IPAC2018 - List of Keywords (betatron)

Paper	Title	Other Keywords	Page
MOPMF010	Measurement and Simulation of Betatron Coupling Beam Transfer Function in RHIC	coupling, simulation, experiment, quadrupole	99
	Y. Luo, W. Fischer, A. Marusic, M.G. Minty 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. Transfer function measurements are important for characterizing betatron tunes, betatron coupling, and beam spectrum in the routine operation of the Relativistic Heavy Ion Collider (RHIC). To counteract the linear betatron coupling, we developed a technique to continuously measure the betatron coupling coefficient with a base band phase lock loop tune meter in 2006. Based on this technique, we demonstrated and built a robust tune/coupling feedback in RHIC. In this article, we revisit the BTF measurement with betatron coupling to benchmark our BTF simulation code. We also compared the values of eigenmode projection ratios from BTF with those calculated with the single particle model.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF010
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MOPMF038	Cleaning Performance of the Collimation System with Xe Beams at the Large Hadron Collider	simulation, collimation, heavy-ion, proton	176
	N. Fuster-Martínez, R. Bruce, P.D. Hermes, J.M. Jowett, D. Mirarchi, S. Redaelli CERN, Geneva, Switzerland
	The LHC heavy-ion program with Pb ions has delivered substantial physics results since the startup of the LHC. There was a Xe run in 2017 in which collimation losses and cleaning were assessed. These studies give a unique opportunity for very valuable benchmark of simulation models with measurements, which could also be very important to understand limitations for future runs with Pb and other species. In this paper, we present collimation loss maps measured in the first ever operation of the LHC with Xe ions. The measurements are compared with simulations and first conclusions are discussed for possible future operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF038
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MOPML021	Shorter Treatment Time by Intensity Modulation with a Betatron Core Extraction	extraction, proton, radiation, synchrotron	439
	M. G. Pullia, E. Bressi, G.M.A. Calvi, M. Donetti, L. Falbo, S. Foglio, V. Lante, A. Parravicini, C. Priano, E. Rojatti, S. Savazzi, C. Viviani CNAO Foundation, Pavia, Italy
	The CNAO (National Center for Oncological Hadrontherapy) main accelerator is a synchrotron capable to accelerate carbon ions up to 400 MeV/u and protons up to 250 MeV. Three treatment rooms are available and are equipped with horizontal beam lines; one of the treatment rooms also features a vertical treatment line to allow additional treatment ports. All of the beamlines are equipped with an active beam scanning system for dose delivery. With such a dose distribution technique, particles are sent to different depths by changing the energy from the synchrotron and are moved transversally by means of two scanning magnets. The number of particles to be deposited in each position varies strongly within the same iso-energetic layer. Part of the dose needed in a given position is in fact delivered by particles directed to deeper layers. In order to maintain the required precision on the number of particles delivered to each spot, the intensity is reduced when spots that require low number of particles are present in a layer. A method to shorten the irradiation time based on variable intensity within the same layer is presented that works also with a betatron based extraction scheme.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML021
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MOPML035	Betatron Frequencies in Cotangential Trajectory Accelerator for Proton Beam Therapy	alignment, cyclotron, resonance, extraction	485
	T. Aoki, F. Ebina, C. Hori, Y. Nakashima, T. Seki Hitachi Ltd., Ibaraki-ken, Japan T. Hae Hitachi Ltd., Hitachi Research Laboratory, Ibaraki-ken, Japan
	It is important that downsizing of an accelerator for spreading proton beam therapy. The synchrotron is the solution of accelerator of proton beam therapy system which can vary energy of extracted beam in the range of from 70 MeV to 235 MeV with a merit of requiring no energy selection system. In order to downsize accelerator with above merit, we suggested smaller variable energy accelerator which have cotangential trajectories. This new type accelerator is expected to realize variability of beam energy with static main magnetic field. One of technological problems of this new type accelerator is stability of betatron oscillation. We plan to utilize week focusing field as main magnetic field, which is decreasing on the radial direction outward and uniform in longitudinal direction, of this new type accelerator. We found the main magnetic field which realizes stable betaron oscillations in the range of from 70 MeV to 235 MeV as the result of estimating the betaron oscillations in this main field by numerical calculation. We report new type accelerator concept and results of analysis of betatron oscillation in cotangential trajectories.
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TUPAF029	Observation of Fast Losses in the LHC Operation in 2017	operation, detector, beam-losses, monitoring	740
	A.A. Gorzawski, N. Fuster-Martínez, S. Redaelli, C. Xu, C. Zamantzas CERN, Geneva, Switzerland R.B. Appleby UMAN, Manchester, United Kingdom H. Garcia Morales Royal Holloway, University of London, Surrey, United Kingdom
	Four diamond detectors that provide beam loss measurements with time resolution in the nanosecond range were added in the vicinity of the primary collimators of the Large Hadron Collider (LHC). This is a powerful diagnostic tool that provides the unique chance to measure bunch-by-bunch losses. The operation of the LHC in 2017 presented several unusual events of fast, high intensity beam losses, many of them captured by the diamond detectors in the betatron cleaning region. In this paper we review some of the relevant loss cases that were analyzed in the wider scope of determining the source of the instability generating these losses. We show few of the possible applications of this detectors in daily operations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF029
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TUPAF047	Systematic Studies of Transverse Emittance Measurements Along the CERN PS Booster Cycle	emittance, scattering, brightness, proton	806
	A. Santamaría García, S.C.P. Albright, H. Bartosik, J.A. Briz Monago, G.P. Di Giovanni, V. Forte, B. Mikulec, F. Roncarolo, V. Vlachoudis CERN, Geneva, Switzerland
	The CERN Proton Synchrotron Booster (PSB) will need to deliver 2 times the current brightness to the Large Hadron Collider (LHC) after the LHC Injectors Upgrade (LIU) to meet the High-Luminosity-LHC beam requirements. Beam intensity and transverse emittance are the key parameters to increase brightness, the latter being more difficult to manipulate. It is, therefore, crucial to monitor not only the emittance evolution between the different injectors but also along each acceleration cycle. To this end, detailed emittance measurements were carried out for the four rings of the PSB at various times in the cycle with different beam types. A thorough analysis of systematic error sources was conducted including multiple Coulomb scattering happening during profile measurements with wire scanners, where experimental and analytical treatments of the emittance blow-up were compared to FLUKA simulations. In order to properly account for the dispersive contribution, the full momentum spread profile was considered using a deconvolution method. We conclude with an assessment of this first comprehensive emittance evolution measurement along the PSB cycle.
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TUPAL018	Pulse-by-Pulse Switching of Operational Parameters in J-PARC 3-GeV RCS	emittance, operation, injection, extraction	1041
	H. Hotchi, H. Harada, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, Y. Watanabe, M. Yoshimoto JAEA/J-PARC, Tokai-mura, Japan
