04 Hadron Accelerators
A08 Linear Accelerators

Paper	Title	Page
TUOAA03	The Linac4 Project at CERN	900
	M. Vretenar, L. Arnaudon, P. Baudrenghien, C. Bertone, Y. Body, J.C. Broere, O. Brunner, M.C.L. Buzio, C. Carli, F. Caspers, J.-P. Corso, J. Coupard, A. Dallocchio, N. Dos Santos, R. Garoby, F. Gerigk, L. Hammouti, K. Hanke, M.A. Jones, I. Kozsar, J.-B. Lallement, J. Lettry, A.M. Lombardi, L.A. Lopez Hernandez, C. Maglioni, S.J. Mathot, S. Maury, B. Mikulec, D. Nisbet, C. Noels, M.M. Paoluzzi, B. Puccio, U. Raich, S. Ramberger, C. Rossi, N. Schwerg, R. Scrivens, G. Vandoni, J. Vollaire, S. Weisz, Th. Zickler CERN, Geneva, Switzerland
	As the first step of a long-term programme aiming at an increase in the LHC luminosity, CERN is building a new 160 MeV H− linear accelerator, Linac4, to replace the ageing 50 MeV Linac2 as injector to the Proton-Synchrotron Booster (PSB). Linac4 is an 86-m long normal-conducting linac made of an H− source, a Radio Frequency Quadrupole (RFQ), a chopping line and a sequence of three accelerating structures: a Drift-Tube Linac (DTL), a Cell-Coupled DTL (CCDTL) and a Pi-Mode Structure (PIMS). The civil engineering has been recently completed, and construction of the main accelerator components has started with the support of a network of international collaborations. The low-energy section up to 3 MeV including a 3-m long 352 MHz RFQ entirely built at CERN is in the final construction phase and is being installed on a dedicated test stand. The present schedule foresees beam commissioning of the accelerator in the new tunnel in 2013/14; the moment of connection of the new linac to the CERN accelerator chain will depend on the LHC schedule for long shut-downs.
	Slides TUOAA03 [10.347 MB]
WEPS031	Future Heavy Ion Linacs at GSI	2550
	W.A. Barth, G. Clemente, L.A. Dahl, S. Mickat, B. Schlitt, W. Vinzenz GSI, Darmstadt, Germany
	The UNILAC-upgrade program for FAIR will be realized in the next three years; the required U28+-beam intensity of 15 emA (for SIS 18 injection). The replacement of the Alvarez-DTL by a new high energy linac is advised to provide a stable operation for the next decades. An additional linac-upgrade option sufficient to boost the beam energy up to 150 MeV/u may help to reach the desired heavy ion intensities in the SIS 100. The SHIP-upgrade program has also to be realized until 2011, such that an enhanced primary beam intensity at the target is available. It is planned to build a new cw-heavy ion-linac behind the present high charge state injector. This linac should feed the GSI flagship experiments SHIP and TASCA, as well as material research, biophysics and plasma physics experiments in the MeV/u-area. The whole injector family is housed by the existing constructions. Different layout scenarios of a multipurpose high intensity heavy ion facility will be presented.
WEPS032	Conceptual Study for the New HE-Linac at GSI	2553
	G. Clemente, W.A. Barth, B. Schlitt GSI, Darmstadt, Germany
	The commissioning of the first three modules of the FAIR accelerator facility is planned to be completed in 2016. At that time the DTL section of the UNILAC will be more than 40 years old. Different proposals for a new high intensity, heavy ion linac which will replace the ALVAREZ DTL as synchrotron injector are under discussion. This new High Energy-UNILAC will be design accordingly to the advanced FAIR requirements and will allow for complete and reliable multi-ion-operation for at least the next 30 years. In a first step it is foreseen to replace the first two DTL cavity, up to 4.7 AMeV. 4 IH cavities will be used to accelerate U4+ to 3 AMeV and, after gas stripping, another cavity will provide the second step of acceleration for U38+ to 4.77 AMeV. For the next upgrade different options concerning the injection energy are under investigation. The main target is to provide a higher charge state and a higher injection energy to increase the life time of the heavy ion beam inside the synchrotron. The paper presents the beam dynamics and RF investigation for the first upgrade together with a conceptual study design for the complete replacement of the GSI ALVAREZ DTL.
