offset from the axis of the cavities. The dependence of beam emittance on systematic errors in the cell frequencies is investigated. We also vary the bunch spacing in order to simulate a systematic frequency error. While scanning the bunch spacing over a wide range, the emittance presents sharp peaks since only few modes contribute effectively to emittance growth. The locations of these peaks sets the frequency tolerances on the structures.

MOP42	Linac Alignment and Frequency Tolerances from the Perspective of Contained Emittances for the G/NLC	emittance, alignment, simulation, dipole	135
	R.M. Jones SLAC/ARDA, Menlo Park, California
	We maintain the stable progress of a beam consisting of a train of bunched charges, by a careful design of the geometry of the structures [1]. In practice, the next generation of linear colliders will consist of several tens of thousands of X-band accelerating structures and this will entail inevitable errors in the dimensions and alignments of cells -and groups thereof. These errors result in a dilution of the beam emittance and consequently a loss in overall luminosity of the collider. For this reason it is important to understand the alignment tolerances and frequency tolerances that are imposed for a specified emittance budget. Here we specify an emittance dilution of no more than 10% of the initial value and we track the progress of the beam down the linac whilst accelerating structures (and sub-groups thereof) are misaligned in a random manner and at the same time random frequency are incorporated with structures. This results in tolerances in both frequency errors and sets of alignment errors to be imposed on the structures for a specified emittance dilution. [1] R.M. Jones, 1997, SLAC NLC-Note 24.

MOP43	The Impact of Longitudinal Drive Beam Jitter on the CLIC Luminosity	luminosity, feedback, simulation, lattice	138
	D. Schulte, E. J. N. Wilson, F. Zimmermann CERN, Geneva
	In the compact linear collider (CLIC) now under study at CERN, the RF power which accelerates the main beam is provided by decelerating a high current drive beam. Errors in the timing and intensity of the drive beam can turn into RF phase and amplitude errors that are coherent along the whole main linac and the resulting error of the final beam energy, in combination with the limited bandwidth of the beam delivery system, can lead to a significant loss of luminosity. We discuss the stability tolerances that must be applied to the drive beam to avoid this loss. We also examine one of the most important sources of this jitter, which stems from the combination of RF jitter in the drive beam accelerator and subsequent bunch compression. Finally we give details of a potential feedback system that can reduce the drive beam jitter.

MOP44	Electron-Cloud Effects in the Positron Linacs of Future Linear Colliders	electron, positron, simulation, acceleration	141
	D. Schulte, A. Grudiev, F. Zimmermann CERN, Geneva K. Oide KEK, Ibaraki
	Inside the rf structures of positron linacs for future linear colliders, electron multipacting may occur under the combined influence of the beam field and the electromagnetic rf wave. The multipacting could lead to an electron-cloud build up along the bunch train. We present simulation results of this effect for various proposed designs, and discuss possible consequences and eventual countermeasures.
	Transparencies

MOP45	A Potential Signal for Luminosity Optimisation in CLIC	luminosity, photon, emittance, simulation	144
	D. Schulte CERN, Geneva
	Luminosity optimisation will be challenging in the compact linear collider (CLIC) studied at CERN. In particular, the signals which can be used for luminosity optimisation need to be identified. The strong beam-beam interaction in CLIC will give rise to the emission of a few megawatts of beamstrahlung; this is a potential candidate for such a signal. In this paper luminosity optimisation using the beamstrahlung is attempted for realistically shaped bunches.

MOP48	Gamma and X-rays Production for Experiments at ELSA Facility	electron, laser, emittance, target	153
	J. Lemaire CEA/DAM, Bruyères-le-Châtel
	The ELSA facility is a high brightness 18 MeV electron source dedicated to electron radiation, gamma-rays and picosecond hard and soft X-rays. It consists of a 144 MHz RF photoinjector producing short bunches which are further accelerated to a final energy varying from 2 to 18 MeV thanks to three 433 MHz RF cavities. Former beam compression design used a half turn magnet compressor system. It has been recently replaced by a double alpha magnet compressor. Electron beams are now delivered to a new experimental room. We present the new panel of interests offered by this facility in term of gamma-ray and X-ray production.

MOP49	Status And Operating Experience of The TTF Coupler	vacuum, klystron, superconductivity, free-electron-laser	156
	W.-D. Möller, D. Kostin DESY, Hamburg
	Five accelerating modules are installed in the VUV FEL linac so far. This includes 40 high power couplers connected to the superconducting cavities, eight in every module. All of them are processed and operated up to the cavity performance limits. The coupler processing procedure is described. The performance in relation to the test results on the coupler test stands are discussed.
	Transparencies

MOP62	Energy Spread in BTW Accelerating Structures at ELETTRA	single-bunch, simulation, electron, target	159
	P. Craievich, R.J. Bakker, G. D'Auria, S.D. Di Mitri Sincrotrone Trieste S.C.p.A., Basovizza, Trieste
	The FEL project FERMI@ELETTRA will use the existing 1.0 GeV Linac, based on Backward Travelling Wave (BTW) structures, to produce VUV radiation between 100–10 nm. The project will be articulated in two different phases (100–40 nm/40–10 nm) and will require high quality beam with short bunches (500/160 fsec). Hence, wakefield effects have to be considered with respect to the electron beam quality. The single bunch energy spread induced by the short-range longitudinal wakefield is analyzed and results of start-to-end simulations are reported.

MOP67	TESLA RF Power Coupler Thermal Calculations	background, simulation	174
	D. Kostin, M. Dohlus, W.-D. Möller DESY, Hamburg
	The main RF power coupler is one of the key elements of the accelerating module for the superconducting linac. It provides RF power to the cavity and interconnect different temperature layers in the module. Therefore statistical and dynamical thermal losses have to be optimized. Different operating modes as well as geometries were investigated. Coupler design optimization studies are carried out for TESLA and for the XFEL case. Especially long pulse operation for the X-FEL is being investigated.

MOP68	Ribbon Ion Beam Dynamics in Undulator Linear Accelerator	focusing, undulator, acceleration, ion	177
	E.S. Masunov, S.M. Polozov MEPhI, Moscow
	The possibility to use radio frequency undulator fields for ion beam focusing and acceleration in linac (UNDULAC-RF) is discussed. In periodical resonator structure the accelerating force is produced by the combination of two or more space harmonics of a longitudinal or a transverse undulator field. The particle motion equations in Hamilton form are carried out by means of smooth approximation. The analysis of 3D effective potential permits to find the conditions under which focusing and acceleration of the particles occur simultaneously. The analytical results are verified with a numerical simulation. Examples illustrating the efficiency of the proposed method of acceleration are given for longitudinal and transverse undulators. The results are compared with a conventional linac and the other possibility of ion beam acceleration in UNDULAC-E(M) where electrostatic and magnetic fields are used. E.S. Masunov, Technical Physics, Vol. 46, No.11, 2001, pp. 1433-1436.

MOP69	RF Control Modelling Issues for Future Superconducting Accelerators	resonance, feedback, diagnostics, beam-loading	180
	A. Hofler, J. R. Delayen TJNAF, Newport News, Virginia V. Ayvazyan, A. Brandt, S. Simrock DESY, Hamburg T. Czarski WUT, Warsaw T. Matsumoto KEK, Ibaraki
	The development of superconducting accelerators has reached a high level of maturity following the successes of ATLAS at Argonne, CEBAF at Jefferson Lab, the TESLA Test Facility at DESY and many other operational accelerators. As a result many new accelerators under development (e.g. SNS) or proposed (e.g. RIA) will utilize this technology. Covering all aspects from cw to pulsed rf and/or beam, non-relativistic to relativistic particles, medium and high gradients, light to heavy beam loading, linacs, rings, and ERLs, the demands on the rf control system can be quite different for the various accelerators. For the rf control designer it is therefore essential to understand these issues and be able to predict rf system performance based on realistic rf control models. This paper will describe the features that should be included in such models and present an approach which will drive the development of a generic rf system model.

MOP70	A Pass Band Performance Simulation Code of Coupled Cavities	simulation, coupling, RF-structure, beam-loading	183
	X. Tao, D. Tong TSINGHUA, Beijing
	A simulation code of accelerating cavities named PPSC is developed by the solutions of the microwave equivalent circuit equations. PPSC can give the pass band performance of periodic or non-periodic accelerating structures, such as the dispersion frequency and the reflection factor of the cavity, the field distribution of each mode and so on. The natural parameters of the structure, such as the number of the cavities, the resonant frequencies and Q-factors of each cavity, the coupling factor between two cavities, and the locations of the couplers, can be changed easily to see the different results of the simulation. The code is written based on MS Visual Basic under MS windows. With these, a user-friendly interface is made. Some simple examples was simulated and gave reliable results.

MOP71	Advanced Beam-Dynamics Simulation Tools for RIA	simulation, beam-losses, rfq, acceleration	186
	T.P. Wangler, R. Garnett LANL, Los Alamos, New Mexico N. Aseev, P.N. Ostroumov ANL/Phys, Argonne, Illinois R. Crandall TechSource, Santa Fe, NM D. Gorelov, R.C. York NSCL, East Lansing, Michigan J. Qiang, R. Ryne LBNL, Berkeley, California
	Understanding beam losses is important for the high-intensity RIA driver linac. Small fractional beam losses can produce radioactivation of the beamline components that can prevent or hinder hands-on maintenance, reducing facility availability. Operational and alignment errors in the RIA driver linac can lead to beam losses caused by irreversible beam-emittance growth and halo formation. We are developing multiparticle beam-dynamics simulation codes for RIA driver-linac simulations extending from the low-energy beam transport (LEBT) line to the end of the linac. These codes run on the NERSC parallel supercomputing platforms at LBNL, which allow us to run simulations with large numbers of macroparticles for the beam-loss calculations. The codes have the physics capabilities needed for RIA, including transport and acceleration of multiple-charge-state beams, and beam-line elements such as high-voltage platforms within the linac, interdigital accelerating structures, charge-stripper foils, and capabilities for handling the effects of machine errors and other off-normal conditions. We will present the status of the work, including examples showing some initial beam-dynamics simulations.

MOP81	Analysis of the Qualification-Tests Performance of the Superconducting Cavities for the SNS Linac	simulation, radiation, electron, ion	210
	J. R. Delayen, J. Mammosser, O. Ozelis Jefferson Lab, Newport News, Virginia
	Thomas Jefferson National Accelerating Facility (Jefferson Lab) is producing superconducting radio frequency (SRF) cryomodules for the Spallation Neutron Source (SNS) cold linac. This consists of 11 medium-beta (β=0.61) cyomodules of 3 cavities each, and 12 high-beta (β=0.81) cryomodules of 4 cavities each. Before assembly into cavity strings the cavities undergo individual qualification tests in a vertical cryostat (VTA). In this paper we analyze the performance of the cavities during these qualification tests, and attempt to correlate this performance with cleaning, assembly, and testing procedures. We also compare VTA performance with performance in completed cryomodules.

MOP86	Cold Test Results of the ISAC-II Medium Beta High Gradient Cryomodule	coupling, alignment, acceleration, lattice	222
	R.E. Laxdal, Y. Bylinskii, G.S. Clark, K. Fong, A.K. Mitra, R. L. Poirier, B. Rawnsley, T. Ries, I. Sekatchev, G. Stanford, V. Zvyagintsev TRIUMF, Vancouver
	Many proposals (RIA, Eurisol, ISAC-II) are emerging for a new generation of high gradient heavy ion accelerators. The ISAC-II medium beta cryomodule represents the first realized application that encorporates many new techniques to improve the performance over machines presently being used for beam delivery. The machine lattice, compatible with multi-charge acceleration, uses high field (9T) superconducting solenoids with bucking coils for active fringe field compensation. The bulk niobium quarter wave medium beta cavity produces 6 MV/m over an effective length of 18cm with a peak surface field of ~30 MV/m. TRIUMF has developed a mechanical tuner capable of both coarse (kHz) and fine (Hz) frequency adjustments of the cavity. The demonstrated tuner resolution is better than 0.1 μm (0.6 Hz). A new rf coupling loop has been developed that operates at 200 Watts forward power with less than 0.5 Watt of power being added to the helium load. Cold alignment in ISAC-II has been done with rf pick-ups using a stretched wire technique. Finally all cryomodule and testing has been done in a clean environment. The alignment cryogenic, solenoid and rf performance will be presented.
	Transparencies

MOP87	Conceptual Layout of the European X-FEL Linear Accelerator Cryogenic Supply	vacuum, booster, electron, superconducting-magnet	225
	B. Petersen, H. Lierl, A. Zolotov DESY, Hamburg
	As a source for the European x-ray free electron laser (European X-FEL project) at DESY a superconducting linear accelerator will deliver a pulsed electron beam of about 20 GeV. A conceptual layout for the cryogenic supply of the linac is presented. The linac will consist of about 1000 superconducting niobium 1.3 GHz 9-cell cavities, which will be cooled in a liquid helium bath at a temperature of 2 K. Eight cavities and one superconducting magnet package will be assembled to a cryomodule of 12.2 m length. The cryomodules are equipped with two thermal shields at a 5 K and 80 K temperature level respectively. The linac of about 1.6 km length will be divided in 10 cryogenic sub units. Each sub unit will consist of 12 cryomodules. In addition to the main linac, two injector sections have to be supplied separately by means of helium refrigerators and a related helium distribution system.

MOP89	A Wire Position Monitor System for the ISAC-II Cryomodule Components Alignment	alignment, vacuum, impedance, acceleration	231
	B. Rawnsley, Y. Bylinskii, G. Dutto, K. Fong, R.E. Laxdal, T. Ries TRIUMF, Vancouver D. Giove INFN/LASA, Segrate (MI)
	TRIUMF is developing ISAC-II, a superconducting (SC) linac. It will comprise 9 cryomodules with a total of 48 niobium cavities and 12 SC solenoids. They must remain aligned at liquid He temperatures: cavities to ±400 μm and solenoids to ±200 μm after a vertical contraction of ~4 mm. A wire position monitor (WPM) system based on a TESLA design has been developed, built, and tested with a prototype cryomodule. The system is based on the measurement of signals induced in pickups by a 215 MHz signal carried by a wire through the WPMs. The wire is stretched between the warm tank walls parallel to the beam axis providing a position reference. The sensors, one per cavity and two per solenoid, are attached to the cold elements to monitor their motion during pre-alignment, pumping and cool down. A WPM consists of four 50 Ω striplines spaced 90° apart. A GaAs multiplexer scans the WPMs and a Bergoz card converts the RF signals to DC X and Y voltages. National Instruments I/O cards read the DC signals. The data acquisition is based on a PC running LabVIEW. System accuracy is ~7 μm. The paper describes system design, WPM calibration and test results.

TU101	Engineering and Building RF Structures - The Works	rfq, vacuum, simulation, radio-frequency	237
	D. Schrage LANL, Los Alamos, New Mexico
	The translation of the physics designs of linear accelerators into engineering and manufacturing requirements is discussed. The stages of conceptual design, prototyping, final design, construction, and installation are described for both superconducting (LANL β = 0.175 Spoke Cavity) and normal-conducting (APT/LEDA 6.7 MeV RFQ) accelerators. An overview of codes which have linked accelerator cavity and thermal/structural analysis modules is provided.
	Transparencies

TU103	Development of the UNILAC Towards a Megawatt Beam Injector	ion, heavy-ion, rfq, proton	246
	W. Barth, L. Dahl, J. Glatz, L. Groening, S. Richter, S. Yaramishev GSI, Darmstadt
	For the future Facility for Antiproton and Ion Research (FAIR) at Darmstadt the present GSI-accelerator complex, consisting of the linear accelerator UNILAC and the heavy ion synchrotron SIS18, is foreseen to serve as an U²⁸⁺ injector for up to 10¹² particles/sec. After a new High Current Injector was installed, many different ion species were accelerated in the UNILAC for physics experiments. In 2001 a high energy physics experiment used up to 2·10⁹ uranium ions per spill (U⁷³⁺), while a MEVVA ion source was in routine operation for the first time. In the past two years different hardware measures and a careful fine tuning in all sections of the UNILAC resulted in an increase of the beam intensity to 9.5·10¹⁰ U²⁷⁺ ions per 100 μs or 1.5·10¹⁰ U⁷³⁺ ions per 100 μs. The contribution reports results of beam measurements during the high current operation with uranium beams (pulse beam power up to 0.5 MW). One of the major tasks was to optimize the beam matching to the Alvarez-DTL. In addition further upgrades, including improved beam diagnostics, are described, which allow to fill the SIS18 up to the space charge limit of 2.7·10¹¹ U²⁸⁺ ions per cycle.
	Transparencies

TU104	Developments and Future Plans at ISAC/TRIUMF	target, ion, ion-source, cyclotron	251
	P. Schmor TRIUMF, Vancouver
	The ISAC (Isotope Separator and Accelerator) at TRIUMF uses the ISOL (On Line Isotope Separator) technique with up to 100 microA of 500 MeV protons from the TRIUMF cyclotron driver to create exotic isotopes in a thick target. An ion beam formed from these exotic isotopes is transported at 2 keV/u, mass separated, injected into a room temperature RFQ Linac and then into a five-tank drift tube linac that provides variable-energy accelerated exotic-beams from 0.15 to 1.8 MeV/u for nuclear astrophysics experiments. Super conducting rf cavities are presently being added to the linac chain to permit a further increase in the maximum energy of the exotic beams to 6.5 MeV/u. An ECR-based charge state booster is also being added in front of the RFQ to increase the available mass range of the accelerated isotopes from 30 to about 150. A second proton beam line and new target station for target and ion source development have been proposed for ISAC. In the future this new target station could be used as an independent simultaneous source of exotic beams for the experimental program.
	Transparencies