	J-PARC 3-GeV RCS (rapid cycling synchrotron) provides a high-power beam both to MLF (materials and life science experimental facility) and MR (main ring synchrotron) by switching the beam destination pulse by pulse. The beam properties required from MLF and MR are different; MLF needs a wide-emittance beam with less charge density, while MR requires a low-emittance beam with less beam halo. To meet the antithetic requirements while keeping beam loss at permissible levels, RCS has recently initiated pulse-by-pulse switching of operational parameters (betatron tune, chromaticity, painting emittance, etc.). This paper presents the recent efforts toward the performance upgrade of RCS while discussing the related beam dynamics issues.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL018
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TUPAL028	New Feature of the Oscillating Synchrotron Motion Derived from the Hamiltonian Composed of Three Motions	synchrotron, closed-orbit, experiment, storage-ring	1060
	K. Jimbo Kyoto University, Kyoto, Japan
	The equation for the synchrotron motion was derived from the Hamiltonian, which was composed of coasting, betatron and synchrotron motions. The betatron oscillation is　the horizontal oscillation. The synchrotron oscillation is not only an oscillation of the revolution frequency but also an oscillation of the average radius. The synchrotron oscillation is both longitudinal and horizontal oscillations and it is possible to exchange energy with the betatron oscillation. The synchrotron oscillation occurs under a constant particle velocity and the Hamiltonian is conserved. K.Jimbo, Physical Review Special Topics - Accelerator and Beams 19, 010102 (2016).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL028
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TUZGBF3	Betatron Core Slow Extraction at CNAO	extraction, synchrotron, cavity, acceleration	1237
	L. Falbo, E. Bressi, S. Foglio, C. Priano CNAO Foundation, Milan, Italy
	CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. Beam is extracted with a momentum selection scheme in which beam enters the third order resonance driven by a betatron core. When irradiating a tumor, it is thought as divided in the longitudinal plane in several slices while each slice is divided in the transverse plane in several spots called voxels. Considering the dose uniformity that can be obtained during extraction, the machine must extract an average intensity related to the voxel that requires less dose. Therefore during a treatment, for some slices, a technique is needed to lower the extracted beam intensity with respect to the nominal one. A way to guarantee the correct average intensity according to the treatment planning requirements, is to introduce a mechanical filter (a degrader) that reduces the intensity of the accelerated particles. However this method used in the first treatments at CNAO showed some disadvantages and it has been replaced by what has been called the "dynamic betatron" method. The paper shows the implementations and the advantages of this method in the CNAO treatments.
	Slides TUZGBF3 [2.146 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF3
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WEPAK007	Slow Extraction Spill Characterization From Micro to Milli-Second Scale	extraction, power-supply, resonance, experiment	2095
	R. Singh, P. Boutachkov, P. Forck, S. Sorge, H. Welker GSI, Darmstadt, Germany
	This contribution deals with the topic of slow extraction spill quality characterization based on the measurements performed at GSI SIS-18. The sensitivity of the spill to power supply ripples are studied by introducing external ripples. An estimate of sources of inherent power supply ripples along with ripple magnitude are thus obtained. Spill characterization in time and frequency domain are discussed and exemplified by a typical spill and the differences from an ideal or Poisson spill. An appropriate spill characterization aims to provide a suitable abstraction for communication about the spill quality requirements between accelerator operations and users.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAK007
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THYGBD4	Landau Damping by Electron Lenses	electron, proton, octupole, collider	2921
	A.V. Burov, Y.I. Alexahin, V.D. Shiltsev, A. Valishev Fermilab, Batavia, Illinois, USA
	Modern and future particle accelerators employ increasingly higher intensity and brighter beams of charged particles and become operationally limited by coherent beam instabilities. Usual methods to control the instabilities, such as octupole magnets, beam feedback dampers and use of chromatic effects, become less effective and insufficient. We show that, in contrast, Lorentz forces of a low-energy, magnetically stabilized electron beam, or "electron lens", easily introduces transverse nonlinear focusing sufficient for Landau damping of transverse beam instabilities in accelerators. It is also important to note that, unlike other nonlinear elements, the electron lens provides the frequency spread mainly at the beam core, thus allowing much higher frequency spread without lifetime degradation. For the parameters of the Future Circular Collider, a single conventional electron lens a few meters long would provide stabilization superior to tens of thousands of superconducting octupole magnets.
	Slides THYGBD4 [4.502 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD4
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THYGBF1	High Power Beam Operation of the J-PARC RCS and MR	operation, extraction, emittance, quadrupole	2938
	Y. Sato KEK, Ibaraki, Japan
	This invited talk presents the most recent status of improving J-PARC main ring (MR) beam operation together with the rapid cycling synchrotron (RCS) effort. The RCS has optimized the beam performance for the MR injection as well as the muon and neutron targets, where each requires different emittance and beam halo size. The MR has two extraction modes; fast extraction (FX) for the long baseline neutrino oscillation experiment, T2K, and slow extraction (SX) for experiments in the hadron experimental facility. At present, achieved beam intensities are 2.4·10¹⁴ protons per pulse (ppp) with cycle time 2.48 s (470 kW) in the FX mode and 5.10¹³ ppp with cycle time 5.52 s (44 kW) in the SX mode. For the FX operation, recent improvements are settings of new betatron tune, corrections of resonances near the betatron tune, and adopting 2nd harmonic rf voltage to reduce space charge effect. Beam instabilities have been suppressed with controlling chromaticity correction and transverse feedback systems. For the SX mode, a dynamic bump scheme for reducing extracted beam loss is successfully adopted. A high extraction efficiency of 99.5 % is achieved at the 44 kW beam operation.
	Slides THYGBF1 [6.664 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBF1
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THPAF010	Reduction of Coherent Betatron Oscillations Using RF Electric Fields in the Fermilab Muon g-2 Experiment	dipole, quadrupole, experiment, simulation	2961
	O. Kim, S. Hacıömeroğlu, Y.I. Kim, Y.K. Semertzidis CAPP/IBS, Daejeon, Republic of Korea Y.F. Orlov Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	The Fermilab Muon g-2 experiment aims to measure the muon anomalous magnetic moment with a 140 parts-per-billion precision to investigate the greater than 3 standard deviation difference between the Standard Model prediction and the previous measurement by the BNL Muon g-2 experiment. The coherent betatron oscillation (CBO) beam effects must be corrected for in the decay-positron time spectra fits used in high precision muon storage ring based anomalous magnetic moment measurements. This MC simulation study indicates that the application of radio frequency (RF) electric fields to the muon storage ring beam can reduce the CBO amplitude by up to a factor of 10, as well to increase the symmetry of the beam phase space. This is achieved by correcting the mismatched oscillation phases between the high and low momentum muon populations by modulating the muon beam betatron oscillation frequencies with off-resonance RF fields.