WEPS033	Matching a Laser Driven Proton Injector to a CH - Drift Tube Linacs	2556
	A. Almomani, M. Droba, U. Ratzinger IAP, Frankfurt am Main, Germany I. Hofmann HIJ, Jena, Germany
	Experimental results and theoretical predictions in laser acceleration of protons achieved energies of ten to several tens of MeV. The LIGHT project (Laser Ion Generation, Handling and Transport) is proposed to use the PHELIX laser accelerated protons and to provide transport, focusing and injection into a conventional accelerator. This study demonstrates transport and focusing of laser-accelerated 10 MeV protons by a pulsed 18 T magnetic solenoid. The effect of co-moving electrons on the beam dynamics is investigated. The unique features of the proton distribution like small emittances and high yield of the order of 1013 protons per shot open new research area. The possibility of creating laser based injectors for ion accelerators is addressed. With respect to transit energies, direct matching into DTL's seems adequate. The bunch injection into a proposed CH− structure is under investigation at IAP Frankfurt. Options and simulation tools are presented.
WEPS034	A CW RFQ Prototype	2559
	U. Bartz, A. Schempp IAP, Frankfurt am Main, Germany
	A short RFQ prototype was built for RF-tests of high power RFQ structures. We will study thermal effects and determine critical points of the design. HF-simulations with CST Microwave Studio and measurements were done. The cw-tests with 20 kW/m RF-power and simulations of thermal effects with ALGOR were finished successfully. The optimization of some details of the HF design is on focus now. First results and the status of the project will be presented.
WEPS035	Beam Measurements with the New RFQ Beam Matching Section at the Frankfurt Funneling Experiment	2562
	M. Baschke, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany H. Zimmermann Accelerator Services, Oberursel, Germany
	Funding: BMBF Funneling is a method to increase low energy beam currents in multiple stages. The Frankfurt Funneling Experiment is a model of such a stage. The experiment is built up of two ion sources with electrostatic lens systems, a Two-Beam-RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ. A funneling deflector combines the bunches to a common beam axis. A new beam transport system between RFQ accelerator and deflector has been constructed and mounted. With these extended RFQ-electrodes the drift between the Two-Beam-RFQ and the rf-deflector will be minimized and therefore unwanted emittance growth reduced. After first rf measurements current work are beam tests with the improved Two-Beam-RFQ. First results will be presented.
WEPS036	First Coupled CH Power Cavity for the FAIR Proton Injector	2565
	R. M. Brodhage, C. Fix, H. Podlech, U. Ratzinger IAP, Frankfurt am Main, Germany G. Clemente, L. Groening GSI, Darmstadt, Germany
	For the research program with cooled antiprotons at FAIR a dedicated 70 MeV, 70 mA proton injector is required. The main acceleration of this room temperature linac will be provided by six CH cavities operated at 325 MHz. Each cavity will be powered by a 2.5 MW Klystron. For the second acceleration unit from 11.5 MeV to 24.2 MeV a 1:2 scaled model has been built. Low level RF measurements have been performed to determine the main parameters and to prove the concept of coupled CH cavities. For this second tank technical and mechanical investigations have been performed in 2010 to develop a complete technical concept for the manufacturing. In Spring 2011, the construction of the first power prototype has started. The main components of this cavity will be ready for measurements in summer 2011. At that time, the cavity will be tested with a preliminary aluminum drift tube structure, which will allow precise frequency and field tuning. This paper will report on the recent technical development and achievements. It will outline the main fabrication steps towards that novel type of proton DTL. Also first low level RF measurements are expected.
WEPS037	RF Design of a 325 MHz 4-ROD RFQ	2568
	B. Koubek, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany L. Groening GSI, Darmstadt, Germany
	Usually 4-ROD Radio Frequency Quadrupoles (RFQ) are built for frequencies up to 216 MHz. For higher frequencies 4-VANE structures are more common. The advantages of 4-Rod structures, the greater flexibility for tuning and being more comfortable for maintenance, are motivating the development of a 4-Rod RFQ for higher frequencies than 216 MHz. In particular a 325 MHz RFQ with an output energy of 3 MeV is needed for the proton linac for the FAIR project of GSI. This paper reports about the design studies and the latest developments of this RFQ.
WEPS038	Development of CH-Cavities for the 17 MeV MYRRHA-Injector	2571
	D. Mäder, H. Klein, H. Podlech, U. Ratzinger, M. Vossberg, C. Zhang IAP, Frankfurt am Main, Germany
	Funding: European Union FP7 MAX Contract Number 269565 MYRRHA is conceived as an accelerator driven system (ADS) for transmutation of high level nuclear waste. The neutron source is created by coupling a proton accelerator of 600 MeV with a 4 mA proton beam, a spallation source and a sub-critical core. The IAP of Frankfurt University is responsible for the development of the 17 MeV injector operated at 176 MHz. The injector consists of a 1.5 MeV 4-Rod-RFQ and six CH-drifttube-structures. The first two CH-structures will be operated at room temperature and the other CH-structures are superconducting cavities assembled in one cryo-module. To achieve the extremely high reliability required by the ADS application, the design of the 17 MeV injector has been intensively studied, with respect to thermal issues, minimum peak fields and field distribution.