TU201	The KEK C-Band RF System for a Linear Collider	klystron, collider, linear-collider, RF-structure	256
	H. Matsumoto, S. Takeda, S.S. Win, M. Yoshida KEK, Ibaraki H. Baba, T. Shintake RIKEN Spring-8 Harima, Hyogo J-O. Oh PAL, Pohang
	The C-band (5712 MHz) main linac has been developed just motivated by the urgent and essential physics program at the e⁺e^- linear collider. In total ~8000 accelerating structures and ~4000 klystrons with modulators are needed for 500 GeV C.M. energy. Therefore these units have to meet strict requirements for: high reliability, simplicity, easy operation, reasonable power efficiency and low cost. This list provides a guiding principle and the boundary conditions for our design work. We have already developed the conventional and PPM type 50 MW class C-band klystrons, modulators, and HOM-free accelerator structures. The first high power an rf compressor cavity made of a low thermal expansion material was designed to provide stable operation even with a very high Q of 200 k, it was successfully operated an output rf power of 135 MW at KEK. The C-band linac rf-system will be used for the SASE-FEL project at SPring-8, but it will also serve to verify the design and components, which can eventually be deployed for the main linac rf system in a future linear collider.
	Transparencies

TU204	Effect of High Solenoidal Magnetic Fields on Breakdown Voltages of High Vacuum 805 MHz Cavities	vacuum, collider, factory, background	271
	A. Moretti, A.D. Bross, S. Geer, Z. Qian Fermilab, Batavia, Illinois D.M. Errede University of Illinois at Urbana-Champaign, Urbana, Illinois D. Li LBNL/AFR, Berkeley, California J. Norem ANL, Argonne, Illinois R.A. Rimmer Jefferson Lab, Newport News, Virginia Y. Torun IIT, Chicago, Illinois M.S. Zisman LBNL, Berkeley, California
	The demonstration of muon ionization cooling by a large factor is necessary to demonstrate the feasilibility of a collider or neutrino factory. An important cooling experiment, MICE [1], has been proposed to demonstrate 10 % cooling which will validate the technology. Ionization cooling is accomplished by passing a high-emittance beam in a multi-Tesla solenoidal channel alternately through regions of low Z material and very high accelerating RF Cavities. To determine the effect of very large solenoidal magnetic fields on the generations of Dark current, X-Rays and breakdown Voltage gradients of vacuum RF cavities, a test facility has been established at Fermilab in Lab G. This facility consists of a 12 MW 805 MHz RF station, and a large bore 5 T solenoidal superconducting magnet containing a pill box type Cavity with thin removable window apertures allowing dark current studies and breakdown studies of different materials. The results of this study will be presented. The study has shown that the peak achievable accelerating gradient is reduced by almost a factor two in a 4 T field. [1] http://mice.iit.edu/.
	Transparencies

TU301	High Power CW Superconducting Linacs for EURISOL and XADS	proton, cyclotron, target, ion	275
	J.-L. Biarrotte IPN, Orsay
	A multi-MW superconducting proton linac is proposed as the baseline solution for the EURISOL and the XADS driver accelerators. In the EURISOL project, which studies the design of the next-generation European ISOL facility, it is used to produce both neutron-deficient and neutron-rich exotic nuclei far from the valley of stability. In the PDS-XADS project, which aims to the demonstration of the feasibility of an ADS system for nuclear waste transmutation, it is used to produce the neutron flux required by the associated sub-critical reactor. In this paper, we report the main results and conclusions reached within these preliminary design studies. A special emphasis is given on the on-going and future R&D to be done to accomplish the demonstration of the full technology.
	Transparencies

TU302	Future Developments in Electron Linac Diagnostics	emittance, instrumentation, laser, electron	280
	M.C. Ross SLAC/NLC, Menlo Park, California
	The next generation of electron linacs will fill two different roles: ultra-low emittance, very high power accelerators for linear colliders and ultra-short bunch, high stability accelerators for SASE X-ray production. In either case, precision control based on non-invasive, reliable, beam instrumentation will be required. For the linear collider, low emittance transport is an important concern for both warm and superconducting linacs. Instrumentation will be used to control and diagnostics will be used to validate emittance preserving strategies, such as beam based alignment and dispersion - free steering. Tests at the KEK ATF and the SLAC FFTB have demonstrated the required performance for beam position and beam size monitors. Linacs intended for FEL's will require precision bunch length diagnostics because of expected non-linear micro-bunching processes. A wide variety of devices are now in development at FEL prototypes, including TTF2 at DESY and SPPS at SLAC. We present a review of the new diagnostic systems.
	Transparencies

TUP01	RFQ Drift-Tube Proton Linacs in IHEP	focusing, rfq, quadrupole, emittance	285
	Yu. Budanov, O.K. Belyaev, S.V. Ivanov, A.P. Maltsev, I.G. Maltsev, V.B. Stepanov, S.A. Strekalovskyh, V.A. Teplyakov, V. Zenin IHEP Protvino, Protvino, Moscow Region
	A linac with drift tubes and RF quadrupoles (alias, an RFQ DTL) constitutes a natural extension of the RFQ concept towards higher beam energies. Complementing an RFQ with drift tubes intermitted by spacer electrodes separates functions of focusing and acceleration. Such a structure allows for an increased accelerating rate and upgrades shunt impedance to values competitive against those inherent in the other common accelerator types. Various accelerating/focusing structures for the RFQ DTLs were implemented in IHEP. Their succession is marked by a progress in performance, which is due to efforts in design, manufacturing technology and calculation technique advances that facilitated R&D of such the structures. A sound practical expertise in the field is accumulated. The 30 MeV RFQ DTL is in service as an injector for a 1.5 GeV PS of IHEP since 1985. An upgraded successor – the RFQ DTL, employing a cavity loaded by a novel accelerating/focusing structure with an increased accelerating rate, is now being assembled and tested. Its pre-commissioning results will be outlined. Prospects in R&D of a structure suitable for a front-end part of the CERN SPL will be evaluated.
	Transparencies

TUP02	Development of a 352 MHz Cell-Coupled Drift Tube Linac Prototype	coupling, quadrupole, focusing, alignment	288
	M. Vretenar, Y. Cuvet, J. Genest, C. Völlinger CERN, Geneva F. Gerigk CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
	At linac energies above 40 MeV, alternative structures to the conventional Drift Tube Linac can be used to increase efficiency and to simplify construction and alignment. In the frame of the R&D activities for the CERN SPL and Linac4, a prototype of Cell-Coupled Drift Tube Linac (CCDTL) at 352 MHz has been designed and built. This particular CCDTL concept is intended to cover the energy range from 40 to 90 MeV and consists of modules of ~5 m length made of 3 or 4-gap DTL tanks linked by coupling cells. The focusing quadrupoles are placed between tanks, and are aligned independently from the RF structure. The CCDTL prototype consists of two half tanks connected by a coupling cell and requires an RF power of 120 kW to achieve the design gradient. RF tests will be made at low and high power, the latter up to a 20% duty cycle. This paper introduces the main features of this CCDTL design, describes the RF and mechanical design of the prototype and presents the first measurement results.

TUP03	Design of the LINAC4, A New Injector for the CERN Booster	rfq, proton, injection, quadrupole	291
	M. Vretenar, R. Garoby, K. Hanke, A.M. Lombardi, C. Rossi CERN, Geneva F. Gerigk CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon
	A new H^- linac (LINAC4) is presently under study at CERN. This accelerator, based on normal conducting structures at 352 and 704 MHz, will provide a 40 mA 160MeV H^- beam to the CERN booster, thus overcoming the present space-charge bottleneck at injection with a 50 MeV proton beam. LINAC4 is conceived as the first stage of a future 2.2 GeV superconducting linac (SPL) and it is therefore designed for a higher duty cycle than required for injection in the booster. This paper discusses the design choices, presents the layout of the facility and illustrates the advantages for the LHC and other CERN users. An R&D and construction strategy mainly relying upon international collaborations is also presented.

TUP04	The SPL Front End: A 3 MeV H^- Test Stand at CERN	rfq, proton, quadrupole, simulation	294
	R. Garoby, L. Bruno, F. Caspers, J. Genest, K. Hanke, M. Hori, D. Kuchler, A.M. Lombardi, M. Magistris, A. Millich, M. Paoluzzi, C. Rossi, E.Zh. Sargsyan, M. Silari, T. Steiner, M. Vretenar CERN, Geneva P.-Y. Beauvais CEA/DSM/DAPNIA, Gif-sur-Yvette
	In the frame of the SPL (Superconducting Proton Linac) study at CERN, a new 160 MeV proton injector for the CERN PS Booster is presently under development. This linear accelerator (Linac4) would not only be a first step towards a future, multi-MW superconducting linac, but would also improve in the medium term both the beam availability and beam quality for CERN’s proton users. Within the framework of the Linac 4 study and with the support of the EU funded Joint Research Activity HIPPI, a 3 MeV test stand is under construction at CERN. This test stand will explore some of the most critical issues of the linac, such as the beam dynamics at low energy, with special emphasis on the Chopper line that has been designed to generate the required time structure of the beam, to clean the beam halo, and to match it to the subsequent RF structures. In this context, a new Beam Shape and Halo Monitor is under construction. The beam acceleration will be performed by an RFQ that is being developed in France within the IPHI collaboration between CEA and CNRS. Moreover, the test stand will be equipped with an additional 1 MW RF klystron to test different RF structures that are being designed at 352 MHz as preliminary studies for the Linac4. High Intensity Pulsed Proton Injectors
	Transparencies

TUP05	Beam Dynamics for a new 160 MeV H^- Linac at CERN (LINAC4)	emittance, rfq, quadrupole, simulation	297
	F. Gerigk CCLRC/RAL/ASTeC, Chilton, Didcot, Oxon E. Benedico Mora, A.M. Lombardi, E.Zh. Sargsyan, M. Vretenar CERN, Geneva
	LINAC4 is a normal conducting H^- linac proposed at CERN to provide a higher proton flux to the CERN accelerator chain. It should replace the existing LINAC2 as injector for the PS booster. The same machine can also operate in the future as the front end of the SPL, a 2.2 GeV superconducting linac with 1.8 mA average current. At present the test set-up for LINAC4 consists of a Radio Frequency Quadrupole (RFQ), a chopper line, a Drift Tube Linac (DTL), and Cell Coupled DTL (CCDTL) operating at 352.2 MHz and finally a Side Coupled Linac (SCL) at 702.2 MHz. This paper discusses the overall beam dynamics concept, presents the optics for the different sections of the machine and compares end-to-end simulations realised with two tracking codes (PATH and IMPACT). Estimates of beam loss due to various error sources are presented and the challenging features in the current design are highlighted.
	Transparencies

TUP06	Results of the High-Power Conditioning and the First Beam Acceleration of the DTL-1 for J-PARC	coupling, rfq, acceleration, quadrupole	300
	F. Naito, S. Anami, J. Chiba, Y. Fukui, K. Furukawa, Z. Igarashi, K. Ikegami, M. Ikegami, E. Kadokura, N. Kamikubota, T. Kato, M. Kawamura, H. Kobayashi, C. Kubota, E. Takasaki, H. Tanaka, S. Yamaguchi, K. Yoshino KEK, Ibaraki K. Hasegawa, Y. Kondo, A. Ueno JAERI, Ibaraki-ken T. Itou, Y. Yamazaki JAERI/LINAC, Ibaraki-ken T. Kobayashi J-PARC, Ibaraki-ken
	The first tank of the DTL for Japan Proton Accelerator Research Complex (J-PARC) was installed in the test facility at KEK. The DTL tank is 9.9 m in length and consists of the 76 cells. The resonant frequency of the tank is 324 MHz. After the installation of the tank, the high-power conditioning was carried out deliberately. Consequently the peak rf power of 1.3 MW (pulse repetition 50 Hz, pulse length 600 μs) was put into the tank stably. (The required power is about 1.1 MW for the designed accelerating field of 2.5 MV/m on the axis.) Following the conditioning, negative hydrogen beam, accelerated by the RFQ linac up to 3 MeV, was injected to the DTL and accelerated up to its design value of 19.7 MeV. The peak current of 30 mA was achieved with almost 100% transmission. In this paper, the conditioning history of the DTL and the result of the first beam test will be described.

TUP07	A Linac-to-Booster Injection Line for Transverse Matching and Correlated Injection Painting	booster, injection, simulation, focusing	303
	R. Garnett, L. Rybarcyk LANL, Los Alamos, New Mexico
	In this paper we discuss a compact linac-to-booster ring transfer line originally proposed for the Los Alamos Advanced Hydrotest Facility design to vertically inject a 157 MeV H^- beam from the linac into a 10 GeV booster. TRACE 3-D and PARMILA simulations were used to demonstrate the performance of the transfer line to deliver the required transverse beam to the foil while also allowing correlated longitudinal injection painting. Schemes for both transverse and longitudinal matching are important for high-intensity ring applications where low beam loss operation is desirable. The main features of the beam line layout, a proposed longitudinal painting scheme, and the simulation results will be discussed.

TUP08	Carbon Ion Injector Linac for a Heavy Ion Medical Synchrotron	rfq, ion, focusing, vacuum	306
	D.A. Swenson LLC, Albuquerque, New Mexico
	The design of a Carbon Ion Injector Linac for a heavy ion medical synchrotron will be presented. The linac is designed to accelerate quadruply-ionized carbon ions (¹²C⁴⁺) with a charge/mass ratio (q/A) of 0.333, and all other ions with the same or higher charge/mass ratios, such as H¹⁺, H₂¹⁺, D¹⁺, T¹⁺, ³He¹⁺, ⁴He²⁺, ⁶Li²⁺, ¹⁰B⁴⁺, and ¹⁶O⁶⁺ to an output energy of 7 MeV/u. The 200 MHz linac consists of an Radio Frequency Quadrupole (RFQ) linac to accelerate the ions from an input energy of 0.008 MeV/u to an intermediate energy of 0.800 MeV/u, and an Rf-Focused Interdigital (RFI) linac to accelerate these ions to the output energy. The combined linac structures have a total length of 7.8 meters and a total peak rf power requirement of about 600 kW. The RFQ linac employs a radial-strut, four-bar design that is about twice as efficient as the conventional four-bar RFQ design. The RFI linac, which is basically an interdigital drift tube structure with rf quadrupole focusing incorporated into each drift tube, is about 5 times more efficient than the conventional Drift Tube Linac (DTL) structure. Details of the linac structures and their calculated performance will be presented.

TUP13	Test and First Experiments with the new REX-ISOLDE 200 MHz IH-Structure	injection, impedance, acceleration, ion	318
	T. Sieber CERN, Geneva D. Habs, O.K. Kester LMU, Garching
	For the REX-ISOLDE accelerator, a new accelerating structure is at the moment installed and tested. It willl raise the final energy from the present 2.3 MeV/u to 3 MeV/u. The aim is to increase the mass range of the nuclei available for nuclear spectroscopy from mass 40 to mass 80. The new accelerator component is a 0.5 m IH-structure, working at the double REX frequency of 202.56 MHz. It was originally developed as a 7-Gap resonator for the MAFF* project and later adapted to the requirements at REX by changing from a 7-Gap to a 9-Gap resonator to match the lower injection energy. The poster presents the design of the resonator and the results of the rf-tests, commissioning and first operation during the 2004 running period. *H. Bongers et al., The IH-7-Gap Resonators of the Munich Accelerator for Fission Fragments (MAFF) Linac, proceedings of the PAC2001, Chicago, June 2001, p.3945

TUP14	Status of the RFI Linac Prototype	rfq, ion, ion-source, quadrupole	321
	D.A. Swenson, W.J. Starling LLC, Albuquerque, New Mexico
	A prototype of the Rf Focused Interdigital (RFI) linac structure is currently under construction at Linac Systems. The RFI linac structure is basically an interdigital (or Wideröe) linac structure with rf quadrupole focusing incorporated into each drift tube. The 200 MHz RFI prototype, consisting of a short RFQ linac followed by a short RFI linac, will accelerate a 20 mA beam of protons from an injection energy of 25 keV to an output energy of 2.50 MeV in a total linac structure length of 1.44 meters. The linac structures are designed for continuous (cw) operation, and will be tested initially at a 33% duty factor. The peak structure power of 66 kW and peak beam power of 50 kW will be supplied by a 144 kW, 33% duty rf power system. A microwave ion source will supply the proton beam and an articulated Einzel lens will steer and focus the beam into the RFQ aperture. The mechanical design of the linac structures will be presented, the calculated performance will be described, the status of the components will be reported. The prototype is scheduled to come into operation in the fall of this year.

TUP18	Beam Dynamics Issues of SPES-1 Linac	quadrupole, simulation, rfq, emittance	330
	E. Fagotti INFN Milano, Milano M. Comunian, A. Palmieri, A. Pisent INFN/LNL, Legnaro, Padova
	An Independent Superconducting Cavity Linac able to accelerate 10 mA CW proton beam up to 20 MeV has been studied for the SPES-1 project. This paper presents the results of beam dynamics studies through SPES linac including mapped fields effects on cavities and magnets.

