IPAC2012 - List of Keywords (resonance)

Paper	Title	Other Keywords	Page
MOOBC03	A Multi Purpose X Band Accelerating Structure	wakefield, FEL, linac, alignment	70
	M.M. Dehler, A. Citterio, R. Zennaro Paul Scherrer Institut, Villigen, Switzerland G. D'Auria, C. Serpico ELETTRA, Basovizza, Italy D. Gudkov, A. Samoshkin JINR, Dubna, Moscow Region, Russia S. Lebet, G. Riddone, J. Shi CERN, Geneva, Switzerland
	In a collaboration between CERN, PSI and Sincrotrone Trieste (ST), a series of four multipurpose X-band accelerating structures has been designed and fabricated. The structures have 72 cells with a phase advance of 5 pi/6 and include upstream and downstream wakefield monitors to measure the beam alignment. We give an overview of the electrical and mechanical design and describe the fabrication of the first units. We also present the results of the low level RF tests. Using measurements of the internal cell to cell misalignment, the residual transverse wake and the noise floor of the wake field monitors are computed. Furthermore, we present the first experiences running the structures under high power.
	Slides MOOBC03 [15.521 MB]

MOEPPB015	Excitation of Intra-bunch Vertical Motion in the SPS - Implications for Feedback Control of Ecloud and TMCI Instabilities	pick-up, feedback, betatron, synchrotron	112
	J.D. Fox, J.M. Cesaratto, M.T.F. Pivi, C.H. Rivetta, O. Turgut, S. Uemura SLAC, Menlo Park, California, USA W. Höfle, U. Wehrle CERN, Geneva, Switzerland
	Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP). Electron cloud and transverse mode coupled-bunch instabilities (TMCI) limit the bunch intensity in the CERN SPS. Intra-bunch fast feedback systems are a possible method to control these effects. This paper presents experimental measurements of single-bunch motion in the SPS driven by a GHz bandwidth vertical excitation system. The primary goal is to quantify the change in internal bunch dynamics as instability thresholds are approached, and quantify the frequencies of internal modes as Ecloud effects become significant. The beam response is sampled at 20 GS/sec. in response to arbitrary excitation patterns, with data in 2011 taken at 3 bunch intensities. We show the excitation of barycentric, head-tail and higher vertical modes. The beam motion is analyzed in the time domain, via animated presentations of the sampled vertical signals, and in the frequency domain, via spectrograms showing the modal frequencies vs. time. The demonstration of the excitation of selected internal modes is a significant step in development of the feedback control techniques. "A 4 GS/Sec. Synchronized Vertical Excitation System for SPS Studies - Steps Towards Wideband Feedback," these proceedings.

MOPPC002	Local Chromatic Correction Scheme and Crab-waist Collisions for an Ultra-low β^* at the LHC	sextupole, optics, quadrupole, luminosity	118
	J.L. Abelleira, S. Russenschuck, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland J.L. Abelleira EPFL, Lausanne, Switzerland C. Milardi, M. Zobov INFN/LNF, Frascati (Roma), Italy K. Ohmi KEK, Ibaraki, Japan D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu- CARD, grant agreement no. 227579. We discuss potential merits and the parameter range of interest for a possible crab-waist collision scheme at the LHC, and report preliminary optics studies of a local chromatic correction scheme with flat beams (β_x^>>β_y^), which could boost the LHC luminosity by about an order of magnitude and would also allow for crab-waist collisions.

MOPPC009	Multipactor for E-cloud Diagnostics	electron, cyclotron, vacuum, dipole	139
	P. Costa Pinto, F. Caspers, P. Edwards, M. Holz, M. Taborelli CERN, Geneva, Switzerland
	Electron cloud in particle accelerators can be mitigated by coating the vacuum beam pipe with thin films of low secondary electron yield (SEY). SEY of small samples can be measured in the laboratory. Verifying the performance of long pipes is more complex, since it requires their insertion in the accelerator and the subsequent measurement of the beam induced pressure rise. RF induced multipacting in a coaxial waveguide configuration is proposed as a test before insertion in the machine. The technique is applied to two main bending dipoles of the SPS, where the RF power is fed though a tungsten wire stretched along the vacuum chamber (6.4 m). A dipole with a bare stainless steel chamber shows a clear power threshold initiating an abrupt rise in reflected power and pressure. The effect is enhanced at RF frequencies corresponding to cyclotron resonances for given magnetic field. Preliminary result show that the dipole with a carbon coated vacuum chamber does not exhibit any pressure rise or reflected RF power up to the maximum available input power. In the event of a large scale coating production this technique will be a valuable resource for quality control.

MOPPC021	Explore the Possibility of Accelerating Polarized He-3 Beam in RHIC	proton, betatron, closed-orbit, neutron	172
	M. Bai, E.D. Courant, W. Fischer, V. Ptitsyn, T. Roser BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. As the world’s first high energy polarized proton collider, RHIC has made significant progress in measuring the proton spin structure in the past decade. In order to have better understanding of the contribution of up and down quarks to the proton spin structure, collisions of high energy polarized neutron beams are required. In this paper, we present studies of accelerating polarized Helium-3 in RHIC with the current dual snake configuration. The possibilities of adding two more pairs of snakes for accelerating polarized He-3 were explored. Results of a six snake configuration in RHIC are also reported in the paper.

MOPPC023	Polarization Transmission at RHIC, Numerical Simulations	polarization, simulation, optics, proton	178
	F. Méot, M. Bai, C. Liu, M.G. Minty, V.H. Ranjbar BNL, Upton, Long Island, New York, USA
	Ray-tracing methods, using the computer code Zgoubi, have proven efficient for beam and spin dynamics simulations in RHIC (see earlier PAC and IPAC publications). More simulations and results are being produced, including spin code benchmarking and cross-checking, effects of strongest resonances and working point on transport of polarization, polarization with Run 9 and Run 11 measured ramp orbit and optics, polarization profiles, etc. The numerical methods involved are recalled, a status of the work is given.

MOPPC026	Simulations of Coherent Beam-Beam Effects with Head-on Compensation	electron, proton, simulation, lattice	187
	S.M. White, W. Fischer, Y. Luo BNL, Upton, Long Island, New York, USA
	Funding: Work partially supported by Brookhaven Science Associates, LARP, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Electron lenses are foreseen to be installed in RHIC in order to mitigate the head-on beam-beam effects. This would allow operation with higher bunch intensity and result in a significant increase in luminosity. We report on recent strong-strong simulations that were carried out using the RHIC upgrade parameters to assess the impact of coherent beam-beam effects in the presence of head-on compensation.

MOPPC057	Some Comments to Magnetic Field Representation for Beam Dynamic Calculations	multipole, dipole, quadrupole, vacuum	262
	P. Schnizer, E.S. Fischer GSI, Darmstadt, Germany A. Mierau TEMF, TU Darmstadt, Darmstadt, Germany B. Schnizer TUG/ITP, Graz, Austria
	Machines with high currents and small apertures, as used for SIS100 of the FAIR project, require a sincere understanding of the resonances excited by the magnetic field distortions; typically performed by tracking codes. These codes model the field errors using a Taylor Series approximation of the field quality at the track of the ideal particle. The path of the particle within the elliptic aperture of the dipole is curved; thus the standard approach of using plane circular multipoles fails to model the real symmetry of the magnetic field, an important feature of effective field description for beam loss calculations. Therefore toroidal elliptic multipoles were developed which allow describing the magnetic field concisely in an elliptic vacuum chamber in curved dipoles and quadrupoles. In this talk we present the appropriate description and its limitation, illustrate their usefullness based on the static and transient magnetic field measurements of the first curved SIS100 dipole next to the SIS18 dipole.

MOPPC058	Eigenmode Computation for Ferrite-loaded Cavity Resonators	cavity, heavy-ion, acceleration, ion	265
	K. Klopfer, W. Ackermann, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	The GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt is operating the heavy-ion synchrotron SIS18 for fundamental research. Within the ring two ferrite-loaded cavity resonators are installed. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing velocity. Within the resonator structures dedicated biased ferrite rings are installed. In the whole setup a properly chosen bias current is used to modify the differential permeability of the ferrite material which consequently enables to adjust the eigenfrequency of the resonator system. The goal of the current study is to numerically determine the lowest eigensolutions of accelerating ferrite-loaded cavities based on the Finite Integration Technique. Since the underlying eigenmodes depend on the differential permeability, the static magnetic field generated by the bias current has to be computed in a first step. The eigenmodes can then be determined with the help of a dedicated Jacobi-Davidson eigensolver. Particular emphasis is put on the implementation to enable high performance computations based on distributed memory machines.

MOPPC067	Design and Construction of Inductive BPM	simulation, impedance, electron, vacuum	289
	M.Sh. Shafiee, E.E. Ebrahimibasabi, S.A.H. Feghhi, N. Goudarzi sbu, Tehran, Iran M. Jafarzadeh ILSF, Tehran, Iran
	To have a controllable Electron machine, that is required to be able to control beam orbits by knowing the beam position. The basic requirement for detecting the position of electron is calibrating and testing the BPMs. For this purpose wire method is used. Since we hadn't access to accelerator, for having experience at beam diagnostic we used this method for testing our constructed inductive BPM including 4 cm square poly ethylene core with 15 turns coil in each side. In this case study that was tested by a pulsed current (as an electron bunch) produced by a pulse generator. At first Tektronix 2235A oscilloscope was calibrated and used to measure the induced voltage of each coils, then by using of microcontroller, protocol RS232 and GUI induced voltages were read. The electrical center was measured with respect to the mechanical center and wire position was detected with 1mm Resolution. Conversion between the BPM signals and the actual wire position were done. Results were compared and presented.

MOPPC072	Mathematical Model of Charged Particles Dynamics Optimization in RFQ Accelerators	rfq, emittance, controls, focusing	298
	A.D. Ovsyannikov St. Petersburg State University, St. Petersburg, Russia
	Mathematical model of optimization of transverse motion of charged particles in accelerators is suggested. Linear and nonlinear systems are considered when describing the transverse motion. Interaction of the particles is taken into account. Optimization algorithm based on minimax functionals is built. Numerical results for RFQ accelerators are presented.

MOPPD018	A FFAG Design Study for an Accelerator-driven System	proton, synchrotron, acceleration, focusing	403
	T.-Y. Lee, H.-S. Kang, H.-S. Lee PAL, Pohang, Kyungbuk, Republic of Korea
	Design of a 1 GeV FFAG accelerator is studied for the accelerator-driven sub-critical nuclear reactor system. Scaling and non-scaling lattices are studied and compared with each other. Corresponding magnet design and RF system are considered.

MOPPD021	An Experimental Investigation of Slow Integer Tune Crossing in the EMMA Non-scaling FFAG	acceleration, simulation, closed-orbit, proton	412
	J.M. Garland, H.L. Owen UMAN, Manchester, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Student STFC grant number: ST/G004277/1. Results are presented from a slow integer tune crossing experiment performed in the EMMA accelerator. Under nominal conditions EMMA accelerates an electron beam from 10–20 MeV rapidly in 5–10 turns in a novel “serpentine” channel causing several transverse integer tunes to be crossed. During this rapid acceleration it has been shown that the betatron amplitude of the beam does not grow. If the potential of non-scaling FFAGs were to be realized in such fields as high-current proton acceleration then tune space would be crossed slower with acceleration in an RF bucket. The crossing speed in a non-scaling FFAG is in a previously unstudied intermediate region and hence conventional crossing theory may not apply. It was proposed to observe the effects on betatron amplitude when a beam crosses integer tunes by the variation of tune with momentum over a range of crossing speeds derived from different acceleration rates. This method can be realized by synchrotron acceleration inside a stable RF bucket. Betatron amplitude growth and beam loss as a function of turn are explored when crossing an integer tune and a relationship between crossing speed and these quantities is established.

MOPPD023	Correction of the nu_r=3/2 Resonance in TRIUMF Cyclotron	cyclotron, TRIUMF, extraction, simulation	415
	T. Planche, R.A. Baartman, Y.-N. Rao TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	Imperfections in the TRIUMF cyclotron are a source of field errors which slightly violate the 6-fold symmetry of the ring. Among them, the third harmonic of the magnetic gradient errors drives the ν_r=3/2 resonance. This results in a modulation of the current density versus radius observed after the resonance crossing all the way to the extraction (480 MeV). The cyclotron has sets of harmonic correction coils at different radii, each set constituted of 6 pairs of coils placed in a 6-fold symmetrical manner. The 6-fold symmetry of this layout makes that a single set of harmonic coils cannot provide a full correction of third harmonic errors driving the ν_r=3/2 resonance. The last two sets of harmonic correction coils (number 12 and 13) are azimuthally displaced. In this study, we use this fact to achieve a full correction of the resonance. We also present experimental measurements that demonstrate the full correction.

MOPPD027	A Compact High Intensity Cyclotron Injector for DAEδALUS Experiment	extraction, cyclotron, beam-losses, simulation	424
	L. Calabretta, D. Rifuggiato INFN/LNS, Catania, Italy A. Adelmann Paul Scherrer Institut, Villigen, Switzerland A. Calanna, D. Campo CSFNSM, Catania, Italy M.M. Maggiore, L.A.C. Piazza INFN/LNL, Legnaro (PD), Italy J.J. Yang CIAE, Beijing, People's Republic of China
	Funding: Istituto Nazionale di Fisica Nucleare - Laboratori Nazionale del Sud. The experiment DAEδALUS, recently proposed by MIT scientist to search for CP violation in the neutrino sector, needs three accelerator with energy of about 800 MeV, average power of some MW and duty cycle of 20%. To reduce the cost of the accelerators a cyclotron complex consisting of an injector and of a booster ring cyclotron has been proposed. The main characteristics of the new kind of separated sector cyclotron injector able to accelerate a H²⁺ molecule beam up to 60 MeV/n will be presented. Due to the low duty cycle, the peak current to be accelerated is 5 mA. The problem related to the injection of a H²⁺ beam, delivered by a compact ion source, and to the space charge effects will be discussed. To allow an easier injection in the booster Superconducting Ring Cyclotron the extraction energy has been increased up to 60 MeV/n. The pole gap was decreased to 60 mm to achieve a more efficient beam extraction. The updated configuration of the magnetic sectors, of the isochronous magnetic field and beam dynamics along extraction path and during the acceleration will be presented, too. J. Alonso et al., "Novel Search for CP Violation in the Neutrino Sector: DAEδALUS," Jun2010 e-Print: arXiv:1006.0260 ** L. Calabretta, Proc. of IPAC 2011, WEPS073, p. 2673 (2011).

MOPPD062	Aperture Measurements in the LHC Interaction Regions	injection, emittance, luminosity, optics	508
	S. Redaelli, M.C. Alabau Pons, R.W. Assmann, R. Bruce, M. Giovannozzi, G.J. Müller, M. Pojer, J. Wenninger CERN, Geneva, Switzerland
	The aperture of the LHC interaction regions is crucial for the LHC performance because it determines the smaller β^* that can be achieved. The aperture has been measured at a maximum energy of 3.5 TeV and at different β^* values, following optimized procedure to allow safe measurements at high energy. In this paper, the results of these aperture measurements, which are used as a reference for β^* reach and crossing scheme estimates at the LHC interaction points, are presented.

MOPPP074	Magnetic Field Measurement for a THz Undulator Using the Vibrating Wire Method	undulator, electron, radiation, laser	732
	S. Kashiwagi, H. Hama, F. Hinode, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003. We constructed the undulator that is a basically a Halbach planer type for a generation of intense coherent terahertz radiation from the very short electron bunch. The period length of the undulator and the number of periods are 100 mm and 25, respectively. Its maximum magnetic field is 0.41 T and the K-value is 3.82 with 54 mm gap. The vibrating wire method is studied to measure the periodic magnetic field of the undulator. By measuring amplitudes and phases of standing waves excited on the wire by the Lorentz force between AC current and magnetic field, we can reconstruct the magnetic field distribution along the wire. The theoretical analysis has been performed for the THz undulator and derived a relation between a reproducibility of undulator field and the number of the harmonic mode to use for the reconstruction. A model experiment was demonstrated using 20cm wire and one pair of permanent magnet block. The theoretical study and the results of model experiment using the vibrating wire method will be shown in this conference.

MOPPR006	Surface Waves for Testing of Beam Instrumentation	instrumentation, impedance, induction, electromagnetic-fields	780
	F. Stulle, J.F. Bergoz BERGOZ Instrumentation, Saint Genis Pouilly, France
	The fundamental TM wave can be guided as a surface wave along a single dielectric coated wire. Such a setup is known as a Goubau line. Close to the wire the TM wave resembles closely the radial electric and azimuthal magnetic fields of a charged particle beam moving in an accelerator. Hence, it can be used to test beam instrumentation in the workshop. We introduce the principle, discuss benefits, and compare measurements of a beam instrumentation device performed with a Goubau line to measurements performed with a standard bench testing setup.

MOPPR073	Analysis of Resonant TE Wave Modulation Signals for Electron Cloud Measurements	electron, coupling, factory, cavity	957
	S. De Santis LBNL, Berkeley, California, USA D. Alesini INFN/LNF, Frascati (Roma), Italy J.P. Sikora CLASSE, Ithaca, New York, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231. Recent TE wave measurements of the electron cloud density in the beampipe at CesrTA and DAΦNE have shown that, especially near cutoff, the microwave excitation takes place by coupling to a standing wave, rather than to a propagating TE mode. With the beampipe acting as a resonant cavity, the effect of the periodic electron cloud density is a modulation of the cavity's resonant frequency. As a result, the measured sidebands are a combination of amplitude, phase, and frequency modulation, as the periodic cloud density modulates this resonant frequency. The quality factor Q of the resonance will determine its response to transients in the electron cloud density, and the resulting effect on modulation sidebands. In order to estimate the peak electron cloud density and its spacial distribution, knowledge of the Q and the standing wave pattern need to be determined, either by experimental measurements or simulation codes. In this paper we analyze the dependence of the modulation sidebands on the electron cloud density in two different regimes, when the cloud rise/decay time is much longer, or much shorter than the filling time of the resonance.

MOPPR074	Using TE Wave Resonances for the Measurement of Electron Cloud Density	cavity, electron, simulation, vacuum	960
	J.P. Sikora, M.G. Billing, D. L. Rubin, R.M. Schwartz CLASSE, Ithaca, New York, USA D. Alesini INFN/LNF, Frascati (Roma), Italy B.T. Carlson CMU, Pittsburgh, Pennsylvania, USA S. De Santis LBNL, Berkeley, California, USA K.C. Hammond Harvard University, Cambridge, Massachusetts, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231. In the past few years, electron cloud density has been measured by means of its effect on TE waves propagated through the accelerator vacuum chamber. This technique has been the object of careful studies and has been used in several laboratories around the world (CERN, SLAC, FNAL, Cornell, INFN-LNF). Recent measurements at CesrTA and DAΦNE show that in a majority of practical cases, the theoretical model that relates the cloud density to the phase shift induced on a TE wave propagating in beam pipe may not be the correct one. Instead, the measurement results have to be analyzed considering the effect of the electron cloud on a standing wave excited between the input and output couplers - typically Beam Position Monitors (BPMs). This standing wave pattern is not confined to the portion of beampipe between the BPMs and must be understood in order to correctly interpret the measurement. In this paper we present evidence that the transmission function near cutoff between two BPMs is the result of coupling to standing waves trapped in the vacuum chamber. This evidence includes measurements at DAΦNE, Cesr-TA, a test waveguide, computer EM simulations, and analytical calculations.

