04 Hadron Accelerators
A08 Linear Accelerators

Paper	Title	Page
TUOBA02	Beam Commissioning and Operation of New Linac Injector for RIKEN RI-beam Factory	1071
	K. Yamada, S. Arai, M. Fujimaki, T. Fujinawa, H. Fujisawa, N. Fukunishi, Y. Higurashi, E. Ikezawa, H. Imao, O. Kamigaito, M. Kase, M. Komiyama, K. Kumagai, T. Maie, T. Nakagawa, J. Ohnishi, H. Okuno, N. Sakamoto, K. Suda, H. Watanabe, T. Watanabe, Y. Watanabe, H. Yamasawa RIKEN Nishina Center, Wako, Japan A. Goto NIRS, Chiba-shi, Japan Y. Sato J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	A new linac injector called RILAC2* has successfully commissioned at the RIKEN RI beam factory (RIBF). The RILAC2 can accelerate very heavy ions with m/q of 7, such as 124Xe19+ and 238U35+ from a 28 GHz superconducting ECR ion source**, up to an energy of 680 keV/nucleon in the cw mode. Ions are directory injected into the RIKEN Ring Cyclotron without charge stripping in order to increase the beam intensity, as well as performing independent RIBF experiments and super-heavy-element synthesis. The key features of RILAC2 are the powerful ECRIS, higher extraction voltage of the ECRIS compared to the voltage of the existing injector linac to reduce the space charge effect, improvement of the rf voltage and phase stability, improvement of the vacuum level to reduce the loss by charge exchange, and the compact equipments yet to be installed in the existing AVF cyclotron vault. The first beam acceleration was achieved on December 21, 2010. After the several beam acceleration tests in 2011, we started to operate the RILAC2 to supply beams for the RIBF experiments. * O. Kamigaito et al., Proc. of PASJ3-LAM31, WP78, p. 502 (2006); K. Yamada et al., Proc. of IPAC'10, MOPD046, p.789 (2010). ** T. Nakagawa et al., Rev. Sci. Instrum. 79, 02A327 (2008).
	Slides TUOBA02 [9.947 MB]
TUOBA03	H− and Proton Beam Loss Comparison at SNS Superconducting Linac	1074
	A.P. Shishlo, A.V. Aleksandrov, J. Galambos, M.A. Plum ORNL, Oak Ridge, Tennessee, USA E. Laface ESS, Lund, Sweden V.A. Lebedev Fermilab, Batavia, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. A comparison of beam loss in the superconducting part (SCL) of the Spallation Neutron Source (SNS) linac for H− and protons is presented. During the experiment the nominal beam of negative hydrogen ions in the SCL was replaced by a proton beam created by insertion of a thin stripping carbon foil placed in the low energy section of the linac. The observed significant reduction in the beam loss for protons is explained by a domination of the intra-beam stripping mechanism of the beam loss for H-. The details of the experiment are discussed, and a preliminary estimation of the cross section of the reaction H− + H− -> H− + H0 + e is presented.
	Slides TUOBA03 [0.772 MB]
WEXA03	Accelerator Physics and Technology for ESS	2073
	H. Danared ESS, Lund, Sweden
	A conceptual design of the 2.5 GeV proton linac of the European Spallation Source, ESS, was presented in a Conceptual Design Report in early 2012. Work is now progressing towards a Technical Design Report at the end of 2012. Changes to the linac configuration during the last year include a somewhat longer DTL and a change to fully segmented cryomodules. This paper reviews the current design status of the accelerator and its subsystems.
	Slides WEXA03 [15.485 MB]
THEPPB001	Design and Fabrication of The ESS-Bilbao RFQ Prototype Models	3228
	I. Bustinduy, F.J. Bermejo, J. Feuchtwanger, N. Garmendia, A. Ghiglino, O. González, P.J. González, I. Madariaga, J.L. Muñoz, I. Rueda, F. Sordo Balbin, A. Vélez, D. de Cos ESS Bilbao, Bilbao, Spain V. Etxebarria, J. Portilla University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain A. Garbayo AVS, Eibar, Gipuzkoa, Spain S. Jolly UCL, London, United Kingdom S.R. Lawrie, A.P. Letchford STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom J.K. Pozimski, P. Savage Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	As part of the development of the ESS-Bilbao Accelerator in Spain, two different sets of radio frequency quadrupole (RFQ) models have been developed. On one hand, a set of four oxygen free high conductivity copper weld test models has been designed and manufactured, in order to test different welding methods as well as other mechanical aspects involved in the fabrication of the RFQ. On the other hand, a 352.2 MHz four vane RFQ cold model, with a length of 1 meter, has been designed and built in Aluminum. It serves as a good test bench to investigate the validity of different finite element analysis (FEA) software packages. This is a critical part, since the design of the final RFQ will be based on such simulations. The cold model also includes 16 slug tuners and 8 couplers/pick-up ports, which will allow to use the bead-pull perturbation method, by measuring the electric field profile, Q-value and resonant modes. In order to investigate fabrication tolerances, the cold model also comprises a longitudinal test modulation in the vanes, which is similar to the one designed for the final RFQ.