WEPS039	General Layout of the 17 MeV Injector for MYRRHA	2574
	H. Podlech, M. Busch, F.D. Dziuba, H. Klein, D. Mäder, U. Ratzinger, A. Schempp, R. Tiede, C. Zhang IAP, Frankfurt am Main, Germany M. Amberg HIM, Mainz, Germany
	Funding: European Union FP7 MAX Contract Number 269565 The MYRRHA Project (Multi Purpose Hybrid Reactor for High Tech Applications) at Mol/belgium will be a user facility with emphasis on research with neutron generated by a spallation source. One main aspect is the demonstration of nuclear waste technology using an accelerator driven system. A superconducting linac delivers a 4 mA, 600 MeV proton beam. The first accelerating section is covered by the 17 MeV injector. It consists of a proton source, an RFQ, two room temperature CH cavities and 4 superconducting CH-cavities. The initial design has used an RF frequency of 352 MHz. Recently the frequency of the injector has been set to 176 MHz. The main reason is the possible use of a 4-rod-RFQ with reduced power dissipation and energy, respectively. The status of the overall injector layout including cavity design is presented.
	Poster WEPS039 [2.281 MB]
WEPS040	The Driver Linac of the Neutron Source FRANZ	2577
	U. Ratzinger, B. Basten, L.P. Chau, H. Dinter, M. Droba, M. Heilmann, M. Lotz, O. Meusel, I. Müller, D. Mäder, Y.C. Nie, D. Noll, H. Podlech, A. Schempp, W. Schweizer, K. Volk, C. Wiesner, C. Zhang IAP, Frankfurt am Main, Germany
	FRANZ is under construction at the Goethe University Frankfurt. A 2MeV ± 100 keV proton beam will produce 1 keV to 200 keV neutrons on a Li7 target. Experiments are planned in the field of nuclear astrophysics as well as in applied physics. A dc operated proton source with a maximum beam current of 200 mA was successfully beam tested end of 2010. FRANZ will have two experimental areas: One for activation experiments with cw proton beams of a few mA generating a usable neutron flux of some 10 billion per square cm per second, the other one for 250 kHz, 1 ns short neutron bunches generated by 1 ns proton pulses of a few Ampere beam current. A special 2 MeV, 175 MHz high current cavity is realized at present as a RFQ-DTL combination. Novel techniques have been invented to reach the needed pulsed target beam current by a bunch compressor system. Work supported by HICforFAIR and GSI.
WEPS041	Tuning of the New 4-Rod RFQ for FNAL	2580
	J.S. Schmidt, B. Koubek, A. Schempp IAP, Frankfurt am Main, Germany
	For the injector upgrade at FNAL a 4-rod Radio Frequency Quadrupole (RFQ) with a resonance frequency of 200 MHz has been build. With this short structure of only 1.3 m a very compact injector design has been realized. Simulations with CST Microwave Studio® were performed for the design. Their results leading to the RF characterizations of the RFQ and the final RF setup which has been accomplished at IAP of the Goethe-University Frankfurt are presented in this paper.
WEPS043	From EUROTRANS to MAX: New Strategies and Approaches for the Injector Development	2583
	C. Zhang, H. Klein, D. Mäder, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede IAP, Frankfurt am Main, Germany
	Funding: The research leading to these results has received funding from the European Atomic Energy Community’s (Euratom) Seventh Framework Programme FP7/2007-2011 under grant agreement n° [269565]. As the successor of the EUROTRANS project, the MAX project is aiming to continue the R&D effects for a European Accelerator-Driven System and to bring the conceptual design to reality. The layout of the driver linac for MAX will follow the reference design made for the XT-ADS phase of the EUROTRANS project. For the injector part, new design strategies and approaches, e.g. half resonant frequency, half transition-energy between the RFQ and the CH-DTL, and using the 4-rod RFQ structure instead of the originally proposed 4-vane RFQ, have been conceived and studied to reach a more reliable CW operation at reduced costs. In this paper, the design and simulation results of the MAX injector are presented.