TUXA03	Increasing the AGS Beam Polarization with 80 Tune Jumps	polarization, quadrupole, emittance, closed-orbit	1015
	V. Schoefer, L. A. Ahrens, M. Bai, E.D. Courant, W. Fu, C.J. Gardner, J.W. Glenn, H. Huang, F. Lin, A.U. Luccio, J.-L. Mi, J. Morris, P.J. Rosas, T. Roser, P. Thieberger, N. Tsoupas, A. Zelenski, K. Zeno BNL, Upton, Long Island, New York, USA
	Vertical depolarizing resonances in the AGS are removed by partial Siberian snakes. These magnets move the stable spin direction and lead to horizontal depolarizing resonances. The tune jump quadrupole system increases the crossing rate for horizontal resonances by a factor of six. This presentation will review the fundamental mechanism of depolarizing resonances, the partial Siberian snake solution and describe recent experimental evidence at the AGS demonstrating improvements to beam polarization and the beam dynamics challenges posed by the tune jump.
	Slides TUXA03 [5.199 MB]

TUOAA01	3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields	plasma, electron, wiggler, simulation	1059
	S.A. Veitzer, P. Stoltz Tech-X, Boulder, Colorado, USA J.A. Crittenden, K.G. Sonnad CLASSE, Ithaca, New York, USA
	Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499) and by the National Science Foundation Grant PHY-0734867. Electron clouds have the potential to pose serious limitations on accelerator performance in both hadron and lepton beams. Experiments using rf diagnostics are being performed to measure electron cloud densities at a number of accelerator facilities. However, it is difficult to calibrate plasma density with signal strength in these experiments, and modeling involves a number of technical and numerical challenges. Typically 2-Dimensional electrostatic methods have been used to model cloud buildup under beam crossing conditions. However, since traveling-wave rf experiments typically occur over many meters of beam pipe where magnetic fields are changing, one needs to develop 3-Dimensional electromagnetic models in order to accurately simulate rf diagnostics. We have developed accurate models of electron cloud-induced phase shifts in rf in a system with spatially varying magnetic field configurations using the plasma simulation code VORPAL. We present here results for measuring phase shifts in the CESR wiggler with realistic, spatially non-uniform magnetic field configurations.
	Slides TUOAA01 [18.367 MB]

TUOAC02	Development of HTS Magnets	dipole, superconductivity, synchrotron, neutron	1095
	K. Hatanaka, M. Fukuda, N. Hamatani, N. Izumi, K. Kamakura, T. Saito, H. Ueda, Y. Yasuda, T. Yorita RCNP, Osaka, Japan T. Kawaguchi KT Science Ltd., Akashi, Japan
	A quarter of a century has passed since the discovery of high-temperature superconductor (HTS) materials in 1986. Although many prototype devices using HTS wires have been developed, these applications are presently rather limited in accelerator and beam line facilities. We have investigated the performance of HTS wires applied for magnets excited by alternating current (AC) as well as direct current (DC) for a decade. In order to check feasibilities of pulse magnets using HTS wire, we have fabricated a super-ferric dipole magnet to be operated by lumping currents. Upper and lower coil consists of 3 double pancakes of 200 turns. Critical currents were measured of wire measured at 77K. Self-field Ic of wire was higher than 160A. Ic values of double pancakes were 60-70A. After stacking, they were 47A and 51A for the upper and lower coil, respectively. Cooling tests were successfully done and the Ic values were measured to be 280A at 20K. Performance tests are ongoing in the pulse mode operation.
	Slides TUOAC02 [5.252 MB]

TUEPPB002	Numerical Simulations of Transverse Beam Diffusion Enhancement by the Use of Electron Lens in the Tevatron Collider	electron, simulation, collider, beam-beam-effects	1113
	V. Previtali, G. Stancari, A. Valishev Fermilab, Batavia, USA D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	Funding: "Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. This work was partially supported by the US LHC Accelerator Research Program (LARP)." Transverse beam diffusion for the Tevatron machine has been calculated using the Lifetrac code. The following effects were included: random noise (representing residual gas scattering, voltage noise in the accelerating cavities) lattice nonlinearities and beam-beam interactions. The time evolution of particle distributions with different initial amplitudes in Hamiltonian action has been simulated for 6 million turns, corresponding to a machine time of about 2 minutes. For each particle distribution, several cases have been considered: a single beam in storage ring mode, the collider case, and the effects of a hollow electron beam collimator

TUPPC009	Dihedral Group and Repetitive Achromats with Mirror Symmetric or Mirror Antisymmetric Basic Cell	multipole, electron, focusing, free-electron-laser	1170
	V. Balandin, R. Brinkmann, W. Decking, N. Golubeva DESY, Hamburg, Germany
	Using the group-theoretical point of view for the design of magnetic optical achromats as introduced in, we study in this paper second- and third-order repetitive achromats with a mirror symmetric or mirror antisymmetric basic cell. We also compare these achromats with repetitive achromats designed without internal cell symmetries taken into account. V.Balandin, R.Brinkmann, W.Decking, N.Golubeva. Two Cell Repetitive Achromats and Four Cell Mirror Symmetric Achromats, Proceedings of IPAC'10, Kyoto, Japan.

TUPPC014	Design Study of Nonlinear Optics for a Very Low-emittance Lattice of the SPring-8 II	lattice, sextupole, emittance, optics	1185
	Y. Shimosaki, K.K. Kaneki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, M. Takao JASRI/SPring-8, Hyogo-ken, Japan
	A feasibility of a very low-emittance storage ring has been studied for an upgrade project, SPring-8 II. Its ultimate goal is to provide a superior brilliance for 0.5 ~ 100 keV photons. A sextupole bend lattice with the natural emittance of 70 pmrad at 6 GeV has been examined as the first candidate. The nonlinear optics has been optimized to enlarge the dynamic aperture by correcting nonlinear resonances based on an isolated resonance Hamiltonian with thick lens approximation, and by non-interleaved sextupole method. A genetic algorithm, which has been examined to improve the performance of the present SPring-8, will be adopted for detailed optimization of the tunes and sextupole strength to adjust the non-interleaved scheme and to correct higher order resonances. The correction scheme of nonlinear optics and its results will be presented in detail. Y. Shimosaki et al., IPAC’11, TUOAB01, p. 942 (2011). **Y. Shimosaki et al., "Optimization of Lower Emittance Optics for the SPring-8 Storage Ring", these proceedings.

TUPPC016	Progress of Emittance Coupling Correction at the SPring-8 Storage Ring	coupling, betatron, storage-ring, survey	1191
	M. Takao, M. Masaki, Y. Shimosaki, K. Soutome, S. Takano, C. Zhang JASRI/SPring-8, Hyogo-ken, Japan
	The vertical beam spread, or the emittance coupling, is one of the most important parameters for the high brilliance light source storage ring. By the precise alignment of the magnets and the proper COD correction, at the commissioning phase of the SPring-8 storage ring we succeeded in achieving the very small coupling ~0.2 % without correction. However, the coupling had grown large with the years, so recently we have corrected it and recovered the initial performance. The scheme of the coupling correction at the SPring-8 storage ring is the global one, which is based on the perturbation theory with single resonance approximation. In the beginning of the correction the coupling was corrected by means of minimizing the vertical beam size. Then the performance of the coupling correction has been further improved by changing the scheme to minimizing the betatron coupling mode in the vertical oscillation of the horizontally kicked beam. This result implies that the higher order coupling contributes to the emittance coupling, which can be corrected by the higher skew multi-pole magnet. The present status of the coupling correction at the SPring-8 storage ring will be reported.

TUPPC037	Update on LHeC Ring-Ring Optics	sextupole, insertion, optics, lattice	1242
	M. Fitterer KIT, Karlsruhe, Germany O.S. Brüning, H. Burkhardt, B.J. Holzer, J.M. Jowett CERN, Geneva, Switzerland M. Klein The University of Liverpool, Liverpool, United Kingdom
	An update of the LHeC Ring-Ring optics is presented which accounts for chromatic corrections and more flexibility in the tune adjustment.

TUPPC057	RHIC Spin Flipper Commissioning Results	dipole, polarization, injection, proton	1302
	M. Bai, W.C. Dawson, J. Kewisch, Y. Makdisi, P. Oddo, C. Pai, P.H. Pile, T. Roser BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The five ac dipole design of RHIC spin flipper in the Blue ring was first commissioned during the RHIC 2012 polarized proton operation. The advantage of this design is to eliminate the vertical coherent betatron oscillations outside the spin flipper. Spin flipping efficiency was measured with both 100 GeV and 250 GeV polarized proton beams. This paper presents the latest commissioning results. M. Bai , T. Roser, C. Dawson, Y. Makdisi, W. Meng, F. Meot, P. Oddo, C. Pai, P. Pile, RHIC Spin Flipper New Design and Commissioning Plan, IPAC10 proceedings, IPAC 2010, Kyoto, Japan, 2010

TUPPC063	The AGS Synchrotron with Four Helical Magnets	injection, betatron, optics, quadrupole	1320
	N. Tsoupas, H. Huang, W.W. MacKay, T. Roser, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the US Department of Energy. The idea of using two partial helical magnets was applied successfully to the AGS synchrotron, to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. This modification provides many advantages over the present setup of the AGS that uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides a larger “spin tune gap” for the placement of both the vertical and horizontal tunes of the AGS during acceleration, second. Although the same spin gap can be obtained with two partial helices of equal strength, the required strength of the two helices makes it impractical. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and comparison of these results with the present setup of the AGS that uses two partial helical magnets. T. Roser et al., Proc. EPAC04, p. 1577 (2004). H. Huang et al., PRL 99, 154801(2007). * N. Tsoupas et. al., these proceedings.

TUPPC065	High Intensity Beam Analysis for the Superconducting Radio-frequency Linac (SRF-Linac) of the IFMIF-EVEDA Accelerators	emittance, linac, SRF, space-charge	1323
	W. Simeoni CEA/IRFU, Gif-sur-Yvette, France N. Chauvin, P.A.P. Nghiem, D. Uriot CEA/DSM/IRFU, France
	In this proceeding we analyze space charge effects on the beam dynamics of IFMIF accelerators. The objective is to be able to characterize and understand the crucial issues like halo formation, emittance growth and sudden particle losses in the SRF-Linac. We use the Hofmann stability charts to identify modes of collective space charge density oscillations that are responsible for the transfer and growth of the emittance. With identification of modes we are able to treat the parametric resonance between the modes and the nonlinear motion of an individual ion the amplitude of which is greater than the core radius. The resulting phase space consists of an inner separatrix containing the core and an outer separatrix that becomes the locus near which the halo particles enter and cluster.

TUPPC067	How to Achieve Longitudinally Polarized Electrons using Integer Spin Tune Resonances	polarization, synchrotron, dipole, electron	1326
	O. Boldt, A. Dieckmann, F. Frommberger, W. Hillert, J.F. Schmidt ELSA, Bonn, Germany
	Funding: Bundesministerium für Bildung und Forschung Commonly, strong solenoids are used in circular accelerators to achieve longitudinal polarization. In practice, however, these solenoids cause a phase space coupling, which has to be compensated for by sophisticated decoupling schemes. We suggest to adiabatically ramp into an integer spin tune resonance, while preserving the degree of polarization. When appropriately adjusting the driving horizontal field contributions at the final energy, the resulting polarization is longitudinal at predefined positions in the accelerator. Here, depending on the energy spread, the degree of polarization is conserved for several seconds. The contribution shows the numerical analysis of this scenario being confirmed by first demonstration tests at the ELSA stretcher ring.

TUPPC069	Third-Order Apochromatic Drift-Quadrupole Beamline	quadrupole, betatron, beam-transport, focusing	1329
	N. Golubeva, V. Balandin, R. Brinkmann, W. Decking DESY, Hamburg, Germany
	We have shown that for every drift-quadrupole system there exists an unique set of Twiss parameters (apochromatic Twiss parameters), which will be transported through that system without first order chromatic distortions. In this paper we continue the development of the theory of apochromatic focusing and present the design of a straight drift-quadrupole system which can transport apochromatic beam ellipses without influence not only of the second but also of the third order chromatic and geometric aberrations of the beamline transfer map. V.Balandin, R.Brinkmann, W.Decking, N.Golubeva. Apochromatic Beam Transport in Drift-Quadrupole Systems. Proceedings of IPAC'10, Kyoto, Japan.

TUPPC073	Frequency Map Analysis for SuperB	lattice, dynamic-aperture, emittance, sextupole	1341
	S.M. Liuzzo, M.E. Biagini, P. Raimondi INFN/LNF, Frascati (Roma), Italy T. Demma LAL, Orsay, France Y. Papaphilippou CERN, Geneva, Switzerland
	The frequency map analysis is applied to the SuperB HER and LER lattices including the Final Focus, in order to understand the dynamic aperture limitation and provide insight for a working point optimization. In this respect, frequency and diffusion maps are evaluated applying random magnet misalignments and tilts, before and after correction of orbit, dispersion and coupling using Low Emittance Tuning techniques. The same analysis is performed for on and off momentum particles. The lattice properties are further investigated using working point scans and the correction of non linear resonance driving terms and amplitude detuning.

TUPPC074	Study of Resonance Driving Term in Electron Storage Rings	damping, radiation, storage-ring, electron	1344
	G. Liu, W. Li, L. Wang USTC/NSRL, Hefei, Anhui, People's Republic of China
	The resonance driving term (RDT) is useful to analyze and optimize the nonlinear performance of the storage ring. In addition to analytical calculation of RDT, experimental measurement of RDT has been made in some proton storage rings based on turn-by-turn BPM data. For electron storage rings, the analysis is more complicated due to decoherence effects and strong radiation damping. The relation between spectral decomposition of BPM data and RDT is derived and validated using beam numerical tracking data in this paper.

TUPPC077	Numerical Study of Beam Trapping in Stable Islands for Simple 2D Models of Betatronic Motion	emittance, simulation, extraction, octupole	1350
	M. Giovannozzi, C. Hernalsteens CERN, Geneva, Switzerland
	An essential ingredient for the proposed Multi-Turn Extraction (MTE) at the CERN PS is the beam trapping in stable islands. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, the splitting process is studied quantitatively by means of numerical simulations performed on 2D model representing the horizontal non-linear betatronic motion. The results are reviewed and discussed in details.

TUPPC090	Beam Physics of Integrable Optics Test Accelerator at Fermilab	simulation, betatron, lattice, optics	1371
	A. Valishev, S. Nagaitsev Fermilab, Batavia, USA V.V. Danilov ORNL, Oak Ridge, Tennessee, USA D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. Fermilab's Integrable Optics Test Accelerator is an electron storage ring designed for testing advanced accelerator physics concepts, including implementation of nonlinear integrable beam optics and experiments on optical stochastic cooling. The machine is currently under construction at the Advanced Superconducting Test Accelerator facility. In this report we present the goals and the current status of the project, and describe the details of machine design. In particular, we concentrate on numerical simulations setting the requirements on the design and supporting the choice of machine parameters.

TUPPC096	Optimization of the Dynamic Aperture for SPEAR3 Low-emittance Upgrade	sextupole, emittance, dynamic-aperture, optics	1380
	L. Wang, X. Huang, Y. Nosochkov, J.A. Safranek SLAC, Menlo Park, California, USA M. Borland ANL, Argonne, USA
	A low emittance upgrade is planned for SPEAR3. As the first phase, the emittance is reduced from 10nm to 7nm without addition magnets. A further upgrade with even lower emittance will require a damping wiggler. There is a smaller dynamic aperture for the lower emittance optics due to the stronger nonlinearity. A Multi-Objective Genetic Optimization (MOGA) code is used to maximize the dynamic aperture. Both the dynamic aperture and beam lifetime are optimized simultaneously. Various configurations of the sextupole magnets have been studied in order to find the best configuration. The betatron tune also can be optimized to minimize resonance effects. The optimized dynamic aperture increases 15% from the normal case and the life time increases from 15 hours to 17 hours. It is important that the increase of the dynamic aperture is mainly in the beam injection direction. Therefore the injection efficiency will benefit from this improvement.

TUPPC101	A Model of the AGS Based on Stepwise Ray-Tracing Through the Measured Field Maps of the Main Magnets	quadrupole, sextupole, focusing, simulation	1395
	Y. Dutheil, F. Méot, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Two dimensional mid-plane magnetic field maps of two of the main AGS magnets were produced, from Hall probe measurements, for a series of different current settings. The analysis of these data yielded the excitation functions and harmonic coefficients of the main magnets [BNL TN 424 & TN 429] which have been used so far in all the models of the AGS. The constant increase of computation power makes it possible today to directly use stepwise ray-tracing through these measured field maps with a reasonable computation time. We describe in detail how these field maps have allowed generation of models of the 6 different types of AGS main magnets, and how they are being handled with the Zgoubi ray-tracing code. We give and discuss a number of results so obtained regarding both beam and spin dynamics in the AGS, and provide comparisons with other numerical and analytical modeling methods.

TUPPD011	Studies of the Twin Helix Parametric-resonance Ionization Cooling Channel with COSY INFINITY	simulation, emittance, quadrupole, collider	1428
	J.A. Maloney, K.B. Beard, R.P. Johnson Muons, Inc, Batavia, USA A. Afanasev GWU, Washington, USA S.A. Bogacz, Y.S. Derbenev, V.S. Morozov JLAB, Newport News, Virginia, USA B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA
	Funding: Supported in part by SBIR Grant DE-SC00005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A primary technical challenge to the design of a high luminosity muon collider is an effective beam cooling system. An epicyclic twin-helix channel utilizing parametric-resonance ionization cooling has been proposed for the final 6D cooling stage. A proposed design of this twin-helix channel is presented that utilizes correlated optics between the horizontal and vertical betatron periods to simultaneously focus transverse motion of the beam in both planes. Parametric resonance is induced in both planes via a system of helical quadrupole harmonics. Ionization cooling is achieved via periodically placed wedges of absorbing material, with intermittent rf cavities restoring longitudinal momentum necessary to maintain stable orbit of the beam. COSY INFINITY is utilized to simulate the theory at first order. The motion of particles around a hyperbolic fixed point is tracked. Comparison is made between the EPIC cooling channel and standard ionization cooling effects. Cooling effects are measured, after including stochastic effects, for both a single particle and a distribution of particles.

TUPPD017	Electromagnetic Design of RF Cavities for Accelerating Low-Energy Muons	cavity, linac, vacuum, solenoid	1446
	S.S. Kurennoy LANL, Los Alamos, New Mexico, USA
	A high-gradient linear accelerator for accelerating low-energy muons and pions in a strong solenoidal magnetic field has been proposed for homeland defense and industrial applications.* The acceleration starts immediately after collection of pions from a target in a solenoidal magnetic field and brings decay muons, which initially have kinetic energies mostly around 15-20 MeV, to 200 MeV over a distance of ~10 m. At this energy, both ionization cooling and further, more conventional acceleration of the muon beam become feasible. A normal-conducting linac with external-solenoid focusing can provide the required large beam acceptances. The linac consists of independently fed zero-mode (TM010) RF cavities with wide beam apertures closed by thin conducting edge-cooled windows. Electromagnetic design of the cavity, including its RF coupler, tuning and vacuum elements, and field probes, has been developed with the CST MicroWave Studio, and will be presented. * S.S. Kurennoy, A.J. Jason, H. Miyadera, “Large-Acceptance Linac for Accelerating Low-Energy Muons.” Proceed. IPAC10, p. 3518.