THPPC010	Beam Start-up of J-PARC Linac after the Tohoku Earthquake	3293
	M. Ikegami, Z. Fang, K. Futatsukawa, T. Miyao KEK, Ibaraki, Japan T. Maruta, A. Miura, H. Sako, J. Tamura, G.H. Wei JAEA/J-PARC, Tokai-mura, Japan
	The beam operation of J-PARC linac was interrupted by the Tohoku earthquake in March 2011. After significant recovering effort including the realignment of most linac components, we have resumed the beam operation of J-PARC linac in December 2011. In this paper, we present the experience in the beam start-up tuning after the earthquake and the status of the linac operation thereafter.
THPPC015	Design of a Four-vane 325 MHz RFQ Cold Model at Tsinghua University	3308
	L. Du, J.C. Cai, X. Guan, Q.Z. Xing TUB, Beijing, People's Republic of China
	Funding: Work supported by National Natural Science Foundation of China (Project 11175096). The design of a Radio Frequency Quadrupole (RFQ) accelerator cold model at Tsinghua University is presented in this paper. The 1-meter-long aluminium cold model is chosen to be the same as the low-energy part of the 3-meter-long RFQ for the Compact Pulsed Hadron Source (CPHS) project at Tsinghua University. This cold model will be used mainly for the RFQ field study and education. It will work at the RF frequency of 325 MHz. All the simulations are finished by the SUPERFISH and MAFIA codes.
THPPP031	RF Design of ESS RFQ	3800
	O. Piquet, M. Desmons, A. France CEA/DSM/IRFU, France O. Delferrière CEA/IRFU, Gif-sur-Yvette, France
	The low energy front end of ESS is based on a 352 MHz, 5-m long Radiofrequency Quadrupole (RFQ) cavity. It will accelerate and bunch proton beams from 75 keV to 3 MeV. The beam current is 50 mA (75 mA as an upgrade scenario) for 4% duty cycle. A complete RF analysis of the ESS RFQ has been performed using 3D RF simulating codes and a RFQ 4-wire transmission line model. Proposed RFQ is a 4 vane-type structure where 2D cross-section is optimized for lower power dissipation, while featuring simple geometrical shape suitable for easy machining. RF calculations are performed for the whole RFQ, and mainly for the following parts: end cells, vacuum port, tuners and RF coupling ports. Power losses are particularly calculated in order to achieve Thermo-mechanical calculations.
THPPP032	Advanced Layout Studies for the GSI CW-Linac	3803
	W.A. Barth, S. Mickat GSI, Darmstadt, Germany S. Jacke HIM, Mainz, Germany
	Beam dynamics studies were made with the LORASR code for the planned superconducting (sc)continuous wave (cw) linear accelerator. It comprises a fixed accelerating part with an output energy of 3.5 MeV/u at a design mass/charge ratio of 6 and an energy variable part with an output energy of up to 7.3 MeV/u. The general layout, which provides for nine cavities combined with seven separate solenoids for a total length of 12.7 m, is based on a basic design by A. Minaev*. The recent studies show the parameter study for output energy variation. The statistical rotational and transverse offset error calculations illuminate the tolerances for acceptable errors. These are particularly relevant in the beam dynamics within a superconducting environment. Further calculations focus on varying the charge-to-mass ratio to reach linac energies up to 10 MeV/u, meeting the requirements of future UNILAC experiments. *A. Minaev et al., “Superconducting, energy variable heavy ion linac with constant beta, multicell cavities of CH-type,” PRST-AB 12, 120101 (2009).
THPPP033	New Developments for the Present and Future GSI Linacs	3806
	L. Groening, W.A. Barth, G. Clemente, V. Gettmann, B. Schlitt GSI, Darmstadt, Germany M. Amberg, K. Aulenbacher, S. Mickat HIM, Mainz, Germany F.D. Dziuba, H. Podlech, U. Ratzinger, C. Xiao IAP, Frankfurt am Main, Germany
	For more than three decades, GSI has successfully operated the Universal Linear Accelerator (UNILAC), providing ions from protons to uranium at energies from 3 to 11 MeV/u. The UNILAC will serve for a comparable period as injector for the upcoming FAIR facility which will ask for short pulses of high peak currents of heavy ions. The UNILAC Alvarez-type DTL has been in operation since the earliest days of the machine, and it needs to be replaced to assure reliable operation for FAIR. This new DTL will serve the needs of FAIR, while demands of high duty cycles of moderate currents of intermediate-mass ions will be met by construction of a dedicated superconducting cw-linac. FAIR requires additionally provision of primary protons for its pbar physics program. A dedicated proton linac is under design for that task. The contribution will present the future linacs to be operated at GSI. Finally we introduce a novel method to provide flat ion beams for injection into machines having flat injection acceptances.