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THPAF020	Measurement of Transverse Impedance of Specific Components in CESR Using BPM Measurements of Pinged Bunches	impedance, undulator, cavity, experiment	2990
	M.P. Ehrlichman, J.P. Shanks, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	A beam-based technique is applied to determine the quadrupole impedance of large-impedance components of the CESR storage ring. Two bunches separated by ~1/3 of the ring circumference are charged to 0.85 and 0.3 mA. Each bunch is given a single kick, either horizontal or vertical. Turn-by-turn, bunch-by-bunch position information is recorded for ~16 k turns. BPM-by-BPM phase is calculated using the All-phase FFT method of spectral analysis. The difference in the BPM-to-BPM phase advance between the two bunches is a measurement of the local transverse impedance. The impedances of the small-aperture in-vacuum undulators, collimators, scrapers, RF cavities, electrostatic separators, and bulk impedance of the remaining ring are determined in this manner.
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THPAF045	Performance Optimisation of Turn-by-Turn Beam Position Monitor Data Harmonic Analysis	optics, lattice, software, electron	3064
	L. Malina, J.M. Coello de Portugal, J. Dilly, P.K. Skowroński, R. Tomás, M.S. Toplis CERN, Geneva, Switzerland J.M. Coello de Portugal UPC, Barcelona, Spain
	Nowadays, turn-by-turn beam position monitor data is increasingly utilized in many accelerators, as it allows for fast and simultaneous measurement of various optics parameters. The accurate harmonic analysis of turn-by-turn data costs beam time when needed online. Generally, the electronic noise is avoided by cleaning of the data based on singular value decomposition. In this paper, we exploit the cleaning procedure to compress the data for the harmonic analysis. This way the harmonic analysis is sped up by an order of magnitude. The impact on measurement accuracy is discussed.
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THPAF046	Optics Measurements in Storage Rings Based on Simultaneous 3-Dimensional Beam Excitation	optics, dipole, synchrotron, storage-ring	3068
	L. Malina, J.M. Coello de Portugal CERN, Geneva, Switzerland J.M. Coello de Portugal UPC, Barcelona, Spain
	Optics measurements in storage rings usually employ excitation in both transverse directions. This needs to be repeated at several different beam energies and is time-consuming. In this paper, we develop a new optics measurement technique, which excites the beam in all three spatial dimensions simultaneously. It allows measuring the linear optics and chromatic properties at the same time, leading to speed up of the optics measurements. The measurement method has been successfully demonstrated in the LHC using AC-dipoles and RF frequency modulation. Analysis methods have been derived for the 3-dimensional beam excitation case. We quantify the resolution of the measured optical quantities. The first results suggest that the added complexity does not deteriorate the resolution of the linear optics measurement. In the future, this method can serve as an operational tool to check the optics or even to correct it.
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THPAF067	Effects of Synchrotron Motion on Nonlinear Integrable Optics	synchrotron, optics, coupling, lattice	3131
	S.D. Webb, N.M. Cook RadiaSoft LLC, Boulder, Colorado, USA J.S. Eldred Fermilab, Batavia, Illinois, USA
	Funding: This work was supported in part by the Department of Energy, Office of Science, Office of High Energy Physics under contract number DE-SC0011340. An integrable Rapid-Cycling Synchrotron (iRCS) has been proposed as a replacement for the Fermilab Booster to achieve multi-MW beam power for the Fermilab high-energy neutrino program.* The successful application of nonlinear integrable optics to proton synchrotrons requires careful examination of single-particle longitudinal effects, especially synchrotron motion. For example, synchrobetatron coupling may excite transverse resonances in the ring. We will use the Synergia code to simulate the effects of this synchrobetatron coupling on the iRCS design with nonlinear inserts. Our goal will be to identify new invariants in the presence of this coupling. Assuming the synchrotron tune is sufficiently small, we have identified one or more adiabatic invariants of the motion. These invariants suggest that integrable optics with synchrobetatron coupling retains integrability when averaged over a synchrotron period. * J. Eldred and A. Valishev, "Design Considerations for Proposed Fermilab Integrable RCS," arXiv 1703.00952 (2017).
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THPAF074	Landau Damping Studies for the FCC: Octupole Magnets, Electron Lens and Beam-Beam Effects	octupole, damping, flattop, feedback	3150
	C. Tambasco, J. Barranco García, T. Pieloni, L. Rivkin EPFL, Lausanne, Switzerland S. Arsenyev, X. Buffat, D. Schulte CERN, Geneva, Switzerland
	Funding: This work is supported by the Swiss State Secretariat for Education, Research and Innovation SERI. Stability studies for the FCC-hh operational cycle are explored using Landau octupoles and electron lenses alone and in the presence of long-range as well as head-on beam-beam effects. Pros and cons of the various methods are compared and an optimum operational scenario to guarantee the maximum stability is proposed.
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THPAK007	Beam Extraction from TR24 Cyclotron at IPHC	extraction, cyclotron, closed-orbit, emittance	3218
	N.Yu. Kazarinov, I.A. Ivanenko JINR, Dubna, Moscow Region, Russia F.R. Osswald IPHC, Strasbourg Cedex 2, France
	The CYRCé cyclotron is used at IPHC (Institut Pluridisciplinaire Hubert Curien) for the production of radio-isotopes for diagnostics, medical treatments and fundamental research in radiobiology. The TR24 cyclotron manufactured and commercialized by ACSI delivers a 16-25 MeV proton beam with intensity from few nA up to 500 microA. The TR24 is a separated-sector isochronous cyclotron with normal-conducting magnet and stripper foil. It is a challenge to fit the high intensity proton beam used for target irradiation to radiobiology and analytical applications due to requirements on beam quality and energy resolution. Field distribution in the region of the extraction performed with OPERA 3D as well as beam dynamics related with stripping are analysed. 3D calculation model and hypothesis about geometry and beam are described. Our goal is to evaluate the extraction efficiency and the beam characteristics in the focusing plane outside the cyclotron which will serve as inputs for the design of future beam lines and enable beam matching conditions. Therefore, different issues are discussed: energy dispersion, transverse dynamics and orbit separation.
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THPAK034	Practical Betatron Tune Behavior During Acceleration in Scaling FFAG Rings at KURNS	booster, acceleration, proton, extraction	3287
	Y. Ishi, Y. Fuwa, Y. Kuriyama, Y. Mori, H. Okita, T. Uesugi Kyoto University, Research Reactor Institute, Osaka, Japan J.-B. Lagrange Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	In scaling FFAG* accelerators, ideally, betatron tunes are fixed for each closed orbit concerned with the certain beam energy. Therefore, they should not vary during the acceleration. However, it is not the case since practical implementations of the magnetic field can not provide perfect scaling conditions. There are two types of radial scaling FFAG ring at Kyoto University Research Reactor Institute: one has no return yokes so called 'yoke free type' adopted by MAIN RING which has a large tune variations causing non negligible beam losses; the other has return yokes and filed clamps adopted by BOOSTER RING which has smaller tune variations compared with MAIN RING. We report the tune measurements and calculations based on 3-d magnetic field calculations about these two types of ring and discuss the scaling conditions in FFAG accelerators. FFAG : FFAG stands for fixed filed alternating gradient. It describes one the focusing scheme in the circular accelerator.*