WEPS044	Status of the Ion Source and RFQ Test Bench at the Heidelberg Ion Beam Therapy Centre	2586
	R. Cee, E. Feldmeier, M. Galonska, Th. Haberer, J.M. Mosthaf, B. Naas, A. Peters, S. Scheloske, J. Schreiner, T. Winkelmann HIT, Heidelberg, Germany
	The possibility of cancer treatment with proton and carbon beams provides HIT (Heidelberg Ion Beam Therapy Centre) with an exceptional feature and gives it a unique position in Europe. In the future, the variety of available ions will be extended towards helium and oxygen. To allow fast switching between three of these ion species an additional ion-source / spectrometer combination will be installed in the LEBT. For comprehensive tests of the new components a dedicated test bench including a beam emittance analyzer has been set up at the HIT facility. It opens up the opportunity to perform detailed investigations of the improved ECR ion source with its enhanced extraction system and the redesigned RFQ of the HIT injector. Parallel to the measurements, the beam optical model of the assembly could be refined to better reproduce the beam diagnostic results. Since August 2010 the test bench has been in operation in different configurations. Behind the RFQ a beamline comprising a phase-probe-based time-of-flight system and beam current measurement devices is set up. The aim is to determine the RFQ working point and to validate the optimizations in terms of particle transmission.
WEPS045	Feasibility Study of a High-gradient Linac for Hadrontherapy	2589
	S. Verdú-Andrés, U. Amaldi, A. Degiovanni TERA, Novara, Italy A. Faus-Golfe, S. Verdú-Andrés IFIC, Valencia, Spain P.A. Posocco CERN, Geneva, Switzerland
	Funding: The research leading to this results has been funded by the Seventh Framework Program [FP7/2007-2013] under grant agreement number 215840-2. Compact, reliable and little consuming accelerators are needed for tumor treatment with hadrons. As solution, TERA proposes CABOTO (CArbon BOoster for Therapy in Oncology), a linac which boosts the energy of carbon ions and H2 molecules coming from a cyclotron. The linac, typically a Side-Coupled Linac (SCL), is divided into several modules. The beam energy can be varied in steps of about 15 MeV/u without using absorbers by acting on the power (amplitude and/or phase) that feeds the different modules of the linac. This work presents the structure design of a 5.7 GHz high repetition rate SCL for a cyclinac, that accelerates carbon ions from 150 up to 400 MeV/u in less than 25 meters. The beam dynamics for this linac and its particular energy selection system is also discussed for different beam energy outputs.
WEPS046	Longitudinal Beam Acceptance of J-PARC Drift Tube Linac	2592
	T. Maruta KEK/JAEA, Ibaraki-Ken, Japan M. Ikegami KEK, Ibaraki, Japan A. Miura, G.H. Wei JAEA/J-PARC, Tokai-mura, Japan H. Sako JAEA, Ibaraki-ken, Japan
	The longitudinal acceptance of the J-PARC Drift Tube Linac (DTL) was measured by synchronous phase scan method. The IMPACT simulation indicated DTL longitudinal acceptance is shrinked if the DTL tank level reduced, but beam energy finally acheved at the Linac is almost same as the case of nominal tank level. We measured the acceptance and confirmed the simulation is correct.
WEPS047	Beamloss Study at J-PARC Linac by using Geant4 Simulation	2595
	T. Maruta JAEA/J-PARC, Tokai-mura, Japan
	Beamloss is one of the key issue for intense hadron beam accelerators. Most of case, origin of beamloss is scattering process between beam particle and residual gas inside vacuum duct. In the case of J-PARC Linac, H− ions emitted from an Ion source are accelerated up to 181 MeV, then the beam is transported to RCS. The H− ion is the system comprised from a proton and two electrons. If the H− ion is scattered with residual gas, these one or two electrons are escaped, then H− becomes H0 or H+(proton). H0 or H+ is uncontrollable and finally it goes to beam duct. This process is based on physics process, and Geant4 is matched to this kind of simulation study. I programmed SDTL (50 MeV) to L3BT (181 MeV) section at J-PARC Linac by using Geant4 code. I also wrote H− and H0 library which makes it possible for Geant4 to simulate them. I will show the simulation results.