THPPP034	Optimization of a CW RFQ Prototype	3809
	U. Bartz, J. Gerbig, H.C. Lenz, A. Schempp IAP, Frankfurt am Main, Germany
	A short RFQ prototype was built for RF-tests of high power RFQ structures. We studied thermal effects to 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 RF design is on focus now. Results and the status of the project will be presented
THPPP036	First Measurements of an Coupled CH Power Cavity for the FAIR Proton Injector	3812
	R. M. Brodhage, 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 to develop a complete technical concept for manufacturing. In Spring 2011, the construction of the first power prototype has started. The main components of this cavity were ready for measurements in fall 2011. At that time, the cavity was tested with a preliminary aluminum drift tube structure, which will allow precise frequency and field tuning. This paper will report on the recent technical developments and achievements. It will outline the main tuning and commissioning steps towards that novel type of proton DTL and it will show very promising results of the latest measurements.
THPPP037	Status of the 325 MHz 4-ROD RFQ	3815
	B. Koubek, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany L. Groening GSI, Darmstadt, Germany
	For the FAIR project of GSI as part of the proton linac, a 325 MHz 4-ROD RFQ with an output energy of 3 MeV is planned. Due to the simulations regarding the RF design, a prototype of this RFQ was built. Measurements with this prototype to verify the simulation results have been done. In addition, simulations with increasing cell numbers and simulations concerning the boundary fields of the electrodes are presented in this paper.
THPPP038	Simulations of the Influence of 4-Rod RFQ Elements on its Voltage Distribution	3818
	J.S. Schmidt, B. Koubek, A. Schempp IAP, Frankfurt am Main, Germany
	The influence of tuning methods and other design elements of 4-rod-RFQs on the voltage distribution have been studied during the last months. Every change in the field geometry or the voltage distribution could for example lead to particle losses or a raise in the surface current on single parts of the RFQ. That’s why further research had to be done about the behavior of the 4-rod-RFQ especially in the comparison of structures at 100 or 200 MHz. The results of an analysis which is concentrated on simulations using CST Microwave Studio to evaluate the effects of the overhang of electrodes, modulation and piston tuners on the fields in the RFQ are presented in this paper.
THPPP039	Simulations for a Buncher-Cavity at GSI	3821
	P.L. Till, B. Koubek, A. Schempp, J.S. Schmidt IAP, Frankfurt am Main, Germany
	Buncher cavities can be used to bunch and rebunch or re-accelerate particle beams. A special form of these buncher cavities is a spiral structure. one of its main features is the easy adjustable frequency. A two-gap structure for the GSI has been simulated and will be build at the University of Frankfurt. This structure shall replace an existing buncher at GSI. It is designed to an frequency of 36 MHz. Also general simulations of spiral bunchers will be presented.
THPPP040	Heavy-ion Beam Acceleration at RIKEN for the Super-Heavy Element Search	3823
	M. Kase, M. Fujimaki, Y. Higurashi, E. Ikezawa, O. Kamigaito, M. Komiyama, T. Nakagawa, K. Ozeki, N. Sakamoto, K. Suda RIKEN Nishina Center, Wako, Japan T. Aihara, T.O. Ohki, K. Oyamada, M. Tamura, A. Uchiyama, H. Yamauchi SHI Accelerator Service Ltd., Tokyo, Japan
	In RIKEN Nishina accelerator center, the experiment on the super-heavy element (Z=113) search has been being carried out since 2003. The RIKEN heavy-ion linac is supplying a heavy-ion beam of 70Zn with energies around 5MeV/nucleon. The beam intensities are required more than 1 particle maicro amper on the target. Very long-term and stable operations are intrinsic for this kind of experiments. So far two events for Z=113 have been found during a net irradiation time of 10345 hours (431 days) with a total dose 1.1 x 1020 (12.8 mg). Heavy operation of the linac will be reported.
