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

injection

Paper	Title	Other Keywords	Page
MO204	Status of REX-ISOLDE	ion, linac, emittance, 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.
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MOP03	Proposal for Reduction of Transverse Emittance of BNL 200 MeV Linac	emittance, linac, 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).

MOP07	High Current Beam Transport to SIS18	emittance, ion, simulation, space-charge	45
	S. Richter, W. Barth, L. Dahl, J. Glatz, L. Groening, S. Yaramishev GSI, Darmstadt
	The optimized transversal and longitudinal matching of space charged dominated ion beams to SIS18 is essential for a loss free injection. This paper focuses on the beam dynamics in the transfer line (TK) from the post-stripper accelerator to the SIS18. Transverse beam emittance measurements at different positions along the TK were done. Especially, the different foil stripping modes were investigated. A longitudinal emittance measurement set-up was commissioned at the entry to the TK. It is used extensively to tune all the rebunchers along the UNILAC. An addition, a test bench is in use for measurements of longitudinal bunch profiles, which enables to monitor for the final debunching to SIS18. Multi particle simulations by means of PARMILA allow a detailed analysis of experimental results for different ion currents.

MOP19	Particle Distributions at the Exit of the J-PARC RFQ	simulation, rfq, linac, beam-transport	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.

MOP27	Commissioning of a 6 MeV X-Band SW Accelerating Guide	electron, linac, vacuum, gun	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.

MOP37	Optimization of Positron Capture in NLC	positron, target, electron, emittance	120
	Y.K. Batygin SLAC, Stanford
	In the Next Linear Collider design, the positron capture system includes a positron production target, a flux concentrator, and a linac to accelerate positrons up to 1.9 GeV, the injection energy of the positron pre-damping ring. Two schemes for positron production have been studied: a conventional approach with a 6.2 GeV electron beam interacting with a high-Z target and polarized positron production using polarized photons generated in a helical undulator by a 150 GeV electron beam which then interact with a positron production target. The capture system has been optimized to insure high positron yield into the 6-dimensional acceptance of the pre-damping ring. Various parameters affecting the positron capture have been analyzed, including: positron deceleration after the flux concentrator, transverse and longitudinal electron beam sizes for positron generation, energy compression after acceleration, etc. As a result of these optimization studies, the positron yield in the conventional scheme has been increased from 1.0 to at least 1.5 and for the polarized positron scheme from 0.25 to 0.30 while maintaining 60% positron polarization.
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TUP03	Design of the LINAC4, A New Injector for the CERN Booster	linac, rfq, proton, 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.

TUP07	A Linac-to-Booster Injection Line for Transverse Matching and Correlated Injection Painting	booster, linac, 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.

TUP13	Test and First Experiments with the new REX-ISOLDE 200 MHz IH-Structure	impedance, linac, 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

TUP21	Beam Dynamics Design of J-PARC Linac High Energy Section	linac, 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, linac, simulation, emittance	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.
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TUP23	A Simulation Study on Error Effects in J-PARC Linac	emittance, linac, 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.

TUP27	Acceleration of Several Charge States of Lead Ion in CERN LINAC3	rfq, linac, ion, acceleration	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.

TUP44	Linac Upgrades for FERMI@ELETTRA	linac, gun, klystron, 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.

TUP50	Cumulative Beam Breakup with Time-Dependent Parameters	focusing, coupling, linear-collider, dipole	384
	J. R. Delayen Jefferson Lab, Newport News, Virginia
	A general analytical formalism developed recently for cumulative beam breakup (BBU) in linear accelerators with arbitrary beam current profile and misalignments [1] is extended to include time-dependent parameters such as energy chirp or rf focusing in order to reduce BBU-induced instabilities and emittance growth. Analytical results are presented and applied to practical accelerator configurations. [1] J. R. Delayen, Phys. Rev. ST Accel. Beams 6, 084402 (2003)

TUP65	RF Tuning Schemes for J-PARC DTL and SDTL	linac, simulation, klystron, 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, linac, 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	focusing, quadrupole, lattice, linac	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.

WE205	KEKB Injector Linac and Upgrade for SuperKEKB	klystron, linac, acceleration, 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