TUPPD031	Novel Techniques for Isotope Harvesting at FRIB	simulation, optics, ion, target	1470
	M.A.C. Cummings Muons, Inc, Batavia, USA L.L. Bandura FRIB, East Lansing, Michigan, USA
	Exotic isotopes have applications in medicine, industry, and national security. Historically, the U.S. has relied on foreign sources for these isotopes. FRIB will be a domestic source of these isotopes. While FRIB is mainly focused on producing exotic isotopes for basic nuclear physics experiments, it also offers an opportunity to harvest unused isotopes for other applications. It is critical that isotope harvesting take place in a synergistic manner that does not adversely affect experiments that will be simultaneously taking place at the facility. Beam optics schemes will be calculated to determine the best locations and methods of separation. These calculations will use COSY Monte Carlo and G4beamline in conjunction with other state of the art ion optical codes that simulate isotope dynamics in magnetic fields and in matter. The results of these simulations will be used to determine the best beam-target combinations to produce the isotopes that are most in-demand and calculate purities of these isotopes in multiple locations in the fragment separators. Trapping and extraction schemes will also be described to maximally recover pure isotope samples.

TUPPD043	Resonant Reaction with a Superintense Circulating Beam	target, proton, electron, storage-ring	1497
	V.G. Dudnikov, C.M. Ankenbrandt Muons, Inc, Batavia, USA
	A system for efficient generation of resonance reaction in the interaction of the circulating ion beam with a thin internal target is considered. Features of this system are high intense space charge compensated circulating ion beam with an intensity greater then a space charge limit in a near integrable nonlinear focusing system. Ionization energy loss is compensated by inductive electric field. Multiple scattering and energy straggling are compensated by electron cooling with a tabular electron beam. In this method it is possible to compensate an energy loss of circulating particles after crossing the target and have a crossing of resonant energy in every passing of target. For sharp resonance reactions and monoenergetic beams a thin target method can increase greatly the energy efficiency.

TUPPP045	Creation of FELWI using Large Amplification Regime	electron, undulator, FEL, microtron	1707
	K.B. Oganesyan ANSL, Yerevan, Armenia A.I. Artemyev, D.N. Klochkov GPI, Moscow, Russia Y. Rostovtsev University of North Texas, Denton, Texas, USA
	Funding: ISTC project A-1602 The interaction between noncollinear laser and relativistic electron beams in static magnetic undulator has been studied within the framework of dispersion equations. In the limit of small-signal gain the spatial growth rates are found for the collective (Raman) and single-electron (Thompson) regimes. For a free-electron laser without inversion (FELWI), estimates of the threshold laser power are found. The large-amplification regime should be used to bring an FELWI above the threshold laser power.

TUPPR049	An X-band Standing Wave Dielectric Loaded Accelerating Structure	multipactoring, cavity, coupling, simulation	1927
	C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA S.H. Gold NRL, Washington, DC, USA S. Kazakov Fermilab, Batavia, USA R. Konecny ANL, Argonne, USA
	Funding: DOE SBIR Phase I grant #DE-SC0006303 An 11.4 GHz standing wave dielectric loaded accelerating structure was recently developed. We expect to achieve a 120 MV/m gradient powered by a 10 MW 200 ns rf pulse from the X-band Magnicon at the Naval Research Laboratory. The structure uses on-axis rf coupling, which helps to localize the maximum EM fields within the dielectric region. Bench testing shows excellent agreement with the simulation results. The high power rf test is scheduled for January 2012.

TUPPR077	Simulation Studies for the LHC Long-Range Beam-Beam Compensators	optics, simulation, collider, betatron	2002
	T.L. Rijoff, R.J. Steinhagen, F. Zimmermann CERN, Geneva, Switzerland
	The LHC performance and the minimum crossing angle are limited by long-range beam-beam collisions. Wire compensators can mitigate part of the long-range effects and may allow for smaller crossing angles, smaller β^*, or higher beam intensity. A prototype long-range wire compensator should be installed in the LHC by 2014/15. We report simulation studies examining and comparing the efficiency of the wire compensation, in terms of tune footprint or dynamic aperture, at various candidate locations, with different wire shapes, and for varying transverse distance from the beam.

TUPPR079	Ion Polarization in the MEIC Figure-8 Ion Collider Ring	polarization, ion, proton, collider	2008
	V.S. Morozov, Y.S. Derbenev, Y. Zhang JLAB, Newport News, Virginia, USA P. Chevtsov Paul Scherrer Institut, Villigen, Switzerland Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The nuclear physics program envisaged at the Medium-energy Electron-Ion Collider (MEIC) currently being developed at the Jefferson Lab calls for collisions of 3-11 GeV/c longitudinally polarized electrons and 20-100 GeV/c, in equivalent proton momentum, longitudinally or transversely polarized light ions. In this paper, we present a scheme based on figure-8 shaped booster and collider rings that provides the required ion polarization arrangement in the MEIC's ion collider ring. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

WEOAB01	New Results from the EMMA Experiment	acceleration, injection, betatron, electron	2134
	B.D. Muratori, J.K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom C.S. Edmonds, K.M. Hock, M.G. Ibison, I.W. Kirkman The University of Liverpool, Liverpool, United Kingdom J.M. Garland, H.L. Owen UMAN, Manchester, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. After demonstration of acceleration in the serpentine channel in April 2011, the beam study with EMMA continues to explore the large transverse and longitudinal acceptance and effects of integer tune crossing with slower rate on the betatron amplitude. Together with a comparison of detailed models based on measured field maps and the experimental mapping of the machine by relating the initial and final phase space coordinates. These recent results together with more practical improvements such as injection orbit matching with real-time monitoring of the coordinates in the transverse phase space will be reported in this paper.
	Slides WEOAB01 [2.120 MB]

WEPPC008	FNAL Project X Conical Half-Wave Resonator Design	cavity, simulation, cryomodule, proton	2221
	E.N. Zaplatin FZJ, Jülich, Germany A. Kanareykin Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: This work is supported by the DOE SBIR Program, contract # DE-SC0006302. A high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory (Project X) should provide beam for a variety of physics projects. The superconducting resonators of different types will be used as accelerating structures. Here we describe the design of conical Half-Wave Resonator that is considered as an option for a first accelerating cavity for β=v/c=0.11 with the resonance frequency 162.5 MHz. A careful study of the fields in the cavity has been carried out in order to optimize the electromagnetic parameters of the structure (peak fields, quality factor, dissipation power). An intensive investigations were provided of the liquid helium vessel design to minimize cavity frequency shifts from the external loads. Different tuning schemes have been studied to secure a frequency tuning range to cope with fabrication tolerances. The paper reports results of numerical simulations of the cavity shape optimization and structural analyses. The detailed developments of the structure using numerical coupled analyses allowed to minimize the level of expected microphonics in cavity.

WEPPC017	Design of a High-Speed Pulsed 324MHz Solid-State Amplifier for Use in a Beam Chopper	impedance, proton, insertion, feedback	2242
	S.C. Dillon, B.S. Nobel, C.P. Schach Tomco Technologies, Stepney, South Australia, Australia
	A 324MHz 30kW high-speed pulsed solid-state amplifier has been designed for use in a beam chopper at the Japan Proton Accelerator Complex (J-PARC). This paper discusses the various design challenges and presents the initial performance test results. In particular, the amplifier achieves pulse rise and fall times of less than 15 nanoseconds, is easily upgradeable in power, and withstands 100% power reflection without damage.

WEPPC056	Pressure Sensitivity Characterization of Superconducting Spoke Cavities	cavity, simulation, linac, electromagnetic-fields	2339
	D. Passarelli, M.H. Awida, I.V. Gonin, L. Ristori, V.P. Yakovlev Fermilab, Batavia, USA
	The following proposal illustrates a method to characterize the pressure sensitivity behavior of superconducting spoke cavities. This methodology relies on evaluating the variation of resonant frequency of a cavity by observing only the displacements at designed regions of the cavity. The proposed method permits a reduced computational burden and a systematic approach to achieve a minimum value of pressure sensitivity in a complex system of dressed cavity. This method has been used to characterize the superconducting spoke cavities typs⁻¹ (SSR1), under development for Project X, and to design the helium containment vessel in such way to reduce the pressure sensitivity value to zero.

WEPPC068	Multipacting Simulation and Analysis for the FRIB β = 0.085 Quarter Wave Resonators using Track3P	cavity, simulation, linac, niobium	2366
	L. Ge, C. Ko, Z. Li SLAC, Menlo Park, California, USA J. Popielarski FRIB, East Lansing, Michigan, USA
	Funding: Work supported by DOE Office of Science under Cooperative Agreement DE- SC0000661, DOE Contract No. DE-AC02-76SF00515, and used resources of NERSC supported by DOE Contract No. DE-AC02- 05CH11231. The drive linac for the Facility for Rare Isotope Beams (FRIB) utilizes several types of low beta superconducting resonators to accelerate the ion beams from 0.3 MeV per nucleon to 200 MeV per nucleon. Multipacting is an issue of concern for such superconducting resonators as they have unconventional shapes. We have used the parallel codes Tack3P and Omega3P, developed at SLAC under the support of the DOE SciDAC program, to analyze the multipacting barriers of such resonators. In this paper, we will present the simulation results for the β(v/c) = 0.085 Quarter Wave Resonator (QWR) for the FRIB project. Experimental data will also be presented to benchmark with the simulation results.

WEPPC071	Quench Studies of a Superconducting RF Cavity	cavity, superconducting-RF, superconductivity, superconducting-cavity	2375
	D. Gonnella, M. Liepe, S. Posen CLASSE, Ithaca, New York, USA
	In tests of superconducting RF cavities, it is important to understand the cause of high field quenches. Quenches at high field above 25 MV/m are a limiting factor in the performance of high accelerating field cavities but their causes are currently not well understood. An ILC shaped single cell cavity with quench field near 40 MV/m was tested with temperature mapping to determine the cause of its hard quench. Prior to quench, heating on the order of 25 mK was concentrated in two hot spots. After a quench, these two hot spots remain and a new one appears with much higher heating (about 40 mK). The quench location was found by the temperature mapping system to be centered at the new hot spot, not at the two hot spot locations before that dominated quench. By studying the quench location and heating on the surface of the cavity, some hints were gained as to the cause of this quench.

WEPPC081	Measurement of the Mechanical Properties of Superconducting Cavities During Operation	cavity, linac, feedback, simulation	2399
	S. Posen, M. Liepe CLASSE, Ithaca, New York, USA
	The Horizontal Test Cryostat (HTC) contains the first prototype 7-cell 1.3 GHz superconducting cavity for the Cornell ERL main linac. In this paper, experimental measurements of the cavity's mechanical properties are presented. The mechanical resonances were studied using a Dynamic Signal Analyzer, which measured the transfer function from the fast piezo tuner to itself and the cavity frequency. The microphonics detuning of the cavity was measured, and found to satisfy the specification that the maximum detuning be below 20 Hz, even without feedback from the piezos. Correlations were studied between the microphonics detuning and the helium pressure, piezo sense signal, and the ground vibrations. The Lorentz force detuning (LFD) coefficient was also measured. The frequencies of the mechanical resonances were compared to simulation. In addition, the performance of the frequency tuners was evaluated. Both the mechanical tuner and the piezo were found to be highly linear with very little hysteresis even on small scales.

WEPPD068	High Power Collinear Load Coated with FeSiAl	cavity, simulation, linac, factory	2678
	L.G. Shen, X.L. Fu, Y. Sun, F. Zhang USTC/PMPI, Hefei, Anhui, People's Republic of China Y.J. Pei USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: This work is supported by the NSFC (NO. 10775128 and NO.51075381) Aimed at substituting output coupler to absorb remnant power of the LINAC, collinear load coated with high loss materials is expected to come reality. FeSiAl load is studied. The effect of the coating volume upon the cavity frequency and Q factor is analyzed and the dimension compensations of the cavities are suggested to tune the load cavities at 2856 MHz. Orthogonal Experimental Method is utilized to investigate the sensitivity of permittivity (both real part and imaginary part) and permeability (both real part and imaginary part) to cavity characteristics. Five cavities with different coating dimensions are manufactured and their operating frequencies and Q are measured. Compared with the simulations, they show that the Q factor, which is characterization of the actual attenuation of the FeSiAl, agrees very well with the theoretical value and Q factor of the resonant cavity is measured with the probe method. The relationship between Q factor and the length of the test probe is deduced and eventually the individual Q value of a load cavity is extracted. Simulation shows the FeSiAl load can support average power over 15 kW and the one-way attenuation is about 30 dB.

WEPPD072	Frequency Fine-tuning of a Spin-flip Cavity for Antihydrogen Atoms	cavity, antiproton, coupling, vacuum	2690
	S. Federmann, F. Caspers, E. Mahner CERN, Geneva, Switzerland B. Juhasz, E. Widmann SMI, Vienna, Austria
	As part of the ASACUSA collaboration physics program a spin-flip cavity for measurements of the ground-state hyperfine transition frequency of anti-hydrogen atoms is needed. The purpose of the cavity is to excite anti-hydrogen atoms depending on their polarisation by a microwave field operating at 1.42 GHz. The delicacy of designing such a cavity lies in achieving and maintaining the required properties of this field over a large aperture of 10cm and for a long period of time (required amplitude stability is 1% within 12h). The present paper presents the frequency fine tuning techniques to obtain the desired centre frequency of 1.42 GHz with a Q value below 500 as well as the tuning circuit used for the frequency sweep over the desired bandwidth of 6 MHz.

WEPPP005	Progress on Muon Parametric-resonance Ionization Cooling Channel Development	emittance, simulation, quadrupole, betatron	2729
	V.S. Morozov, Y.S. Derbenev JLAB, Newport News, Virginia, USA A. Afanasev GWU, Washington, USA K.B. Beard, R.P. Johnson Muons, Inc, Batavia, USA B. Erdelyi, J.A. Maloney Northern Illinois University, DeKalb, Illinois, USA
	Funding: Supported in part by DOE SBIR grant DE-SC0005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Parametric-resonance Ionization Cooling (PIC) is intended as the final 6D cooling stage of a high-luminosity muon collider. To implement PIC, a continuous-field twin-helix magnetic channel was developed. A 6D cooling with stochastic effects off is demonstrated in a GEANT4/G4beamline model of a system where wedge-shaped Be absorbers are placed at the appropriate dispersion points in the twin-helix channel and are followed by short rf cavities. To proceed to cooling simulations with stochastics on, compensation of the beam aberrations from one absorber to another is required. Initial results on aberration compensation using a set of various-order continuous multipole fields are presented. As another avenue to mitigate the aberration effect, we optimize the cooling channel’s period length. We observe a parasitic parametric resonance naturally occurring in the channel’s horizontal plane due to the periodic beam energy modulation caused by the absorbers and rf. We discuss options for compensating this resonance and/or properly combining it with the induced half-integer parametric resonance needed for PIC. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

WEPPP006	Using Simulations to Understand Particle Dynamics and Resonance in the Micro-accelerator Platform	laser, electron, coupling, acceleration	2732
	J.C. McNeur, G. Travish UCLA, Los Angeles, USA H. Hairong UESTC, Chengdu, Sichuan, People's Republic of China R.B. Yoder Manhattanville College, Purchase, New York, USA
	Funding: Work funded in part by grant HDTRA1-09-1-0043 from the US Defense Threat Reduction Agency and under a grant from NNSA/NA-221 Office of Nonproliferation and Verification Research and Development. The Micro-Accelerator Platform (MAP) is a slab-symmetric micron-scale electron accelerator. Electrons gain energy via a standing wave electromagnetic resonance powered by a side coupled Ti:Sapphire laser. In this paper, we will discuss simulations of resonance and particle dynamics in this structure. Three-dimensional simulations showing evidence of stable 1 GeV/m acceleration are detailed along with simulations studying defocusing and wakefield effects in the MAP. Additionally, optimization of the structure and the coupling of laser power into the cavity will be explored.

WEPPR004	Effect of Beam-beam Interactions on Stability of Coherent Oscillations in a Muon Collider	collider, luminosity, lattice, quadrupole	2940
	K. Ohmi KEK, Ibaraki, Japan Y. Alexahin Fermilab, Batavia, USA
	In order to achieve the peak luminosity of a muon collider in the 10³⁵ cm^-2 s^-1 range the number of muons per bunch should be of the order of a few units of 10¹² rendering the beam-beam parameter as high as 0.1 per IP. Such strong beam-beam interaction can be a source of instability if the working point is chosen close to a coherent beam-beam resonance. On the other hand, the beam-beam tune spread can provide a mechanism of suppression of the beam-wall driven instabilities. In this report the coherent instabilities driven by beam-beam and beam-wall interactions are studied with the help of BBSS code for the case of 1.5 TeV c.o.m muon collider.

WEPPR008	Simulation of Controlled Longitudinal Emittance Blow-up in J-PARC RCS	emittance, simulation, cavity, extraction	2952
	M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii KEK, Ibaraki, Japan T. Toyama J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	In the J-PARC RCS, a high intensity beam is prepared for the MR. The longitudinal beam emittance at the RCS extraction should be optimized to avoid beam loss during and after MR injection. In order to match the longitudinal emittance shape between the RCS and the MR, it is desirable to enlarge the longitudinal emittance during the RCS acceleration. We have performed the particle tracking simulation for the controlled longitudinal emittance blow up in the RCS.

WEPPR011	Numerical Simulation Study of the Montague Resonance at the CERN Proton Synchrotron	emittance, simulation, space-charge, synchrotron	2958
	J. Qiang, R.D. Ryne LBNL, Berkeley, California, USA G. Franchetti, I. Hofmann GSI, Darmstadt, Germany E. Métral CERN, Geneva, Switzerland
	Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP) under Contract No. DE-AC02-05CH11231. The Montague resonance provides a coupling between the vertical and the horizontal dynamics of beams and can cause particle losses due to unequal aperture sizes of the accelerator. In this paper, we present a new numerical simulation study of a previous Montague resonance crossing experiment at the CERN PS including detailed three-dimensional space-charge effects and machine nonlinearity. The simulation reproduces the experimental data and suggests that the longitudinal synchrotron motion played an important role in enhancing transverse resonance coupling.

WEPPR012	Simulating High-Intensity Proton Beams in Nonlinear Lattices with PyORBIT	lattice, space-charge, simulation, proton	2961
	S.D. Webb, D.T. Abell, D.L. Bruhwiler, J.R. Cary Tech-X, Boulder, Colorado, USA V.V. Danilov, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA S. Nagaitsev, A. Valishev Fermilab, Batavia, USA
	High-intensity proton linacs and storage rings are essential for a) state-of-the-art neutron source user facilities, b) extending the high-energy physics intensity frontier, c) as a driver to generate pions for a future neutrino factory or muon collider, and d) for transmutation of radioactive waste and associated energy production. For example, Project X at Fermilab will deliver MW proton beams at energies ranging from 3 to 120 GeV. Nonlinear magnetic lattices with large tune spreads and with integrable, nearly integrable* and chaotic* dynamics have been proposed to maximize dynamic aperture and minimize particle loss. We present PyORBIT*** simulations of proton dynamics in such lattices, including the effects of transverse space charge. * V. Danilov and S. Nagaitsev, PR ST-AB 13 084002 (2010) K. Sonnad and J. Cary, Phys. Rev. E 69 056501 (2004) * A. Shishlo, J. Holmes and T. Gorlov, From Proceedings of IPAC '09 351-354

WEPPR024	Motion of Charged Particle Dense Bunch in Nonuniform External Fields	emittance, vacuum, focusing	2985
	H.Y. Barminova ITEP, Moscow, Russia A.S. Chikhachev Allrussian Electrotechnical Institute, Moskow, Russia
	At the output of a linear resonance accelerator, a charged particle beam consists of a bunch series, with the relation between bunch length and transverse bunch size changing widely. It is of importance to describe bunch dynamics in a selfconsistent manner,* . Usually the charged bunch is described as ellipsoid with uniform density. Such description allows easy consideration of its own bunch fields. In the case of a nonstationary distribution it is difficult to build distribution function describing 3D-ellipsoid with uniform density** . In this paper such function is found for bunch formed as rotation ellipsoid. Radii ellipsoid equations are obtained for a bunch moving in nonuniform stationary external fields. * A.S. Chikhachev. Kinetic theory of quasystationary state of charged particle beams. Moscow,2001. ** I.M. Kapchinsky. Theory of linear resonanse accelerators. Particle dynamics. Moscow,1982.