TUP20	Some Relevant Aspects in the Design and Construction of a 30-62 MeV Linac Booster for Proton Therapy	proton, coupling, cyclotron, booster	336
	V.G. Vaccaro, S. Falco Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli A. D'Elia Naples University Federico II, Napoli D. Davino Universita' degli Studi del Sannio, Benevento M.R. Masullo INFN-Napoli, Napoli
	Recent results in accelerator physics showed the feasibility of a coupling scheme between a cyclotron and a linac for proton acceleration. Cyclotrons with energies up to 30 MeV, mainly devoted to radioisotopes production, are available in a large number of medical centres. This suggested to design a linac booster able to increase the proton energy up to 62 MeV as required for treating tumours like the ocular ones. In this paper we will review the rationale of the project; we will discuss the basic design of a compact 3 GHz SCL (Side Coupled Linac) with a new approach to the linac cavities. Among the many challenges of such a project one of the most interesting is the tuning of the cavities. Because the tuning can be done only after assembling the system, it is difficult to detect which cavities are responsible for the detuning: indeed the resonant behavior of single cavity is lost since the resonances merge into the resonant modes of the whole system. It is shown how, from the measured mode frequencies of the system, it is possible to derive the unknown resonances of each cavity and then refine the tuning. The proposed procedure is quite general and is not restricted to the SCL.

TUP21	Beam Dynamics Design of J-PARC Linac High Energy Section	injection, simulation, beam-transport, rfq	339
	M. Ikegami, T. Kato, S. Noguchi KEK, Ibaraki H. Ao, Y. Yamazaki JAERI/LINAC, Ibaraki-ken K. Hasegawa, T. Ohkawa, A. Ueno JAERI, Ibaraki-ken N. Hayashizaki TIT, Tokyo V.V. Paramonov RAS/INR, Moscow
	J-PARC linac consists of a 3 MeV RFQ linac, a 50 MeV DTL (Drift Tube Linac), a 190 MeV SDTL (Separate-type DTL), and a 400 MeV ACS (Annular-Coupled Structure) linac. Recently, the beam dynamics design of the ACS part has been slightly modified to reduce construction cost. Namely, the number of klystron modules are reduced from 23 to 21, and the number of accelerating cells in one klystron module is increased from 30 to 34 to maintain the total energy gain. This design change curtails the margin for RF power by around 5 %, and the total length of the ACS section is nearly unchanged. The beam matching section between SDTL and ACS is also revised correspondingly. These modifications of the design are described in this paper together with 3D particle simulation results for the new design.

TUP22	A Simulation Study on Chopper Transient Effects in J-PARC Linac	beam-losses, simulation, emittance, injection	342
	M. Ikegami KEK, Ibaraki Y. Kondo, T. Ohkawa, A. Ueno JAERI, Ibaraki-ken
	J-PARC linac has an RF chopper system to reduce uncontrolled beam loss in the succeeding ring injection. The chopper system is located in MEBT (Medium Energy Beam Transport line) between a 3 MeV RFQ and a 50 MeV DTL, and consists of two RFD (Radio-Frequency Deflection) cavities and a beam collector. During the rising- and falling-times of the RFD cavities, the beams are half-kicked and cause excess beam loss downstream. In this paper, the behavior of these half-kicked beams is examined with 3D PARMILA simulations, and resulting beam loss is estimated.
	Transparencies

TUP23	A Simulation Study on Error Effects in J-PARC Linac	emittance, injection, simulation, beam-losses	345
	M. Ikegami KEK, Ibaraki Y. Kondo, T. Ohkawa, A. Ueno JAERI, Ibaraki-ken
	In high-current proton linacs, prevention of excess beam loss is essentially important to enable hands-on maintenance. In addition, requirements on the momentum spread and transverse emittance are quite severe for J-PARC linac to realize effective injection to the succeeding RCS (Rapid Cycling Synchrotron). As losses and beam-quality deterioration are believed to be mainly caused by various errors, such as misalignment, RF mistuning, etc, it is essentially important to perform particle simulations for J-PARC linac with as realistic errors as possible to estimate their effects. In this paper, effects of realistic errors on beam loss and beam-quality deterioration in J-PARC linac are examined with a systematic 3D simulations with PARMILA. Necessity of transverse collimation is also discussed.

TUP26	Alternating Phase Focusing in Low-Velocity Heavy-Ion Superconducting Linac	focusing, emittance, ion, heavy-ion	348
	P.N. Ostroumov, K.W. Shepard ANL/Phys, Argonne, Illinois A. Kolomiets ITEP, Moscow E.S. Masunov MEPhI, Moscow
	The low-charge-state injector linac of the RIA post-accelerator is based on ~60 independently phased SC resonators providing total ~70 MV accelerating potential. The low charge-state beams, however, require stronger transverse focusing, particularly at low velocities, than is used in existing SC ion linacs. For the charge-to-mass ratios considered here (q/A = 1/66) the proper focusing can be reached by the help of strong SC solenoid lenses with the field up to 15 T. Magnetic field of the solenoids can be reduced to 9 T applying an Alternating Phase Focusing (APF). A method to set the rf field phases has been developed and studied both analytically and by the help of the three-dimensional ray tracing code. The paper discusses the results of these studies.

TUP27	Acceleration of Several Charge States of Lead Ion in CERN LINAC3	rfq, ion, acceleration, injection	351
	V. Coco, J.A. Chamings, A.M. Lombardi, E.Zh. Sargsyan, R. Scrivens CERN, Geneva
	CERN’s LINAC3 is designed to accelerate a 100 μAe Pb²⁵⁺ ion beam from 2.5 keV/u to 4.2 MeV/u. The beam is then stripped using a carbon foil and the resulting 25 μAe 54⁺ beam is accumulated and cooled in the Low Energy Ion Ring (LEIR) before transfer to the Proton Synchrotron (PS) and ultimately to the Large Hadron Collider (LHC). The Pb²⁵⁺ ions are selected with a spectrometer from a mixture of ten charge states produced by an Electron Cyclotron Resonance (ECR) source. In view of the fact that the stripping efficiency to Pb⁵⁴⁺ is mostly dependent on energy and not on initial charge state, the feasibility of simultaneously accelerating to 4.2 MeV/u several charge states has been investigated. In this paper we report two possible technical solutions, their advantage in terms of intensity for the downstream machines and the experimental results supporting these conclusions.

TUP29	Proton Beam Dynamics of the SARAF Linac	simulation, emittance, proton, beam-losses	354
	A. Shor, D. Berkovits, G. Feinberg, S. Halfon SOREQ, Yavne K. Dunkel ACCEL, Bergisch Gladbach
	We have performed proton beam dynamics simulation for the SARAF, 40 MeV and 4 mA, linac. The calculation is using the GPT code and includes effects of space charge. It demonstrates that for an initial 6D Waterbag distribution beam, a tune can be obtained with longitudinal rms emittance growth of about 10 % and transverse normalized rms emittance growth of 20%, and a transverse beam envelope of 5000 macro-particle well within the linac beam pipe. Beam loss is estimated by fitting a radial Gaussian to the particle distribution along the linac. A 1 nA beam envelope is obtained by extrapolating the tail of the radial-Gaussian function. The 1nA beam envelope is still well within the beam bore radius. Benchmark simulation with a 6D Gaussian initial distribution, with the same rms quantities, exhibits a more extended tail that may result in a higher beam loss. This point will receive a further study.
	Transparencies

TUP41	Multi-Bunch Beam Dynamics Studies for the European XFEL	emittance, simulation, electron, collider	357
	N. Baboi DESY, Hamburg
	In the X-ray free electron laser planned to be built at DESY (TESLA XFEL) the acceleration of the electron bunches will be made with 9-cell superconducting cavities. These cavities have been initially developed within the TESLA linear collider study. The impact of the higher order modes (HOM) has been shown to be within the acceptable beam dynamics limits for the collider. For the XFEL the dynamics is relaxed from point of view of multi-bunch effects (e.g. shorter length, higher emittance). However the lower energy and different time structure of the beam make the study of the HOM effects in the XFEL linac necessary. Multi-bunch beam dynamics studies are ongoing. The results of the HOM measurements at the TESLA Test Facility are used. Several options for the beam structure, as necessary for various applications, are studied. The results will be discussed.
	Transparencies

TUP42	Beam Optics Studies for the TESLA Test Facility Linac	undulator, optics, focusing, quadrupole	360
	P. Castro, V. Balandin, N. Golubeva DESY, Hamburg
	The aim of the TESLA Test Facility Linac is to create electron bunches of small transverse emittance and high peak current with energies up to 1 GeV for the VUV-FEL at DESY. The linac consists of a RF photo-cathode gun, a superconducting linac, two magnetic chicanes (for bunch compression), a long undulator magnet section and a beam line bypassing the undulator (for commissioning purposes). A study of (linear) beam optics of the linac is presented for the case of beam commissioning (and beam measurements), FEL operation and long bunch train operation. The requirements of each part of the linac upon the optics are discussed in detail and an appropriate solution for each case is shown, as well as the matching solution to the rest of the accelerator. The chromatic properties of the linac have been studied also.

TUP43	The Superconducting CW Driver Linac for the BESSY-FEL User Facility	emittance, simulation, gun, beam-loading	363
	J. Knobloch BESSY GmbH, Berlin
	A CW FEL User Facility for the VUV to soft X-ray spectral range based on a cascaded HGHG-FEL scheme is planned at the BESSY site. The Technical Design Report has recently been submitted to the German Wissenschaftsrat. Beam acceleration to 2.3 GeV is provided by a 144-cavity superconducting driver linac based on TESLA technology modified for CW operation. Initially, a high-rep-rate normal-conducting photoinjector will be used but a fully CW superconducting version is being investigated for a future upgrade. Bunch compression to 2 kA peak current is achieved in a three-stage scheme involving two bunch compressors and an arc. An overview of the linac layout, including the rf and cryogenic distribution, is provided here. We also discuss the impact of CW operation and the modifications to the TESLA technology that are necessary. Predictions of the linac performance are also given.
	Transparencies

TUP44	Linac Upgrades for FERMI@ELETTRA	gun, klystron, injection, laser	366
	G. D'Auria, R.J. Bakker, P. Craievich, G. De Ninno, S.D. Di Mitri, M. Ferianis, P.G. Pangon, R.L. Rumiz, T.L. Tosi, D. Zangrando Sincrotrone Trieste S.C.p.A., Basovizza, Trieste C. Bocchetta, M. Danailov, B. Diviacco, V. Verzilov ELETTRA, Basovizza, Trieste
	To fulfill the stringent requirements expected from the FERMI project, the existing Linac needs some modifications in the layout and an upgrading of the present plants. Moreover, for the next two years, until the new injection system (now under construction) is fully commissioned, the Linac has to be kept in operation as injector for the ELETTRA Storage Ring. Therefore most of the planned activities have to be carried out without interfering with the normal operation of the machine. Details on the new Linac layout and related activities are discussed.

TUP49	Simulations of the Ion-Hose Instability for DARHT-II Long-Pulse Experiments	simulation, induction, electron, resonance	381
	K. C. D. Chan, C. Ekdahl LANL, Los Alamos, New Mexico C. Genoni, P. Hughes MRC, Albuquerque, NM
	Ion-hose effect has been described extensively in literatures. Computer simulations of the effect typically use particle-in-cell (PIC) computer codes or codes using the spread-mass formulation [1]. PIC simulations, though offering more reliable results, will require extended running time in large computers To support commissioning experiments in the DARHT-II induction linac in Los Alamos National Laboratory, we have modified a spread-mass code so that we can survey quickly the parameter space for the experiment. It can also be used to provide quick answers during experiment. The code was originally written by Genoni from Mission Research Corporation (MRC) for constant linac parameters. We have modified it so that parameters can have dependence along the length of the linac. In this paper, we will describe simulation results using this code for the DARHT-II commissioning experiment and also our benchmarking results comparing to LSP, a PIC code from MRC. [1] T. C. Genoni and T. P. Hughes, "Ion-hose instability in a long-pulselinear induction accelerator", PRST-AB, 6, 030401 (2003)

TUP52	Methods for Measuring and Controlling Beam Breakup in High Current ERLs	feedback, damping, electron, pick-up	387
	C. Tennant, K. Jordan, E. Pozdeyev, R.A. Rimmer, H. Wang Jefferson Lab, Newport News, Virginia S. Simrock DESY, Hamburg
	It is well known that high current Energy Recovery Linacs (ERL) utilizing superconducting cavities are susceptible to a regenerative type of beam breakup (BBU). The BBU instability is caused by the transverse deflecting higher-order modes (HOMs) of the cavities which can have high impedance. We present MATLab simulation results for the BBU stability using the analysis tools of control theory. In this framework, methods of experimentally determining the threshold current and the means of suppressing the onset of the instability become more transparent. A scheme was developed to determine the threshold current due to a particular HOM by measuring the decay and rise times of the mode's field in response to an amplitude modulated beam as a function of the average electron beam current. To combat the harmful effects of a particularly dangerous mode, two methods of directly damping HOMs through the cavity HOM couplers were demonstrated. In an effort to suppress the BBU in the presence of multiple, dangerous HOMs, a conceptual design for a bunch-by-bunch transverse feedback system has been developed. By implementing beam feedback, the threshold for instability can be increased substantially.

TUP56	Simulation of RF Breakdown Effects on NLC Beam	electron, simulation, acceleration, ion	396
	V.A. Dolgashev SLAC/ARDB, Menlo Park, California T.O. Raubenheimer SLAC/NLC, Menlo Park, California
	The linacs of the Next Linear Collider (NLC) will contain several thousand traveling wave X-Band accelerator structures operating at input power of about 60 MW. At this input power prototypes of NLC structures have breakdown rates lower than one breakdown in ten hours. RF breakdowns disrupt flow of energy inside the structure and create arcs with electron and ion currents. Electromagnetic fields of these currents interact with the NLC beam. We simulated deflection of the NLC beam caused by breakdown currents using the particle-in-cell code MAGIC. In this paper we present modeling considerations and simulation results.

TUP58	Alternative Linac Layout for European XFEL Project	emittance, space-charge, gun, simulation	399
	Y. Kim, K. Flöttmann, T. Limberg DESY, Hamburg Y. Kim, D. Son CHEP Korea, Daegu
	To satisfy required beam parameters and to increase the jitter tolerance, we have designed an alternative linac layout with two bunch compressor stages for the European XFEL project. In this paper, we describe start-to-end (S2E) simulation of the alternative linac layout for the European XFEL project, and compare its results with our current linac layout with one bunch compressor stage.

TUP61	Beam Analysis Using the IPNS Linac ESEM	diagnostics, synchrotron, quadrupole, target	405
	J.C. Dooling, F. R. Brumwell, L. Donley, G.E. McMichael, V. F. Stipp ANL, Argonne, Illinois
	The Energy Spread and Energy Monitor (ESEM) is an on-line, non-intrusive diagnostic used to characterize the output beam from the 200 MHz, 50 MeV linac. The energy spread is determined from a 3-size, longitudinal emittance measurement and energy is derived from TOF analysis. Presently, a single particle distribution is used to yield energy and energy-spread results. Effort is on-going to allow for more realistic distributions to be included. Signals are detected on terminated 50 Ω, stripline BPMs. Each BPM is constructed with four striplines: top, bottom, left and right. Until recently, the ESEM signals were taken solely from bottom striplines in four separate BPM locations in the transport line between the linac and synchrotron. We have begun to use the top stripline data to examine, in more detail, beam position and attempt to measure beam size. The electrostatic coupling between the stripline and the beam depends on the capacitance, which in turn is inversely related to the beam-stripline separation. The electrostatic portion of fluctuations in beam motion will be nonlinear, possibly allowing one to infer beam size.

TUP63	The First Results of Bunch Shape Measurements in SNS Linac	electron, emittance, target, background	408
	A. Feschenko, A. Gaidash, Yu. Kisselev, L.V. Kravchuk, A. Liyu, A. Menshov, A.N. Mirzojan RAS/INR, Moscow S. Assadi, W. Blokland, S. Henderson, E.P. Tanke ORNL/SNS, Oak Ridge, Tennessee D.-O. Jeon ORNL, Oak Ridge
	Three Bunch Shape Monitors with transverse scanning of low energy secondary electrons for the SNS Linac have been developed and fabricated. The peculiarity of the detectors is using of energy separation of the electrons. The separation enables to minimize influence of detached electrons originated from dissociation of H-minus ions in the detector wire target. The first detector was used at the exit of the first DTL tank during its commissioning. The results of Bunch Shape measurements are presented and discussed. These results were used to verify beam quality, to set parameters of the accelerating field, to estimate a longitudinal beam halo and to restore a longitudinal beam emittance.
	Transparencies

TUP64	Bunch Length Measurements at LEBRA	electron, klystron, simulation, undulator	411
	K. Yokoyama KEK, Ibaraki K. Hayakawa, Y. Hayakawa, K. Nakao, I. Sato, T. Tanaka LEBRA, Funabashi
	The bunch length of the electron beam from the FEL linac at LEBRA (Laboratory for Electron Beam Research and Application) was estimated from the phase ellipse coefficient which is deduced from the dependence of the beam spread on the accelerating phase. The bunch length of FWHM was estimated approximately 0.33 mm from the results of the experiments. Besides, the pulse length of the FEL lights around the wavelength of 1.5 μm was measured by means of the autocorrelation. The pulse length was less than 0.06 mm according to the number of interfacial waves. These results indicate that the pulse length of the FEL lights isn’t equivalent to the electron bunch length.