THPPP041	A CW High Charge State Heavy Ion RFQ Accelerator for SSC-LINAC Injector	3826
	G. Liu, J.E. Chen, S.L. Gao, Y.R. Lu, Z. Wang, X.Q. Yan, Q.F. Zhou, K. Zhu PKU/IHIP, Beijing, People's Republic of China Y. He, C. Xiao, Y.Q. Yang, Y.J. Yuan, H.W. Zhao IMP, Lanzhou, People's Republic of China
	Funding: Supported by NSFC(11079001). The cooler storage ring synchrotron CSR of HIRFL started running in 2008. The SFC (Sector Focusing Cyclotron) and SSC (Separator Sector Cyclotron) form an injector for the CSR. To improve beam intensity and/or injection efficiency, a new linear injector, the SSC-LINAC, for the SSC has been proposed to replace the existing SFC. The SSC-LINAC consists of an ECR ion source, LEBT, a RFQ, MEBT, and four IH-DTLs. This paper only represents the design research of the RFQ accelerator, which has a frequency of 53.667MHz. The ions up to uranium with ratio of mass-to-charge up to 7 are accelerated and injected into the CSR by the SSC-LINAC. The SSC-LINAC works on CW mode. The RFQ beam dynamic design study is based on 238U34+ beams with intensity of 0.5mA. The inter-vane voltage is 70kV with a maximum modulation factor of 1.93. It uses a 2.5m-long 4-rod structure to accelerate uranium ions from 3.728keV/u to 143keV/u with transmission efficiency of 94%. The RFQDYN code checks the transmission of different kinds of ions in the RFQ. The specific shunt impedance of RFQ is optimized to 438kΩ.m. The design of cavity tuning and the water cooling system are also included in this paper. Corresponding authors: yrlu@pku.edu.cn, hey@impcas.ac.cn
THPPP042	The First Step of RFQ Development in KBSI	3829
	J.W. Ok, S. Choi, B.C. Kim, B.S. Lee, J.Y. Park, M. Won, J.H. Yoon Korea Basic Science Institute, Busan, Republic of Korea
	The RFQ for accelerating an ion beam is being developed in Korea Basic Science Institute (KBSI). The KBSI RFQ is designed to accelerate 1 mA lithium beam (Q/A=3/7) at 88 MHz. It is considered to be a 4-vane RFQ structure. The injection beam energy into RFQ is 12 keV/u, the output beam energy downstream from RFQ is 300 keV/u. The RFQ has to show stable operation, meet availability, and have the minimum losses so as to guarantee the best performance/cost ratio. At the first step, two dimensional geometry structure was studied using SUPERFISH code for the resonance frequency of quadrupole and dipole modes. Three dimensional field distributions were investigated by CST microwave studio. The beam dynamics in RFQ accelerator were studied using PARMTEQM code. Based on these results, the structural analysis should be studied and a cold model will be fabricated and investigated. The practical KBSI RFQ will be manufactured in next year.
THPPP043	Installation of 100-MeV Proton Linac for PEFP	3832
	Y.-S. Cho, S. Cha, J.S. Hong, J.-H. Jang, D.I. Kim, H.S. Kim, H.-J. Kwon, B.-S. Park, J.Y. Ryu, K.T. Seol, Y.-G. Song, S.P. Yun KAERI, Daejon, Republic of Korea
	Funding: This work was supported by the Ministry of Education, Science and Technology of the Korean Government. The Proton Engineering Frontier Project (PEFP) at Korea Atomic Energy Research Institute (KAERI) is developing a 100-MeV proton linac in order to supply 20-MeV and 100-MeV proton beams to users for proton beam application. The linac consists of a 50-keV injector, a 3-MeV radio frequency quadrupole (RFQ) and a 100-MeV drift tube linac (DTL). The operation of the 20-MeV part of linac at Daejeon site was finished on November 2011. It was disassembled and moved to the Gyeongju site for installation as a low energy part of the linac. We completed the fabrication and test of the accelerating structures. The installation of the proton linac started in December 2011 at the new project site. The user service is scheduled for 2013 through the beam commissioning in 2012. This work summarized the installation status of the proton linac.
THPPP044	RF Set-up Scheme for PEFP DTL	3835
	J.-H. Jang, Y.-S. Cho, H.S. Kim, H.-J. Kwon KAERI, Daejon, Republic of Korea
	Funding: This work was supported by the Ministry of Education, Science and Technology of the Korean Government. The proton engineering frontier project (PEFP) is developing a 100-MeV proton linac which consists of a 50 keV injector, a 3-MeV radio frequency quadrupole (RFQ) and a 100-MeV drift tube linac (DTL). The installation of the linac was started in December 2011. The beam commissioning is scheduled for 2012. The phase scan signature method is a common technique to determine the rf set point including the amplitude and phase in DTL tanks. This work summarized the rf set-up scheme for PEFP DTL tanks by using the phase scan signature method.