WEPS048	Dependence of Beam Loss on Vacuum Pressure Level in J-PARC Linac	2598
	G.H. Wei KEK/JAEA, Ibaraki-Ken, Japan K. Hirano, T. Maruta, A. Miura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan K. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	In J-PARC linac, a 181-MeV negative hydrogen beam is supported to a succeeding 3-GeV synchrotron with normal operation power at 100-300 kW. During operation, a beam loss in the straight section of the beam transport line immediately after the linac exit is found. The residual radiation level reaches 0.3 mSv/h on the surface of the vacuum chamber several hours after the beam shutdown with the linac beam power of 12 kW. We suppose that the residual gas scattering of negative hydrogen ions generates neutral hydrogen atoms and they give rise to the beam loss by hitting the vacuum chamber wall. To confirm this speculation, the vacuum pressure level in the linac had been changed in order to find the dependence of the beam loss on it. After data analysis, we found the relationship between beam loss amplitude, which was attained from beam loss signal, and vacuum pressure was linear. Corresponding deduction and simulation has been down according to the residual gas components in linac chamber. In this paper, we present the experimental result and some simulations in this study.
WEPS049	Floor Deformation of J-PARC Linac after the Tohoku Earthquake in Japan	2601
	T. Morishita, H. Asano JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan M. Ikegami KEK, Ibaraki, Japan
	J-PARC linac has finalized its precise alignment at the end of summer 2006, and the beam provision to the Rapid Cycling Synchrotron has been started at Sept. 2007. Since then, the deformation of the accelerator tunnel is small enough to keep the soundness of the alignment accuracy. Therefore, the linac has been operated without realignment of the accelerator components for these four years. However, the alignment has seriously been damaged due to the large earthquake at Mar. 11th, 2011 in eastern Japan. Now, work for restoration is being continued. In this paper, the deformation of the linac tunnel floor due to the earthquake is reported. Since then, aftershock happens frequently. We also report the stability of the tunnel floor.
WEPS050	The MEBT Design for the China Accelerator Driven System	2604
	H. Geng, H.F. Ouyang, J. Tang IHEP Beijing, Beijing, People's Republic of China Z. Li, S. Pei, F. Yan IHEP Beijng, Beijing, People's Republic of China
	The Medium Eneryg Beam Transport (MEBT) line plays an important role in transporting and matching the beam from the RFQ exit to the entrance to the next type of acceleration structures while provides enough beam diagnostics for beam commissing and tuning. The beam dynamics design for the 1GeV China Accelerator Driven System (CADS) is making great progress. In this paper, we will describe the design–both element choosing and beam dynamics study of the 3MeV MEBT for the CADS project.
WEPS051	Linac for the Compact Pulsed Hadron Source Project at Tsinghua University Beijing	2607
	X. Guan TUB, Beijing, People's Republic of China
	Funding: Work supported by the “985 Project” of the Ministry of Education of China, & Tsinghua University Independent Science and research Plan 20091081263. A project of the Compact Pulsed Hadron Source (CPHS) led by the Department of Engineering Physics of Tsinghua University in Beijing, China has been reported in this paper. CPHS consists of a proton linac, a neutron target station (a Be target, moderators and reflector), and a small-angle neutron scattering instrument, a neutron imaging/radiology station, and a proton irradiation station. The accelerator part is composed of an ECR ion source. LEBT section, a RFQ accelerator, a DTL linac and a HEBT. An ECR ion source will give us a up to 60mA at 50keV proton beam with proton ration larger than 85%, and 0. 2 πmm mrad normalized emittance. A short LEBT will be used to matching the beam from ion source to the RFQ entrance. A 3 meters long RFQ machine can accelerate the proton to 3MeV. The Drift Tube Linac with permanent magnets focusing lens will accept the proton beam direct from RFQ. A 4.3 meters length of DTL with 43 cells will accelerate the beam up to 13MeV. The initial phase of the CPHS construction is scheduled to complete in the end of 2012.
WEPS052	Progress of Linear Injector for SSC at HIRFL	2610
	Y. He, X. Du, L.P. Sun, Z.J. Wang, C. Xiao, Y.Q. Yang, Y.J. Yuan, X.H. Zhang, Z.L. Zhang IMP, Lanzhou, People's Republic of China J.E. Chen, S.L. Gao, G. Liu, Y.R. Lu, K. Zhu PKU/IHIP, Beijing, People's Republic of China J. Wang Lanzhou University of Technology, People's Republic of China
	A heavy ion linear accelerator for Separate Sector Cyclotron (SSC) is constructing at Heavy Ion Research Facility at Lanzhou (HIRFL). It is a new injector for SSC to improve its output beam intensity of 2 times for Super Heavy Experiment (SHE) and 10 times for injection of Cooling Storage Ring (CSR) than old Cyclotron. It has a normal conducting linac at upstream of SSC and one superconducting cryomodule at downstream of SSC to shift beam energy. The designed current of the linac is 0.5 mA and output energy is 0.57 MeV/u and 1.02 MeV/u. Beam dynamic study and prototype fabrication are introduced in the paper.