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THPAK036	Accurate Modeling of Fringe Field Effects on Nonlinear Integrable Optics in IOTA	optics, quadrupole, octupole, lattice	3294
	C.E. Mitchell, R.D. Ryne LBNL, Berkeley, California, USA F.H. O'Shea RadiaBeam, Santa Monica, California, USA
	Funding: This work is supported by the U.S. Department of Energy, Office of High Energy Physics. The Integrable Optics Test Accelerator (IOTA) is a novel storage ring under commissioning at Fermi National Accelerator Laboratory designed to investigate the dynamics of beams with large transverse tune spread in the presence of strongly nonlinear integrable optics. Uncontrolled nonlinear effects resulting from magnetic fringe fields can affect the integrability of particle motion, and long-term numerical tracking requires an accurate representation of these effects. Surface fitting algorithms provide a robust and reliable method for extracting this information from 3-dimensional magnetic field data provided on a grid. These algorithms are applied to investigate the unique nonlinear magnetic insert of the IOTA ring, and consequences of the fringe fields to the long-term dynamics of the beam are discussed.
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THPAK118	Beam Dynamics Studies for a Strong-Focusing Cyclotron	cavity, dipole, focusing, cyclotron	3522
	J. Gerity, S. Assadi, P.M. McIntyre, A. Sattarov Texas A&M University, College Station, USA
	Results are presented from end-to-end simulation of a 100 MeV strong focusing cyclotron (SFC). The develop-ment of the high-current SFC is motivated by applica-tions for production of medical isotopes and for a proton driver for subcritical fission. It uses a novel superconducting cavity to provide suffi-cient energy gain to fully separate all turns. An arc-contour F-D doublet, trim dipole winding, and sextupole are located along each turn within the aperture of each sector dipole to control the betatron and synchrotron motion and to stabilize non-linear dynamics with high-current operation. The phase space evolution of a proton bunch in the SFC was simulated using both the code OPAL and an ad hoc Runge-Kutta tracker. Iterative optimization of the dipole, quadrupole, and sextupole fields was used to provide precise isochronicity, favorable betatron phase advance, and cancellation of dispersion in each cell.
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THPAK126	Revised Optics Design for the JLEIC Ion Booster	booster, lattice, sextupole, injection	3537
	E.W. Nissen, T. Satogata JLab, Newport News, Virginia, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177. We outline the recently redesigned booster for the pro-posed Jefferson Lab Electron Ion Collider (JLEIC). This booster will inject protons (or ions of equivalent rigidity) at 280 MeV and accelerate them to 8 GeV kinetic energy. To avoid transition crossing, the booster uses flexible momentum compaction (FMC) lattices to raise the transi-tion gamma above the reach of the machine. We also include several families of sextupoles to simultaneously control the chromaticities, and nonlinear dispersions that were excited by the FMC cells.
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THPMF035	Numerical Analysis of Excitation Property of Pulse Picking by Resonant Excitation at BESSY II	synchrotron, kicker, emittance, radiation	4131
	J.G. Hwang, M. Koopmans, R. Müller, M. Ries, A. Schälicke HZB, Berlin, Germany
	The pulse picking by resonant excitation (PPRE) method is applied at BESSY II to provide pseudo single bunch operation by separating the radiation from one horizontally enlarged bunch from the light of the multi-bunch filling. The bunch is enlarged by an excitation with an external signal close to the tune resonance. The variation of the beam size depends strongly on the frequency and amplitude of the excitation signal. In this paper we show the properties of the PPRE bunch studied by analytical modeling and numerical calculations using Elegant. The simulation results are compared with beam size measurements using a new interferometry beam size monitor at BESSY II.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMF035
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THPML072	Injection Comparison using Bunch-by-Bunch Beam Size Measurement System at SSRF	injection, damping, SRF, storage-ring	4811
	H.J. Chen, J. Chen, B. Gao, Y.B. Leng SINAP, Shanghai, People's Republic of China
	Injection transient process happens every 5-10 minutes in storage ring during normal top-up operating mode at SSRF, which is a proper window for machine status and injection performance evaluation. In the recent year, a bunch-by-bunch beam size measurement system has been implemented at SSRF, which has the capability to offer transverse bunch-by-bunch position and size information and is a powerful tool for injection study. In this paper, we summarize three injection study results from July 2017 to April 2018, including betatron oscillation amplitude, spectrum, horizontal tune and damping time comparison. The oscillation amplitude and temporal behavior of recent injection are all better than results before contributed to the injection optimization work during maintenance in 2018 winter. In addition, the principal component analysis method is also applied to further study the injection behavior in turn-by-turn or bunch-by-bunch direction to the refilled bucket.
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THPML084	Validating the COBEA Algorithm at the DELTA Storage Ring	storage-ring, optics, closed-orbit, lattice	4851
	B. Riemann, B.D. Isbarn, S. Khan, S. Koetter, T. Weis DELTA, Dortmund, Germany
	Closed-Orbit Bilinear-Exponential Analysis (COBEA) is an algorithm to decompose monitor-corrector response matrices into (scaled) beta optics values, phase advances, scaled dispersion and betatron tunes. No explicit magnetic lattice model is required for COBEA - only the sequence of monitors and correctors along the beam path (no lengths, no strengths approach). To obtain absolute beta values, the length of one drift space can be provided as optional input. In this work, the application of COBEA to the DELTA storage ring, operated by TU Dortmund University, is discussed, and its results for betatron tunes and scaled dispersion are compared with those of conventional, direct measurement methods. COBEA is also put in a historical perspective to other diagnostic algorithms. Improvements in the Python implementation of COBEA, which is available as free software, are presented. Due to COBEA being relatively modest regarding its requirements on input data respectively hardware, it should be applicable to the majority of existing storage rings.
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THPML111	Test of the Tune Measurement System Based on BBQ at HLS-II Storage Ring	storage-ring, ion-source, experiment, controls	4926
	L.T. Huang, F.L. Gao, P. Lu, B.G. Sun, H.Q. Wang, J.G. Wang, Q. Wang, F.F. Wu, Y.L. Yang, T.Y. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by the National Science Foundation of China (Grant No. 11705203, 11575181) The HLS-II storage ring is a crucial part of Hefei Light Source. Tune is one of the most important parameters of the electron storage ring, of which the tune measurement system is an integral component. In this paper, the design of a new tune measurement system based on BBQ (base band tune), is presented. Some experiments are performed to test this system. The new system is compared with the original system and the TBT (turn-by-turn) method respectively. The obtained results illustrate higher accuracy and higher stability for the new system. A new approach of calculating the betatron oscillation amplitude is proposed, and the betatron oscillation amplitudes in the normal running stage for the HLS-II storage ring are estimated at 95 nm (horizontal) and 60 nm (vertical).
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Paper