TUP65	RF Tuning Schemes for J-PARC DTL and SDTL	simulation, klystron, injection, diagnostics	414
	M. Ikegami KEK, Ibaraki Y. Kondo, A. Ueno JAERI, Ibaraki-ken
	J-PARC linac consists of a 3 MeV RFQ linac, a 50 MeV DTL (Drift Tube Linac), a 190 MeV SDTL (Separate-type DTL), and a 400 MeV ACS (Annular-Coupled Structure) linac. In high-current proton linacs, precise tuning of RF amplitude and phase is indispensable to reduce uncontrolled beam loss and beam-quality deterioration. Especially, accurate RF tuning is essential for J-PARC linac, because requirement for the momentum spread is extremely severe to enable effective injection to the succeeding RCS (Rapid Cycling Synchrotron). In this paper, planned tuning schemes for the DTL and SDTL are presented together with the beam diagnostic layout for the tuning.

TUP66	An Alternate Scheme for J-PARC SDTL Tuning	emittance, simulation, injection, rfq	417
	M. Ikegami KEK, Ibaraki Y. Kondo, A. Ueno JAERI, Ibaraki-ken
	J-PARC linac consists of a 3 MeV RFQ linac, a 50 MeV DTL (Drift Tube Linac), a 190 MeV SDTL (Separate-type DTL), and a 400 MeV ACS (Annular-Coupled Structure) linac. As presented in a separate paper, we plan to perform phase-scan with precise TOF (Time Of Flight) beam-energy measurement in RF tuning of SDTL tanks. As a back-up method, we are considering to prepare an RF tuning scheme with rough TOF measurement for SDTL. In this paper, the principle of this scheme is presented, and its advantages and disadvantages are discussed based on a systematic particle simulation.

TUP67	Beam-Based Alignment Measurements of the LANSCE Linac	injection, focusing, quadrupole, lattice	420
	R.C. McCrady, L. Rybarcyk LANL, Los Alamos, New Mexico
	We have made measurements of the alignment of the LANSCE Drift Tube linac (DTL) and Side Coupled linac (SCL) using beam position measurements and analyzing them with linear models. In the DTL, we varied the injection steering, measured the beam position after each DTL tank, and analyzed the data with a linear model using R-matrices that were computed by the Trace-3D computer program. The analysis model allowed for tank-to-tank misalignments. The measurements were made similarly in the SCL, where the analysis model allowed for misalignments of each quadrupole doublet lens. We present here the analysis techniques, the resulting alignment measurements and comparisons to measurements made with optical instruments.

TUP69	Precision Alignments of Stripline BPMs with Quadrupole Magnets for TTF2	quadrupole, alignment, synchrotron, pick-up	426
	G. Priebe, D. Nölle, M. Wendt, M. Werner DESY, Hamburg
	We report on our alignment setup to calibrate beam position monitors (BPM) with respect to the magnetic axis of the quadrupole magnets used in the warm sections of the TESLA Test Facility (TTF2). The Stripline BPM's are fixed inside the quadrupole magnets. A streched wire measurement was used to calibrate the electrical axis of the BPM wrt. to the magnetic axis of the quadrupole.

TUP70	Systematic Calibration of Beam Position Monitor in the High Intensity Proton Accelerator (J-PARC) LINAC	quadrupole, pick-up, simulation, proton	429
	S. Sato, K. Hasegawa, F. Hiroki, J. Kishiro, Y. Kondo, M. Tanaka, T. Tomisawa, A. Ueno, H. Yoshikawa JAERI, Ibaraki-ken Z. Igarashi, M. Ikegami, N. Kamikubota, S. Lee, K. Nigorikawa, T. Toyama KEK, Ibaraki
	In J-PARC, a MW class of proton accelerator is under construction. Improperly- tuned beam would critically result in unacceptable (>0.1%) energy loss. Systematic strategy of fine calibrations of the beam position monitor (BPM) detectors, is therefore required. First, Off-beam-line calibrations of BPMs are taken, with a dedicatedly- designed bench, which has a beam-simulating electric wire carrying 324 MHz. And then discrepancies are calibrated for each BPM between reconstructed electrical center of pick-up plates and measured mechanical center, before the installation of BPM on the beam line. Secondly, after BPMs are installed on the beam line, real beam is used for systematic calibrations (Beam Based Calibration (BBC)). The discrepancies are calibrated between electromagnetic center of Q-magnets and reconstructed beam position. In KEK we have the first stage of J-Parc LINAC with Ion source, RFQ, DTL, Q- and steering-magnets, and lots of BPMs. Implementation of BBC is going with SAD-language, which can also be used for beam steering and beam trajectory simulations, e.g. TRACE-3D. In this presentation, such strategic BPM calibration system will be intensively described.

TUP73	Beam Instrumentation Using BPM System of the SPring-8 Linac	feedback, storage-ring, synchrotron, booster	438
	K. Yanagida, T. Asaka, H. Dewa, H. Hanaki, T. Kobayashi, A. Mizuno, S. Suzuki, T. Taniuchi, H. Tomizawa JASRI-SPring-8, Hyogo
	A beam position monitor (BPM) system of the SPring-8 linac has been operated since 2002. The following upgrade programs have been carried out during this period: The BPMs were installed in the linac's dispersive sections. A synchronized accumulation of beam position data into the database system started. A feedback control of steering magnets for beam position stabilization has been under development. In this conference the authors report a performance of the BPM system, and discuss its usefulness for beam diagnostics, machine diagnostics and beam stabilization.

TUP74	The Beam Diagnostics System in the J-PARC LINAC	beam-losses, quadrupole, radiation, diagnostics	441
	S. Lee, Z. Igarashi, T. Toyama KEK, Ibaraki H. Akikawa JAERI/LINAC, Ibaraki-ken F. Hiroki, J. Kishiro, S. Sato, M. Tanaka, T. Tomisawa JAERI, Ibaraki-ken H. Yoshikawa JAERI/FEL, Ibaraki-ken
	Large amount of beam monitors will be installed in J-PARC linac. Electrostatic computations are used to adjust the BPM cross-section parameters to obtain 50 Ω transmission lines. BPMs are designed to control the offset between quadrupole magnet and BPM electrical centers less than 0.1mm. We present a procedure of beam based calibration/alignment (BBC/BBA) method to confirm the displacement of linac BPMs. The fast current transformer (FCT) has response of relative bunch phase <1%. To measure the beam energy at every accelerator tank and injection point of 3 GeV RCS, phase difference of FCT pairs are used, and 10^-4 order energy resolutions can be expected. The loss monitor system (BLM) is composed of scintillator and Ar-CH₄/CO₂ gas filled proportional counter. To prevent the activation and heat load by intense beam loss, fast time response of loss signals is required. Profile measurements can also be used to determine the beam emittance of a matched beam in a periodic focusing lattice. The thin sensing wire scanner (WS) has been designed to obtain a current density distribution of the beam. This paper describes the instruments and R&D result of beam monitors in J-PARC linac.

TUP75	The High Accuracy RF Phase Detector Research for 200 MeV LINAC	synchrotron, radiation, electron, synchrotron-radiation	444
	S. Dong, G. Huang, D. Jia, G. Li, Y.G. Zhou USTC/NSRL, Hefei, Anhui
	The basic configuration of one experimental RF Phase detector and its research significance is introduced by characteristic of Hefei 200 MeV RF Linear accelerator and developments of RF Phase detector technology. The beam energy could be stabilized by implementing RF Phase detector into phase locked system for 5 cascaded accelerator tubes, which composed 200 MeV linac as the injector of Hefei Light Source (HLS). The tabletop experiments are given and the RF Phase detector is tuned in the off-line status. The microwave in 2856 MHz under CW mode is differentiated accurately by the developed RF phase detector. The measured results are better than prediction. The accuracy of the basic configuration of the RF Phase detector is verified, which establishes foundations for further in-line experiments.

TUP76	Adaptive Feedforward Cancellation of Sinusoidal Disturbances in Superconducting RF Cavities	damping, feedback, simulation, superconducting-RF	447
	T.H. Kandil, T.L. Grimm, W. Hartung, H. Khalil, J. Popielarski, J. Vincent, R.C. York NSCL, East Lansing, Michigan
	A control method, known as adaptive feedforward cancellation (AFC) is applied to damp sinusoidal disturbances due to microphonics in superconducting RF (SRF) cavities. AFC provides a method for damping internal, and external sinusoidal disturbances with known frequencies. It is preferred over other schemes because it uses rudimentary information about the frequency response at the disturbance frequencies, without the necessity of knowing an analytic model (transfer function) of the system. It estimates the magnitude and phase of the sinusoidal disturbance inputs and generates a control signal to cancel their effect. AFC, along with a frequency estimation process, is shown to be very successful in the cancellation of sinusoidal signals from different sources. The results of this research may significantly reduce the power requirements and increase the stability for lightly loaded continuous-wave SRF systems.

TUP77	Status of RF Control System for ISAC II Superconducting Cavities	feedback, controls, resonance, alignment	450
	K. Fong, S. Fang, M.P. Laverty TRIUMF, Vancouver
	The rf control system for ISAC II superconducting cavities is a hybrid analogue/digital system using self-excited feedback loop. It has undergone more than a year of testing and improvements have been made to every aspect of the system, including power up sequencing, phase detection, loop regulation, data acquisition as well as communication with EPICS. With a loaded Q of 100,000, amplitude regulation bandwidth of 20 Hz, phase regulation bandwidth of 5 Hz have been achieved.

TUP79	A New RF System for the CEBAF Normal Conducting Cavities	simulation, feedback, electron, extraction	456
	C. Hovater, H. Dong, A. Hofler, G. Lahti, J. Musson, T. Plawski TJNAF, Newport News, Virginia
	The CEBAF Accelerator at Jefferson Lab is a 6 GeV five pass electron accelerator consisting of two superconducting linacs joined by independent magnetic transport arcs. CEBAF also has numerous normal conducting cavities for beam conditioning in the injector and for RF extraction to the experimental halls. The RF systems that presently control these cavities are becoming expensive to maintain, therefore a replacement RF control system is now being developed. For the new RF system, cavity field control is maintained digitally using an FPGA which contains the feedback algorithm. The system incorporates digital down conversion, using quadrature under-sampling at an IF frequency of 70 MHz. The VXI bus-crate was chosen as the operating platform because of its excellent RFI/EMI properties and its compatibility with the EPICS control system. The normal conducting cavities operate at both the 1497 MHz accelerating frequency and the sub-harmonic frequency of 499 MHz. To accommodate this, the new design will use different receiver-transmitter daughter cards for each frequency. This paper discuses the development of the new RF system and reports on initial results.

TUP80	A Long-Pulse Modulator for the TESLA Test Facility (TTF)	klystron, cathode, coupling, linear-collider	459
	W. Kaesler PPT, Dortmund
	The long-pulse (1.6 ms) klystron modulator for TTF is a hardtube pulser using a Bouncer-circuit for droop compensation. It is built up with new advanced components representing industrial standards. The on-/off switch is a rugged 12 kV IGCT-stack with a fast 4kA turn-off capability. The 100 kJ storage capacitor bank contains only three capacitors with self-healing, segmented PP-foil technology. A new 100 kA solid-state switch based on light triggered thyristors (LTT) replaced the standard ignitrons as crowbar switches. The 300 kW high voltage power supply is based on modern switched mode technology.

TUP85	J-PARC Linac Alignment	alignment, quadrupole, beam-transport, monitoring	474
	M. Ikegami, C. Kubota, F. Naito, E. Takasaki, H. Tanaka, K. Yoshino KEK, Ibaraki H. Ao, T. Itou JAERI/LINAC, Ibaraki-ken K. Hasegawa, T. Morishita, N. Nakamura, A. Ueno JAERI, Ibaraki-ken
	J-PARC linac consists of a 3 MeV RFQ linac, a 50 MeV DTL (Drift Tube Linac), a 190 MeV SDTL (Separate-type DTL), and a 400 MeV ACS (Annular-Coupled Structure) linac, and its total length is more than 400 m including the beam transport line to the succeeding RCS (Rapid Cycling Synchrotron). In high-current proton accelerators, precise alignment of accelerator components is indispensable to reduce uncontrolled beam loss and beam quality deterioration. In this paper, planned schemes for the linac alignment is presented together with instrumentation for the long-term ground-motion watching.

TUP86	Coupler Development and Gap Field Analysis for the 352 MHz Superconducting CH-Cavity	quadrupole, coupling, simulation, proton	477
	H. Liebermann, H. Podlech, U. Ratzinger, A.C. Sauer IAP, Frankfurt-am-Main
	The cross-bar H-type (CH) cavity is a multi-gap drift tube structure based on the H-210 mode currently under development at IAP Frankfurt and in collaboration with GSI. Numerical simulations and rf model measurements showed that the CH-type cavity is an excellent candidate to realize s.c. multi-cell structures ranging from the RFQ exit energy up to the injection energy into elliptical multi-cell cavities. The reasonable frequency range is from about 150 MHz up to 800 MHz. A 19-cell, β=0.1, 352 MHz, bulk niobium prototype cavity is under development at the ACCEL-Company, Bergisch-Gladbach. This paper will present detailed MicroWave Studio simulations and measurements for the coupler development of the 352 MHz superconducting CH cavity. It will describe possibilities for coupling into the superconducting CH-Cavity. The development of the coupler is supported by measurement on a room temperature CH-copper model. We will present the first results of the measurements of different couplers, e.g. capacitive and inductive couplers, at different places of the CH Cavity.

TUP87	Technologies of The Peripheral Equipments of The J-PARC DTL1 for the Beam Test	power-supply, site, proton, quadrupole	480
	K. Yoshino, Y. Fukui, E. Kadokura, T. Kato, C. Kubota, F. Naito, E. Takasaki, H. Tanaka KEK, Ibaraki T. Itou JAERI/LINAC, Ibaraki-ken
	First beam test of the DTL1 was performed in November of 2003 at KEK site. A 30 mA H^- beam was successfully accelerated from 3 to 19.7 MeV. In order to prepare the beam test, various peripheral equipments were developed: the electrode plates for connecting the hollow-conductor coil and the power cable were developed since quadrupole electromagnets are built in all DTs (77 sets) of the DTL1, the water-cooled multiconductor copper tube (Control Copper Tube) were used as the power cable from the electrode plate to power supply, and the interlock system assembled by PLCs (Programmable Logic Controller) was also prepared for the surveillance of many cooling channel.

TUP88	CLIC Magnet Stabilization Studies	quadrupole, luminosity, site, collider	483
	S. Redaelli, R.W. Assmann, W. Coosemans, G. Guignard, D. Schulte, I. Wilson, F. Zimmermann CERN, Geneva
	One of the main challenges for future linear colliders is producing and colliding high energy e⁺e^- beams with transverse spot sizes at the collision point in the nanometre range. Preserving small emittances along several kilometres of linac requires the lattice quadrupoles to be stable to the nanometre level. Even tighter requirements are imposed on the stability of the final focus quadrupoles, which have to be stable to a fraction of the colliding beam size to reliably steer the opposing beams in collision. The Compact LInear Collider (CLIC), presently under investigation at CERN, aims at colliding e⁺e^- beams with a vertical spot size of 0.7 nm, at a centre-of-mass energy of 3 TeV. This requires a vertical stability to the 1.3 nm level for the 2600 linac quadrupoles and to the 0.2 nm level for the two final focus quadrupoles. The CLIC Stability Study has demonstrated for the first time that CLIC prototype quadrupoles can be stabilized to the 0.5 nm level in a normal working area on the CERN site. Detailed tracking simulations show that with this level of stability, approximately 70% of the CLIC design luminosity would be achieved. This paper summarizes the work and the achievements of the CLIC Stability Study.
	Transparencies

TUP89	Static Absolute Force Measurement for Preloaded Piezoelements Used for Active Lorentz Force Detuning System	resonance, impedance, vacuum, linear-collider	486
	S. P. Sekalski, A. Napieralski, S. P. Sekalski TUL, Lodz A. Bosotti INFN/LASA, Segrate (MI) M. Fouaidy IPN, Orsay L. Lilje, S. Simrock DESY, Hamburg R. Paparella, P.F. Puricelli INFN Milano, Milano
	To reach high gradients in pulsed operation of superconducting (SC) cavities an active Lorentz force detuning compensation system is needed. For this system a piezoelement can be used as an actuator (other option is a magnetostrictive device). To guarantee the demanded lifetime of the active element, the proper preload force adjustment is necessary. To determine this parameter an absolute force sensor is needed which will be able to operate at cryogenic temperatures. Currently, there is no calibrated commercial available sensor, which will be able to measure the static force in such an environment. The authors propose to use a discovered phenomenon to estimate the preload force applied to the piezoelement. The principle of the proposed solution based on a shape of impedance curve, which changes with the value of applied force. Especially, the position of resonances are monitored. No need of specialized force sensor and measurement in-situ are additional advantages of proposed method.