WEPS053	The Conceptual Design of One of Injector II of ADS in China	2613
	Y. He, H. Jia, C. Li, Y. Liu, Z.J. Wang, C. Xiao, Y. Yang, B. Zhang, H.W. Zhao IMP, Lanzhou, People's Republic of China
	A 10mA / 50 MeV superconducting proton linac as the demo of an ADS driver is designing and constructing in China. One of 10 MeV segments and corresponding prototypes are designed and fabricating at Institute of Modern Physics of the Chinese Academy of Sciences. It consists of 2.5 MeV RFQ and superconducting structure from 2.5 to 10 MeV. The conceptual design and development of prototype are introduced in the paper.
WEPS054	The Comparison of ADS Injector II with HWR Cavity and CH Cavity	2616
	Z.J. Wang, Y. He IMP, Lanzhou, People's Republic of China
	High current superconducting proton linac is being studied for Accelerator-driven System (ADS) Project hold by the Chinese Academic of Sciences (CAS). The injector II, which will accelerate proton beam from 2.1 MeV to 10 MeV, will be operated with superconducting cavity. At low energy part, there are two alternative choose, one is HWR cavity, the other is CH cavity. In this paper, the comparison of design with the two type cavities will be presented in view of beam dynamics.
WEPS055	Beam Commissioning Plan of PEFP 100-MeV linac	2619
	J.-H. Jang, Y.-S. Cho, H.-J. Kwon KAERI, Daejon, Republic of Korea
	Funding: This work was supported by Ministry of Education, Science and Technology of the Korean Government. Proton engineering frontier project (PEFP) is developing a 100-MeV proton linear accelerator. It is scheduled to install the linac at Kyeungju site from the end of 2011. The linear accelerator consists of a 50-keV injector, a 3-MeV radio-frequency quadrupole (RFQ), and a 100-MeV drift tube linac (DTL). An important characteristic of this accelerator is extracting 20-MeV proton beams just after four DTL tanks. In this region, a medium energy beam transport (MEBT) will be installed for matching the proton beam to the following accelerator and extracting proton beams. The 100-MeV proton beams will be supplied to the users through another beam line which is located after the linac. This work summarized the beam commissioning plan of the proton linear accelerator.
WEPS056	First Beam Test of 81.5 MHz RFQ for ITEP-TWAC	2622
	V. Andreev, N.N. Alexeev, A. Kolomiets, B. Kondratyev, V.A. Koshelev, A.M. Kozodaev, V.G. Kuzmichev, Y. Orlov, V. Stolbunov, T. Tretyakova ITEP, Moscow, Russia
	The 4 vane RFQ resonator with magnetic coupling windows as initial part of high-current Heavy Ion Linac for ITEP TWAC Facility is presently under commissioning at ITEP. It was constructed for acceleration of ions with 1/3 charge-to-mass ratio to the energy of 1.57 MeV/u with beam current up to 100 mA. Additional beam dynamics simulations have been carried out for actual fields of the RFQ in order to determine both extreme output beam properties for different ion species with charge-to-mass ratio in the range of 1-0.25 and limitations for high-brightness of the high-current injector. The beam test of RFQ has been started with protons at relatively low electrode voltage for experimental studying the RFQ beam dynamics. First results of the beam test in comparison with beam dynamics simulations are presented.
WEPS057	Beam Dynamics Simulation in DTL with RF Quadrupole Focusing	2625
	S.M. Polozov, A.S. Plastun MEPhI, Moscow, Russia
	There are a number of ion linear accelerators using RF focusing. Radio Frequency Quadrupole (RFQ) is the most useful RF linac in low energy range. Using of RFQ for medium energies is impractical because of low energy gain rate. Therefore, proposed to combine Drift Tube Linac (DTL), keeping tolerable energy gain rate, and RFQ. Such linac consists of periodic sequence of a several number of drift tubes and RF quadrupole electrodes, located in the same IH resonator. Different variants of the structure will be considered. Beam dynamics simulation will be carried out through these variants. Main parameters of the linac will be determine. The RF model design, providing combination of DTL and RFQ, will be proposed.