THPPP045	Five Year Operation of the 20-MeV Proton Accelerator at KAERI	3838
	H.-J. Kwon, Y.-S. Cho, J.-H. Jang, D.I. Kim, H.S. Kim, B.-S. Park, J.Y. Ryu, K.T. Seol, Y.-G. Song, S.P. Yun KAERI, Daejon, Republic of Korea
	Funding: This work was supported by the Ministry of Science and Technology of the Korean Government. A 20-MeV proton linear accelerator has been operating since 2007 by Proton Engineering Frontier Project (PEFP) at Korea Atomic Energy Research Institute (KAERI), Daejeon site. The performance test of the accelerator itself has been done with limited operating conditions. In addition, the 20-MeV accelerator was used as a test bench of the 100-MeV accelerator components. Besides the machine study itself, it supplied proton beams to more than 1600 samples for users. The 20-MeV accelerator was disassembled at the end of 2011 and will be installed at Gyeong-Ju site as an injector for the 100-MeV linac in 2012. In this paper, the 5 year operation experiences of the 20-MeV linac at Daejeon site are summarized and the technical issues are discussed.
THPPP046	ESS End-to-End Simulations: a Comparison Between IMPACT and MADX	3841
	E. Laface, R. Miyamoto ESS, Lund, Sweden D.C. Plostinar, C.R. Prior STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	The European Spallation Source will be a 5 MW superconducting proton linac for the production of spallation neutrons. It is composed of an ion source, a radio frequency quadrupole, a drift tube linac and a superconducting linac as well as the low, medium and high, energy beam transport sections. At present these components of the linac are in the design phase: the optimization of the accelerator parameters requires an intensive campaign of simulations to test the model of the machine under possible operational conditions. In this paper the results of simulations performed with the IMPACT and MADX-PTC codes are presented and a comparison is made between them and independent simulations using TraceWin. The dynamics of the beam envelope and single and multi-particle tracking are reported.
THPPP048	Linac4 - Low Energy Beam Measurements	3847
	L.M. Hein, G. Bellodi, J.-B. Lallement, A.M. Lombardi, O. Midttun, P.A. Posocco, R. Scrivens CERN, Geneva, Switzerland
	Linac4 is a160 MeV normal-conducting linear accelerator for negative Hydrogen ions (H−), which will replace the 50 MeV proton Linac (Linac2) as linear injector for the CERN accelerators. The low energy part, comprising a 45 keV Low Energy Beam Transport system (LEBT), a 3 MeV Radiofrequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) is being assembled in a dedicated test stand for pre-commissioning with a proton beam. During 2011 extensive measurements were done after the source and after the LEBT with the aim of preparing the RFQ commissioning and validating the simulation tools, indispensable for future source upgrades. The measurements have been thoroughly simulated with a multi-particle code, including 2D magnetic field maps, error studies, steering studies and the generation of beam distribution from measurements. Emittance, acceptance and transmission measurements will be presented and compared to the results of the simulations.
THPPP049	Tuning Procedure for the LINAC4 PI Mode Structure (PIMS)	3850
	P. Ugena Tirado, F. Gerigk, R. Wegner CERN, Geneva, Switzerland
	PI-Mode-Structure (PIMS) cavities will be used in the high energy section of LINAC4 (102-160 MeV). Each cavity is made of 7 coupled cells, operated in the π-mode at a resonant frequency of 352.2 MHz. The cell length remains constant for each of the 12 cavities but changes from cavity to cavity to synchronise with the increased beam energy. This paper reports on the tuning process required to get a constant voltage in each cell at the resonant frequency and consisting in re-machining to the required level the tuning rings located on each cell-wall. An algorithm based on single cell detuning, equivalent circuit simulations and precise 3D simulations for the 3 different cell types of each cavity has been developed and successfully applied to the tuning of the first PIMS cavity. In order to reduce the simulation effort for the remaining 11 cavities, an interpolation algorithm based on 3 cavities has been developed and validated. In a second tuning step, after the electron beam welding of all cells, the final adjustment of single-cell frequencies and field flatness is achieved by cutting the length of one plunger tuner per cell.