TUP90	Improvements of RF Characteristics in the SDTL of the J-PARC Proton LINAC	simulation, insertion, proton, focusing	489
	S. Wang IHEP Beijing, Beijing T. Kato KEK, Ibaraki V.V. Paramonov RAS/INR, Moscow
	A separated drift tube linac (SDTL)* was selected as an accelerator structure of Japan Proton Accelerator Complex (J-PARC), which follows DTL. The SDTL of J-PARC consists of 32 short tanks, ranging from 1.5 to 2.5 m in length. A design of frequency tuners of the SDTL was performed by taking account of 3-D field distribution calculated with MAFIA. The effects of stems on the resonant frequency and field distribution were also analyzed. An easy and effective compensation method for perturbation by stems of both end cells was proposed and applied to the SDTL tanks. * T. Kato. Proposal of a Separated-type Proton Drift Tube Linac for a Medium-Energy Structure. KEK Report 92-10, (1992)

TUP91	Compact Electron-Linac Design Concept for a Gamma Ray Source	klystron, electron, linear-collider, collider	492
	K. C. D. Chan, B.E. Carlsten, G. Dale, R. Garnett, C. Kirbie, F.L. Krawczyk, S.J. Russell, T.P. Wangler LANL, Los Alamos, New Mexico E. Wright CPI, Palo Alto, California
	Gamma-ray sources, particularly sources that are easily transportable, are in high demand for different homeland security applications. We have carried out a review of commercially available electron-linac-based sources, and have investigated alternative compact electron-linac systems that use updated technologies compared with sources that are available commercially. As the results, we propose to develop a new source using an electron linac operating at 17 GHz. It uses a klystron, instead of a magnetron, and a IGBT-switched HV power supply. The source design takes advantages of the advances in X-band linac technology and solid-state HV technology. The higher frequency and upgraded technologies offer smaller size, lighter weight, better efficiency, easier operation, and higher reliability, compared with commercially-available linacs. In this paper, we will describe the source design and our choice of technologies.

TUP95	Evaluation of Magnetic Field Enhancement Along a Boundary	dipole, linear-collider, simulation, collider	501
	Y. Iwashita Kyoto ICR, Kyoto T. Higo KEK, Ibaraki
	Generally, a cavity has convex corners on its inner surface, where the surface field becomes higher than the average accelerating gradient. This effect has been paid attention not to exceed a criterion only on surfaces that have high electric field gradient. A high magnetic field area, however, sometimes seems harmful on a stable operation too. Such enhancement factors are evaluated in a 2D model to show a feasible crossing angle limit on a convex angle of two surfaces.

TUP96	Mechanical Stability Simulations on a Quarter Wave Resonator for the SPIRAL II Project	simulation, acceleration, vacuum, coupling	504
	H. Saugnac, J.-L. Biarrotte, S. Blivet, S. Bousson, M. Fouaidy, T. Junquera, G. Olry IPN, Orsay
	In the framework of the SPIRAL II project, IPN Orsay is studying a 88 MHz β=0.12 super conducting quarter wave resonator prototype. Due to its low RF bandwidth (around 60 Hz) the resonator must have a very high mechanical stability and have small sensitivity to dynamic mechanical loads. To simulate the effects of geometrical deformations on the fundamental RF frequency a three dimensional analysis is required. The simulations were made by coupling mechanical FEM analysis performed in COSMOS/GEOSTAR™ with the RF electromagnetic FEM code MICAV™ integrated in the COSMOS/GEOSTAR™ interface. Static mechanical loads were first studied to reduce the effects of external pressure on the RF frequency shift and evaluate the tuning sensitivity of the cavity. Then, simulations on the dynamic response of the resonator, using the modal superposition analysis method, with random external pressure variations and harmonic excitation of the cavity were performed. This paper presents the results of the simulations and mechanical solutions chosen to increase the cavity RF frequency stability.

WE101	Gradient Limitations for High-Frequency Accelerators	collider, linear-collider, plasma, vacuum	513
	S. Döbert SLAC, Stanford
	While the physics of gradient limitations in high frequency rf accelerators still lacks a full theoretical understanding, a fairly complete empirical picture has emerged from the experimental work done in the past few years to characterize this phenomenon.Experimental results obtained mostly in the framework of the NLC/GLC project at 11 GHz and from the CLIC study at 30 GHz will be used to illustrate the important trends.The dependence of achievable gradient on pulse length, operating frequency and fabrication materials will be described. Also, the performance results most relevant to linear colliders will be presented in some detail. Specifically, these relate to the requirements that the structures sustain a certain gradient without incurring damaged, and that more importantly, they run reliably at this gradient, with breakdown rates less one in a million pulses. Finally interesting observations concerning the dynamics of breakdowns like spatial and temporal correlations and dark currents will be covered briefly, including the insights they provide into the breakdown mechanism.
	Transparencies

WE102	State of the Art SRF Cavity Performance	damping, electron, higher-order-mode, coupling	518
	L. Lilje DESY, Hamburg
	The paper will review superconducting RF cavity performance for β=1 cavities used in both linear and circular accelerators. These superconducting cavities are used in two kinds of applications: High current storage rings and efficient high duty cycle linacs. In recent years the performance of those cavities has been improving steadily. High accelerating gradients have been achieved using advanced surface preparation techniques like electropolishing and surface cleaning methods like high pressure water rinsing. High intensity beams can be handled with advanced higher-order-mode damping schemes.
	Transparencies

WE103	State of the Art in RF Control	feedback, diagnostics, resonance, laser	523
	S. Simrock DESY, Hamburg
	Nowadays the designer of a new rf control system has access to a wealth of powerful digital, analog, and rf circuitry. The requirements for the rf control system have changed from only controlling the amplitude and phase of the accelerating field to the required degree to stability. Additional tasks include exception handling and extensive build-in diagnostics while pursuing issues related to reliability, operability, and maintainability. Also operation close to the performance limit must be supported while maximizing the availability of the accelerator. With many accelerator projects in planning or under construction several state-of-the art rf control designs have evolved. This paper will present an overview of this new technology and discuss its performance.
	Transparencies

WE201	Results from the Initial Operations of the SNS Front End and Drift Tube Linac	emittance, rfq, ion-source, ion	533
	V. Aleksandrov ORNL/SNS, Oak Ridge, Tennessee
	The Spallation Neutron Source accelerator systems will deliver a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron scattering research. The accelerator complex consists of an H^- injector (the Front-End), capable of producing one millisecond long pulses with 38 mA of peak current at a repetition rate of 60 Hz, a 1 GeV linear accelerator, an accumulator ring and associated transport lines. A 2.5 MeV beam from the injector is accelerated to 86 MeV in the Drift Tube Linac, then to 185 MeV in a Coupled-Cavity Linac and finally to 1 GeV in a Superconducting Linac. The staged beam commissioning of the accelerator is proceeding in parallel with component installation. The Front End and Drift Tube Linac tanks 1-3 have been commissioned at ORNL. The primary design goals of peak current, transverse emittance and beam energy have been achieved. Beam with 38 mA peak current, 1 msec beam pulse length, and 1 mA average beam current has been accelerated through the DTL tank 1. Results and status of the beam commissioning program will be presented. * on behalf of the SNS Project
	Transparencies

WE202	Recent Results in the Field of High Intensity CW Linac Development for RIB Production	target, rfq, proton, ion	538
	A. Pisent INFN/LNL, Legnaro, Padova
	High Intensity CW Linacs have been proposed as driver accelerators for RIB production in various projects, since thy can drive in steady conditions a MW power range target for the production of spallation neutrons that induce fission in a natural uranium target. Particularly important for this application, with a relatively low beam current, is the necessity to develop a superconducting intermediate energy part with good power conversion efficiency. The second specific requirement of RIB facility drivers, that is also fulfilled by a superconducting intermediate energy linac, is the necessity to keep some flexibility in the species that can be accelerated (deuterons or light ions). In EURISOL RTD project a 1 GeV 5 mA proton linac, has been proposed for this application. In SPES project, recently approved for its initial phase at LNL, a lower energy proton beam will be used on a solid target. The results of the specific R&D programs on in the field of CW RFQ and superconducting low energy linacs will be illustrated. In particular for LNL the status of the RFQ construction and the superconducting cavities prototype tests will be given.
	Transparencies

WE203	Challenges of Linac Driven Light Sources	radiation, brilliance, synchrotron, synchrotron-radiation	543
	C. Bocchetta ELETTRA, Basovizza, Trieste
	The use of linacs allows novel light sources to be conceived by not being limited by equilibrium dynamics or IBS effects. These new sources can be single pass or recirculated (with or without energy recovery) or linac augmented storage rings. They allow tuneable polarised radiation of unprecedented brilliance, short pulse lengths that may reach the atto-second scale and full coherence. Both SC and NC machines are being proposed, designed and constructed. Photon output characteristics range from incoherent synchrotron radiation to SASE to seeded HGHG. The proposed beams can be low to high average current and pulse time structures range from CW to highly variable with mutual exclusion amongst different forms of operation. The multiple challenges of these machines reside not only in the requirement of beams of extremely high quality (energy, emittance, energy-spread and temporal stability) for the brightest, shortest wavelength sources but also in the demanding technologies and control of beam-machine interactions for the high current energy recovery ones. The paper gives an overview of these broad challenges and of the directions taken to reach the objectives of a user facility.
	Transparencies

WE204	PAL Linac Upgrade for a 1-3 Å XFEL	undulator, emittance, radiation, electron	544
	J-O. Oh, W. Namkung POSTECH, Pohang Y. Kim DESY, Hamburg
	With the successful SASE FEL saturation at 80 nm wavelength at TTF1, TTF2 will begin re-commissioning in the fall of 2004 as an FEL user facility to 6 nm with 1 GeV beams. The high gain harmonic generation is also confirmed by the DUV-FEL experiments at 266 nm with seeding wavelength at 800 nm. In order to realize a hard X-ray SASE FEL (SASE XFEL) with a lower energy beams, we need a long in-vacuum mini-gap undulator and a GeV-scale FEL driving linac that can supply an extremely low slice emittance, a high peak current, and an extremely low slice energy spread. PAL is operating a 2.5 GeV electron linac as a full-energy injector to the PLS storage ring. By adding an RF photo-cathode gun, two bunch compressors, and a 0.5 GeV S-band injector linac to the existing PLS linac, and by installing a 60 m long in-vacuum undulator, the PLS linac can be converted to a SASE XFEL facility (PAL XFEL) which supplies coherent X-ray down to 0.3 nm wavelength. The third harmonic enhancement technique can supply coherent hard X-ray beams to 0.1 nm. The technical parameters related to these goals are examined, and preliminary design details are reviewed for the PAL linac upgrade idea for a 1-3 Å PAL XFEL.
	Transparencies

WE205	KEKB Injector Linac and Upgrade for SuperKEKB	klystron, acceleration, injection, positron	549
	S. Michizono KEK, Ibaraki
	KEKB Injector linac has provided the 8 GeV electrons and 3.5 GeV positrons to the KEKB asymmetric collider rings designed for the B-physics study. The KEKB has recorded the highest luminosity records to which the linac contributes with an advanced operational stability. The dualbunch injection and continuous injection schemes have been adopted. The operational status of the KEKB injector linac is summarized here. The Super KEKB project aiming for the ten-times higher luminosity is under consideration as the upgrade of KEKB. In this upgrade, the injector linac has to increase the positron acceleration energy from 3.5 GeV to 8 GeV. In order to double the acceleration field (from 20 to 40 MV/m), the C-band rf system has been tested. The newly developed components, such as an acceleration structure and an rf window, are summarized. A C-band acceleration structure is installed in KEKB linac after the rf conditioning of more than 40 MW. The energy gain of more than 40 MV/m is confirmed by the beam analysis. The C-band acceleration unit has been operated continuously for the stability test. The recent operational status of the c-band acceleration unit will be also reported.
	Transparencies

TH101	Status of the J-PARC Linac, Initial Results and Upgrade Plan	rfq, emittance, ion, proton	554
	Y. Yamazaki JAERI/LINAC, Ibaraki-ken
	The J-PARC linac building will be completed by March, 2005, when the installation of the linac components will start. On the other hand, the front end linac, comprising the 3 MeV RFQ linac, the MEBT with the beam chopper, and the 20 MeV DTL first tank, is under beam commissioning in the KEK site. A peak current of 30 mA, which is enough for the 0.6 MW operation of Rapid-Cycling Synchrotron (RCS), was accelerated up to 20 MeV on the second day of the beam commissioning, last November. The detailed study of the system is under way, including the stability test of many components. The front end linac will be shipped to the JAERI Tokai site after the building completion there. The beam commissioning of the 181 MeV linac will start in September 2006, that of the 3 GeV RCS in May, 2007, and that of the 50 GeV Main Synchrotron (MR) in November 2007. The beam acceleration in the MR will be done by March, 2008. It is strongly recommended by the government committee that the upgrade to the 400 MeV linac should start immediately after the completion of the above accelerator system, that is, in April 2008, with the period of three years, aiming the 1 MeV RCS beam power.
	Transparencies

TH102	Overview of High Intensity Linac Programs in Europe	proton, rfq, ion, target	559
	M. Vretenar, R. Garoby CERN, Geneva
	Recent years have seen a boost in the European Union (EU) engagement for accelerator research in Europe. Laboratories and institutions from member states are invited to combine their efforts and to define common goals and strategies, in order to receive a financial support up to 50% of the total project cost. In the field of High Intensity Linacs, the EU had already supported the EURISOL initiative for nuclear physics, which this year is applying for funding of a Design Study, and the development of linacs for Waste Transmutation. More recently, an initiative for high-energy physics has been approved, which includes a programme for the development of pulsed linac technologies. Together with the ongoing national projects, these European initiatives represent a strong focussed effort towards the development of linac technologies, intended to overcome difficulties coming from decreasing national budgets. This paper presents a summary of the requests coming from the European physics communities and an overview of linac R&D activities sponsored by the EU, together with some information on parallel national projects. The parameter choices as well as the main technical features of the different projects are presented and compared.
	Transparencies

TH103	Summary of the Argonne Workshop on High Gradient RF	electron, ion, linear-collider, simulation	564
	J. Norem ANL, Argonne, Illinois
	Workshop on High Gradient rf was held at Argonne from October 7 - 9, 2003. This workshop reviewed the problems encountered when a number of accelerator technologies approached the high gradient limits. The aim of the workshop was to involve materials scientists and try to look at trigger mechanisms and surface interactions, in addition to reviewing progress. Talks were presented on superconducting rf, progress with high and low frequency copper cavities, and dielectrics. The focus was on both experimental and theoretical aspects of the problem. The overall picture presented at the workshop will be summarized.
	Transparencies

TH104	Industrial RF Linac Experiences and Laboratory Interactions	vacuum, proton, site, electron	569
	M. Peiniger ACCEL, Bergisch Gladbach
	Since more than two decades ACCEL Instruments GmbH at Bergisch Gladbach (formerly Siemens/Interatom) is supplying the worldwide accelerator labs with key components like rf cavities and power couplers, s.c. magnets, insertion devices, vacuum chambers and x-ray beamline equipment. Starting with the design and production of turn key SRF accelerating modules in the late 80th, meanwhile ACCEL is engineering, manufacturing, on site commissioning and servicing complete accelerators with guaranteed beam performance. Today, with a staff of more than 100 physicists and engineers and about the same number of manufacturing specialists in our dedicated production facilities, ACCEL's know how and sales volume in this field has accumulated to more than 2000 man years and several hundred Mio €, respectively. Basis of our steady development is a cooperative partnership with the world leading research labs in the respective fields. As an example, for the supply of a turn key 100 MeV injector linac for the Swiss Light Source, and meanwhile also for the Diamond Light Source as well as for the Australian Synchrotron Project, we established a very fruitful partnership with DESY.
	Transparencies

TH201	IOT RF Power Sources for Pulsed and CW Linacs	klystron, gun, electron, simulation	574
	H.P. Bohlen CPI, Palo Alto, California Y. Li, R.N. Tornoe CPI/EIMAC, San Carlos, California
	For many years, klystrons have been the preferred RF power amplifiers for both pulsed and CW linacs at UHF and higher frequencies. Their properties have earned them that position. But in recent years in UHF terrestrial television transmitters the earlier predominant klystron has been replaced the Inductive Output Tube (IOT) because the IOT provides higher efficiency and, due to its excellent linearity, can handle the simultaneous amplification of both the vision and the sound signal. Its robustness and life expectancy equals that of a klystron, and it more than compensates its lower gain by a lower price and a smaller size. For linac operation, derivates of UHF TV IOTs, capable of up to 80 kW CW output power, are already available and operating. In L-Band, they are presently joined by recently developed 15 to 30 kW CW IOTs. HOM-IOTs are expected to extend the CW range in UHF to 1 MW and beyond. Pulsed operation of an IOT can be achieved without a high-voltage modulator. Since the beam current is grid-controlled it is sufficient to pulse the drive power.
	Transparencies