WEPPR052	Octupole Magnets for the Instability Damping at the J-PARC Main Ring	octupole, damping, sextupole, dynamic-aperture	3045
	S. Igarashi, T. Koseki, K. Ohmi, M.J. Shirakata, H. Someya, T. Toyama KEK, Ibaraki, Japan A. Ando J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	Octupole magnets have been installed for the instability damping at the J-PARC main ring. The transverse instability was observed during the injection and acceleration periods and caused the beam losses. The chromaticity tuning and bunch-by-bunch feedback system have been applied to suppress the instability. Octupole magnets were considered to create a larger amplitude dependent betatron tune shift and to supply additional option for the instability damping. The side effects of the dynamic aperture reduction and the resonances have been studied.

WEPPR062	The Mode Matching Method Applied to Beam Coupling Impedance Calculations of Finite Length Devices	impedance, coupling, simulation, cavity	3069
	N. Biancacci, E. Métral, B. Salvant CERN, Geneva, Switzerland M. Migliorati, L. Palumbo URLS, Rome, Italy V.G. Vaccaro Naples University Federico II and INFN, Napoli, Italy
	The infinite length approximation is often used to simplify the calculation of the beam coupling impedance of accelerator elements. This is expected to be a reasonable assumption for devices whose length is greater than the transverse dimension but may be less accurate approximation for segmented devices. This contribution presents the study of the beam coupling impedance in the case of a finite length device: a cylindrical cavity loaded with a toroidal slab of material. In order to take into account the finite length we will decompose the field in the cavity and in the beam pipe into a set of orthonormal modes and apply the mode matching method to obtain the impedance. To validate our method, we will present comparisons between analytical formulas and 3D electromagnetic CST simulations as well as applications to the impedance of short beam pipe inserts, where the longitudinal and transverse dimensions are difficult to model in numerical simulations.

WEPPR068	Mitigation of Electron Cloud Instabilities in the LHC Using Sextupoles and Octupoles	electron, octupole, sextupole, damping	3084
	K.S.B. Li, G. Rumolo CERN, Geneva, Switzerland
	Coherent electron cloud instabilities pose a serious limitation for luminosity upgrades in the Large Hadron Collider (LHC) at CERN. In particular, when bunch spacings reach below 50 ns, electron cloud formation is enhanced which in turn drives beam instabilities. The beam can be stabilised by shifting the tune and by increasing the tune spread using sextupoles or octupoles, respectively. The resulting values for the chromaticity and the detuning parameters must be selected with care, however, in order not to run into head-tail instabilities or to considerably reduce the dynamic aperture. A simulation study has been launched to estimate the parameters necessary for stabilisation of the beam under the influence of electron clouds.

WEPPR077	Analysis of Long-range Wakefields in CLIC Main Linac Accelerating Structures with Damping Loads	wakefield, simulation, damping, HOM	3111
	G. De Michele Paul Scherrer Institut, Villigen, Switzerland G. De Michele EPFL, Lausanne, Switzerland A. Grudiev CERN, Geneva, Switzerland
	The baseline design of the CLIC accelerating structure foresees a moderate detuning and heavy damping of high order modes (HOMs), which are the source of long-range transverse wakefields. Such unwanted fields produce bunch-to-bunch instabilities so the HOMs must be suppressed. In order to damp these modes, the CLIC RF structure is equipped with lossy material inserted into four rectangular waveguides coupled to each accelerating cell. The lossy material absorbs EM (electromagnetic) wave energy with little reflection back to the accelerating cells. In the past, computations of the long-range wake of CLIC accelerating modes have been done using perfectly absorbing boundaries to terminate the damping waveguides. In this paper, 3D EM simulations of CLIC baseline accelerating structure with HOMs damping loads will be presented. A comparison between different EM codes (GdfidL, CST PARTICLE STUDIO®) will be discussed as well as the analysis of different types of absorbing materials with respect to the wakefields damping.

WEPPR095	Radial Eigenmodes for a Toroidal Waveguide with Rectangular Cross Section	impedance, electron, wakefield, synchrotron	3159
	R. Li JLAB, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. In applying mode expansion to solve the CSR impedance for a section of toroidal vacuum chamber with rectangular cross section, we identify the eigenvalue problem for the radial eigenmodes which is different from that for cylindrical structures. In this paper, we present the general expressions of the radial eigenmodes, and discuss the properties of the eigenvalues on the basis of the Sturm-Liouville theory.

THYB01	Beam-beam Limit in a Hadron Collider	luminosity, emittance, simulation, collider	3208
	K. Ohmi KEK, Ibaraki, Japan
	Beam-beam limit phenomenon is observed in degradation of luminosity lifetime and/or beam life time in hadron colliders, especially in LHC. We focus the luminosity degradation in this paper. Various effects to degrade the luminosity grow severe in a high beam intensity. Coherent beam-beam instability, incoherent beam-beam emittance growth and those cupeled with lattice errors, external noises, intra-beam scattering. The beam-beam limit in an ideal machine and a machine with above errors is discussed with theory and simulation. Experimental results are reviewed and compare with the theory and simulations.
	Slides THYB01 [4.712 MB]

THPPC001	Simulation and Design of a 70 MeV Cyclotron RF System	cyclotron, simulation, cavity, vacuum	3269
	G. Gold, R.R. Johnson, B.F. Milton, V. Sabaiduc BCSI, Vancouver, BC, Canada
	The electromagnetic and mechanical design of the resonant cavity for a 70 MeV compact commercial cyclotron has been conducted by Best Cyclotron Systems Inc. Various resonator configurations have been studied for a radial, single-stem design and an optimal solution was selected with excellent electromagnetic properties and minimized construction and operational cost. Rapid model iterations during the design, using CST Microwave Studio and ANSYS, allowed for accurate tuning of geometry to precisely define the shape of the accelerating voltage profile, surface current distribution, and total power loss. The RF system of the BEST 70p cyclotron will operate at the fourth harmonic with two λ/2 separated resonant cavities shielded at the center allowing for beam modulation techniques to be applied through phase modulation of the accelerating voltage.

THPPC015	Design of a Four-vane 325 MHz RFQ Cold Model at Tsinghua University	rfq, cavity, dipole, simulation	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.

THPPC020	Accurate Measurement of Ferrite Garnets to be used for Fast-tuned Ferrite Loaded Cavities in the Range of 20-40 MHz	cavity, impedance, vacuum, dipole	3317
	C. Vollinger, F. Caspers CERN, Geneva, Switzerland
	For the implementation of ferrite-tuned cavities with perpendicular biased ferrites in the frequency range of 20 to 40 MHz, different types of ferrite garnets were evaluated in terms of their electromagnetic properties. We describe a precision measurement method applicable to small-sized ferrite samples of 1-square-inch surface and 2 mm thickness in the given frequency range. During measurement, these samples are exposed to varying magnetic bias fields of different orientations. Two different techniques for the determination of the real and the imaginary part of the permeability are required to achieve sufficiently accurate results. We present a detailed description of these methods as well as results obtained.

THPPC036	The Alpha Ferrite-loaded Coaxial Resonator Cavity	cavity, damping, storage-ring, radiation	3365
	A.N. Pham, S.-Y. Lee, T.H. Luo IUCEEM, Bloomington, Indiana, USA
	Funding: Grant N00164-08-GM03 P00004 from the NSWC Crane Division, DOE Grant DE-FG02-92ER40747, and NSF Grant PHY-0852368 (IU: 48-432-31). The Advanced Electron Photon Facility (ALPHA),* is a joint collaboration between the Indiana University Center for Exploration of Energy and Matter and the Crane Naval Surface Warfare Center. The ALPHA storage ring will serve as a debuncher in single pass mode of operation. With a set of two gradient damping wigglers, the storage ring can also accumulate to achieve high charge density beams. In this report, we present the design, fabrication, and testing of the 15 MHz ferrite-loaded quarter-wave rf coaxial resonator cavity that will be utilized in the ALPHA storage ring. Topics pertaining to beam lifetime, radiation damping, ferrite-loaded transmission lines, and key cavity parameters will be discussed. * S.Y. Lee, P.E. Sokol, et al, "The ALPHA Project at IU CEEM," Proceedings of the IPAC2010. ** S.Y. Lee, et al, "A low energy electron storage ring with tunable compaction factor," RSI 78, 2007.

THPPC044	Development of the Dual Slot Resonance Linac	linac, coupling, cavity, impedance	3383
	N. Barov, X. Chang, R.H. Miller, D.J. Newsham Far-Tech, Inc., San Diego, California, USA
	Funding: Work supported by DOE Grant DE-FG02-08ER85034 We report the status of the Dual Slot Resonance (DSR) linac under development by FAR-TECH. In this linac type, cell-to-cell coupling is provided by a pair of close-coupled resonant slots, resulting in very strong coupling vs. a typical side-coupled linac design, as well as a much more compact radial space requirement. We discuss the status of the structure fabrication, the RF distribution system, and installation and testing at the UCLA Pegasus facility.

THPPC049	Progress on the MICE 201 MHz RF Cavity at LBNL	cavity, simulation, coupling, electron	3398
	T.H. Luo, D.J. Summers UMiss, University, Mississippi, USA A.J. DeMello, D. Li, S.P. Virostek, M.S. Zisman LBNL, Berkeley, California, USA
	The international Muon Ionization Cooling Experiment (MICE) aims at demonstrating transverse cooling of muon beams by ionization. The ionization cooling channel of MICE requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. In this paper, we present recent progresses on MICE RF cavity at LBNL, which includes electro-polishing, intended to improve the cavity performance in the presence of strong external magnetic field; low power RF measurements on resonant frequency and Q value of each cavity with a pair of curved- beryllium windows to terminate the cavity irises. Multipacting simulations are conducted using SLAC’s ACE-3P code to study the effects in the cavity and coupler regions with the influence by external magnetic field.

THPPC077	Resonance Control of Superconducting Cavities at Heavy Beam Loading Conditions	cavity, controls, beam-loading, LLRF	3467
	M.K. Grecki, S. Pfeiffer DESY, Hamburg, Germany
	Funding: The research leading to these results has received funding from the European Commission under the EuCARD FP7 Research Infrastructures grant agreement no. 227579 The SC cavities operated at high Q level need to be precisely tuned to the RF frequency. Well tuned cavities assure the good field stability and require minimum level of RF power to reach the operating gradient level. The TESLA cavities at FLASH are tuned with the help of slow (step motors) and fast (piezo) tuners driven by the control system. The goal of this control system is to keep the detuning of the cavity as close to zero as possible in the presence of disturbing effects (Lorentz force detuning and microphonics). The detuning of the cavity can be determined using a few measurement methods. The most common is to measure detuning from the phase derivative at the end of the RF pulse. In order to calculate the detuning during the whole RF pulse the cavity equation must be solved taking into account all the driving forces (RF power delivered to the cavity and beam contribution). This in not the trivial task, particularly in the heavy beam conditions, since all signals must be precisely calibrated. This work presents the methods and algorithms to evaluate and control the detuning of the superconducting cavities in the heavy beam loading conditions adequate for ILC operation. Grecki M., Piezo operation experience at FLASH, LLRF-2011, DESY, 09.2011 ** Grecki M. et al. Piezo Control for Lorentz Force Detuned SC Cavities of DESY FLASH, IPAC'10, Kyoto, Japan, pp.1452-1454

THPPC089	LLRF Control for SPX @ APS Demonstration Experiment	cavity, LLRF, controls, low-level-rf	3491
	G. Huang, J.M. Byrd, K. Campbell, L.R. Doolittle, J.B. Greer LBNL, Berkeley, California, USA N.D. Arnold, T.G. Berenc, F. Lenkszus, H. Ma ANL, Argonne, USA
	The SPX experiment at APS is part of the APS upgrade project, using two deflecting cavity to chirp the electron pulse and then generate short pulse x-ray. To minimize the influence to other users on the storage ring, the phase synchronization of the two deflecting cavity are required to be better then 77 femto-second. A LLRF4 board based system is designed to demonstrate the capability of meeting this requirement. This paper discuss the hardware and firmware design of the demo experiment including the cavity emulator, frequency reference generation and LLRF control algorithm.

THPPD050	Fast Ramping Arbitrary Waveform Power Supplies for Correction Coils in a Circular Electron Accelerator	electron, controls, dipole, power-supply	3623
	A. Dieckmann, A. Balling, O. Boldt, F. Frommberger, W. Hillert, W. Lindenberg ELSA, Bonn, Germany
	New fast ramping power supplies working in pulsed bridge technology upgrade the existing Corrector System at ELSA. Current changes of ±0.8 A/msec are achieved. The newly developed CAN-Bus Interface allows linear interpolation of up to 250 support points with minimal time steps of 1msec. The first stage uses 24 power supplies to improve the position of the beam orbit in the horizontal plane using dipole correction coils. It will be extended to include the vertical plane with new corrector coils in the near future. This poster describes the operating principles of the power supply and the interface.

THPPP026	Experimental Effects of Orbit on Polarization Loss in RHIC	polarization, acceleration, injection, proton	3788
	V.H. Ranjbar Tech-X, Boulder, Colorado, USA M. Bai, H. Huang, A. Marusic, M.G. Minty, V. Ptitsyn BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We are performing several experiments during the RHIC ramp to better understand the impact of orbit errors on the polarization at our current working point. These will be conducted by exciting specified orbit harmonics during the final two large intrinsic resonance crossing in RHIC during the 250 GeV polarized proton ramp. The resultant polarization response will then be measured.

THPPP030	Near Integer Tune for Polarization Preservation in the AGS	optics, polarization, acceleration, injection	3797
	N. Tsoupas, L. A. Ahrens, M. Bai, K.A. Brown, J.W. Glenn, H. Huang, W.W. MacKay, T. Roser, V. Schoefer, K. Zeno BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the US Department of Energy. The high energy (T=250 GeV) polarized proton beam experiments performed in RHIC, require high polarization of the beam. In order to preserve the polarization of the proton beam, during the acceleration in the AGS, which is the pre-injector to RHIC, two partial helical magnets have been installed in AGS. In order to minimize the loss of the beam polarization due to the various intrinsic spin resonances occurring during the proton acceleration, we constrain the value of the vertical tune to be higher than 8.97. With the AGS running at near integer tune the perturbations caused by the partial helical magnets is large resulting in large beta and dispersion waves. To mitigate the adverse effect of the partial helices on the optics of the AGS, we have introduced compensation quads** in AGS. In this paper we present the beam optics of the AGS which ameliorates this effect of the partial helices. * H. Huang, et al., Proc. EPAC06, p. 273, (2006). ** N. Tsoupas et al., Proc. PAC07, p. 3723 (2007).

THPPP038	Simulations of the Influence of 4-Rod RFQ Elements on its Voltage Distribution	rfq, simulation, linac, insertion	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	simulation, cavity, impedance, induction	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.

THPPP041	A CW High Charge State Heavy Ion RFQ Accelerator for SSC-LINAC Injector	rfq, linac, focusing, ion	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

THPPR005	The Preliminary Test of a Digital Control System Based on the FPGA for a PEFP 120-keV RF Cavity	cavity, controls, accelerating-gradient, proton	3975
	Y.M. Li, S. Cha UST, Daejeon City, Republic of Korea Y.-S. Cho, J.-H. Jang, H.S. Kim, H.-J. Kwon, Y.M. Li, K.T. Seol, Y.-G. Song KAERI, Daejon, Republic of Korea
	Funding: Proton Engineering Frontier Project, Korea Atomic Energy Research Institute, Ministry of Education, Science and Technology of the Republic of Korea. PEFP developed a 120-keV RF cavity for their ion implantation applications. Due to ambient disturbances, the cavity’s resonance frequency may vary in long-term test. We designed a digital control system to change the frequency of the RF sources for tracking the cavity’s frequency variations. The digital control system has functions such as, phase shift, phase comparison, proportional-integral compensation, waveform generation and frequency/pulse modulation, and driving signal generator. Most of them are implemented digitally in a Virtex II 4000 Field Programmable Gate Array (FPGA). In this research we show the design and the preliminary test results of the digital control system. * Work supported by the Ministry of Science and Technology

THPPR039	Controlled Transverse Blow-Up of High-energy Proton Beams for Aperture Measurements and Loss Maps	injection, emittance, feedback, proton	4059
	W. Höfle, R.W. Assmann, S. Redaelli, R. Schmidt, D. Valuch, D. Wollmann, M. Zerlauth CERN, Geneva, Switzerland
	A technique was developed to blow-up transversely in a controlled way high energy proton beams in the LHC. The technique is based on band limited white noise excitation that is injected into the transverse damper feedback loop. The injected signal can be gated to selectively blow-up individual trains of bunches. The speed of transverse blow-up can be precisely controlled. This opens the possibility to perform safely and efficiently aperture measurements and loss maps with high intensity bunch trains well above stored beam energies that are considered to be safe. In particular, lengthy procedures for measurements at top energy, otherwise requiring multiple fills of individual bunches, can be avoided. In this paper, the method is presented and results from beam measurements are discussed and compared with alternative blow-up methods.

THPPR065	High Flux Laser-Compton Scattered Gamma-ray Source by Compressed Nd:YAG Laser Pulse.	laser, electron, photon, microtron	4124
	I. Daito, R. Hajima, T. Hayakawa, Y. Hayashi, M. Kando, H. Kotaki, T. Shizuma JAEA, Kyoto, Japan H. Ohgaki Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	A non-destructive detection system of nuclear materials hidden in cargo containers is under development in Japan Atomic Energy Agency and Kyoto University. The system is able to be used for the identification of isotopes of special nuclear material in a container by employing Nuclear Resonance Fluorescence triggered by mono-energetic Laser Compton Scattered (LCS) gamma-ray tuned at the energy of the nuclear resonance. One of the most important technologies for such system is generation of gamma-rays at a flux of 3 x10⁵ photon/s. In order to achieve this gamma-ray flux with a compact system, a pulse compression system for Nd:YAG laser based on Stimulated Brillouin Scattering (SBS) has been developed. The laser pulse with a duration of 10 ns (FWHM) from a commercially available Nd:YAG laser is compressed down to a few hundreds ps. As a feasibility study of the proposed system, 400 keV gamma-ray generation is performed at Kansai Photon Science Institute by using 150 MeV electron beam from microtron accelerator and compressed Nd:YAG laser. Experimental results of laser pulse compression and gamma-ray generation are presented.