WEPS058	The Medium Energy Beam Transport Line (MEBT) of IFMIF/EVEDA LIPAc	2628
	I. Podadera, J.C. Calvo, J.M. Carmona, A. Ibarra, D. Iglesias, A. Lara, C. Oliver, F. Toral CIEMAT, Madrid, Spain
	Funding: Work partially supported by Spanish Ministry of Science and Innovation under project AIC10-A-000441 and ENE2009-11230. The IFMIF-EVEDA Linear IFMIF Prototype Accelerator (LIPAc)will be a 9 MeV, 125 mA CW deuteron accelerator which aims to validate the technology that will be used in the future IFMIF accelerator. The acceleration of the beam will be carried out in two stages. An RFQ will increase the energy up to 5 MeV before a Superconducting RF (SRF) linac made of a chain of eight Half Wave Resonators bring the particles to the final energy. Between both stages, a Medium Energy Beam Transport line (MEBT) is in charge of transporting and matching the beam between the RFQ and the SRF. The transverse focusing of the beam is controlled by five quadrupole magnets with integrated steerers, grouped in one triplet and one doublet. Two buncher cavities surrounding the doublet handle the longitudinal dynamics. Two movable collimators are also included to purify the beam optics coming out the RFQ and avoid losses in the SRF. From the inputs of the beam dynamics group, CIEMAT is in charge of designing, manufacturing and integrating all the components of the beamline. In this contribution, the MEBT subsystem will be described and the main objectives and issues for each component will be discussed.
WEPS059	Layout of the ESS Linac	2631
	H. Danared, M. Eshraqi, W. Hees, A. Jansson, M. Lindroos, S. Peggs, A. Ponton ESS, Lund, Sweden
	The European Spallation Source will use a 2.5 GeV, 50 mA pulsed proton linac to produce an average 5 MW of power on the spallation target. It will consist of normal-conducting part accelerating particles to 50 MeV in an RFQ and a drift-tube linac and a superconducting part with spoke resonators and two families of elliptical cavities. A high-energy beam transport takes the particles through an upgrade section and at least one bend and demagnifies the beam on to the target. The paper will present the current layout of the linac and discuss parameters that define its length from source to target.
WEPS060	Design and Optimization of ESS LINAC	2634
	M. Eshraqi ESS, Lund, Sweden
	The {\sc linac} of the European Spallation Source will accelerate the proton beam to its final energy mainly by using superconducting structures. Therefore choosing the right transition energy between these superconducting structures as well as choosing the cavity length and number of cells which enhances the acceleration is of great importance. Two types of {\sc linac}s will be studied, a {\sc linac} with superconducting quadrupoles and a {\sc linac} with normal conducting, resistive, quadrupoles. The procedure to find the optimized {\sc linac} will be described here.
WEPS061	ESS LINAC, Design and Beam Dynamics	2637
	M. Eshraqi, H. Danared ESS, Lund, Sweden
	The European Spallation Source, {\sc ESS}, will use a linear accelerator delivering a high intensity proton beam with an average beam power of 5~MW to the target station at 2.5~GeV in long pulses of 2~msec. The ESS {\sc Linac} will use two types of superconducting cavities, spoke resonators at low energy and elliptical cavities at high energies. The possibilities to upgrade to a higher power {\sc Linac} at fixed energy are considered. This paper will present a review of the superconducting {\sc Linac} design and the beam dynamics studies.
WEPS062	Design and Beam Dynamics Study of Hybrid ESS LINAC	2640
	M. Eshraqi, H. Danared, W. Hees, A. Jansson ESS, Lund, Sweden
	The European Spallation Source, {\sc ESS}, will use a superconducting linear accelerator delivering high current long pulses with an average beam power of 5~MW to the target station at 2.5~GeV. A new cryomodule architecture is proposed which allows for a transition between cryomodules in the sub-100~K region, this region can work even at room temperature. This new hybrid design will generate a lower heat load with respect to a fully segmented design - while still providing easy access to individual cryomodules for maintenance and repair. This paper will present a review of the {\sc linac} design, beam dynamics studies and a preliminary cryogenic analysis of the transition region.
WEPS063	Compersation of Effect of Malfunctioning Spoke Resonators on Ess Beam Quality	2643
	M. Eshraqi ESS, Lund, Sweden
	The {\sc linac} of the European Spallation Source will accelerate the proton beam to 2.5~GeV, 98\% of this energy is gained using superconducting structures. The superconducting {\sc linac} is composed of two types of cavities, double spoke resonators and five-cell elliptical cavities. The {\sc linac}, which is five times more powerful than the most powerful existing {\sc linac}, and the spoke cavities that have never been used at such a scale make it necessary to study the effect of one or a few spoke resonators not functioning properly and to find a solution where the defect is compensated by retuning of the neighbouring cavities.