THPPP050	HIE-ISOLDE SC Linac: Operational Aspects and Commissioning Preparation	3853
	D. Voulot, E. Bravin, M.A. Fraser, B. Goddard, Y. Kadi, D. Lanaia, A.S. Parfenova, M. Pasini, A.G. Sosa, F. Zocca CERN, Geneva, Switzerland
	In the framework of the HIE-ISOLDE project, the REX linac will be upgraded in stages to 5.5 MeV/u and 10 MeV/u using superconducting (SC) quarter-wave cavities. The linac lattice is now frozen and the beam dynamics has been checked. The beam properties at the output of the NC linac for the different stages have been measured and are compatible with the SC linac acceptance. The high-energy beam transfer design is being finalised and a study has been launched for a buncher/chopper system allowing 100 ns bunch spacing for time-of-flight measurements. A compact diagnostic box for the inter-cryomodule region is under development and a new Si-detector based monitor for energy and phase measurements has been tested.
THPPP051	Status of the RAL Front End Test Stand	3856
	A.P. Letchford, M.A. Clarke-Gayther, D.C. Faircloth, S.R. Lawrie STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom S.M.H. Alsari, M. Aslaninejad, A. Kurup, P. Savage Imperial College of Science and Technology, Department of Physics, London, United Kingdom J.J. Back University of Warwick, Coventry, United Kingdom G.E. Boorman, A. Bosco Royal Holloway, University of London, Surrey, United Kingdom C. Gabor, D.C. Plostinar STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom A. Garbayo AVS, Eibar, Gipuzkoa, Spain S. Jolly UCL, London, United Kingdom J.K. Pozimski STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	The Front End Test Stand (FETS) under construction at RAL is a demonstrator for front end systems of a future high power proton linac. Possible applications include a linac upgrade for the ISIS spallation neutron source, new future neutron sources, accelerator driven sub-critical systems, a neutrino factory etc. Designed to deliver a 60mA H-minus beam at 3MeV with a 10% duty factor, FETS consists of a high brightness ion source, magnetic low energy beam transport (LEBT), 4-vane 324MHz radio frequency quadrupole, medium energy beam transport (MEBT) containing a high speed beam chopper plus comprehensive diagnostics. This paper describes the current status of the project and future plans.
THPPP052	Modelling the ISIS 70 MeV Linac	3859
	D.C. Plostinar, C.R. Prior, G.H. Rees STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom A.P. Letchford STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom A.W. Mitchell University of Warwick, Coventry, United Kingdom
	The ISIS linac consists of four DTL tanks that accelerate a 50 pps, 20 mA H− beam up to 70 MeV before injecting it into an 800 MeV synchrotron. Over the last decades, the linac has proved to be a stable and reliable injector for ISIS, which is a significant achievement considering that two of the tanks are nearly 60 years old. At the time the machine was designed, the limited computing power available and the absence of modern modeling codes, made the creation of a complex simulation model almost impossible. However, over the last few years, computer tools have became an integral part of any accelerator design, so in this paper we present a beam dynamics model of the ISIS linac. A comparison between the simulation results and machine operation data will be discussed, as well as possible linac tuning scenarios and recommended upgrades based on the new model.
THPPP053	The Manufacture and Assembly of the FETS RFQ	3862
	P. Savage, J.K. Pozimski Imperial College of Science and Technology, Department of Physics, London, United Kingdom A. Garbayo AVS, Eibar, Gipuzkoa, Spain A.P. Letchford STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom D.S. Wilsher STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
	The Rutherford Appleton Laboratory (RAL) Front End Test Stand (FETS) uses a 324 MHz 4-vane RFQ to accelerate H− ions from 65keV to 3MeV. The RFQ is a copper structure that has been designed as 4 nominally one metre long assemblies. Each assembly consists of 2 major vanes and 2 minor vanes that are bolted together and sealed using an O ring. The mechanical design for the FETS RFQ is complete and the manufacture is underway. In order to achieve the designed physics performance the vanes must be machined and assembled to high degree of accuracy. This requirement has demanded a tight synergy between the design, manufacture and metrology services. Together they have developed detailed procedures for the manufacturing, inspection, alignment and assembly phases. The key points of these procedures will be detailed in this paper.
THPPP054	A New Half-Wave Resonator Cryomodule Design for Project-X	3865
	Z.A. Conway, A.O. Bergado, R.L. Fischer, M. Kedzie, M.P. Kelly, B. Mustapha, P.N. Ostroumov ANL, Argonne, USA V.A. Lebedev Fermilab, Batavia, USA
	Funding: This work was supported by the U.S. Department of Energy, Office of High Energy Physics and Nuclear Physics, under Contract DE-AC02-76CH03000 and DE-AC02-06CH11357. We present the current status of our Project-X half-wave resonator cryomodule development effort. The Project-X injector requires a single cryomodule with 9 superconducting, 162.5-MHz, β = 0.11, half-wave resonators interleaved with 6 integrated superconducting solenoids/steering coils. This cryomodule is being designed and build by ANL with the intent of delivering a device which has all external connections to the cryogenic, RF, and instrumentation systems located at removable junctions separated from the clean cavity vacuum system. Issues include the ease of assembly, cavity cleanliness, interfacing to subsystems (e.g., cryogenics, couplers, tuners, etc.), and satisfying the ANL/FNAL/DOE guidelines for vacuum vessels. We employ proven warm-to-cold low-particulate beamline transitions to minimize unused space along the linac, a top-loading box design that minimizes the size of the clean room assembly, and compact beamline devices to minimize the length of the focusing period.