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MOOBC03

A Multi Purpose X Band Accelerating Structure

wakefield, FEL, linac, alignment

70

M.M. Dehler, A. Citterio, R. Zennaro
Paul Scherrer Institut, Villigen, Switzerland
G. D'Auria, C. Serpico
ELETTRA, Basovizza, Italy
D. Gudkov, A. Samoshkin
JINR, Dubna, Moscow Region, Russia
S. Lebet, G. Riddone, J. Shi
CERN, Geneva, Switzerland

In a collaboration between CERN, PSI and Sincrotrone Trieste (ST), a series of four multipurpose X-band accelerating structures has been designed and fabricated. The structures have 72 cells with a phase advance of 5 pi/6 and include upstream and downstream wakefield monitors to measure the beam alignment. We give an overview of the electrical and mechanical design and describe the fabrication of the first units. We also present the results of the low level RF tests. Using measurements of the internal cell to cell misalignment, the residual transverse wake and the noise floor of the wake field monitors are computed. Furthermore, we present the first experiences running the structures under high power.

Slides MOOBC03 [15.521 MB]

MOEPPB015

Excitation of Intra-bunch Vertical Motion in the SPS - Implications for Feedback Control of Ecloud and TMCI Instabilities

pick-up, feedback, betatron, synchrotron

112

J.D. Fox, J.M. Cesaratto, M.T.F. Pivi, C.H. Rivetta, O. Turgut, S. Uemura
SLAC, Menlo Park, California, USA
W. Höfle, U. Wehrle
CERN, Geneva, Switzerland

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
Electron cloud and transverse mode coupled-bunch instabilities (TMCI) limit the bunch intensity in the CERN SPS. Intra-bunch fast feedback systems are a possible method to control these effects. This paper presents experimental measurements of single-bunch motion in the SPS driven by a GHz bandwidth vertical excitation system*. The primary goal is to quantify the change in internal bunch dynamics as instability thresholds are approached, and quantify the frequencies of internal modes as Ecloud effects become significant. The beam response is sampled at 20 GS/sec. in response to arbitrary excitation patterns, with data in 2011 taken at 3 bunch intensities. We show the excitation of barycentric, head-tail and higher vertical modes. The beam motion is analyzed in the time domain, via animated presentations of the sampled vertical signals, and in the frequency domain, via spectrograms showing the modal frequencies vs. time. The demonstration of the excitation of selected internal modes is a significant step in development of the feedback control techniques.
* "A 4 GS/Sec. Synchronized Vertical Excitation System for SPS Studies - Steps Towards Wideband Feedback," these proceedings.

MOPPC002

Local Chromatic Correction Scheme and Crab-waist Collisions for an Ultra-low β^* at the LHC

sextupole, optics, quadrupole, luminosity

118

J.L. Abelleira, S. Russenschuck, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
J.L. Abelleira
EPFL, Lausanne, Switzerland
C. Milardi, M. Zobov
INFN/LNF, Frascati (Roma), Italy
K. Ohmi
KEK, Ibaraki, Japan
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu- CARD, grant agreement no. 227579.
We discuss potential merits and the parameter range of interest for a possible crab-waist collision scheme at the LHC, and report preliminary optics studies of a local chromatic correction scheme with flat beams (β_x^*>>β_y^*), which could boost the LHC luminosity by about an order of magnitude and would also allow for crab-waist collisions.

MOPPC009

Multipactor for E-cloud Diagnostics

electron, cyclotron, vacuum, dipole

139

P. Costa Pinto, F. Caspers, P. Edwards, M. Holz, M. Taborelli
CERN, Geneva, Switzerland

Electron cloud in particle accelerators can be mitigated by coating the vacuum beam pipe with thin films of low secondary electron yield (SEY). SEY of small samples can be measured in the laboratory. Verifying the performance of long pipes is more complex, since it requires their insertion in the accelerator and the subsequent measurement of the beam induced pressure rise. RF induced multipacting in a coaxial waveguide configuration is proposed as a test before insertion in the machine. The technique is applied to two main bending dipoles of the SPS, where the RF power is fed though a tungsten wire stretched along the vacuum chamber (6.4 m). A dipole with a bare stainless steel chamber shows a clear power threshold initiating an abrupt rise in reflected power and pressure. The effect is enhanced at RF frequencies corresponding to cyclotron resonances for given magnetic field. Preliminary result show that the dipole with a carbon coated vacuum chamber does not exhibit any pressure rise or reflected RF power up to the maximum available input power. In the event of a large scale coating production this technique will be a valuable resource for quality control.

MOPPC021

Explore the Possibility of Accelerating Polarized He-3 Beam in RHIC

proton, betatron, closed-orbit, neutron

172

M. Bai, E.D. Courant, W. Fischer, V. Ptitsyn, T. Roser
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
As the world’s first high energy polarized proton collider, RHIC has made significant progress in measuring the proton spin structure in the past decade. In order to have better understanding of the contribution of up and down quarks to the proton spin structure, collisions of high energy polarized neutron beams are required. In this paper, we present studies of accelerating polarized Helium-3 in RHIC with the current dual snake configuration. The possibilities of adding two more pairs of snakes for accelerating polarized He-3 were explored. Results of a six snake configuration in RHIC are also reported in the paper.

MOPPC023

Polarization Transmission at RHIC, Numerical Simulations

polarization, simulation, optics, proton

178

F. Méot, M. Bai, C. Liu, M.G. Minty, V.H. Ranjbar
BNL, Upton, Long Island, New York, USA

Ray-tracing methods, using the computer code Zgoubi, have proven efficient for beam and spin dynamics simulations in RHIC (see earlier PAC and IPAC publications). More simulations and results are being produced, including spin code benchmarking and cross-checking, effects of strongest resonances and working point on transport of polarization, polarization with Run 9 and Run 11 measured ramp orbit and optics, polarization profiles, etc. The numerical methods involved are recalled, a status of the work is given.

MOPPC026

Simulations of Coherent Beam-Beam Effects with Head-on Compensation

electron, proton, simulation, lattice

187

S.M. White, W. Fischer, Y. Luo
BNL, Upton, Long Island, New York, USA

Funding: Work partially supported by Brookhaven Science Associates, LARP, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron lenses are foreseen to be installed in RHIC in order to mitigate the head-on beam-beam effects. This would allow operation with higher bunch intensity and result in a significant increase in luminosity. We report on recent strong-strong simulations that were carried out using the RHIC upgrade parameters to assess the impact of coherent beam-beam effects in the presence of head-on compensation.

MOPPC057

Some Comments to Magnetic Field Representation for Beam Dynamic Calculations

multipole, dipole, quadrupole, vacuum

262

P. Schnizer, E.S. Fischer
GSI, Darmstadt, Germany
A. Mierau
TEMF, TU Darmstadt, Darmstadt, Germany
B. Schnizer
TUG/ITP, Graz, Austria

Machines with high currents and small apertures, as used for SIS100 of the FAIR project, require a sincere understanding of the resonances excited by the magnetic field distortions; typically performed by tracking codes. These codes model the field errors using a Taylor Series approximation of the field quality at the track of the ideal particle. The path of the particle within the elliptic aperture of the dipole is curved; thus the standard approach of using plane circular multipoles fails to model the real symmetry of the magnetic field, an important feature of effective field description for beam loss calculations. Therefore toroidal elliptic multipoles were developed which allow describing the magnetic field concisely in an elliptic vacuum chamber in curved dipoles and quadrupoles. In this talk we present the appropriate description and its limitation, illustrate their usefullness based on the static and transient magnetic field measurements of the first curved SIS100 dipole next to the SIS18 dipole.

MOPPC058

Eigenmode Computation for Ferrite-loaded Cavity Resonators

cavity, heavy-ion, acceleration, ion

265

K. Klopfer, W. Ackermann, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

The GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt is operating the heavy-ion synchrotron SIS18 for fundamental research. Within the ring two ferrite-loaded cavity resonators are installed. During the acceleration phase their resonance frequency has to be adjusted to the revolution frequency of the heavy-ions to reflect their increasing velocity. Within the resonator structures dedicated biased ferrite rings are installed. In the whole setup a properly chosen bias current is used to modify the differential permeability of the ferrite material which consequently enables to adjust the eigenfrequency of the resonator system. The goal of the current study is to numerically determine the lowest eigensolutions of accelerating ferrite-loaded cavities based on the Finite Integration Technique. Since the underlying eigenmodes depend on the differential permeability, the static magnetic field generated by the bias current has to be computed in a first step. The eigenmodes can then be determined with the help of a dedicated Jacobi-Davidson eigensolver. Particular emphasis is put on the implementation to enable high performance computations based on distributed memory machines.

MOPPC067

Design and Construction of Inductive BPM

simulation, impedance, electron, vacuum

289

M.Sh. Shafiee, E.E. Ebrahimibasabi, S.A.H. Feghhi, N. Goudarzi
sbu, Tehran, Iran
M. Jafarzadeh
ILSF, Tehran, Iran

To have a controllable Electron machine, that is required to be able to control beam orbits by knowing the beam position. The basic requirement for detecting the position of electron is calibrating and testing the BPMs. For this purpose wire method is used. Since we hadn't access to accelerator, for having experience at beam diagnostic we used this method for testing our constructed inductive BPM including 4 cm square poly ethylene core with 15 turns coil in each side. In this case study that was tested by a pulsed current (as an electron bunch) produced by a pulse generator. At first Tektronix 2235A oscilloscope was calibrated and used to measure the induced voltage of each coils, then by using of microcontroller, protocol RS232 and GUI induced voltages were read. The electrical center was measured with respect to the mechanical center and wire position was detected with 1mm Resolution. Conversion between the BPM signals and the actual wire position were done. Results were compared and presented.

MOPPC072

Mathematical Model of Charged Particles Dynamics Optimization in RFQ Accelerators

rfq, emittance, controls, focusing

298

A.D. Ovsyannikov
St. Petersburg State University, St. Petersburg, Russia

Mathematical model of optimization of transverse motion of charged particles in accelerators is suggested. Linear and nonlinear systems are considered when describing the transverse motion. Interaction of the particles is taken into account. Optimization algorithm based on minimax functionals is built. Numerical results for RFQ accelerators are presented.

MOPPD018

A FFAG Design Study for an Accelerator-driven System

proton, synchrotron, acceleration, focusing

403

T.-Y. Lee, H.-S. Kang, H.-S. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

Design of a 1 GeV FFAG accelerator is studied for the accelerator-driven sub-critical nuclear reactor system. Scaling and non-scaling lattices are studied and compared with each other. Corresponding magnet design and RF system are considered.

MOPPD021

An Experimental Investigation of Slow Integer Tune Crossing in the EMMA Non-scaling FFAG

acceleration, simulation, closed-orbit, proton

412

J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Student STFC grant number: ST/G004277/1.
Results are presented from a slow integer tune crossing experiment performed in the EMMA accelerator. Under nominal conditions EMMA accelerates an electron beam from 10–20 MeV rapidly in 5–10 turns in a novel “serpentine” channel causing several transverse integer tunes to be crossed. During this rapid acceleration it has been shown that the betatron amplitude of the beam does not grow. If the potential of non-scaling FFAGs were to be realized in such fields as high-current proton acceleration then tune space would be crossed slower with acceleration in an RF bucket. The crossing speed in a non-scaling FFAG is in a previously unstudied intermediate region and hence conventional crossing theory may not apply. It was proposed to observe the effects on betatron amplitude when a beam crosses integer tunes by the variation of tune with momentum over a range of crossing speeds derived from different acceleration rates. This method can be realized by synchrotron acceleration inside a stable RF bucket. Betatron amplitude growth and beam loss as a function of turn are explored when crossing an integer tune and a relationship between crossing speed and these quantities is established.

MOPPD023

Correction of the nu_r=3/2 Resonance in TRIUMF Cyclotron

cyclotron, TRIUMF, extraction, simulation

415

T. Planche, R.A. Baartman, Y.-N. Rao
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

Imperfections in the TRIUMF cyclotron are a source of field errors which slightly violate the 6-fold symmetry of the ring. Among them, the third harmonic of the magnetic gradient errors drives the ν_r=3/2 resonance. This results in a modulation of the current density versus radius observed after the resonance crossing all the way to the extraction (480 MeV). The cyclotron has sets of harmonic correction coils at different radii, each set constituted of 6 pairs of coils placed in a 6-fold symmetrical manner. The 6-fold symmetry of this layout makes that a single set of harmonic coils cannot provide a full correction of third harmonic errors driving the ν_r=3/2 resonance. The last two sets of harmonic correction coils (number 12 and 13) are azimuthally displaced. In this study, we use this fact to achieve a full correction of the resonance. We also present experimental measurements that demonstrate the full correction.

MOPPD027

A Compact High Intensity Cyclotron Injector for DAEδALUS Experiment

extraction, cyclotron, beam-losses, simulation

424

L. Calabretta, D. Rifuggiato
INFN/LNS, Catania, Italy
A. Adelmann
Paul Scherrer Institut, Villigen, Switzerland
A. Calanna, D. Campo
CSFNSM, Catania, Italy
M.M. Maggiore, L.A.C. Piazza
INFN/LNL, Legnaro (PD), Italy
J.J. Yang
CIAE, Beijing, People's Republic of China

Funding: Istituto Nazionale di Fisica Nucleare - Laboratori Nazionale del Sud.
The experiment DAEδALUS*, recently proposed by MIT scientist to search for CP violation in the neutrino sector, needs three accelerator with energy of about 800 MeV, average power of some MW and duty cycle of 20%. To reduce the cost of the accelerators a cyclotron complex consisting of an injector and of a booster ring cyclotron has been proposed**. The main characteristics of the new kind of separated sector cyclotron injector able to accelerate a H²⁺ molecule beam up to 60 MeV/n will be presented. Due to the low duty cycle, the peak current to be accelerated is 5 mA. The problem related to the injection of a H²⁺ beam, delivered by a compact ion source, and to the space charge effects will be discussed. To allow an easier injection in the booster Superconducting Ring Cyclotron the extraction energy has been increased up to 60 MeV/n. The pole gap was decreased to 60 mm to achieve a more efficient beam extraction. The updated configuration of the magnetic sectors, of the isochronous magnetic field and beam dynamics along extraction path and during the acceleration will be presented, too.
* J. Alonso et al., "Novel Search for CP Violation in the Neutrino Sector: DAEδALUS," Jun2010 e-Print: arXiv:1006.0260
** L. Calabretta, Proc. of IPAC 2011, WEPS073, p. 2673 (2011).

MOPPD062

Aperture Measurements in the LHC Interaction Regions

injection, emittance, luminosity, optics

508

S. Redaelli, M.C. Alabau Pons, R.W. Assmann, R. Bruce, M. Giovannozzi, G.J. Müller, M. Pojer, J. Wenninger
CERN, Geneva, Switzerland

The aperture of the LHC interaction regions is crucial for the LHC performance because it determines the smaller β^* that can be achieved. The aperture has been measured at a maximum energy of 3.5 TeV and at different β^* values, following optimized procedure to allow safe measurements at high energy. In this paper, the results of these aperture measurements, which are used as a reference for β^* reach and crossing scheme estimates at the LHC interaction points, are presented.

MOPPP074

Magnetic Field Measurement for a THz Undulator Using the Vibrating Wire Method

undulator, electron, radiation, laser

732

S. Kashiwagi, H. Hama, F. Hinode, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003.
We constructed the undulator that is a basically a Halbach planer type for a generation of intense coherent terahertz radiation from the very short electron bunch. The period length of the undulator and the number of periods are 100 mm and 25, respectively. Its maximum magnetic field is 0.41 T and the K-value is 3.82 with 54 mm gap. The vibrating wire method is studied to measure the periodic magnetic field of the undulator. By measuring amplitudes and phases of standing waves excited on the wire by the Lorentz force between AC current and magnetic field, we can reconstruct the magnetic field distribution along the wire. The theoretical analysis has been performed for the THz undulator and derived a relation between a reproducibility of undulator field and the number of the harmonic mode to use for the reconstruction. A model experiment was demonstrated using 20cm wire and one pair of permanent magnet block. The theoretical study and the results of model experiment using the vibrating wire method will be shown in this conference.

MOPPR006

Surface Waves for Testing of Beam Instrumentation

instrumentation, impedance, induction, electromagnetic-fields

780

F. Stulle, J.F. Bergoz
BERGOZ Instrumentation, Saint Genis Pouilly, France

The fundamental TM wave can be guided as a surface wave along a single dielectric coated wire. Such a setup is known as a Goubau line. Close to the wire the TM wave resembles closely the radial electric and azimuthal magnetic fields of a charged particle beam moving in an accelerator. Hence, it can be used to test beam instrumentation in the workshop. We introduce the principle, discuss benefits, and compare measurements of a beam instrumentation device performed with a Goubau line to measurements performed with a standard bench testing setup.

MOPPR073

Analysis of Resonant TE Wave Modulation Signals for Electron Cloud Measurements

electron, coupling, factory, cavity

957

S. De Santis
LBNL, Berkeley, California, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
J.P. Sikora
CLASSE, Ithaca, New York, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231.
Recent TE wave measurements of the electron cloud density in the beampipe at CesrTA and DAΦNE have shown that, especially near cutoff, the microwave excitation takes place by coupling to a standing wave, rather than to a propagating TE mode. With the beampipe acting as a resonant cavity, the effect of the periodic electron cloud density is a modulation of the cavity's resonant frequency. As a result, the measured sidebands are a combination of amplitude, phase, and frequency modulation, as the periodic cloud density modulates this resonant frequency. The quality factor Q of the resonance will determine its response to transients in the electron cloud density, and the resulting effect on modulation sidebands. In order to estimate the peak electron cloud density and its spacial distribution, knowledge of the Q and the standing wave pattern need to be determined, either by experimental measurements or simulation codes. In this paper we analyze the dependence of the modulation sidebands on the electron cloud density in two different regimes, when the cloud rise/decay time is much longer, or much shorter than the filling time of the resonance.

MOPPR074

Using TE Wave Resonances for the Measurement of Electron Cloud Density

cavity, electron, simulation, vacuum

960

J.P. Sikora, M.G. Billing, D. L. Rubin, R.M. Schwartz
CLASSE, Ithaca, New York, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
B.T. Carlson
CMU, Pittsburgh, Pennsylvania, USA
S. De Santis
LBNL, Berkeley, California, USA
K.C. Hammond
Harvard University, Cambridge, Massachusetts, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231.
In the past few years, electron cloud density has been measured by means of its effect on TE waves propagated through the accelerator vacuum chamber. This technique has been the object of careful studies and has been used in several laboratories around the world (CERN, SLAC, FNAL, Cornell, INFN-LNF). Recent measurements at CesrTA and DAΦNE show that in a majority of practical cases, the theoretical model that relates the cloud density to the phase shift induced on a TE wave propagating in beam pipe may not be the correct one. Instead, the measurement results have to be analyzed considering the effect of the electron cloud on a standing wave excited between the input and output couplers - typically Beam Position Monitors (BPMs). This standing wave pattern is not confined to the portion of beampipe between the BPMs and must be understood in order to correctly interpret the measurement. In this paper we present evidence that the transmission function near cutoff between two BPMs is the result of coupling to standing waves trapped in the vacuum chamber. This evidence includes measurements at DAΦNE, Cesr-TA, a test waveguide, computer EM simulations, and analytical calculations.