Title

Other Keywords

Page

MOPMF010

Measurement and Simulation of Betatron Coupling Beam Transfer Function in RHIC

coupling, simulation, experiment, quadrupole

99

Y. Luo, W. Fischer, A. Marusic, M.G. Minty
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.
Transfer function measurements are important for characterizing betatron tunes, betatron coupling, and beam spectrum in the routine operation of the Relativistic Heavy Ion Collider (RHIC). To counteract the linear betatron coupling, we developed a technique to continuously measure the betatron coupling coefficient with a base band phase lock loop tune meter in 2006. Based on this technique, we demonstrated and built a robust tune/coupling feedback in RHIC. In this article, we revisit the BTF measurement with betatron coupling to benchmark our BTF simulation code. We also compared the values of eigenmode projection ratios from BTF with those calculated with the single particle model.

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MOPMF038

Cleaning Performance of the Collimation System with Xe Beams at the Large Hadron Collider

simulation, collimation, heavy-ion, proton

176

N. Fuster-Martínez, R. Bruce, P.D. Hermes, J.M. Jowett, D. Mirarchi, S. Redaelli
CERN, Geneva, Switzerland

The LHC heavy-ion program with Pb ions has delivered substantial physics results since the startup of the LHC. There was a Xe run in 2017 in which collimation losses and cleaning were assessed. These studies give a unique opportunity for very valuable benchmark of simulation models with measurements, which could also be very important to understand limitations for future runs with Pb and other species. In this paper, we present collimation loss maps measured in the first ever operation of the LHC with Xe ions. The measurements are compared with simulations and first conclusions are discussed for possible future operation.