TH204	End-to-End Beam Dynamics Simulations for the ANL-RIA Driver Linac	simulation, emittance, ion, beam-losses	584
	P.N. Ostroumov ANL/Phys, Argonne, Illinois
	The proposed Rare Isotope Accelerator (RIA) Facility consists of a superconducting (SC) 1.4 GV driver linac capable of producing 400 kW beams of any ion from hydrogen to uranium. The driver is configured as an array of ~350 SC cavities, each with independently controllable rf phase. For the end-to-end beam dynamics design and simulation we use a dedicated code, TRACK. The code integrates ion motion through the three-dimensional fields of all elements of the driver linac beginning from the exit of the electron cyclotron resonance (ECR) ion source to the production targets. TRACK has been parallelized and is able to track large number of particles in randomly seeded accelerators with misalignments and a comprehensive set of errors. The simulation starts with multi-component dc ion beams extracted from the ECR. Beam losses are obtained by tracking up to million particles in hundreds of randomly seeded accelerators. To control beam losses a set of collimators is applied in designated areas. The end-to-end simulations with the TRACK code have been extremely useful for studies of different options of the driver linac design with respect to beam quality, beam losses and sensitivity of beam parameters to various types of errors.
	Transparencies

TH301	Intermediate-Velocity Superconducting Accelerating Structures	ion, proton, impedance, acceleration	589
	J. R. Delayen Jefferson Lab, Newport News, Virginia
	In the last decade, one of the most active areas in the application of the superconducting (SC) rf technology has been for the acceleration of ions to medium energies (~1 GeV/amu). One such accelerator is under construction in the US while others are being proposed in the US, Japan, and Europe. These new facilities require SC accelerating structures operating in a velocity region that has until recently been unexplored, and new types of structures optimized for the velocity range from ~0.2 to ~0.8 c have been developed. We will review the properties of these intermediate-velocity structures, the status of their development, as well as present an overview of the medium-energy superconducting ion accelerator designs being developed world-wide.
	Transparencies

TH302	End-to-End Beam Simulations for the MSU RIA Driver Linac	emittance, simulation, ion, alignment	594
	X. Wu, M. Doleans, D. Gorelov, T.L. Grimm, F. Marti, R.C. York, Q. Zhao NSCL, East Lansing, Michigan
	The Rare Isotope Accelerator (RIA) driver linac proposed by Michigan State University (MSU) will use a 10th sub-harmonic based, superconducting, cw linac to accelerate light and heavy ions to final energies of ≤400 MeV/u with beam powers of 100 to 400 kW. The driver linac uses superconducting quarter-wave, half-wave, and six-cell elliptical cavities with frequencies ranging from 80.5 MHz to 805 MHz for acceleration, and superconducting solenoids and room temperature quadrupoles for transverse focusing. For the heavier ions, two stages of charge-stripping and multiple-charge-state acceleration will be used to meet the beam power requirements and to minimize the requisite accelerating voltage. End-to-end, three-dimensional (3D), beam dynamics simulations from the ECR to the radioactive beam production targets have been performed. These studies include a 3D analysis of multi-charge-state beam acceleration, evaluation of transverse misalignment and rf errors on the machine performance, modeling of the charge-stripping and stripping-chicane performance, and beam switchyard design. The results of these beam dynamics studies will be presented, and further planned beam dynamics studies will be discussed.
	Transparencies

THP03	DESIGN IMPROVEMENT OF THE RIA 80.5 MHZ RFQ	rfq, ion, emittance, simulation	599
	Q. Zhao, V. Andreev, M. Doleans, D. Gorelov, T.L. Grimm, W. Hartung, F. Marti, S.O. Schriber, X. Wu, R.C. York NSCL, East Lansing, Michigan
	An 80.5 MHz, continuous-wave, normal-conducting, radio-frequency quadrupole (RFQ) was designed for the front end of the Rare Isotope Accelerator (RIA) driver linac. It will accelerate various ion beams (hydrogen up to uranium) from 12 keV/u to about 300 keV/u. The 4-meter-long RFQ accepts the pre-bunched beam from the low energy beam transport (LEBT) and captures more than 80% with a current of ~0.3 mA. Beam dynamics simulations show that the longitudinal output emittance is small for both single^- and two-charge-state ion beams with an external multi-harmonic buncher. A 4-vane resonator with magnetic coupling windows was employed in the cavity design to provide large mode separation, high shunt impedance, and a small transverse dimension. The results of beam dynamics as well as the electromagnetic simulations are presented.

THP04	Fabrication of Superconducting Cavities for SNS	electron, vacuum	602
	M. Pekeler, S. Bauer, J. Schwellenbach, M. Tradt, H. Vogel, P. vom Stein ACCEL, Bergisch Gladbach
	During the last three years ACCEL fabricated all 109 superconducting cavities for the Spallation Neutron Source (SNS) in Oakridge, Tennessee. Two series of 35 medium beta (β=0.61) and 74 high beta (β=0.81) cavities have been delivered. Besides cavity manufacturing ACCEL also performed rf tuning and chemical surface preparation. We give an outline on the current manufacturing experience and comment on future developments for industrial cavity production.
	Transparencies

THP05	Superconducting beta=0.15 Quarter-Wave Cavity for RIA	vacuum, superconductivity, ion, resonance	605
	M. Kelly ANL, Argonne, Illinois Z.A. Conway, J.D. Fuerst, M. Kedzie, K.W. Shepard ANL/Phys, Argonne, Illinois
	A production-design 115 MHz niobium quarter-wave cavity with a full stainless steel helium jacket has been built and tested as part of the R&D for the Rare Isotope Accelerator (RIA) driver linac. The two-gap cavity is designed to accelerate ions over the velocity range 0.14<β<0.24. Processing of the cavity RF surfaces, including high-pressure rinsing and assembly of the cavity with a moveable high-power RF coupler were all performed under clean room conditions. Cold test results including high-field cw operation, microphonics, and helium pressure sensitivity will be presented in this paper. Performance of a pneumatically actuated slow-tuner device suitable not only for this cavity but a number of other cavities required for RIA will also be discussed.

THP06	Cold Tests of a Superconducting Co-Axial Half-Wave Cavity for RIA	vacuum, superconductivity, resonance, proton	608
	M. Kelly ANL, Argonne, Illinois J.D. Fuerst, M. Kedzie, K.W. Shepard ANL/Phys, Argonne, Illinois
	This paper reports cold tests of a superconducting niobium half-wave cavity with integral helium vessel, the design of which is suitable for production for the Rare Isotope Accelerator (RIA) driver linac. The cavity operates at 172 MHz and can provide more than 2 MV of accelerating voltage per cavity for ions with 0.24<β<0.37. Cavity RF surfaces were prepared using electropolishing, high-pressure rinsing and clean assembly. Measurements of Q₀ show a residual RF surface resistance RS = 5 nΩs in both 2 K and 4 K operations. The cavity can be operated at 4.5 K with E_Acc >10 MV/m (E_Peak >30 MV/m). Performance exceeds RIA specifications of an input power of 12 Watts at 4.5 K and E_Acc = 6.9 MV/m. RMS frequency jitter is only 1.6 Hz at E_Acc = 8 MV/m and T = 4.5 K as determined from microphonics measurements in a realistic accelerator environment connected to the ATLAS refrigerator.
	Transparencies

THP07	Performance Improvement of the Multicell Cavity Prototype for Proton LINAC Projects	proton, shielding, electron, target	611
	B. Visentin, D. Braud, J.P. Charrier, B. Coadou, Y. Gasser, J.P. Poupeau, P. Sahuquet CEA/DSM/DAPNIA, Gif-sur-Yvette S. Bousson, H. Gassot, H. Saugnac, P. Szott IPN, Orsay G. Devanz CEA/DAPNIA-SACM, Gif-sur-Yvette Cedex
	The CEA-Saclay/IPN-Orsay collaboration allowed to develop a multicell superconducting cavity prototype (704 MHz, β=0.65). Since the first experimental results[], achieved in a vertical cryostat and the horizontal one "CryHoLab", the accelerating field Eacc has been recently improved up to 19 MV/m (E_peak = 43 MV/m, B_peak = 83 mT, Q₀ = 9.109). E_acc is now limited by quench. The previous one limitation, due to a non understood phenomenon, disappeared . The excellent performances of this 5-cell proton cavity validate the design, the technological choices, the manufacturing and the cavity preparation process. These results augur well for our future R&D program on multicell superconducting cavities within the European CARE/HIPPI framework. [] Proceedings of PAC2003, Portland, USA, TAB047, p.1303**

THP08	The Frankfurt Funneling Experiment	rfq, ion, emittance, simulation	614
	A. Schempp, U. Bartz, N. Müller, J. Thibus, H. Zimmermann IAP, Frankfurt-am-Main
	Funneling is a procedure to multiply beam currents of rf-accelerators at low energies. In the ideal case the beam current can be multiplied in several stages without emittance growth. The Frankfurt Funneling Experiment consists of two ion sources, a Two-Beam RFQ accelerator, two different funneling deflectors and a beam diagnostic equipment system. The whole set-up is scaled for He⁺ instead of Bi⁺ for the first funneling stage of a HIIF driver. The progress of our experiment and the results of the simulations will be presented.

THP10	Tuner Design for High Power 4-Rod-RFQs	rfq, simulation, ion, vacuum	617
	A. Schempp, L. Brendel, B. Hofmann, H. Liebermann IAP, Frankfurt-am-Main
	The performance of high power RFQ linacs, as used in spallations sources and proposed for projects like ADxy, IFMIF or high duty factor drivers for RIB application are limited by beam dynamics properties as well as technical limits like sparking, power density, cooling and thermal stresses. A "one piece structure" even possible in theory has to have means for tuning the real fields like exchangable or moving tuners. Tuner design features will be discussed and results will be presented.

THP11	Design of A 352 MHz-Proton-RFQ for GSI	rfq, proton, emittance, antiproton	620
	A. Schempp, L. Brendel, B. Hofmann IAP, Frankfurt-am-Main
	Part of the future project of GSI is a new p-linac for the production of Antiprotons. The 4- Rod-RFQ operating at 350 MHz has to accelerate up to 100 mA protons from an ECR source. Design studies have been made using the Parmteq- and Microwave Studio codes to optimize beam dynamics properties and the field distribution of the RFQ. Results of the design studies will be presented.

THP12	Superconducting RFQs in the PIAVE Injector	feedback, rfq, cryogenics, target	623
	G. Bisoffi, G. Bassato, G. Bezzon, A. Calore, S. Canella, F. Chiurlotto, A. Lombardi, P. Modanese, A.M. Porcellato, S. Stark INFN/LNL, Legnaro, Padova
	The PIAVE superconducting RFQs were installed on the linac line and connected to the TCF50 cryogenic system. First results on the on-line resonator performance (e.g. Q-curves, amplitude and phase locking) are described as well as the behaviour of the fast tuners.

THP13	Construction of a 161 MHz, β=0.16 Superconducting Quarter Wave Resonator with Steering Correction for RIA	light-ion, vacuum, emittance, ion	626
	A. Facco INFN/LNL, Legnaro, Padova C. Compton, T.L. Grimm, W. Hartung, F. Marti, R.C. York NSCL, East Lansing, Michigan V. Zvyagintsev TRIUMF, Vancouver
	We have built a 161 MHz, β=0.16 superconducting Quarter Wave Resonator with steering correction for the low beta section of RIA. This bulk niobium, double wall cavity, compatible with both separate vacuum between beam line and cryostats or unified one, was designed in collaboration between MSU-NSCL and LNL. The design is suitable for extension to other frequencies, e.g. to obtain the 80 MHz, β=0.085 cavity required in RIA. The shaped drift tube allows correction of the residual QWR steering that can cause emittance growth especially in light ions; this could make this resonator a good alternative to Half-Wave resonators in high intensity proton-deuteron linacs, like the SPES injector project at LNL. First test results will be presented.

THP14	High Beta Cavity Optimization for ISAC-II	ion, quadrupole, acceleration, emittance	627
	R.E. Laxdal, V. Zvyagintsev TRIUMF, Vancouver Z.H. Peng CIAE, Beijing
	The linac for ISAC-II comprises twenty cavities of medium beta (β=5.8 and 7.1%) quarter wave cavities now in the installation phase. A second stage will see the installation of ~20 MV of high beta quarter wave cavities (~10.4%). The cavity structure choice depends on the efficiency of operation, cost, stability, beam dynamics and schedule. Two main cavity types are considered; a low frequency 106 MHz option and a high frequency 141 MHz cavity. We compare and contrast the cavity choices.

THP16	Engineering and Cryogenic Testing of the ISAC-II Medium Beta Cryomodule	alignment, target, vacuum, heavy-ion	630
	G. Stanford, Y. Bylinskii, R.E. Laxdal, B. Rawnsley, T. Ries, I. Sekatchev TRIUMF, Vancouver
	The medium beta section of the ISAC-II Heavy Ion Accelerator consists of five cryomodules each containing four quarter wave bulk niobium resonators and one superconducting solenoid. A prototype cryomodule has been designed and assembled at TRIUMF. The cryomodule vacuum space contains a mu-metal shield, an LN2 cooled, copper, thermal shield, plus the cold mass and support system. This paper will describe the design goals, engineering choices and fabrication and assembly techniques as well as report the results of the initial cold tests. In particular we will summarize the alignment procedure and the results from the wire position monitoring system.

THP17	Progress in the Development of the TOP Linac	proton, quadrupole, booster, impedance	633
	L. Picardi, C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma) S. Frullani ISS, Rome
	The TOP Linac (Oncological Therapy with Protons), under development by ENEA and ISS is a sequence of three pulsed (5 msec, 300 Hz) linear accelerators: a 7 MeV, 425 MHz RFQ+DTL (AccSys Model PL-7), a 7–65 MeV, 2998 MHz Side Coupled Drift Tube Linac (SCDTL) and a 65–200 MeV, variable energy 2998 MHz Side Coupled Linac (SCL). The first SCDTL module is composed by 11 DTL tanks coupled by 10 side cavities. The tanks has modified to overcome vacuum leakage that occurred during brazing, and now the module has been completed, and is ready to be tested with protons. The 7 MeV injector has been recently installed in the ENEA Frascati laboratories for preliminary test, before being transferred to the main Oncologycal Hospital in Rome, Istituto Regina Elena.
	Transparencies

THP18	The Acceleration Test of the APF-IH-LINAC	acceleration, ion, focusing, proton	636
	K. Yamamoto, M. Okamura RIKEN, Saitama T. Hattori TIT, Tokyo S. Yamada NIRS, Chiba-shi
	We manufactured an IH linac with Alternating Phase Focusing as a test machine for medical accelerator injection. It will accelerate C⁴⁺ ions from 40 keV/u up to 2 MeV/u. The tank length is around 1.5 m, operation frequency is 100 MHz. We have succeeded to accelerate protons with a simple acceleration system, consisting of a PIG ion source, bending magnets and focus lenses, less than 5m long. This IH linac was calculated using a simple thin lens approximation. Now we are making a beam-tracking program using the results of the electro-magnetic simulation soft (Micro-Wave-Studio, OPERA-3D); it has the merit of easily calculating the 3D-beam dynamics including non-linear effects. We will report the test, the beam simulations and comparisons of the test to the simulations.

THP22	3D Beam Dynamics Simulation in Undulator Linac	simulation, ion, undulator, bunching	642
	E.S. Masunov, S.M. Polozov MEPhI, Moscow
	The ion beam can be bunched and accelerated in linear accelerator with RF undulator (UNDULAC-RF). The acceleration and focusing of beam can be realized without using a synchronous wave. In this paper the computer simulation of high intensity ion beam dynamics in UNDULAC-RF was carried out by means of the "superparticles" method. The computer simulation and optimization of ion dynamics consist of two steps. At the first, the equations of particles motion in polyharmonic fields are devised by means of smooth approximation. Hamiltonian analysis of these equations allows to find a velocity of reference particle in polyharmonic field and to formulate the conditions of good longitudinal bunching and transverse focusing beam. At the second, the 3D ion beam dynamics simulation in an UNDULAC is governed by founded functions of reference particle velocity and a ratio of amplitude harmonics. The influence of the space charge on RF focusing conditions, transmission coefficient, longitudinal and transverse emittances, and other acceleration system characteristics are investigated by computer simulation. Masunov E.S., Sov. Phys.-Tech. Phys., vol. 35, No. 8, p. 962, 1990.

THP29	Development of C-band Accelerating Section for SuperKEKB	acceleration, positron, klystron, coupling	663
	T. Kamitani, N. Delerue, M. Ikeda, K. Kakihara, S. Ohsawa, T. Oogoe, T. Sugimura, T. Takatomi, S. Yamaguchi, K. Yokoyama KEK, Ibaraki Y. Hozumi GUAS/AS, Ibaraki
	For the luminosity upgrade of the present KEK B-factory to SuperKEKB, the injector linac has to increase the positron acceleration energy from 3.5 to 8.0 GeV. In order to double the acceleration field gradient from 21 to 42 MV/m, design studies on C-band accelerator module has started in 2002. First prototype 1-m long accelerating section has been fabricated based upon a design which is half scale of the present S-band section. High power test of the C-band section has been performed at a test stand and later at an accelerator module in the KEKB injector linac. In a beam acceleration test, a field gradient of 41 MV/m is achieved with 43 MW RF power from a klystron. This paper report on the recent status of the high-power test and also the development of a second prototype section.