TUXA03

Increasing the AGS Beam Polarization with 80 Tune Jumps

polarization, quadrupole, emittance, closed-orbit

1015

V. Schoefer, L. A. Ahrens, M. Bai, E.D. Courant, W. Fu, C.J. Gardner, J.W. Glenn, H. Huang, F. Lin, A.U. Luccio, J.-L. Mi, J. Morris, P.J. Rosas, T. Roser, P. Thieberger, N. Tsoupas, A. Zelenski, K. Zeno
BNL, Upton, Long Island, New York, USA

Vertical depolarizing resonances in the AGS are removed by partial Siberian snakes. These magnets move the stable spin direction and lead to horizontal depolarizing resonances. The tune jump quadrupole system increases the crossing rate for horizontal resonances by a factor of six. This presentation will review the fundamental mechanism of depolarizing resonances, the partial Siberian snake solution and describe recent experimental evidence at the AGS demonstrating improvements to beam polarization and the beam dynamics challenges posed by the tune jump.

Slides TUXA03 [5.199 MB]

TUOAA01

3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields

plasma, electron, wiggler, simulation

1059

S.A. Veitzer, P. Stoltz
Tech-X, Boulder, Colorado, USA
J.A. Crittenden, K.G. Sonnad
CLASSE, Ithaca, New York, USA

Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499) and by the National Science Foundation Grant PHY-0734867.
Electron clouds have the potential to pose serious limitations on accelerator performance in both hadron and lepton beams. Experiments using rf diagnostics are being performed to measure electron cloud densities at a number of accelerator facilities. However, it is difficult to calibrate plasma density with signal strength in these experiments, and modeling involves a number of technical and numerical challenges. Typically 2-Dimensional electrostatic methods have been used to model cloud buildup under beam crossing conditions. However, since traveling-wave rf experiments typically occur over many meters of beam pipe where magnetic fields are changing, one needs to develop 3-Dimensional electromagnetic models in order to accurately simulate rf diagnostics. We have developed accurate models of electron cloud-induced phase shifts in rf in a system with spatially varying magnetic field configurations using the plasma simulation code VORPAL. We present here results for measuring phase shifts in the CESR wiggler with realistic, spatially non-uniform magnetic field configurations.

Slides TUOAA01 [18.367 MB]

TUOAC02

Development of HTS Magnets

dipole, superconductivity, synchrotron, neutron

1095

K. Hatanaka, M. Fukuda, N. Hamatani, N. Izumi, K. Kamakura, T. Saito, H. Ueda, Y. Yasuda, T. Yorita
RCNP, Osaka, Japan
T. Kawaguchi
KT Science Ltd., Akashi, Japan

A quarter of a century has passed since the discovery of high-temperature superconductor (HTS) materials in 1986. Although many prototype devices using HTS wires have been developed, these applications are presently rather limited in accelerator and beam line facilities. We have investigated the performance of HTS wires applied for magnets excited by alternating current (AC) as well as direct current (DC) for a decade. In order to check feasibilities of pulse magnets using HTS wire, we have fabricated a super-ferric dipole magnet to be operated by lumping currents. Upper and lower coil consists of 3 double pancakes of 200 turns. Critical currents were measured of wire measured at 77K. Self-field Ic of wire was higher than 160A. Ic values of double pancakes were 60-70A. After stacking, they were 47A and 51A for the upper and lower coil, respectively. Cooling tests were successfully done and the Ic values were measured to be 280A at 20K. Performance tests are ongoing in the pulse mode operation.

Slides TUOAC02 [5.252 MB]

TUEPPB002

Numerical Simulations of Transverse Beam Diffusion Enhancement by the Use of Electron Lens in the Tevatron Collider

electron, simulation, collider, beam-beam-effects

1113

V. Previtali, G. Stancari, A. Valishev
Fermilab, Batavia, USA
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

Funding: "Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. This work was partially supported by the US LHC Accelerator Research Program (LARP)."
Transverse beam diffusion for the Tevatron machine has been calculated using the Lifetrac code. The following effects were included: random noise (representing residual gas scattering, voltage noise in the accelerating cavities) lattice nonlinearities and beam-beam interactions. The time evolution of particle distributions with different initial amplitudes in Hamiltonian action has been simulated for 6 million turns, corresponding to a machine time of about 2 minutes. For each particle distribution, several cases have been considered: a single beam in storage ring mode, the collider case, and the effects of a hollow electron beam collimator

TUPPC009

Dihedral Group and Repetitive Achromats with Mirror Symmetric or Mirror Antisymmetric Basic Cell

multipole, electron, focusing, free-electron-laser

1170

V. Balandin, R. Brinkmann, W. Decking, N. Golubeva
DESY, Hamburg, Germany

Using the group-theoretical point of view for the design of magnetic optical achromats as introduced in*, we study in this paper second- and third-order repetitive achromats with a mirror symmetric or mirror antisymmetric basic cell. We also compare these achromats with repetitive achromats designed without internal cell symmetries taken into account.
* V.Balandin, R.Brinkmann, W.Decking, N.Golubeva. Two Cell Repetitive Achromats and Four Cell Mirror Symmetric Achromats, Proceedings of IPAC'10, Kyoto, Japan.

TUPPC014

Design Study of Nonlinear Optics for a Very Low-emittance Lattice of the SPring-8 II

lattice, sextupole, emittance, optics

1185

Y. Shimosaki, K.K. Kaneki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, M. Takao
JASRI/SPring-8, Hyogo-ken, Japan

A feasibility of a very low-emittance storage ring has been studied for an upgrade project, SPring-8 II. Its ultimate goal is to provide a superior brilliance for 0.5 ~ 100 keV photons. A sextupole bend lattice with the natural emittance of 70 pmrad at 6 GeV has been examined as the first candidate*. The nonlinear optics has been optimized to enlarge the dynamic aperture by correcting nonlinear resonances based on an isolated resonance Hamiltonian with thick lens approximation, and by non-interleaved sextupole method. A genetic algorithm, which has been examined to improve the performance of the present SPring-8**, will be adopted for detailed optimization of the tunes and sextupole strength to adjust the non-interleaved scheme and to correct higher order resonances. The correction scheme of nonlinear optics and its results will be presented in detail.
*Y. Shimosaki et al., IPAC’11, TUOAB01, p. 942 (2011).
**Y. Shimosaki et al., "Optimization of Lower Emittance Optics for the SPring-8 Storage Ring", these proceedings.

TUPPC016

Progress of Emittance Coupling Correction at the SPring-8 Storage Ring

coupling, betatron, storage-ring, survey

1191

M. Takao, M. Masaki, Y. Shimosaki, K. Soutome, S. Takano, C. Zhang
JASRI/SPring-8, Hyogo-ken, Japan

The vertical beam spread, or the emittance coupling, is one of the most important parameters for the high brilliance light source storage ring. By the precise alignment of the magnets and the proper COD correction, at the commissioning phase of the SPring-8 storage ring we succeeded in achieving the very small coupling ~0.2 % without correction. However, the coupling had grown large with the years, so recently we have corrected it and recovered the initial performance. The scheme of the coupling correction at the SPring-8 storage ring is the global one, which is based on the perturbation theory with single resonance approximation. In the beginning of the correction the coupling was corrected by means of minimizing the vertical beam size. Then the performance of the coupling correction has been further improved by changing the scheme to minimizing the betatron coupling mode in the vertical oscillation of the horizontally kicked beam. This result implies that the higher order coupling contributes to the emittance coupling, which can be corrected by the higher skew multi-pole magnet. The present status of the coupling correction at the SPring-8 storage ring will be reported.

TUPPC037

Update on LHeC Ring-Ring Optics

sextupole, insertion, optics, lattice

1242

M. Fitterer
KIT, Karlsruhe, Germany
O.S. Brüning, H. Burkhardt, B.J. Holzer, J.M. Jowett
CERN, Geneva, Switzerland
M. Klein
The University of Liverpool, Liverpool, United Kingdom

An update of the LHeC Ring-Ring optics is presented which accounts for chromatic corrections and more flexibility in the tune adjustment.

TUPPC057

RHIC Spin Flipper Commissioning Results

dipole, polarization, injection, proton

1302

M. Bai, W.C. Dawson, J. Kewisch, Y. Makdisi, P. Oddo, C. Pai, P.H. Pile, T. Roser
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The five ac dipole design of RHIC spin flipper in the Blue ring was first commissioned during the RHIC 2012 polarized proton operation. The advantage of this design is to eliminate the vertical coherent betatron oscillations outside the spin flipper*. Spin flipping efficiency was measured with both 100 GeV and 250 GeV polarized proton beams. This paper presents the latest commissioning results.
* M. Bai , T. Roser, C. Dawson, Y. Makdisi, W. Meng, F. Meot, P. Oddo, C. Pai, P. Pile, RHIC Spin Flipper New Design and Commissioning Plan, IPAC10 proceedings, IPAC 2010, Kyoto, Japan, 2010

TUPPC063

The AGS Synchrotron with Four Helical Magnets

injection, betatron, optics, quadrupole

1320

N. Tsoupas, H. Huang, W.W. MacKay, T. Roser, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: *Work supported by the US Department of Energy.
The idea* of using two partial helical magnets was applied successfully to the AGS synchrotron**, to preserve the proton beam polarization. In this paper we explore in details the idea of using four helical magnets placed symmetrically in the AGS ring. This modification provides many advantages over the present setup of the AGS that uses two partial helical magnets. First, the symmetric placement of the four helical magnets allows for a better control of the AGS optics with reduced values of the beta functions especially near beam injection, second, the vertical spin direction during beam injection and extraction is closer to vertical, and third, it provides a larger “spin tune gap” for the placement of both the vertical and horizontal tunes of the AGS during acceleration, second. Although the same spin gap can be obtained with two partial helices of equal strength, the required strength of the two helices makes it impractical. In this paper we will provide results on the spin tune and on the optics of the AGS with four partial helical magnets, and comparison of these results with the present setup of the AGS that uses two partial helical magnets***.
* T. Roser et al., Proc. EPAC04, p. 1577 (2004).
** H. Huang et al., PRL 99, 154801(2007).
*** N. Tsoupas et. al., these proceedings.

TUPPC065

High Intensity Beam Analysis for the Superconducting Radio-frequency Linac (SRF-Linac) of the IFMIF-EVEDA Accelerators

emittance, linac, SRF, space-charge

1323

W. Simeoni
CEA/IRFU, Gif-sur-Yvette, France
N. Chauvin, P.A.P. Nghiem, D. Uriot
CEA/DSM/IRFU, France

In this proceeding we analyze space charge effects on the beam dynamics of IFMIF accelerators. The objective is to be able to characterize and understand the crucial issues like halo formation, emittance growth and sudden particle losses in the SRF-Linac. We use the Hofmann stability charts to identify modes of collective space charge density oscillations that are responsible for the transfer and growth of the emittance. With identification of modes we are able to treat the parametric resonance between the modes and the nonlinear motion of an individual ion the amplitude of which is greater than the core radius. The resulting phase space consists of an inner separatrix containing the core and an outer separatrix that becomes the locus near which the halo particles enter and cluster.

TUPPC067

How to Achieve Longitudinally Polarized Electrons using Integer Spin Tune Resonances

polarization, synchrotron, dipole, electron

1326

O. Boldt, A. Dieckmann, F. Frommberger, W. Hillert, J.F. Schmidt
ELSA, Bonn, Germany

Funding: Bundesministerium für Bildung und Forschung
Commonly, strong solenoids are used in circular accelerators to achieve longitudinal polarization. In practice, however, these solenoids cause a phase space coupling, which has to be compensated for by sophisticated decoupling schemes. We suggest to adiabatically ramp into an integer spin tune resonance, while preserving the degree of polarization. When appropriately adjusting the driving horizontal field contributions at the final energy, the resulting polarization is longitudinal at predefined positions in the accelerator. Here, depending on the energy spread, the degree of polarization is conserved for several seconds. The contribution shows the numerical analysis of this scenario being confirmed by first demonstration tests at the ELSA stretcher ring.

TUPPC069

Third-Order Apochromatic Drift-Quadrupole Beamline

quadrupole, betatron, beam-transport, focusing

1329

N. Golubeva, V. Balandin, R. Brinkmann, W. Decking
DESY, Hamburg, Germany

We have shown that for every drift-quadrupole system there exists an unique set of Twiss parameters (apochromatic Twiss parameters), which will be transported through that system without first order chromatic distortions*. In this paper we continue the development of the theory of apochromatic focusing and present the design of a straight drift-quadrupole system which can transport apochromatic beam ellipses without influence not only of the second but also of the third order chromatic and geometric aberrations of the beamline transfer map.
* V.Balandin, R.Brinkmann, W.Decking, N.Golubeva. Apochromatic Beam Transport in Drift-Quadrupole Systems. Proceedings of IPAC'10, Kyoto, Japan.

TUPPC073

Frequency Map Analysis for SuperB

lattice, dynamic-aperture, emittance, sextupole

1341

S.M. Liuzzo, M.E. Biagini, P. Raimondi
INFN/LNF, Frascati (Roma), Italy
T. Demma
LAL, Orsay, France
Y. Papaphilippou
CERN, Geneva, Switzerland

The frequency map analysis is applied to the SuperB HER and LER lattices including the Final Focus, in order to understand the dynamic aperture limitation and provide insight for a working point optimization. In this respect, frequency and diffusion maps are evaluated applying random magnet misalignments and tilts, before and after correction of orbit, dispersion and coupling using Low Emittance Tuning techniques. The same analysis is performed for on and off momentum particles. The lattice properties are further investigated using working point scans and the correction of non linear resonance driving terms and amplitude detuning.

TUPPC074

Study of Resonance Driving Term in Electron Storage Rings

damping, radiation, storage-ring, electron

1344

G. Liu, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The resonance driving term (RDT) is useful to analyze and optimize the nonlinear performance of the storage ring. In addition to analytical calculation of RDT, experimental measurement of RDT has been made in some proton storage rings based on turn-by-turn BPM data. For electron storage rings, the analysis is more complicated due to decoherence effects and strong radiation damping. The relation between spectral decomposition of BPM data and RDT is derived and validated using beam numerical tracking data in this paper.

TUPPC077

Numerical Study of Beam Trapping in Stable Islands for Simple 2D Models of Betatronic Motion

emittance, simulation, extraction, octupole

1350

M. Giovannozzi, C. Hernalsteens
CERN, Geneva, Switzerland

An essential ingredient for the proposed Multi-Turn Extraction (MTE) at the CERN PS is the beam trapping in stable islands. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, the splitting process is studied quantitatively by means of numerical simulations performed on 2D model representing the horizontal non-linear betatronic motion. The results are reviewed and discussed in details.

TUPPC090

Beam Physics of Integrable Optics Test Accelerator at Fermilab

simulation, betatron, lattice, optics

1371

A. Valishev, S. Nagaitsev
Fermilab, Batavia, USA
V.V. Danilov
ORNL, Oak Ridge, Tennessee, USA
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy.
Fermilab's Integrable Optics Test Accelerator is an electron storage ring designed for testing advanced accelerator physics concepts, including implementation of nonlinear integrable beam optics and experiments on optical stochastic cooling. The machine is currently under construction at the Advanced Superconducting Test Accelerator facility. In this report we present the goals and the current status of the project, and describe the details of machine design. In particular, we concentrate on numerical simulations setting the requirements on the design and supporting the choice of machine parameters.

TUPPC096

Optimization of the Dynamic Aperture for SPEAR3 Low-emittance Upgrade

sextupole, emittance, dynamic-aperture, optics

1380

L. Wang, X. Huang, Y. Nosochkov, J.A. Safranek
SLAC, Menlo Park, California, USA
M. Borland
ANL, Argonne, USA

A low emittance upgrade is planned for SPEAR3. As the first phase, the emittance is reduced from 10nm to 7nm without addition magnets. A further upgrade with even lower emittance will require a damping wiggler. There is a smaller dynamic aperture for the lower emittance optics due to the stronger nonlinearity. A Multi-Objective Genetic Optimization (MOGA) code is used to maximize the dynamic aperture. Both the dynamic aperture and beam lifetime are optimized simultaneously. Various configurations of the sextupole magnets have been studied in order to find the best configuration. The betatron tune also can be optimized to minimize resonance effects. The optimized dynamic aperture increases 15% from the normal case and the life time increases from 15 hours to 17 hours. It is important that the increase of the dynamic aperture is mainly in the beam injection direction. Therefore the injection efficiency will benefit from this improvement.

TUPPC101

A Model of the AGS Based on Stepwise Ray-Tracing Through the Measured Field Maps of the Main Magnets

quadrupole, sextupole, focusing, simulation

1395

Y. Dutheil, F. Méot, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Two dimensional mid-plane magnetic field maps of two of the main AGS magnets were produced, from Hall probe measurements, for a series of different current settings. The analysis of these data yielded the excitation functions and harmonic coefficients of the main magnets [BNL TN 424 & TN 429] which have been used so far in all the models of the AGS. The constant increase of computation power makes it possible today to directly use stepwise ray-tracing through these measured field maps with a reasonable computation time. We describe in detail how these field maps have allowed generation of models of the 6 different types of AGS main magnets, and how they are being handled with the Zgoubi ray-tracing code. We give and discuss a number of results so obtained regarding both beam and spin dynamics in the AGS, and provide comparisons with other numerical and analytical modeling methods.

TUPPD011

Studies of the Twin Helix Parametric-resonance Ionization Cooling Channel with COSY INFINITY

simulation, emittance, quadrupole, collider

1428

J.A. Maloney, K.B. Beard, R.P. Johnson
Muons, Inc, Batavia, USA
A. Afanasev
GWU, Washington, USA
S.A. Bogacz, Y.S. Derbenev, V.S. Morozov
JLAB, Newport News, Virginia, USA
B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

Funding: Supported in part by SBIR Grant DE-SC00005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A primary technical challenge to the design of a high luminosity muon collider is an effective beam cooling system. An epicyclic twin-helix channel utilizing parametric-resonance ionization cooling has been proposed for the final 6D cooling stage. A proposed design of this twin-helix channel is presented that utilizes correlated optics between the horizontal and vertical betatron periods to simultaneously focus transverse motion of the beam in both planes. Parametric resonance is induced in both planes via a system of helical quadrupole harmonics. Ionization cooling is achieved via periodically placed wedges of absorbing material, with intermittent rf cavities restoring longitudinal momentum necessary to maintain stable orbit of the beam. COSY INFINITY is utilized to simulate the theory at first order. The motion of particles around a hyperbolic fixed point is tracked. Comparison is made between the EPIC cooling channel and standard ionization cooling effects. Cooling effects are measured, after including stochastic effects, for both a single particle and a distribution of particles.

TUPPD017

Electromagnetic Design of RF Cavities for Accelerating Low-Energy Muons

cavity, linac, vacuum, solenoid

1446

S.S. Kurennoy
LANL, Los Alamos, New Mexico, USA

A high-gradient linear accelerator for accelerating low-energy muons and pions in a strong solenoidal magnetic field has been proposed for homeland defense and industrial applications.* The acceleration starts immediately after collection of pions from a target in a solenoidal magnetic field and brings decay muons, which initially have kinetic energies mostly around 15-20 MeV, to 200 MeV over a distance of ~10 m. At this energy, both ionization cooling and further, more conventional acceleration of the muon beam become feasible. A normal-conducting linac with external-solenoid focusing can provide the required large beam acceptances. The linac consists of independently fed zero-mode (TM010) RF cavities with wide beam apertures closed by thin conducting edge-cooled windows. Electromagnetic design of the cavity, including its RF coupler, tuning and vacuum elements, and field probes, has been developed with the CST MicroWave Studio, and will be presented.
* S.S. Kurennoy, A.J. Jason, H. Miyadera, “Large-Acceptance Linac for Accelerating Low-Energy Muons.” Proceed. IPAC10, p. 3518.