THPPP056	Beam Loss Due to Misalignments, RF Jitter and Mismatch in the Fermilab Project-X 3GeV CW Linac	3868
	J.-P. Carneiro, V.A. Lebedev, S. Nagaitsev, J.-F. Ostiguy, A. Saini, B.G. Shteynas, N. Solyak Fermilab, Batavia, USA
	This paper presents an analysis of beam losses along the current design of the FNAL 3 GeV superconducting cw linac. Simulations from the RFQ exit up to the end of the linac (~430 meters) are performed on the FermiGrid using the beam dynamics code TRACK. The impact of beam mismatch, element misalignments, and RF jitter on the beam dynamics is discussed and corresponding beam loss patterns are presented. A correction scheme to compensate for misalignments is described.
THPPP057	PXIE Optics and Layout	3871
	V.A. Lebedev, S. Nagaitsev, J.-F. Ostiguy, A.V. Shemyakin, B.G. Shteynas, N. Solyak Fermilab, Batavia, USA
	The Project X Injector Experiment (PXIE) will serve as a prototype for the Project X front end. The aim is to validate the Project-X design and to decrease technical risks, known to be mainly related to the front end. PXIE will accelerate a 1 mA CW beam to about 25 MeV. It will consist of an ion source, LEBT, CW RFQ, MEBT, two SC cryomodules, a diagnostic section and a beam dump. A bunch-by-bunch chopper located in the MEBT section will allow formation of an arbitrary bunch structure. PXIE deviates somewhat from the current Project-X front end concept in that it provides additional instrumentation and relies on a reduced number of kickers for bunch chopping; the diagnostic section also include an RF separator to allow studying extinction of removed bunches. The paper discusses the main requirements and constraints motivating the facility layout and optics. Final adjustments to the Project X front end design, if needed, will be based on operational experience gained with PXIE. Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
THPPP062	The Six-Cavity Test - Demonstrated Acceleration of Beam with Multiple RF Cavities and a Single Klystron	3877
	J. Steimel, J.-P. Carneiro, B. Chase, S. Chaurize, E. Cullerton, B.M. Hanna, R.L. Madrak, R.J. Pasquinelli, L.R. Prost, L. Ristori, V.E. Scarpine, P. Varghese, R.C. Webber, D. Wildman Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The High Intensity Neutrino Source (HINS) ‘Six-Cavity Test’ has demonstrated the use of high power RF vector modulators to control multiple RF cavities driven by a single high power klystron to accelerate a non-relativistic beam. Installation of 6 cavities in the existing HINS beamline has been completed and beam measurements have started. We present data showing the energy stability of the 7 mA proton beam accelerated through the six cavities from 2.5 MeV to 3.4 MeV.
THPPP063	CW Room Temperature Re-buncher for the Project X Front End	3880
	G.V. Romanov, M.H. Awida, M. Chen, I.V. Gonin, S. Kazakov, R.A. Kostin, V.A. Lebedev, N. Solyak, V.P. Yakovlev Fermilab, Batavia, USA
	At Fermilab there is a plan to construct the Project X Injector Experiment (PXIE) facility - a prototype of the front end of the Project X, a multi-MW proton source based on a superconducting linac. The construction and successful operations of this facility will validate the concept for the Project X front end, thereby minimizing the primary technical risk element within the Project. The front end of the linac contains a cw room-temperature MEBT section which comprises an ion source, RFQ, and high-bandwidth bunch selective chopper. The length of the MEBT exceeds 9 m, so three re-bunching cavities are used to support the beam longitudinal dynamics. The paper reports RF design of the re-bunchers along with preliminary beam dynamic and thermal analysis of the cavities.
THPPP064	Project X RFQ EM Design	3883
	G.V. Romanov Fermilab, Batavia, USA M.D. Hoff, D. Li, J.W. Staples, S.P. Virostek LBNL, Berkeley, California, USA
	Project X is a proposed multi-MW proton facility at Fermi National Accelerator Laboratory (FNAL). The Project X front-end would consist of an H− ion source, a low-energy beam transport (LEBT), a cw 162.5 MHz radio-frequency quadrupole (RFQ) accelerator, and a medium-energy beam transport (MEBT). Lawrence Berkeley National Laboratory (LBNL) and FNAL collaboration is currently developing the designs for various components in the Project X front end. This paper reports the detailed EM design of the cw 162.5 MHz RFQ that provides bunching of the 1-10 mA H− beam with acceleration from 30 keV to 2.1 MeV.