THP30	Production of S-band Accelerating Structures	coupling, vacuum, target, microtron	666
	C. Piel, K. Dunkel, H. Vogel, P. vom Stein ACCEL, Bergisch Gladbach
	ACCEL currently produces accelerating structures for several scientific laboratories. Multi-cell cavities at S-band frequencies are required for the projects CLIC-driver-linac, DLS and ASP pre-injector linac and the MAMI-C microtron. Based on those projects differences and similarities in design, production technologies and requirements will be addressed.

THP32	New Accelerating Modules RF Test at TTF	klystron, pick-up, superconductivity, radiation	672
	D. Kostin DESY, Hamburg
	Five new accelerating modules were installed into the TTF tunnel as a part of the VUV FEL Linac. They are tested prior to the linac operation. The RF test includes processing of the superconducting cavities, as well as maximum module performance tests. The test procedure and the achieved performance together with the test statistical analysis are presented.

THP33	Progress toward NLC/GLC Prototype Accelerator Structures	dipole, simulation, impedance, pick-up	675
	J. Wang, G. Bowden, V.A. Dolgashev, R.M. Jones, J. Lewandowski, C.D. Nantista, S.G. Tantawi SLAC/ARDA, Menlo Park, California C. Adolphsen, D.L. Burke, J.Q. Chan, J. Cornuelle, S. Döbert SLAC/NLC, Menlo Park, California T. Arkan, C. Boffo, H. Carter, N. Khabiboulline FNAL, Batavia, Illinois N. Baboi DESY, Hamburg D. Finley, I. Gonin, S. Mishra, G. Romanov, N. Solyak Fermilab, Batavia, Illinois Y. Higashi, T. Higo, T. Kumi, Y. Morozumi, N. Toge, K. Ueno KEK, Ibaraki Z. Li, R. Miller, C. Pearson, R.D. Ruth, P.B. Wilson, L. Xiao SLAC, Menlo Park, California
	The accelerator structure groups for NLC (Next Linear Collider) and GLC (Global Linear Colliders) have successfully collaborated on the research and development of a major series of advanced accelerator structures based on room-temperature technology at X-band frequency. The progress in design, simulation, microwave measurement and high gradient tests are summarized in this paper. The recent effort in design and fabrication of the accelerator structure prototype for the main linac is presented in detail including HOM (High Order Mode) suppression and couplers, fundamental mode couplers, optimized accelerator cavities as well as plans for future structures. We emphasize techniques to reduce the field on the surface of the copper structures (in order to achieve high accelerating gradients), limit the dipole wakefields (to relax alignment tolerance and prevent a beam break up instability) and improve shunt impedance (to reduce the RF power required).

THP34	A High-Power Test of an X-Band Molybdenum-Iris Structure	vacuum, klystron, linear-collider, collider	678
	W. Wuensch, A. Grudiev, T. Heikkinen, I. Syratchev, T. Taborelli, I. Wilson CERN, Geneva C. Adolphsen SLAC/NLC, Menlo Park, California S. Döbert SLAC, Stanford
	In order to achieve accelerating gradients above 150 MV/m, alternative materials to copper are being investigated by the CLIC study. The potential of refractory metals has already been demonstrated in tests in which a tungsten-iris and a molybdenum-iris structure reached 150 and 193 MV/m respectively (30 GHz and a pulse length of 15 ns). In order to extend the investigation to the pulse lengths required for a linear collider, a molybdenum-iris structure scaled to X-band was tested at the NLCTA. The structure conditioned to only 65 MV/m (100 ns pulse length) in the available testing time and much more slowly than is typical of a copper structure. However the structure showed no sign of saturation and a microscopic inspection of the rf surfaces corroborated that the structure was still at an early stage of conditioning. The X-band and 30 GHz results are compared and what has been learned about material quality, surface preparation and conditioning strategy is discussed.
	Transparencies

THP37	Approaches to Beam Stabilization in X-Band Linear Colliders	feedback, luminosity, ground-motion, linear-collider	687
	J. Frisch, L. Hendrickson, T. Markiewicz, A. Seryi SLAC, Menlo Park, California P. Burrows, S. Molloy, G. White Queen Mary University of London, London C. Perry OXFORDphysics, Oxford, Oxon T.O. Raubenheimer, T. Thomas SLAC/NLC, Menlo Park, California
	In order to stabilize the beams at the interaction point, the X-band linear collider proposes to use a combination of techniques: inter-train and intra-train beam-beam feedback, passive vibration isolation, and active vibration stabilization based on either accelerometers or laser interferometers. These systems operate in a technologically redundant fashion: simulations indicate that if one technique proves unusable in the final machine, the others will still support adequate luminosity. Experiments underway for all of these technologies, have already demonstrated adequate performance.

THP41	Development of High RF Power Delivery System for 1300 MHz Superconducting Cavities of Cornell ERL Injector	coupling, alignment, insertion, superconductivity	694
	S.A. Belomestnykh, M. Liepe, V. Medjidzade, H. Padamsee, V. Veshcherevich LEPP, Ithaca, New York N.P. Sobenin MEPhI, Moscow
	Development of a 150 kW CW RF power delivery system for 1300 MHz superconducting cavities is under way at Cornell University in collaboration with MEPhI. The system is based on a twin-coupler consisting of two identical coaxial antenna-type couplers derived from the TTF-3 input coupler design. Because the average power is much higher than in the TTF-3 coupler, the required coupling is stronger and we wanted to avoid multipacting phenomena, major changes were made to the prototype design. Presented coupler has completely redesigned cold part and significantly improved cooling of warm bellows. The results of thermal and mechanical stress calculations are reported. The magnitudes and phases of RF fields applied to each side of the twin-coupler must be very close to each other. This imposes very strict requirements upon a power dividing system. These requirements and proposed layout of a system satisfying them are discussed.

THP44	The Design and Performance of the Spallation Neutron Source Low-Level RF Control System	controls, feedback, klystron, coupling	703
	M. Champion, M. Crofford, K. Kasemir, H. Ma, C. Piller ORNL/SNS, Oak Ridge, Tennessee L. Doolittle, C. Lionberger, M. Monroy, A. Ratti LBNL, Berkeley, California J. Power, H. Shoee LANL, Los Alamos, New Mexico
	The Spallation Neutron Source linear accelerator low-level RF control system has been developed within a collaboration of Lawrence Berkeley, Los Alamos, and Oak Ridge national laboratories. Three distinct generations of the system, described in a previous publication [1], have been used to support beam commissioning at Oak Ridge. The third generation system went into production in early 2004, with installation in the coupled-cavity and superconducting linacs to span the remainder of the year. The final design of this system will be presented along with results of performance measurements. [1] M. Champion, et al, "The Spallation Neutron Source Accelerator Low Level RF Control System", Proceedings of the PAC2003 Conference, Portland, Oregon.

THP46	Cable Insulation Breakdowns in the Modulator with a Switch Mode High Voltage Power Supply	power-supply, photon, simulation, klystron	709
	A. Cours ANL, Argonne, Illinois
	The Advanced Photon Source modulators are PFN-type pulsers with 40 kV switch mode charging power supplies (PSs). The PS and the PFN are connected to each other by 18 feet of high-voltage (HV) cable. Another HV cable connects two separate parts of the PFN. The cables are standard 75 kV x-ray cables. All four cable connectors were designed by the PS manufacturer. Both cables were operating at the same voltage level (about 35 kV). The PS’s output connector has never failed during five years of operation. One of the other three connectors failed approximately five times more often than the others. In order to resolve the failure problem, a transient analysis was performed for all connectors. It was found that transient voltage in the connector that failed most often was subjected to more high-frequency, high-amplitude AC components than the other three connectors. It was thought that these components caused partial discharge in the connector insulation and led to the insulation breakdown. Modification of the PFN eliminated one HV cable and significantly reduced the AC components during the pulse. A connector with higher partial discharge inception voltage was chosen as a replacement.

THP48	A High-Resolution S-band Down-Converting Digital Phase Detector for SASE FEL Use	photon, feedback, simulation, free-electron-laser	715
	A.E. Grelick, N.D. Arnold ANL/APS, Argonne, Illinois J. Carwardine, N. Dimonte, A. Nassiri, T. Smith ANL, Argonne, Illinois
	Each of the rf phase detectors in the Advanced Photon Source linac consists of a module that down converts from S-band to 20 MHz followed by an analog I/Q detector. Phase is calculated from one digitized sample per pulse each of I and Q. The resulting data has excellent long-term stability but is noisy enough so that a number of samples must be averaged to get a usable reading. The more recent requirement to support a SASE FEL has presented the need to accurately resolve the relative phase of a single pulse. Replacing analog detection with digital sampling and replacing internal intermediate frequency reference oscillators with a lower noise external oscillator were used to control the two largest components of noise. The implementation of a central, ultralow noise reference oscillator and a distribution system capable of maintaining the low phase noise is described, together with the results obtained to date. The principal remaining technical issue is determining the processing power required as a function of measurement channels per processor, measured pulse repetition rate, intrapulse data bandwidth, and digital filter characteristics. The options and tradeoffs involved and the present status are discussed.

THP51	Tuning of External Q And Phase for The Cavities of A Superconducting Linear Accelerator	impedance, scattering, resonance, coupling	724
	V.V. Katalev, S. Choroba DESY, Hamburg
	The RF power required for a certain gradient of a superconducting cavity depends on the beam current and coupling between the cavity and waveguide. The coupling with the cavity may be changed by variation of Qext. Different devices can be used to adjust Qext or phase. In this paper three stub and E-H tuners are compared and their usability for the RF power distribution system for the superconducting accelerator of the European Xray laser and the TESLA linear collider is considered. The tuners were analyzed by using the scattering matrix. Advantages and limitations of the devices are presented.

THP52	RF Reference Distribution System for the J-PARC Linac	klystron, power-supply, feedback, rfq	727
	T. Kobayashi, E. Chishiro JAERI, Ibaraki-ken S. Anami, S. Michizono, S. Yamaguchi KEK, Ibaraki
	J-PARC (Japan Proton Accelerator Complex) linac, which is 300 m long, consists of 324 MHz accelerating section of the upstream and 972 MHz section (as future plan) of the downstream. In the klystron gallery, totally about 50 RF source control stations will stand for the klystrons and solid-state amplifiers. The error of the accelerating field must be within ±1° in phase and ±1% in amplitude. Thus, the high phase stability is required to the RF reference for all of the low-level RF control systems and the beam monitor systems. This paper presents a final design of the RF reference distribution system for this linac. The RF reference (12 MHz) is distributed to all stations optically. Low-jitter E/O and O/E with temperature stabilizers are developed. The reference is optically amplified and divided into 14 transmission lines, and is delivered through PSOF (the phase-stabilized optical fiber), the temperature of which is stabilized by cooling water. Each of the transmitted signals is divided more into 4 signals by an optical coupler. Our objective for the phase stability of the reference aims at <±0.3° at a 972 MHz frequency.

THP53	Quasi-Optical Components for Future Linear Colliders	radiation, impedance, alignment, linear-collider	730
	S. Kuzikov, G. G. Denisov, M. Yu. Shmelyov IAP, Nizhniy Novgorod J.L. Hirshfield Omega-P, Inc., New Haven, Connecticut
	This paper presents a concept of the quasi-optical RF system for future Ka-band electron-positron linear collider. According to this concept two RF feeding systems are considered: a Delay Line Distribution System (DLDS) and a pulse compressor based on the multi-mirror traveling-wave resonator. The DLDS is based on oversized waveguides. In such waveguides the so-called image multiplication phenomena are used for power launching, extracting, combining, and splitting of waves. Recent low power tests of mode launchers and other DLDS components are discussed. The 34 GHz pulse compressors, based on three and four-mirror resonators, are considered. The tests of the prototypes at a low power level under different modulation methods are discussed. The simulations and tests of mode converters, miter bends, RF loads, and other components, to be necessary for both compression systems, also are resulted.

THP55	Electromagnetic Design of New RF Power Couplers for the S-DALINAC	electron, emittance, simulation, electromagnetic-fields	736
	M. Kunze, M. Brunken, H.-D. Gräf, W.F.O. Müller, A. Richter, T. Weiland TU Darmstadt, Darmstadt
	New rf power couplers for the Superconducting Darmstadt Linear Accelerator (S-DALINAC) injector have to be designed to transfer rf power of up to 2 kW to the electron beam. This allows injector operation at beam currents from 0.15 mA to 0.2 mA and electron energies up to 14 MeV. The new couplers should possibly provide a external Q of 5·10⁶. The transverse kick should be as small as possible. The asymmetric field distribution of the couplers causes emittance growth of the electron beam and therefore the transverse kick has to be minimized. Electromagnetic simulations are applied to investigate different coupler designs and to localize possible problems at an early stage. Cavity external Q and transverse kick can be calculated from 3D electromagnetic eigenmode solutions. The present coaxial-coaxial input couplers at the S-DALINAC are limited to power operation below 500 W under full reflection. In order to reach power operation up to 2 kW a realizations of a low-kick waveguide coupler for the S-DALINAC injector is presented, namely a twin-waveguide coupler.
	Transparencies

THP56	Control of the Low Level RF System for J-Parc Linac	klystron, feedback, proton, vacuum	739
	S. Michizono, S. Anami, E. Kadokura, S. Yamaguchi KEK, Ibaraki E. Chishiro, T. Kobayashi, .H. Suzuki JAERI, Ibaraki-ken
	A low level RF (LLRF) system for J-Parc linac generates RF and clock signals, drives a klystron, and stabilizes accelerating fields in the cavities. The LLRF system is controlled by two units: a programmable logic controller (PLC) and a compact PCI (cPCI) controller. Functions of the PLC are ON/OFF and UP/DOWN controls, and STATUS and ANALOG monitors. The PLC is locally operated by a touch panel, and remotely operated by an EPICS IOC with Ethernet communication. The cPCI controller is for RF feedback and feed-forward controls, including a cavity tuner control, and then, locally and remotely operated by communication with the PLC. On the other hand, RF waveform data, which are stored in the memory of DSP and CPU boards in the cPCI, are directory transmitted to an EPICS OPI by a request from EPICS.

THP57	Digital Feedback System for J-Parc Linac RF Source	feedback, simulation, klystron, proton	742
	S. Michizono, S. Anami, S. Yamaguchi KEK, Ibaraki T. Kobayashi J-PARC, Ibaraki-ken
	At the proton linac of J-Parc (Japan Proton Accelerator Research Complex), an accelerating electric field stability of ±1% in amplitude and ±1° in phase is required for the RF system. In order to accomplish these requirements, a digital feedback system is adopted for flexibility of the feedback (FB) and feed forward (FF) algorism implementation. FPGAs are used for the real-time FB system. A DSP board is also utilized for data processing and communication between FPGAs and a crate control CPU (Host). The system was examined with the DTL cavity and it satisfies the stability specification. In this report, the digital rf system is described and operational stability is also summarized.

THP59	Low Level RF Including a Sophisticated Phase Control System for CTF3	klystron, collider, linear-collider, beam-loading	748
	J. Mourier, R. Bossart, J. Nonglaton, I. Syratchev, L. Tanner CERN, Geneva
	CTF3 (CLIC Test Facility 3), currently under construction at CERN, is a test facility designed to demonstrate the key feasibility issues of the CLIC (Compact LInear Collider) two-beam scheme. When completed, this facility will consist of a 150 MeV linac followed by two rings for bunch-interleaving, and a test stand where 30 GHz power will be generated. In this paper, the work that has been carried out on the linac’s low power RF system is described. This includes, in particular, a sophisticated phase control system for the RF pulse compressor to produce a flat-top rectangular pulse over 1.4 μs.

THP61	SKIP - A Pulse Compressor for SuperKEKB	coupling, acceleration, positron, resonance	754
	T. Sugimura, M. Ikeda, K. Kakihara, T. Kamitani, S. Ohsawa, K. Yokoyama KEK, Ibaraki
	An upgrade of KEKB injector linac is planned. A main purpose of this upgrade is to increase injection energy of positrons from 3.5 GeV to 8.0 GeV for the SuperKEKB project. By a limitation of land area, our choice is to double an acceleration field utilizing a C-band accelerator structures instead of present S-band structures. Last year we developed C-band components such as accelerator structure, dummy load, 3 dB hybrid coupler, RF window, sub booster, modulator system, and so on. These components were assembled at a test stand and processed. This accelerator unit was installed in the beam line of injector linac and has been under operation. This summer we will install an RF pulse compressor system to the C-band accelerator unit. This paper reports the status of development of the RF pulse compressor system.

THP65	Low-Power RF Tuning of the Spallation Neutron Source Warm LINAC Structures	coupling, pick-up, target, vacuum	760
	C. Deibele, G. Johnson ORNL, Oak Ridge J. Billen, N.K. Bultman, J. Stovall LANL, Los Alamos, New Mexico J. Error, P. Gibson ORNL/SNS, Oak Ridge, Tennessee J. Manolitsas, D. Trompetter ACCEL, Bergisch Gladbach A. Vasyuchenko RAS/INR, Moscow L. Young TechSource, Santa Fe, NM
	The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built at Oak Ridge National Laboratory. A conventional 402.5 MHz drift-tube linac (DTL) accelerates the beam from 2.5 to 86 MeV, and the 805 MHz coupled-cavity linac (CCL) continues acceleration to 186 MeV. Tuning the six DTL tanks involves adjusting post-coupler lengths and slug tuners to achieve the design resonant frequency and stabilized field distribution. A 2.5 MW klystron feeds RF power into each DTL tank through a ridge-loaded waveguide that does not perturb either the frequency or field distribution in the tank. The CCL consists of 4 RF modules operating in the βλ/2 mode. Each module contains 96 accelerating cavities in 12 segments of 8 cavities each, 11 active bridge coupler cavities, and 106 nominally unexcited coupling cavities. For each RF module, power from a single 5 MW klystron splits once and drives bridge couplers 3 and 9. We will discuss the special tools and measurement techniques developed for the low-power tuning activities.