TUPPD031

Novel Techniques for Isotope Harvesting at FRIB

simulation, optics, ion, target

1470

M.A.C. Cummings
Muons, Inc, Batavia, USA
L.L. Bandura
FRIB, East Lansing, Michigan, USA

Exotic isotopes have applications in medicine, industry, and national security. Historically, the U.S. has relied on foreign sources for these isotopes. FRIB will be a domestic source of these isotopes. While FRIB is mainly focused on producing exotic isotopes for basic nuclear physics experiments, it also offers an opportunity to harvest unused isotopes for other applications. It is critical that isotope harvesting take place in a synergistic manner that does not adversely affect experiments that will be simultaneously taking place at the facility. Beam optics schemes will be calculated to determine the best locations and methods of separation. These calculations will use COSY Monte Carlo and G4beamline in conjunction with other state of the art ion optical codes that simulate isotope dynamics in magnetic fields and in matter. The results of these simulations will be used to determine the best beam-target combinations to produce the isotopes that are most in-demand and calculate purities of these isotopes in multiple locations in the fragment separators. Trapping and extraction schemes will also be described to maximally recover pure isotope samples.

TUPPD043

Resonant Reaction with a Superintense Circulating Beam

target, proton, electron, storage-ring

1497

V.G. Dudnikov, C.M. Ankenbrandt
Muons, Inc, Batavia, USA

A system for efficient generation of resonance reaction in the interaction of the circulating ion beam with a thin internal target is considered. Features of this system are high intense space charge compensated circulating ion beam with an intensity greater then a space charge limit in a near integrable nonlinear focusing system. Ionization energy loss is compensated by inductive electric field. Multiple scattering and energy straggling are compensated by electron cooling with a tabular electron beam. In this method it is possible to compensate an energy loss of circulating particles after crossing the target and have a crossing of resonant energy in every passing of target. For sharp resonance reactions and monoenergetic beams a thin target method can increase greatly the energy efficiency.

TUPPP045

Creation of FELWI using Large Amplification Regime

electron, undulator, FEL, microtron

1707

K.B. Oganesyan
ANSL, Yerevan, Armenia
A.I. Artemyev, D.N. Klochkov
GPI, Moscow, Russia
Y. Rostovtsev
University of North Texas, Denton, Texas, USA

Funding: ISTC project A-1602
The interaction between noncollinear laser and relativistic electron beams in static magnetic undulator has been studied within the framework of dispersion equations. In the limit of small-signal gain the spatial growth rates are found for the collective (Raman) and single-electron (Thompson) regimes. For a free-electron laser without inversion (FELWI), estimates of the threshold laser power are found. The large-amplification regime should be used to bring an FELWI above the threshold laser power.

TUPPR049

An X-band Standing Wave Dielectric Loaded Accelerating Structure

multipactoring, cavity, coupling, simulation

1927

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
S.H. Gold
NRL, Washington, DC, USA
S. Kazakov
Fermilab, Batavia, USA
R. Konecny
ANL, Argonne, USA

Funding: DOE SBIR Phase I grant #DE-SC0006303
An 11.4 GHz standing wave dielectric loaded accelerating structure was recently developed. We expect to achieve a 120 MV/m gradient powered by a 10 MW 200 ns rf pulse from the X-band Magnicon at the Naval Research Laboratory. The structure uses on-axis rf coupling, which helps to localize the maximum EM fields within the dielectric region. Bench testing shows excellent agreement with the simulation results. The high power rf test is scheduled for January 2012.

TUPPR077

Simulation Studies for the LHC Long-Range Beam-Beam Compensators

optics, simulation, collider, betatron

2002

T.L. Rijoff, R.J. Steinhagen, F. Zimmermann
CERN, Geneva, Switzerland

The LHC performance and the minimum crossing angle are limited by long-range beam-beam collisions. Wire compensators can mitigate part of the long-range effects and may allow for smaller crossing angles, smaller β^*, or higher beam intensity. A prototype long-range wire compensator should be installed in the LHC by 2014/15. We report simulation studies examining and comparing the efficiency of the wire compensation, in terms of tune footprint or dynamic aperture, at various candidate locations, with different wire shapes, and for varying transverse distance from the beam.

TUPPR079

Ion Polarization in the MEIC Figure-8 Ion Collider Ring

polarization, ion, proton, collider

2008

V.S. Morozov, Y.S. Derbenev, Y. Zhang
JLAB, Newport News, Virginia, USA
P. Chevtsov
Paul Scherrer Institut, Villigen, Switzerland
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The nuclear physics program envisaged at the Medium-energy Electron-Ion Collider (MEIC) currently being developed at the Jefferson Lab calls for collisions of 3-11 GeV/c longitudinally polarized electrons and 20-100 GeV/c, in equivalent proton momentum, longitudinally or transversely polarized light ions. In this paper, we present a scheme based on figure-8 shaped booster and collider rings that provides the required ion polarization arrangement in the MEIC's ion collider ring.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

WEOAB01

New Results from the EMMA Experiment

acceleration, injection, betatron, electron

2134

B.D. Muratori, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
C.S. Edmonds, K.M. Hock, M.G. Ibison, I.W. Kirkman
The University of Liverpool, Liverpool, United Kingdom
J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. After demonstration of acceleration in the serpentine channel in April 2011, the beam study with EMMA continues to explore the large transverse and longitudinal acceptance and effects of integer tune crossing with slower rate on the betatron amplitude. Together with a comparison of detailed models based on measured field maps and the experimental mapping of the machine by relating the initial and final phase space coordinates. These recent results together with more practical improvements such as injection orbit matching with real-time monitoring of the coordinates in the transverse phase space will be reported in this paper.

Slides WEOAB01 [2.120 MB]

WEPPC008

FNAL Project X Conical Half-Wave Resonator Design

cavity, simulation, cryomodule, proton

2221

E.N. Zaplatin
FZJ, Jülich, Germany
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: This work is supported by the DOE SBIR Program, contract # DE-SC0006302.
A high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory (Project X) should provide beam for a variety of physics projects. The superconducting resonators of different types will be used as accelerating structures. Here we describe the design of conical Half-Wave Resonator that is considered as an option for a first accelerating cavity for β=v/c=0.11 with the resonance frequency 162.5 MHz. A careful study of the fields in the cavity has been carried out in order to optimize the electromagnetic parameters of the structure (peak fields, quality factor, dissipation power). An intensive investigations were provided of the liquid helium vessel design to minimize cavity frequency shifts from the external loads. Different tuning schemes have been studied to secure a frequency tuning range to cope with fabrication tolerances. The paper reports results of numerical simulations of the cavity shape optimization and structural analyses. The detailed developments of the structure using numerical coupled analyses allowed to minimize the level of expected microphonics in cavity.

WEPPC017

Design of a High-Speed Pulsed 324MHz Solid-State Amplifier for Use in a Beam Chopper

impedance, proton, insertion, feedback

2242

S.C. Dillon, B.S. Nobel, C.P. Schach
Tomco Technologies, Stepney, South Australia, Australia

A 324MHz 30kW high-speed pulsed solid-state amplifier has been designed for use in a beam chopper at the Japan Proton Accelerator Complex (J-PARC). This paper discusses the various design challenges and presents the initial performance test results. In particular, the amplifier achieves pulse rise and fall times of less than 15 nanoseconds, is easily upgradeable in power, and withstands 100% power reflection without damage.

WEPPC056

Pressure Sensitivity Characterization of Superconducting Spoke Cavities

cavity, simulation, linac, electromagnetic-fields

2339

D. Passarelli, M.H. Awida, I.V. Gonin, L. Ristori, V.P. Yakovlev
Fermilab, Batavia, USA

The following proposal illustrates a method to characterize the pressure sensitivity behavior of superconducting spoke cavities. This methodology relies on evaluating the variation of resonant frequency of a cavity by observing only the displacements at designed regions of the cavity. The proposed method permits a reduced computational burden and a systematic approach to achieve a minimum value of pressure sensitivity in a complex system of dressed cavity. This method has been used to characterize the superconducting spoke cavities typs⁻¹ (SSR1), under development for Project X, and to design the helium containment vessel in such way to reduce the pressure sensitivity value to zero.

WEPPC068

Multipacting Simulation and Analysis for the FRIB β = 0.085 Quarter Wave Resonators using Track3P

cavity, simulation, linac, niobium

2366

L. Ge, C. Ko, Z. Li
SLAC, Menlo Park, California, USA
J. Popielarski
FRIB, East Lansing, Michigan, USA

Funding: Work supported by DOE Office of Science under Cooperative Agreement DE- SC0000661, DOE Contract No. DE-AC02-76SF00515, and used resources of NERSC supported by DOE Contract No. DE-AC02- 05CH11231.
The drive linac for the Facility for Rare Isotope Beams (FRIB) utilizes several types of low beta superconducting resonators to accelerate the ion beams from 0.3 MeV per nucleon to 200 MeV per nucleon. Multipacting is an issue of concern for such superconducting resonators as they have unconventional shapes. We have used the parallel codes Tack3P and Omega3P, developed at SLAC under the support of the DOE SciDAC program, to analyze the multipacting barriers of such resonators. In this paper, we will present the simulation results for the β(v/c) = 0.085 Quarter Wave Resonator (QWR) for the FRIB project. Experimental data will also be presented to benchmark with the simulation results.

WEPPC071

Quench Studies of a Superconducting RF Cavity

cavity, superconducting-RF, superconductivity, superconducting-cavity

2375

D. Gonnella, M. Liepe, S. Posen
CLASSE, Ithaca, New York, USA

In tests of superconducting RF cavities, it is important to understand the cause of high field quenches. Quenches at high field above 25 MV/m are a limiting factor in the performance of high accelerating field cavities but their causes are currently not well understood. An ILC shaped single cell cavity with quench field near 40 MV/m was tested with temperature mapping to determine the cause of its hard quench. Prior to quench, heating on the order of 25 mK was concentrated in two hot spots. After a quench, these two hot spots remain and a new one appears with much higher heating (about 40 mK). The quench location was found by the temperature mapping system to be centered at the new hot spot, not at the two hot spot locations before that dominated quench. By studying the quench location and heating on the surface of the cavity, some hints were gained as to the cause of this quench.

WEPPC081

Measurement of the Mechanical Properties of Superconducting Cavities During Operation

cavity, linac, feedback, simulation

2399

S. Posen, M. Liepe
CLASSE, Ithaca, New York, USA

The Horizontal Test Cryostat (HTC) contains the first prototype 7-cell 1.3 GHz superconducting cavity for the Cornell ERL main linac. In this paper, experimental measurements of the cavity's mechanical properties are presented. The mechanical resonances were studied using a Dynamic Signal Analyzer, which measured the transfer function from the fast piezo tuner to itself and the cavity frequency. The microphonics detuning of the cavity was measured, and found to satisfy the specification that the maximum detuning be below 20 Hz, even without feedback from the piezos. Correlations were studied between the microphonics detuning and the helium pressure, piezo sense signal, and the ground vibrations. The Lorentz force detuning (LFD) coefficient was also measured. The frequencies of the mechanical resonances were compared to simulation. In addition, the performance of the frequency tuners was evaluated. Both the mechanical tuner and the piezo were found to be highly linear with very little hysteresis even on small scales.

WEPPD068

High Power Collinear Load Coated with FeSiAl

cavity, simulation, linac, factory

2678

L.G. Shen, X.L. Fu, Y. Sun, F. Zhang
USTC/PMPI, Hefei, Anhui, People's Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: This work is supported by the NSFC (NO. 10775128 and NO.51075381)
Aimed at substituting output coupler to absorb remnant power of the LINAC, collinear load coated with high loss materials is expected to come reality. FeSiAl load is studied. The effect of the coating volume upon the cavity frequency and Q factor is analyzed and the dimension compensations of the cavities are suggested to tune the load cavities at 2856 MHz. Orthogonal Experimental Method is utilized to investigate the sensitivity of permittivity (both real part and imaginary part) and permeability (both real part and imaginary part) to cavity characteristics. Five cavities with different coating dimensions are manufactured and their operating frequencies and Q are measured. Compared with the simulations, they show that the Q factor, which is characterization of the actual attenuation of the FeSiAl, agrees very well with the theoretical value and Q factor of the resonant cavity is measured with the probe method. The relationship between Q factor and the length of the test probe is deduced and eventually the individual Q value of a load cavity is extracted. Simulation shows the FeSiAl load can support average power over 15 kW and the one-way attenuation is about 30 dB.

WEPPD072

Frequency Fine-tuning of a Spin-flip Cavity for Antihydrogen Atoms

cavity, antiproton, coupling, vacuum

2690

S. Federmann, F. Caspers, E. Mahner
CERN, Geneva, Switzerland
B. Juhasz, E. Widmann
SMI, Vienna, Austria

As part of the ASACUSA collaboration physics program a spin-flip cavity for measurements of the ground-state hyperfine transition frequency of anti-hydrogen atoms is needed. The purpose of the cavity is to excite anti-hydrogen atoms depending on their polarisation by a microwave field operating at 1.42 GHz. The delicacy of designing such a cavity lies in achieving and maintaining the required properties of this field over a large aperture of 10cm and for a long period of time (required amplitude stability is 1% within 12h). The present paper presents the frequency fine tuning techniques to obtain the desired centre frequency of 1.42 GHz with a Q value below 500 as well as the tuning circuit used for the frequency sweep over the desired bandwidth of 6 MHz.

WEPPP005

Progress on Muon Parametric-resonance Ionization Cooling Channel Development

emittance, simulation, quadrupole, betatron

2729

V.S. Morozov, Y.S. Derbenev
JLAB, Newport News, Virginia, USA
A. Afanasev
GWU, Washington, USA
K.B. Beard, R.P. Johnson
Muons, Inc, Batavia, USA
B. Erdelyi, J.A. Maloney
Northern Illinois University, DeKalb, Illinois, USA

Funding: Supported in part by DOE SBIR grant DE-SC0005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Parametric-resonance Ionization Cooling (PIC) is intended as the final 6D cooling stage of a high-luminosity muon collider. To implement PIC, a continuous-field twin-helix magnetic channel was developed. A 6D cooling with stochastic effects off is demonstrated in a GEANT4/G4beamline model of a system where wedge-shaped Be absorbers are placed at the appropriate dispersion points in the twin-helix channel and are followed by short rf cavities. To proceed to cooling simulations with stochastics on, compensation of the beam aberrations from one absorber to another is required. Initial results on aberration compensation using a set of various-order continuous multipole fields are presented. As another avenue to mitigate the aberration effect, we optimize the cooling channel’s period length. We observe a parasitic parametric resonance naturally occurring in the channel’s horizontal plane due to the periodic beam energy modulation caused by the absorbers and rf. We discuss options for compensating this resonance and/or properly combining it with the induced half-integer parametric resonance needed for PIC.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

WEPPP006

Using Simulations to Understand Particle Dynamics and Resonance in the Micro-accelerator Platform

laser, electron, coupling, acceleration

2732

J.C. McNeur, G. Travish
UCLA, Los Angeles, USA
H. Hairong
UESTC, Chengdu, Sichuan, People's Republic of China
R.B. Yoder
Manhattanville College, Purchase, New York, USA

Funding: Work funded in part by grant HDTRA1-09-1-0043 from the US Defense Threat Reduction Agency and under a grant from NNSA/NA-221 Office of Nonproliferation and Verification Research and Development.
The Micro-Accelerator Platform (MAP) is a slab-symmetric micron-scale electron accelerator. Electrons gain energy via a standing wave electromagnetic resonance powered by a side coupled Ti:Sapphire laser. In this paper, we will discuss simulations of resonance and particle dynamics in this structure. Three-dimensional simulations showing evidence of stable 1 GeV/m acceleration are detailed along with simulations studying defocusing and wakefield effects in the MAP. Additionally, optimization of the structure and the coupling of laser power into the cavity will be explored.

WEPPR004

Effect of Beam-beam Interactions on Stability of Coherent Oscillations in a Muon Collider

collider, luminosity, lattice, quadrupole

2940

K. Ohmi
KEK, Ibaraki, Japan
Y. Alexahin
Fermilab, Batavia, USA

In order to achieve the peak luminosity of a muon collider in the 10³⁵ cm^-2 s^-1 range the number of muons per bunch should be of the order of a few units of 10¹² rendering the beam-beam parameter as high as 0.1 per IP. Such strong beam-beam interaction can be a source of instability if the working point is chosen close to a coherent beam-beam resonance. On the other hand, the beam-beam tune spread can provide a mechanism of suppression of the beam-wall driven instabilities. In this report the coherent instabilities driven by beam-beam and beam-wall interactions are studied with the help of BBSS code for the case of 1.5 TeV c.o.m muon collider.

WEPPR008

Simulation of Controlled Longitudinal Emittance Blow-up in J-PARC RCS

emittance, simulation, cavity, extraction

2952

M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
KEK, Ibaraki, Japan
T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

In the J-PARC RCS, a high intensity beam is prepared for the MR. The longitudinal beam emittance at the RCS extraction should be optimized to avoid beam loss during and after MR injection. In order to match the longitudinal emittance shape between the RCS and the MR, it is desirable to enlarge the longitudinal emittance during the RCS acceleration. We have performed the particle tracking simulation for the controlled longitudinal emittance blow up in the RCS.

WEPPR011

Numerical Simulation Study of the Montague Resonance at the CERN Proton Synchrotron

emittance, simulation, space-charge, synchrotron

2958

J. Qiang, R.D. Ryne
LBNL, Berkeley, California, USA
G. Franchetti, I. Hofmann
GSI, Darmstadt, Germany
E. Métral
CERN, Geneva, Switzerland

Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP) under Contract No. DE-AC02-05CH11231.
The Montague resonance provides a coupling between the vertical and the horizontal dynamics of beams and can cause particle losses due to unequal aperture sizes of the accelerator. In this paper, we present a new numerical simulation study of a previous Montague resonance crossing experiment at the CERN PS including detailed three-dimensional space-charge effects and machine nonlinearity. The simulation reproduces the experimental data and suggests that the longitudinal synchrotron motion played an important role in enhancing transverse resonance coupling.