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MOPML021

Shorter Treatment Time by Intensity Modulation with a Betatron Core Extraction

extraction, proton, radiation, synchrotron

439

M. G. Pullia, E. Bressi, G.M.A. Calvi, M. Donetti, L. Falbo, S. Foglio, V. Lante, A. Parravicini, C. Priano, E. Rojatti, S. Savazzi, C. Viviani
CNAO Foundation, Pavia, Italy

The CNAO (National Center for Oncological Hadrontherapy) main accelerator is a synchrotron capable to accelerate carbon ions up to 400 MeV/u and protons up to 250 MeV. Three treatment rooms are available and are equipped with horizontal beam lines; one of the treatment rooms also features a vertical treatment line to allow additional treatment ports. All of the beamlines are equipped with an active beam scanning system for dose delivery. With such a dose distribution technique, particles are sent to different depths by changing the energy from the synchrotron and are moved transversally by means of two scanning magnets. The number of particles to be deposited in each position varies strongly within the same iso-energetic layer. Part of the dose needed in a given position is in fact delivered by particles directed to deeper layers. In order to maintain the required precision on the number of particles delivered to each spot, the intensity is reduced when spots that require low number of particles are present in a layer. A method to shorten the irradiation time based on variable intensity within the same layer is presented that works also with a betatron based extraction scheme.

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MOPML035

Betatron Frequencies in Cotangential Trajectory Accelerator for Proton Beam Therapy

alignment, cyclotron, resonance, extraction

485

T. Aoki, F. Ebina, C. Hori, Y. Nakashima, T. Seki
Hitachi Ltd., Ibaraki-ken, Japan
T. Hae
Hitachi Ltd., Hitachi Research Laboratory, Ibaraki-ken, Japan

It is important that downsizing of an accelerator for spreading proton beam therapy. The synchrotron is the solution of accelerator of proton beam therapy system which can vary energy of extracted beam in the range of from 70 MeV to 235 MeV with a merit of requiring no energy selection system. In order to downsize accelerator with above merit, we suggested smaller variable energy accelerator which have cotangential trajectories. This new type accelerator is expected to realize variability of beam energy with static main magnetic field. One of technological problems of this new type accelerator is stability of betatron oscillation. We plan to utilize week focusing field as main magnetic field, which is decreasing on the radial direction outward and uniform in longitudinal direction, of this new type accelerator. We found the main magnetic field which realizes stable betaron oscillations in the range of from 70 MeV to 235 MeV as the result of estimating the betaron oscillations in this main field by numerical calculation. We report new type accelerator concept and results of analysis of betatron oscillation in cotangential trajectories.

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TUPAF029

Observation of Fast Losses in the LHC Operation in 2017

operation, detector, beam-losses, monitoring

740

A.A. Gorzawski, N. Fuster-Martínez, S. Redaelli, C. Xu, C. Zamantzas
CERN, Geneva, Switzerland
R.B. Appleby
UMAN, Manchester, United Kingdom
H. Garcia Morales
Royal Holloway, University of London, Surrey, United Kingdom

Four diamond detectors that provide beam loss measurements with time resolution in the nanosecond range were added in the vicinity of the primary collimators of the Large Hadron Collider (LHC). This is a powerful diagnostic tool that provides the unique chance to measure bunch-by-bunch losses. The operation of the LHC in 2017 presented several unusual events of fast, high intensity beam losses, many of them captured by the diamond detectors in the betatron cleaning region. In this paper we review some of the relevant loss cases that were analyzed in the wider scope of determining the source of the instability generating these losses. We show few of the possible applications of this detectors in daily operations.

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TUPAF047

Systematic Studies of Transverse Emittance Measurements Along the CERN PS Booster Cycle

emittance, scattering, brightness, proton

806

A. Santamaría García, S.C.P. Albright, H. Bartosik, J.A. Briz Monago, G.P. Di Giovanni, V. Forte, B. Mikulec, F. Roncarolo, V. Vlachoudis
CERN, Geneva, Switzerland

The CERN Proton Synchrotron Booster (PSB) will need to deliver 2 times the current brightness to the Large Hadron Collider (LHC) after the LHC Injectors Upgrade (LIU) to meet the High-Luminosity-LHC beam requirements. Beam intensity and transverse emittance are the key parameters to increase brightness, the latter being more difficult to manipulate. It is, therefore, crucial to monitor not only the emittance evolution between the different injectors but also along each acceleration cycle. To this end, detailed emittance measurements were carried out for the four rings of the PSB at various times in the cycle with different beam types. A thorough analysis of systematic error sources was conducted including multiple Coulomb scattering happening during profile measurements with wire scanners, where experimental and analytical treatments of the emittance blow-up were compared to FLUKA simulations. In order to properly account for the dispersive contribution, the full momentum spread profile was considered using a deconvolution method. We conclude with an assessment of this first comprehensive emittance evolution measurement along the PSB cycle.

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TUPAL018

Pulse-by-Pulse Switching of Operational Parameters in J-PARC 3-GeV RCS

emittance, operation, injection, extraction

1041

H. Hotchi, H. Harada, K. Okabe, P.K. Saha, Y. Shobuda, F. Tamura, Y. Watanabe, M. Yoshimoto
JAEA/J-PARC, Tokai-mura, Japan

J-PARC 3-GeV RCS (rapid cycling synchrotron) provides a high-power beam both to MLF (materials and life science experimental facility) and MR (main ring synchrotron) by switching the beam destination pulse by pulse. The beam properties required from MLF and MR are different; MLF needs a wide-emittance beam with less charge density, while MR requires a low-emittance beam with less beam halo. To meet the antithetic requirements while keeping beam loss at permissible levels, RCS has recently initiated pulse-by-pulse switching of operational parameters (betatron tune, chromaticity, painting emittance, etc.). This paper presents the recent efforts toward the performance upgrade of RCS while discussing the related beam dynamics issues.