WEPS064	Upgrade Strategies for High Power Proton Linacs	2646
	M. Lindroos, H. Danared, M. Eshraqi, D.P. McGinnis, S. Molloy, S. Peggs, K. Rathsman ESS, Lund, Sweden R.D. Duperrier CEA/DSM/IRFU, France J. Galambos ORNL, Oak Ridge, Tennessee, USA
	High power proton linacs are used as drivers for spallation neutron sources, and are proposed as drivers for sub-critical accelerator driven thorium reactors. A linac optimized for a specific average pulse current can be difficult, or inefficient, to operate at higher currents, for example due to mis-matching between the RF coupler and the beam loaded cavity, and due to Higher Order Mode effects. Hardware is in general designed to meet specific engineering values, such as pulse length and repetition rate, that can be costly and difficult to change, for example due to pre-existing space constraints. We review the different upgrade strategies that are available to proton driver designers, both for linacs under design, such as the European Spallation Source (ESS) in Lund, and also for existing linacs, such as the Spallation Neutron Source (SNS) in Oak Ridge. Potential ESS upgrades towards a beam power higher than 5 MW preserve the original time structure, while the SNS upgrade is directed towards the addition of a second target station.
WEPS065	Segmentation in the Project-X Low Energy CW Linac Front End	2649
	J.-F. Ostiguy, B.G. Shteynas, N. Solyak Fermilab, Batavia, USA
	Funding: Fermi National Accelerator Laboratory (Fermilab) is operated by Fermi Research Alliance, LLC. for the U.S. Department of Energy under contract DE-AC02-07CH11359 The low-energy front-end of the Project-X 2.5 MeV - 3 GeV linac utilizes superconducting single-spoke resonators for acceleration and solenoids for transverse focusing. To take advantage of the available accelerating field in the cavities, it is necessary to minimize the period length. This leads to a compact arrangement of cavities and solenoids with very minimal open longitudinal space. While beam position monitors and correctors can be integrated to the solenoid assemblies inside a cryostat, some instrumentation such as beam profile monitors require dedicated warm longitudinal space. In this paper we discuss an arrangement where the front-end is segmented in crystats comprising about half a dozen lattice periods separated by a minimal amount of warm longitudinal space. We discuss the impact of introducting such openings and present an optical solution integrating them. The strategy and constraints leading to this solution are outlined.
WEPS066	Residual Focusing Asymmetry in Superconducting Spoke Cavities	2652
	J.-F. Ostiguy, N. Solyak Fermilab, Batavia, USA
	Funding: Fermi National Accelerator Laboratory (Fermilab) is operated by Fermi Research Alliance, LLC. for the U.S. Department of Energy under contract DE-AC02-07CH11359. Project-X is a proposed high intensity proton source at Fermilab. Protons (H−) are first accelerated from 2.5 to 3 GeV in a superconducting linac operating in CW mode. While most of the particles are delivered to a variety of precision experiments, a fraction ( about 10%) is further accelerated to 8 GeV in a second superconducting linac operating in pulsed mode. In the low energy front-end of the first stage CW linac, single-spoke cavities are used for acceleration while solenoids and quadrupole doublets provide transverse focusing. The transverse rf defocusing arising from the spoke cavities has a small residual asymmetry whose effect can become noticeable in periods where the transverse phase advance is low. In this paper we discuss this effect, its practical consequences, as well as possible mitigation strategies.
WEPS067	An H-Mode Accelerator with PMQ Focusing as a LANSCE DTL Replacement	2655
	S.S. Kurennoy, L. Rybarcyk, T.P. Wangler LANL, Los Alamos, New Mexico, USA
	High-efficiency normal-conducting RF accelerating structures based on H-mode cavities with a transverse beam focusing by permanent-magnet quadrupoles (PMQ) have been developed for beam velocities in the range of a few percent of the speed of light*. At these low beam velocities, an inter-digital H-mode (IH-PMQ) linac is an order of magnitude more efficient than a standard drift-tube linac (DTL). At the Los Alamos Neutron Science Center (LANSCE), upgrades of the proton linac front end are currently under consideration. In view of these plans, we explore a further option of replacing the aging LANSCE DTL by an efficient H-PMQ accelerator. Here we assume that a 201.25-MHz RFQ-based front end up to 750 keV (4% of the speed of light) is followed first by IH-PMQ structures and then by cross-bar H-mode cavities with PMQ focusing (CH-PMQ). Such an H-PMQ linac would bring proton and H− beams to the energy of 100 MeV and transfer them into the existing side-coupled-cavity linac (CCL). Results of the combined electromagnetic and beam-dynamics modeling of the proposed H-PMQ accelerator will be presented. * S.S. Kurennoy et al., “H-Mode Accelerating Structures with PMQ Beam Focusing,” PRST-AB, 2011 (submitted).