WEPPR012

Simulating High-Intensity Proton Beams in Nonlinear Lattices with PyORBIT

lattice, space-charge, simulation, proton

2961

S.D. Webb, D.T. Abell, D.L. Bruhwiler, J.R. Cary
Tech-X, Boulder, Colorado, USA
V.V. Danilov, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA
S. Nagaitsev, A. Valishev
Fermilab, Batavia, USA

High-intensity proton linacs and storage rings are essential for a) state-of-the-art neutron source user facilities, b) extending the high-energy physics intensity frontier, c) as a driver to generate pions for a future neutrino factory or muon collider, and d) for transmutation of radioactive waste and associated energy production. For example, Project X at Fermilab will deliver MW proton beams at energies ranging from 3 to 120 GeV. Nonlinear magnetic lattices with large tune spreads and with integrable*, nearly integrable** and chaotic* dynamics have been proposed to maximize dynamic aperture and minimize particle loss. We present PyORBIT*** simulations of proton dynamics in such lattices, including the effects of transverse space charge.
* V. Danilov and S. Nagaitsev, PR ST-AB 13 084002 (2010)
** K. Sonnad and J. Cary, Phys. Rev. E 69 056501 (2004)
*** A. Shishlo, J. Holmes and T. Gorlov, From Proceedings of IPAC '09 351-354

WEPPR024

Motion of Charged Particle Dense Bunch in Nonuniform External Fields

emittance, vacuum, focusing

2985

H.Y. Barminova
ITEP, Moscow, Russia
A.S. Chikhachev
Allrussian Electrotechnical Institute, Moskow, Russia

At the output of a linear resonance accelerator, a charged particle beam consists of a bunch series, with the relation between bunch length and transverse bunch size changing widely. It is of importance to describe bunch dynamics in a selfconsistent manner*,** . Usually the charged bunch is described as ellipsoid with uniform density. Such description allows easy consideration of its own bunch fields. In the case of a nonstationary distribution it is difficult to build distribution function describing 3D-ellipsoid with uniform density** . In this paper such function is found for bunch formed as rotation ellipsoid. Radii ellipsoid equations are obtained for a bunch moving in nonuniform stationary external fields.
* A.S. Chikhachev. Kinetic theory of quasystationary state of charged particle beams. Moscow,2001.
** I.M. Kapchinsky. Theory of linear resonanse accelerators. Particle dynamics. Moscow,1982.

WEPPR052

Octupole Magnets for the Instability Damping at the J-PARC Main Ring

octupole, damping, sextupole, dynamic-aperture

3045

S. Igarashi, T. Koseki, K. Ohmi, M.J. Shirakata, H. Someya, T. Toyama
KEK, Ibaraki, Japan
A. Ando
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

Octupole magnets have been installed for the instability damping at the J-PARC main ring. The transverse instability was observed during the injection and acceleration periods and caused the beam losses. The chromaticity tuning and bunch-by-bunch feedback system have been applied to suppress the instability. Octupole magnets were considered to create a larger amplitude dependent betatron tune shift and to supply additional option for the instability damping. The side effects of the dynamic aperture reduction and the resonances have been studied.

WEPPR062

The Mode Matching Method Applied to Beam Coupling Impedance Calculations of Finite Length Devices

impedance, coupling, simulation, cavity

3069

N. Biancacci, E. Métral, B. Salvant
CERN, Geneva, Switzerland
M. Migliorati, L. Palumbo
URLS, Rome, Italy
V.G. Vaccaro
Naples University Federico II and INFN, Napoli, Italy

The infinite length approximation is often used to simplify the calculation of the beam coupling impedance of accelerator elements. This is expected to be a reasonable assumption for devices whose length is greater than the transverse dimension but may be less accurate approximation for segmented devices. This contribution presents the study of the beam coupling impedance in the case of a finite length device: a cylindrical cavity loaded with a toroidal slab of material. In order to take into account the finite length we will decompose the field in the cavity and in the beam pipe into a set of orthonormal modes and apply the mode matching method to obtain the impedance. To validate our method, we will present comparisons between analytical formulas and 3D electromagnetic CST simulations as well as applications to the impedance of short beam pipe inserts, where the longitudinal and transverse dimensions are difficult to model in numerical simulations.

WEPPR068

Mitigation of Electron Cloud Instabilities in the LHC Using Sextupoles and Octupoles

electron, octupole, sextupole, damping

3084

K.S.B. Li, G. Rumolo
CERN, Geneva, Switzerland

Coherent electron cloud instabilities pose a serious limitation for luminosity upgrades in the Large Hadron Collider (LHC) at CERN. In particular, when bunch spacings reach below 50 ns, electron cloud formation is enhanced which in turn drives beam instabilities. The beam can be stabilised by shifting the tune and by increasing the tune spread using sextupoles or octupoles, respectively. The resulting values for the chromaticity and the detuning parameters must be selected with care, however, in order not to run into head-tail instabilities or to considerably reduce the dynamic aperture. A simulation study has been launched to estimate the parameters necessary for stabilisation of the beam under the influence of electron clouds.

WEPPR077

Analysis of Long-range Wakefields in CLIC Main Linac Accelerating Structures with Damping Loads

wakefield, simulation, damping, HOM

3111

G. De Michele
Paul Scherrer Institut, Villigen, Switzerland
G. De Michele
EPFL, Lausanne, Switzerland
A. Grudiev
CERN, Geneva, Switzerland

The baseline design of the CLIC accelerating structure foresees a moderate detuning and heavy damping of high order modes (HOMs), which are the source of long-range transverse wakefields. Such unwanted fields produce bunch-to-bunch instabilities so the HOMs must be suppressed. In order to damp these modes, the CLIC RF structure is equipped with lossy material inserted into four rectangular waveguides coupled to each accelerating cell. The lossy material absorbs EM (electromagnetic) wave energy with little reflection back to the accelerating cells. In the past, computations of the long-range wake of CLIC accelerating modes have been done using perfectly absorbing boundaries to terminate the damping waveguides. In this paper, 3D EM simulations of CLIC baseline accelerating structure with HOMs damping loads will be presented. A comparison between different EM codes (GdfidL, CST PARTICLE STUDIO®) will be discussed as well as the analysis of different types of absorbing materials with respect to the wakefields damping.

WEPPR095

Radial Eigenmodes for a Toroidal Waveguide with Rectangular Cross Section

impedance, electron, wakefield, synchrotron

3159

R. Li
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In applying mode expansion to solve the CSR impedance for a section of toroidal vacuum chamber with rectangular cross section, we identify the eigenvalue problem for the radial eigenmodes which is different from that for cylindrical structures. In this paper, we present the general expressions of the radial eigenmodes, and discuss the properties of the eigenvalues on the basis of the Sturm-Liouville theory.

THYB01

Beam-beam Limit in a Hadron Collider

luminosity, emittance, simulation, collider

3208

K. Ohmi
KEK, Ibaraki, Japan

Beam-beam limit phenomenon is observed in degradation of luminosity lifetime and/or beam life time in hadron colliders, especially in LHC. We focus the luminosity degradation in this paper. Various effects to degrade the luminosity grow severe in a high beam intensity. Coherent beam-beam instability, incoherent beam-beam emittance growth and those cupeled with lattice errors, external noises, intra-beam scattering. The beam-beam limit in an ideal machine and a machine with above errors is discussed with theory and simulation. Experimental results are reviewed and compare with the theory and simulations.

Slides THYB01 [4.712 MB]

THPPC001

Simulation and Design of a 70 MeV Cyclotron RF System

cyclotron, simulation, cavity, vacuum

3269

G. Gold, R.R. Johnson, B.F. Milton, V. Sabaiduc
BCSI, Vancouver, BC, Canada

The electromagnetic and mechanical design of the resonant cavity for a 70 MeV compact commercial cyclotron has been conducted by Best Cyclotron Systems Inc. Various resonator configurations have been studied for a radial, single-stem design and an optimal solution was selected with excellent electromagnetic properties and minimized construction and operational cost. Rapid model iterations during the design, using CST Microwave Studio and ANSYS, allowed for accurate tuning of geometry to precisely define the shape of the accelerating voltage profile, surface current distribution, and total power loss. The RF system of the BEST 70p cyclotron will operate at the fourth harmonic with two λ/2 separated resonant cavities shielded at the center allowing for beam modulation techniques to be applied through phase modulation of the accelerating voltage.

THPPC015

Design of a Four-vane 325 MHz RFQ Cold Model at Tsinghua University

rfq, cavity, dipole, simulation

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.

THPPC020

Accurate Measurement of Ferrite Garnets to be used for Fast-tuned Ferrite Loaded Cavities in the Range of 20-40 MHz

cavity, impedance, vacuum, dipole

3317

C. Vollinger, F. Caspers
CERN, Geneva, Switzerland

For the implementation of ferrite-tuned cavities with perpendicular biased ferrites in the frequency range of 20 to 40 MHz, different types of ferrite garnets were evaluated in terms of their electromagnetic properties. We describe a precision measurement method applicable to small-sized ferrite samples of 1-square-inch surface and 2 mm thickness in the given frequency range. During measurement, these samples are exposed to varying magnetic bias fields of different orientations. Two different techniques for the determination of the real and the imaginary part of the permeability are required to achieve sufficiently accurate results. We present a detailed description of these methods as well as results obtained.

THPPC036

The Alpha Ferrite-loaded Coaxial Resonator Cavity

cavity, damping, storage-ring, radiation

3365

A.N. Pham, S.-Y. Lee, T.H. Luo
IUCEEM, Bloomington, Indiana, USA

Funding: Grant N00164-08-GM03 P00004 from the NSWC Crane Division, DOE Grant DE-FG02-92ER40747, and NSF Grant PHY-0852368 (IU: 48-432-31).
The Advanced Electron Photon Facility (ALPHA)*,** is a joint collaboration between the Indiana University Center for Exploration of Energy and Matter and the Crane Naval Surface Warfare Center. The ALPHA storage ring will serve as a debuncher in single pass mode of operation. With a set of two gradient damping wigglers, the storage ring can also accumulate to achieve high charge density beams. In this report, we present the design, fabrication, and testing of the 15 MHz ferrite-loaded quarter-wave rf coaxial resonator cavity that will be utilized in the ALPHA storage ring. Topics pertaining to beam lifetime, radiation damping, ferrite-loaded transmission lines, and key cavity parameters will be discussed.
* S.Y. Lee, P.E. Sokol, et al, "The ALPHA Project at IU CEEM," Proceedings of the IPAC2010.
** S.Y. Lee, et al, "A low energy electron storage ring with tunable compaction factor," RSI 78, 2007.

THPPC044

Development of the Dual Slot Resonance Linac

linac, coupling, cavity, impedance

3383

N. Barov, X. Chang, R.H. Miller, D.J. Newsham
Far-Tech, Inc., San Diego, California, USA

Funding: Work supported by DOE Grant DE-FG02-08ER85034
We report the status of the Dual Slot Resonance (DSR) linac under development by FAR-TECH. In this linac type, cell-to-cell coupling is provided by a pair of close-coupled resonant slots, resulting in very strong coupling vs. a typical side-coupled linac design, as well as a much more compact radial space requirement. We discuss the status of the structure fabrication, the RF distribution system, and installation and testing at the UCLA Pegasus facility.

THPPC049

Progress on the MICE 201 MHz RF Cavity at LBNL

cavity, simulation, coupling, electron

3398

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
A.J. DeMello, D. Li, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California, USA

The international Muon Ionization Cooling Experiment (MICE) aims at demonstrating transverse cooling of muon beams by ionization. The ionization cooling channel of MICE requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. In this paper, we present recent progresses on MICE RF cavity at LBNL, which includes electro-polishing, intended to improve the cavity performance in the presence of strong external magnetic field; low power RF measurements on resonant frequency and Q value of each cavity with a pair of curved- beryllium windows to terminate the cavity irises. Multipacting simulations are conducted using SLAC’s ACE-3P code to study the effects in the cavity and coupler regions with the influence by external magnetic field.

THPPC077

Resonance Control of Superconducting Cavities at Heavy Beam Loading Conditions

cavity, controls, beam-loading, LLRF

3467

M.K. Grecki, S. Pfeiffer
DESY, Hamburg, Germany

Funding: The research leading to these results has received funding from the European Commission under the EuCARD FP7 Research Infrastructures grant agreement no. 227579
The SC cavities operated at high Q level need to be precisely tuned to the RF frequency*. Well tuned cavities assure the good field stability and require minimum level of RF power to reach the operating gradient level. The TESLA cavities at FLASH are tuned with the help of slow (step motors) and fast (piezo) tuners driven by the control system**. The goal of this control system is to keep the detuning of the cavity as close to zero as possible in the presence of disturbing effects (Lorentz force detuning and microphonics). The detuning of the cavity can be determined using a few measurement methods. The most common is to measure detuning from the phase derivative at the end of the RF pulse. In order to calculate the detuning during the whole RF pulse the cavity equation must be solved taking into account all the driving forces (RF power delivered to the cavity and beam contribution). This in not the trivial task, particularly in the heavy beam conditions, since all signals must be precisely calibrated. This work presents the methods and algorithms to evaluate and control the detuning of the superconducting cavities in the heavy beam loading conditions adequate for ILC operation.
* Grecki M., Piezo operation experience at FLASH, LLRF-2011, DESY, 09.2011
** Grecki M. et al. Piezo Control for Lorentz Force Detuned SC Cavities of DESY FLASH, IPAC'10, Kyoto, Japan, pp.1452-1454

THPPC089

LLRF Control for SPX @ APS Demonstration Experiment

cavity, LLRF, controls, low-level-rf

3491

G. Huang, J.M. Byrd, K. Campbell, L.R. Doolittle, J.B. Greer
LBNL, Berkeley, California, USA
N.D. Arnold, T.G. Berenc, F. Lenkszus, H. Ma
ANL, Argonne, USA

The SPX experiment at APS is part of the APS upgrade project, using two deflecting cavity to chirp the electron pulse and then generate short pulse x-ray. To minimize the influence to other users on the storage ring, the phase synchronization of the two deflecting cavity are required to be better then 77 femto-second. A LLRF4 board based system is designed to demonstrate the capability of meeting this requirement. This paper discuss the hardware and firmware design of the demo experiment including the cavity emulator, frequency reference generation and LLRF control algorithm.

THPPD050

Fast Ramping Arbitrary Waveform Power Supplies for Correction Coils in a Circular Electron Accelerator

electron, controls, dipole, power-supply

3623

A. Dieckmann, A. Balling, O. Boldt, F. Frommberger, W. Hillert, W. Lindenberg
ELSA, Bonn, Germany

New fast ramping power supplies working in pulsed bridge technology upgrade the existing Corrector System at ELSA. Current changes of ±0.8 A/msec are achieved. The newly developed CAN-Bus Interface allows linear interpolation of up to 250 support points with minimal time steps of 1msec. The first stage uses 24 power supplies to improve the position of the beam orbit in the horizontal plane using dipole correction coils. It will be extended to include the vertical plane with new corrector coils in the near future. This poster describes the operating principles of the power supply and the interface.

THPPP026

Experimental Effects of Orbit on Polarization Loss in RHIC

polarization, acceleration, injection, proton

3788

V.H. Ranjbar
Tech-X, Boulder, Colorado, USA
M. Bai, H. Huang, A. Marusic, M.G. Minty, V. Ptitsyn
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We are performing several experiments during the RHIC ramp to better understand the impact of orbit errors on the polarization at our current working point. These will be conducted by exciting specified orbit harmonics during the final two large intrinsic resonance crossing in RHIC during the 250 GeV polarized proton ramp. The resultant polarization response will then be measured.

THPPP030

Near Integer Tune for Polarization Preservation in the AGS

optics, polarization, acceleration, injection

3797

N. Tsoupas, L. A. Ahrens, M. Bai, K.A. Brown, J.W. Glenn, H. Huang, W.W. MacKay, T. Roser, V. Schoefer, K. Zeno
BNL, Upton, Long Island, New York, USA

Funding: *Work supported by the US Department of Energy.
The high energy (T=250 GeV) polarized proton beam experiments performed in RHIC, require high polarization of the beam. In order to preserve the polarization of the proton beam, during the acceleration in the AGS, which is the pre-injector to RHIC, two partial helical magnets* have been installed in AGS. In order to minimize the loss of the beam polarization due to the various intrinsic spin resonances occurring during the proton acceleration, we constrain the value of the vertical tune to be higher than 8.97. With the AGS running at near integer tune the perturbations caused by the partial helical magnets is large resulting in large beta and dispersion waves. To mitigate the adverse effect of the partial helices on the optics of the AGS, we have introduced compensation quads** in AGS. In this paper we present the beam optics of the AGS which ameliorates this effect of the partial helices.
* H. Huang, et al., Proc. EPAC06, p. 273, (2006).
** N. Tsoupas et al., Proc. PAC07, p. 3723 (2007).

THPPP038

Simulations of the Influence of 4-Rod RFQ Elements on its Voltage Distribution

rfq, simulation, linac, insertion

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

simulation, cavity, impedance, induction

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.

THPPP041

A CW High Charge State Heavy Ion RFQ Accelerator for SSC-LINAC Injector

rfq, linac, focusing, ion

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

THPPR005

The Preliminary Test of a Digital Control System Based on the FPGA for a PEFP 120-keV RF Cavity

cavity, controls, accelerating-gradient, proton

3975

Y.M. Li, S. Cha
UST, Daejeon City, Republic of Korea
Y.-S. Cho, J.-H. Jang, H.S. Kim, H.-J. Kwon, Y.M. Li, K.T. Seol, Y.-G. Song
KAERI, Daejon, Republic of Korea

Funding: Proton Engineering Frontier Project, Korea Atomic Energy Research Institute, Ministry of Education, Science and Technology of the Republic of Korea.
PEFP developed a 120-keV RF cavity for their ion implantation applications. Due to ambient disturbances, the cavity’s resonance frequency may vary in long-term test. We designed a digital control system to change the frequency of the RF sources for tracking the cavity’s frequency variations. The digital control system has functions such as, phase shift, phase comparison, proportional-integral compensation, waveform generation and frequency/pulse modulation, and driving signal generator. Most of them are implemented digitally in a Virtex II 4000 Field Programmable Gate Array (FPGA). In this research we show the design and the preliminary test results of the digital control system.
* Work supported by the Ministry of Science and Technology

THPPR039

Controlled Transverse Blow-Up of High-energy Proton Beams for Aperture Measurements and Loss Maps

injection, emittance, feedback, proton

4059

W. Höfle, R.W. Assmann, S. Redaelli, R. Schmidt, D. Valuch, D. Wollmann, M. Zerlauth
CERN, Geneva, Switzerland

A technique was developed to blow-up transversely in a controlled way high energy proton beams in the LHC. The technique is based on band limited white noise excitation that is injected into the transverse damper feedback loop. The injected signal can be gated to selectively blow-up individual trains of bunches. The speed of transverse blow-up can be precisely controlled. This opens the possibility to perform safely and efficiently aperture measurements and loss maps with high intensity bunch trains well above stored beam energies that are considered to be safe. In particular, lengthy procedures for measurements at top energy, otherwise requiring multiple fills of individual bunches, can be avoided. In this paper, the method is presented and results from beam measurements are discussed and compared with alternative blow-up methods.

THPPR065

High Flux Laser-Compton Scattered Gamma-ray Source by Compressed Nd:YAG Laser Pulse.

laser, electron, photon, microtron

4124

I. Daito, R. Hajima, T. Hayakawa, Y. Hayashi, M. Kando, H. Kotaki, T. Shizuma
JAEA, Kyoto, Japan
H. Ohgaki
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A non-destructive detection system of nuclear materials hidden in cargo containers is under development in Japan Atomic Energy Agency and Kyoto University. The system is able to be used for the identification of isotopes of special nuclear material in a container by employing Nuclear Resonance Fluorescence triggered by mono-energetic Laser Compton Scattered (LCS) gamma-ray tuned at the energy of the nuclear resonance. One of the most important technologies for such system is generation of gamma-rays at a flux of 3 x10⁵ photon/s. In order to achieve this gamma-ray flux with a compact system, a pulse compression system for Nd:YAG laser based on Stimulated Brillouin Scattering (SBS) has been developed. The laser pulse with a duration of 10 ns (FWHM) from a commercially available Nd:YAG laser is compressed down to a few hundreds ps. As a feasibility study of the proposed system, 400 keV gamma-ray generation is performed at Kansai Photon Science Institute by using 150 MeV electron beam from microtron accelerator and compressed Nd:YAG laser. Experimental results of laser pulse compression and gamma-ray generation are presented.