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TUPAL028

New Feature of the Oscillating Synchrotron Motion Derived from the Hamiltonian Composed of Three Motions

synchrotron, closed-orbit, experiment, storage-ring

1060

K. Jimbo
Kyoto University, Kyoto, Japan

The equation for the synchrotron motion was derived from the Hamiltonian, which was composed of coasting, betatron and synchrotron motions*. The betatron oscillation is　the horizontal oscillation. The synchrotron oscillation is not only an oscillation of the revolution frequency but also an oscillation of the average radius. The synchrotron oscillation is both longitudinal and horizontal oscillations and it is possible to exchange energy with the betatron oscillation. The synchrotron oscillation occurs under a constant particle velocity and the Hamiltonian is conserved.
*K.Jimbo, Physical Review Special Topics - Accelerator and Beams 19, 010102 (2016).

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TUZGBF3

Betatron Core Slow Extraction at CNAO

extraction, synchrotron, cavity, acceleration

1237

L. Falbo, E. Bressi, S. Foglio, C. Priano
CNAO Foundation, Milan, Italy

CNAO is the only Italian hadrontherapy facility able to treat tumors with beams of protons and carbon ions. Beam is extracted with a momentum selection scheme in which beam enters the third order resonance driven by a betatron core. When irradiating a tumor, it is thought as divided in the longitudinal plane in several slices while each slice is divided in the transverse plane in several spots called voxels. Considering the dose uniformity that can be obtained during extraction, the machine must extract an average intensity related to the voxel that requires less dose. Therefore during a treatment, for some slices, a technique is needed to lower the extracted beam intensity with respect to the nominal one. A way to guarantee the correct average intensity according to the treatment planning requirements, is to introduce a mechanical filter (a degrader) that reduces the intensity of the accelerated particles. However this method used in the first treatments at CNAO showed some disadvantages and it has been replaced by what has been called the "dynamic betatron" method. The paper shows the implementations and the advantages of this method in the CNAO treatments.

Slides TUZGBF3 [2.146 MB]

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WEPAK007

Slow Extraction Spill Characterization From Micro to Milli-Second Scale

extraction, power-supply, resonance, experiment

2095

R. Singh, P. Boutachkov, P. Forck, S. Sorge, H. Welker
GSI, Darmstadt, Germany

This contribution deals with the topic of slow extraction spill quality characterization based on the measurements performed at GSI SIS-18. The sensitivity of the spill to power supply ripples are studied by introducing external ripples. An estimate of sources of inherent power supply ripples along with ripple magnitude are thus obtained. Spill characterization in time and frequency domain are discussed and exemplified by a typical spill and the differences from an ideal or Poisson spill. An appropriate spill characterization aims to provide a suitable abstraction for communication about the spill quality requirements between accelerator operations and users.

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THYGBD4

Landau Damping by Electron Lenses

electron, proton, octupole, collider

2921

A.V. Burov, Y.I. Alexahin, V.D. Shiltsev, A. Valishev
Fermilab, Batavia, Illinois, USA

Modern and future particle accelerators employ increasingly higher intensity and brighter beams of charged particles and become operationally limited by coherent beam instabilities. Usual methods to control the instabilities, such as octupole magnets, beam feedback dampers and use of chromatic effects, become less effective and insufficient. We show that, in contrast, Lorentz forces of a low-energy, magnetically stabilized electron beam, or "electron lens", easily introduces transverse nonlinear focusing sufficient for Landau damping of transverse beam instabilities in accelerators. It is also important to note that, unlike other nonlinear elements, the electron lens provides the frequency spread mainly at the beam core, thus allowing much higher frequency spread without lifetime degradation. For the parameters of the Future Circular Collider, a single conventional electron lens a few meters long would provide stabilization superior to tens of thousands of superconducting octupole magnets.

Slides THYGBD4 [4.502 MB]

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THYGBF1

High Power Beam Operation of the J-PARC RCS and MR

operation, extraction, emittance, quadrupole

2938

Y. Sato
KEK, Ibaraki, Japan

This invited talk presents the most recent status of improving J-PARC main ring (MR) beam operation together with the rapid cycling synchrotron (RCS) effort. The RCS has optimized the beam performance for the MR injection as well as the muon and neutron targets, where each requires different emittance and beam halo size. The MR has two extraction modes; fast extraction (FX) for the long baseline neutrino oscillation experiment, T2K, and slow extraction (SX) for experiments in the hadron experimental facility. At present, achieved beam intensities are 2.4·10¹⁴ protons per pulse (ppp) with cycle time 2.48 s (470 kW) in the FX mode and 5.10¹³ ppp with cycle time 5.52 s (44 kW) in the SX mode. For the FX operation, recent improvements are settings of new betatron tune, corrections of resonances near the betatron tune, and adopting 2nd harmonic rf voltage to reduce space charge effect. Beam instabilities have been suppressed with controlling chromaticity correction and transverse feedback systems. For the SX mode, a dynamic bump scheme for reducing extracted beam loss is successfully adopted. A high extraction efficiency of 99.5 % is achieved at the 44 kW beam operation.

Slides THYGBF1 [6.664 MB]

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THPAF010

Reduction of Coherent Betatron Oscillations Using RF Electric Fields in the Fermilab Muon g-2 Experiment

dipole, quadrupole, experiment, simulation

2961

O. Kim, S. Hacıömeroğlu, Y.I. Kim, Y.K. Semertzidis
CAPP/IBS, Daejeon, Republic of Korea
Y.F. Orlov
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

The Fermilab Muon g-2 experiment aims to measure the muon anomalous magnetic moment with a 140 parts-per-billion precision to investigate the greater than 3 standard deviation difference between the Standard Model prediction and the previous measurement by the BNL Muon g-2 experiment. The coherent betatron oscillation (CBO) beam effects must be corrected for in the decay-positron time spectra fits used in high precision muon storage ring based anomalous magnetic moment measurements. This MC simulation study indicates that the application of radio frequency (RF) electric fields to the muon storage ring beam can reduce the CBO amplitude by up to a factor of 10, as well to increase the symmetry of the beam phase space. This is achieved by correcting the mismatched oscillation phases between the high and low momentum muon populations by modulating the muon beam betatron oscillation frequencies with off-resonance RF fields.