THP66	Measurement and Control of Microphonics in High Loaded-Q Superconducting RF Cavities	damping, beam-loading, superconductivity, feedback	763
	T.L. Grimm, W. Hartung, T.H. Kandil, H. Khalil, J. Popielarski, J. Vincent, R.C. York NSCL, East Lansing, Michigan C. Radcliffe MSU, East Lansing, Michigan
	Superconducting radio frequency (SRF) linacs with light beam loading, such as the CEBAF upgrade, RIA and energy recovery linacs, operate more efficiently with loaded-Q values >1·10⁷. The narrow band-width puts stringent limits on acceptable levels of vibration, also called microphonics, that detune the SRF cavities. Typical sources of vibration are rotating machinery, fluid fluctuations and ground motion. A prototype RIA 805 MHz v/c=0.47 cryomodule is presently under test in realistic operating conditions [1]. Real-time frequency detuning measurements were made for modulation rates from DC to 1 kHz. At 2 K the maximum frequency deviation was less than 100 Hz peak-to-peak, and was consistent with high loaded-Q operation. The measured modulation spectrum was primarily made up of discrete Fourier components with modulation frequencies less than 80 Hz. Using an accelerometer and helium pressure transducer, the primary sources of vibration were determined to be the high power cryoplant motors and 2 K helium fluctuations. Adaptive feedforward was used to decrease the magnitude of individual Fourier components by four to ten times [2]. Details of the experimental setup and measurements will be presented. [1] “Experimental Study of an 805 MHz Cryomodule for the Rare Isotope Accelerator”, T.L. Grimm et al., THP70, these proceedings. [2] “Adaptive Feedforward Cancellation (AFC) of Sinusoidal Disturbances in SRF Cavities”, H. Khalil et al., TUP76, these proceedings.
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THP69	The Tuning Study of the Coupled Cavities for the RF Chopper System of J-PARC	simulation, coupling, proton, insertion	770
	S. Wang, S. Fu IHEP Beijing, Beijing T. Kato KEK, Ibaraki
	A 3 MeV medium-energy beam transport line (MEBT) is located between RFQ and DTL in the linac of the Japan Proton Accelerator Research Complex (J-PARC). MEBT accomplishes beam matching and chopping. An rf deflector (RFD), which is a heavily loaded cavity, was adopted as a chopper in J-PARC linac for chopping 500 μs long macropulses from the ion source into sub-pulses for injecting into the following 3 GeV rapid-cycling ring. A coupled RFD system was proposed in the design of chopper system for saving the cost of rf power source. The tuning of the coupled RFD system was successfully performed. The longer rise time of the second RFD and the delay of the second RFD excitation were found during the tuning of the coupled RFD system, and these phenomena were further analyzed and investigated. Both in the high power and beam tests, the chopper worked well without any discharge under 36 kW peak driving power.

THP70	Experimental Study of an 805 MHz Cryomodule for the Rare Isotope Accelerator	vacuum, resonance, alignment, coupling	773
	T.L. Grimm, S. Bricker, C. Compton, W. Hartung, M. Johnson, F. Marti, J. Popielarski, R.C. York NSCL, East Lansing, Michigan G. Ciovati, P. Kneisel Jefferson Lab, Newport News, Virginia L. Turlington TJNAF, Newport News, Virginia
	The Rare Isotope Accelerator (RIA) driver linac will use superconducting, 805 MHz, 6-cell elliptical cavities with geometric β values of 0.47, 0.61 and 0.81. Each elliptical cavity cryomodule will have four cavities [1]. Room temperature sections between each cryomodule will consist of quadrupole doublets, beam instrumentation, and vacuum systems. Michigan State University (MSU) has designed a compact cryostat that reduces the tunnel cross-section and improves the linac real estate gradient. The cold mass alignment is accomplished with a titanium rail system supported by adjustable nitronic links from the top vacuum plate, and is similar to that used for existing MSU magnet designs. The same concept has also been designed to accommodate the quarter-wave and half-wave resonators with superconducting solenoids used at lower velocity in RIA. Construction of a prototype β=0.47 cryomodule was completed in February 2004 and is presently under test in realistic operating conditions. Experimental results will be presented including: alignment, electromagnetic performance, frequency tuning, cryogenic performance, low-level rf control, and control of microphonics. [1] “Cryomodule Design for the Rare Isotope Accelerator”, T.L. Grimm, M. Johnson and R.C. York, PAC2003, Portland OR (2003)

THP72	A Newly Designed and Optimized CLIC Main Linac Accelerating Structure	damping, luminosity, dipole, vacuum	779
	A. Grudiev, W. Wuensch CERN, Geneva
	A new CLIC main-linac accelerating-structure design, HDS (Hybrid Damped Structure), with improved high-gradient performance, efficiency and simplicity of fabrication is presented. The gains are achieved in part through a new cell design which includes fully-profiled rf surfaces optimized to minimize surface fields and hybrid damping using both iris slots and radial waveguides. The slotted irises allow a simple structure fabrication in quadrants with no rf currents across joints. Further gains are achieved through a new structure optimization procedure, which simultaneously balances surface fields, power flow, short and long-range transverse wakefields, rf-to-beam efficiency and the ratio of luminosity to input power. The optimization of a 30 GHz structure with a loaded accelerating gradient of 150 MV/m results in a bunch spacing of eight rf cycles and 29% rf-to-beam efficiency. The dependencies of performance on operating frequency, accelerating gradient, and phase advance per cell are shown.

THP75	Superconducting Accelerating Structure with Gradient as 2 Times Higher as TESLA Structure	coupling, impedance, acceleration	785
	P. V. Avrakhov, V.E. Balakin PTC LPI, Protvino, Moscow Region
	A proposed new accelerating structure for TESLA is assumed to have an effective gradient 2 times more than existing 9-cell cavity. This structure is an interlaced combination of two side-cavity-coupled standing wave substructures with λ/4 cells length. Intercell coupling provides side-coupled cavities made from a special shape waveguide section. The high accelerating gradient is accomplished by 4 factors: The shortened accelerating cells have transit time factor 0.9 instead of 0.64 for conventional standing wave cells with λ/2 length. The side magnetic coupling has made it possible to reduce the cells beam aperture that reduce relation between the maximum surface field and the acceleration gradient. Stronger intercell coupling allows extending the accelerating cavity and improving a duty factor of linac. Availability of the side coupling elements enables to use them for power input and HOM-couplers. It reduces intercavity distance and enhances duty factor too.

THP82	Experiences in Fabrication and Testing the Prototype of the 4.90 GHz Accelerating Sections for MAMI C	coupling, vacuum, resonance, microtron	788
	A. Jankowiak, H. Euteneuer, S. Schumann, O. Tchoubarov IKP, Mainz
	The fourth stage of the Mainz Microtron (MAMI) is under construction as a 855 to 1500 MeV Harmonic Double Sided Microtron[1], with one of its two linacs operating at the MAMI-frequency of 2.45 GHz, the other at 4.90 GHz. The bi-periodic on axis coupled accelerating structure in operation at MAMI has been optimised for 4.90 GHz[2], such a high frequency till now not having been used for high power cw-acceleration. To ensure a smooth and efficient industrial production of the ten 35 AC-sections needed, a prototype was built and high power tested fully in-house at IKPH. After a short recapitulation of the design of the cavity profile, the configuration of the section with its tuners and diagnostic probes is discussed. Details of the procedures of machining, tuning and brazing the resonator discs, and the rf-parameters achieved for the section are given. Finally, the experiences and measurements during its high power test up to 22 kW are reported: the conditioning behaviour and the irreversible permanent as well as the reversible dynamic changes of passband gap and resonance frequency as a function of maximal applied rf-power. [1] A. Jankowiak et al., "Design and Status of the 1.5 GeV-Harmonic Double Sided Microtron for MAMI", Proceedings EPAC2002, [2] H. Euteneuer et al., "The 4.90GHz Accelerating structure for MAMI C", Proceedings EPAC2000
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THP86	Low Power Measurements on a Finger Drift Tube Linac	simulation, ion, booster, rfq	800
	A. Schempp, K.-U. Kühnel IAP, Frankfurt-am-Main C.P. Welsch MPI-K, Heidelberg
	The efficiency of RFQs decreases at higher particle energies. The DTL structures used in this energy regions have a defocusing influence on the beam. To achieve a focusing effect, fingers with quadrupole symmetry were added to the drift tubes. Driven by the same power supply as the drift tubes, the fingers do not need an additional power source or feedthrough. Beam dynamics have been studied with PARMTEQ . Detailed analysis of the field distribution was done and the geometry of the finger array has been optimized with respect to beam dynamics. A spiral loaded cavity with finger drift tubes was built up and low power measurements were done. In this contribution, the results of the rf simulating with Microwave Studio are shown in comparison with bead pertubation measurement on a prototype cavity.

THP88	Longitudinal Bunch Shape Monitor Using the Beam Chopper of the J-PARC	rfq, emittance, proton, beam-transport	806
	F. Naito KEK, Ibaraki
	We propose the longitudinal bunch shape monitor for the low energy part of the linac of the J-PARC. The monitor uses the beam chopper cavity installled in the MEBT line between thr RFQ and the DTL of the J-PARC as a kind of the bunch rotator. Consequentry the longitudinal bunch shape is measured along the horizontal direction. If we can measure the energy distribution of the bunch also, the longitudinal emittance of the beam is derived. In the paper, the basic idea of the monitor is discussed in detail.

THP89	Measured RF Properties of the DTL for the J-PARC	insertion, target, synchrotron, quadrupole	809
	H. Tanaka, T. Kato, F. Naito, E. Takasaki KEK, Ibaraki H. Asano, T. Morishita JAERI, Ibaraki-ken T. Itou JAERI/LINAC, Ibaraki-ken
	RF properties of the second DTL tank for J-PARC have been measured in KEK. The required flatness and stability of the accelerating field of the tank have been achieved by the tunung of the post-couplers, whose shape were modified to adjust the resonant frequency ?324 MHz). Because the third DTL tank has assembled, the rf measurement and the post-coupler tuning will be started soon. Thus the measured results for both tanks will be described in the paper.

THP90	The Technique for the Numerical Tolerances Estimations in the Construction of Compensated Accelerating Structures	coupling, booster, proton, survey	812
	V.V. Paramonov, A.K. Skasyrskaya RAS/INR, Moscow
	The requirements to the cells manufacturing precision and tining in the multi-cells accelerating structures construction came from the required accelerating field uniformity, based on the beam dynamics demands. The standard deviation of the field distribution depends on accelerating and coupling modes frequencies deviations, stop-band width and coupling coefficient deviations. These deviations can be determined from 3D fields distribution for accelerating and coupling modes and the cells surface displacements. With modern software it can be done separately for every specified part of the cell surface. Finally, the cell surface displacements are defined from the cell dimensions deviations. This technique allows both to define qualitatively the critical regions and to optimize quantitatively the tolerances definition.

THP93	A 3D Self-Consistent, Analytical Model for Longitudinal Plasma Oscillation in a Relativistic Electron Beam	plasma, electron, space-charge, simulation	818
	G. Geloni, E. Saldin, E. Schneidmiller, M.V. Yurkov DESY, Hamburg
	Longitudinal plasma oscillations are becoming a subject of great interest for XFEL physics in connection with LSC microbunching instability[1] and certain pump-probe synchronization schemes[2]. In the present paper we developed the first exact analytical treatment for longitudinal oscillations within an axis-symmetric, (relativistic) electron beam, which can be used as a primary standard for benchmarking space-charge simulation codes. Also, this result is per se of obvious theoretical relevance as it constitutes one of the few exact solutions for the evolution of charged particles under the action of self-interactions. [1] E. Saldin et al., "Longitudinal Space Charge Driven Microbunching instability in TTF linac", TESLA-FEL-2003-02, May 2003, [2] J. Feldhaus et al., "Two-color FEL amplifier for femtosecond-resolution pump-probe experiments with GW-scale X-ray and optical pulses",DESY 03-091, July 2003

THP94	Cold Tests of a 160 MHz Half-Wave Resonator	resonance, coupling, simulation, vacuum	821
	R. Stassen, R. Maier FZJ/IKP, Jülich R. Eichhorn, F. M. Esser, B. Laatsch, G. Schug, H. Singer FZJ, Jülich
	The number of polarized particle in the cooler synchrotron COSY is limited by the present injector system. A new linac was projected based on superconductive half-wave resonators to fill COSY up to the space charge limit. The first prototype of a 160 MHz Half-Wave Resonator (HWR) has been built and tested. RF-measurements in CW as well as in a pulsed operation will be presented. A second prototype with a slightly different way of fabrication will be completed soon. All measurements have been done using the new 4 kW loop-coupler. The use of a cold window allows to change the coupling from 1· 10⁶ to 1· 10¹⁰ without any risk of contamination. The mechanical tuner consisting of a stepper motor driven coarse tuner and a fast piezo system to compensate the Lorentz-Force detuning has successfully integrated into the vertical test-cryostat.

FR101	Overview of Linear Collider Test Facilities and Results	emittance, collider, linear-collider, damping	827
	H. Hayano KEK, Ibaraki
	Linear Collider technology will be recommended by the International Technology Recommendation Panel (ITRP) to the International Linear Collider Steering Committee (ILCSC), soon. Towards this recommendation, many efforts of the developments and the output results of each technology have been made to satisfy the requirements of the technical review committee report (TRC). The test facilities of each linear collider design are the place of the key technology demonstration and realization. The overview of the LC test facilities activities and outputs of TTF, NLCTA, ATF/GLCTA and CTF are summarized and reviewed.
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FR103	Status of the SNS Linac: An Overview	target, laser, proton, rfq	837
	N. Holtkamp ORNL, Oak Ridge
	The Spallation Neutron Source SNS is a second generation pulsed neutron source and under construction at Oak Ridge National Laboratory. The SNS is funded by the U.S. Department of Energy?s Office of Basic energy Sciences and is dedicated to the study of the structure and dynamics of materials by neutron scattering. A collaboration composed of six national laboratories (ANL, BNL, TJNAF, LANL, LBNL, ORNL) is responsible for the design and construction of the various subsystems. With the official start in October 1998, the operation of the facility will begin in 2006 and deliver a 1.0 GeV, 1.4 MW proton beam with a pulse length of approximately 700 nanoseconds on a liquid mercury target. The multi-lab collaboration allowed access to a large variety of expertise in order to enhance the delivered beam power by almost an order of magnitude compared to existing neutron facilities. The SNS linac consists of a combination of room temperature and superconducting structures and will be the first pulsed high power sc linac in the world. The challenges and the achievements will be described in the paper. SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy. SNS is a partnership of six national laboratories: Argonne, Brookhaven, Jefferson, Lawrence Berkeley, Los Alamos and Oak Ridge.
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FR201	Accelerator Control and Global Networks - State of the Art	controls, feedback, linear-collider, collider	847
	D.P. Gurd ORNL, Oak Ridge
	As accelerators increase in size and complexity, demands upon their control systems increase correspondingly. Machine complexity is reflected in complexity of control system hardware and software and careful configuration management is essential. Model-based procedures and fast feedback based upon even faster beam instrumentation are often required. Managing machine protection systems with tens of thousands of inputs is another significant challenge. Increased use of commodity hardware and software introduces new issues of security and control. Large new facilities will increasingly be built by national (e.g. SNS) or international (e.g. a linear collider) collaborations. Building an integrated control system for an accelerator whose development is geographically widespread presents particular problems, not all of them technical. Recent discussions of a “Global Accelerator Network” include the possibility of multiple remote control rooms and no more night shifts. Based upon current experience, observable trends and rampant speculation, this paper looks at the issues and solutions-–-some real, some probable, and some pie-in-the-sky. *Spallation Neutron Source, ORNL and LANL
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FR202	Status of High-Power Tests of Dual Mode SLED-II System for an X-Band Linear Collider	vacuum, linear-collider, collider, coupling	852
	S.G. Tantawi SLAC/ARDA, Menlo Park, California V.A. Dolgashev, C.D. Nantista SLAC/ARDB, Menlo Park, California
	We have produced 400 ns rf pulses of greater than 500 MW at 11.424 GHz with an rf system designed to demonstrate technology capable of powering a TeV scale electron-positron linear collider. Power is produced by four 50 MW X-band klystrons run off a common 400 kV solid-state modulator. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant-line (SLED-II) pulse compression system. Dual-moding of the transmission lines allows power to be directed through a pulse compression path or a bypass path; dual-moding in the pulse compressor allows the delay lines to be about half as long as they otherwise would need to be. We describe the design and performance of various components, including hybrids, directional couplers, power dividers, tapers, mode converters, and loads. These components are mostly overmoded to allow for greater power handling. We also present data on the processing and operation of this system. The power from that system is transported to feed a set accelerator structure. We will present the design and the high power testing data for the overmoded transfer line and the distribution network.
	Transparencies