THPPP065	The FNAL Injector Upgrade Status	3886
	C.-Y. Tan, D.S. Bollinger, K.L. Duel, P.R. Karns, J.R. Lackey, W. Pellico, V.E. Scarpine, R.E. Tomlin Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The new FNAL H− injector upgrade is currently being tested before installation in the Spring 2012 shutdown of the accelerator complex. This line consists of an H− source, low energy beam transport (LEBT) and 200 MHz RFQ. Beam measurements have been performed to validate the design before installation. The results of the beam measurements are presented in this paper.
THPPP066	Beam Tuning Strategy of the FRIB Linac Driver	3889
	Y. Zhang FRIB, East Lansing, Michigan, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. The FRIB linac driver will deliver heavy ion beams up to uranium, with an energy of 200 MeV/u and total power on target of 400 kW. To reach the design power for heaviest ions, multi-charge-state beams will be accelerated simultaneously in this SRF linac. Beam tuning of the linac driver is among the most challenging tasks. In this paper, we discuss the beam tuning strategy, which includes the cavity synchronous phase and acceleration gradient setup, beam trajectory correction, and transverse matching with horizontal-vertical coupled beams as superconducting solenoids are used for transverse focusing in the linac segments.
THPPP067	H− Beam Loss and Evidence for Intrabeam Stripping in the LANSCE Linac	3892
	L. Rybarcyk, C.T. Kelsey, R.C. McCrady, X. Pang LANL, Los Alamos, New Mexico, USA
	Funding: U.S. Dept. of Energy, NNSA, under contract DE-AC52-06NA25396. The LANSCE accelerator complex is a multi-beam, multi-user facility that provides high-intensity H+ and H− particle beams for a variety of user programs. At the heart of the facility is a room temperature linac that is comprised of 100-MeV drift tube and 800-MeV coupled cavity linac (CCL) structures. Although both beams are similar in intensity and emittance, the beam-loss monitors along the CCL show a trend of increased loss for H− that is not present for H+. This difference is attributed to stripping mechanisms that affect H− and not H+. We present the results of an analysis of H− beam loss along the CCL that incorporates beam spill measurements, beam dynamics simulations, analytical models and radiation transport estimates using the MCNPX code. The results indicate a significant fraction of these additional losses result from intrabeam stripping.
THPPP068	Investigation of a Multi-cell Cavity Structure Proposed for Improved Hydroforming	3895
	K.R. Shin ORNL RAD, Oak Ridge, Tennessee, USA A.E. Fathy University of Tennessee, Knoxville, Tennessee, USA J.A. Holmes, Y.W. Kang ORNL, Oak Ridge, Tennessee, USA
	A multi-cell cavity structure with rectangular coupling aperture between cavity cells is proposed. This investigation is to study the RF properties of such structure that may provide high yield in hydroforming. In mechanical point of view, the rectangular aperture iris may provide much improved structure quality in hydroforming since it can help to reduce the stress incurring within the sheet metal with improved structural malleability. The necking procedure can be easier because of greater perimeter in the iris geometry. Peak electric and magnetic fields per accelerating gradient may increase however, compared to traditional TESLA type elliptical cavity structure. The rectangular iris shape provides asymmetric transverse focusing per half RF period. If the horizontal and vertical rectangular irises are interleaved, the net transverse focusing may be achieved. 3D simulations with CST MWS have been carried out to analyze EM field properties and the cavity parameters.
THPPP069	Double-Gap Rebuncher Cavity Design of SNS MEBT	3898
	K.R. Shin ORNL RAD, Oak Ridge, Tennessee, USA A.E. Fathy University of Tennessee, Knoxville, Tennessee, USA Y.W. Kang ORNL, Oak Ridge, Tennessee, USA
	A double-gap rebuncher cavity has been studied through design and analysis with computer simulations. This cavity shape is a two cell abridged form of drift tube linac (DTL), instead an omega form of existing single gap elliptical cavity. The cavity operates in TM010 mode, likewise the commonly used single-gap cavities in some medium energy beam transport (MEBT) line of proton accelerators. The new cavity is more power efficient even with slightly lower Q factor because of utilization of two interactive gaps. The breakdown field can be lowered with adjustment of gap and tube length ratio. Electromagnetic, beam envelope, and thermal simulations are presented with comparison to the properties of the conventional elliptical cavity.