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THPAF020

Measurement of Transverse Impedance of Specific Components in CESR Using BPM Measurements of Pinged Bunches

impedance, undulator, cavity, experiment

2990

M.P. Ehrlichman, J.P. Shanks, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

A beam-based technique is applied to determine the quadrupole impedance of large-impedance components of the CESR storage ring. Two bunches separated by ~1/3 of the ring circumference are charged to 0.85 and 0.3 mA. Each bunch is given a single kick, either horizontal or vertical. Turn-by-turn, bunch-by-bunch position information is recorded for ~16 k turns. BPM-by-BPM phase is calculated using the All-phase FFT method of spectral analysis. The difference in the BPM-to-BPM phase advance between the two bunches is a measurement of the local transverse impedance. The impedances of the small-aperture in-vacuum undulators, collimators, scrapers, RF cavities, electrostatic separators, and bulk impedance of the remaining ring are determined in this manner.

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THPAF045

Performance Optimisation of Turn-by-Turn Beam Position Monitor Data Harmonic Analysis

optics, lattice, software, electron

3064

L. Malina, J.M. Coello de Portugal, J. Dilly, P.K. Skowroński, R. Tomás, M.S. Toplis
CERN, Geneva, Switzerland
J.M. Coello de Portugal
UPC, Barcelona, Spain

Nowadays, turn-by-turn beam position monitor data is increasingly utilized in many accelerators, as it allows for fast and simultaneous measurement of various optics parameters. The accurate harmonic analysis of turn-by-turn data costs beam time when needed online. Generally, the electronic noise is avoided by cleaning of the data based on singular value decomposition. In this paper, we exploit the cleaning procedure to compress the data for the harmonic analysis. This way the harmonic analysis is sped up by an order of magnitude. The impact on measurement accuracy is discussed.

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THPAF046

Optics Measurements in Storage Rings Based on Simultaneous 3-Dimensional Beam Excitation

optics, dipole, synchrotron, storage-ring

3068

L. Malina, J.M. Coello de Portugal
CERN, Geneva, Switzerland
J.M. Coello de Portugal
UPC, Barcelona, Spain

Optics measurements in storage rings usually employ excitation in both transverse directions. This needs to be repeated at several different beam energies and is time-consuming. In this paper, we develop a new optics measurement technique, which excites the beam in all three spatial dimensions simultaneously. It allows measuring the linear optics and chromatic properties at the same time, leading to speed up of the optics measurements. The measurement method has been successfully demonstrated in the LHC using AC-dipoles and RF frequency modulation. Analysis methods have been derived for the 3-dimensional beam excitation case. We quantify the resolution of the measured optical quantities. The first results suggest that the added complexity does not deteriorate the resolution of the linear optics measurement. In the future, this method can serve as an operational tool to check the optics or even to correct it.

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THPAF067

Effects of Synchrotron Motion on Nonlinear Integrable Optics

synchrotron, optics, coupling, lattice

3131

S.D. Webb, N.M. Cook
RadiaSoft LLC, Boulder, Colorado, USA
J.S. Eldred
Fermilab, Batavia, Illinois, USA

Funding: This work was supported in part by the Department of Energy, Office of Science, Office of High Energy Physics under contract number DE-SC0011340.
An integrable Rapid-Cycling Synchrotron (iRCS) has been proposed as a replacement for the Fermilab Booster to achieve multi-MW beam power for the Fermilab high-energy neutrino program.* The successful application of nonlinear integrable optics to proton synchrotrons requires careful examination of single-particle longitudinal effects, especially synchrotron motion. For example, synchrobetatron coupling may excite transverse resonances in the ring. We will use the Synergia code to simulate the effects of this synchrobetatron coupling on the iRCS design with nonlinear inserts. Our goal will be to identify new invariants in the presence of this coupling. Assuming the synchrotron tune is sufficiently small, we have identified one or more adiabatic invariants of the motion. These invariants suggest that integrable optics with synchrobetatron coupling retains integrability when averaged over a synchrotron period.
* J. Eldred and A. Valishev, "Design Considerations for Proposed Fermilab Integrable RCS," arXiv 1703.00952 (2017).

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THPAF074

Landau Damping Studies for the FCC: Octupole Magnets, Electron Lens and Beam-Beam Effects

octupole, damping, flattop, feedback

3150

C. Tambasco, J. Barranco García, T. Pieloni, L. Rivkin
EPFL, Lausanne, Switzerland
S. Arsenyev, X. Buffat, D. Schulte
CERN, Geneva, Switzerland

Funding: This work is supported by the Swiss State Secretariat for Education, Research and Innovation SERI.
Stability studies for the FCC-hh operational cycle are explored using Landau octupoles and electron lenses alone and in the presence of long-range as well as head-on beam-beam effects. Pros and cons of the various methods are compared and an optimum operational scenario to guarantee the maximum stability is proposed.

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THPAK007

Beam Extraction from TR24 Cyclotron at IPHC

extraction, cyclotron, closed-orbit, emittance

3218

N.Yu. Kazarinov, I.A. Ivanenko
JINR, Dubna, Moscow Region, Russia
F.R. Osswald
IPHC, Strasbourg Cedex 2, France

The CYRCé cyclotron is used at IPHC (Institut Pluridisciplinaire Hubert Curien) for the production of radio-isotopes for diagnostics, medical treatments and fundamental research in radiobiology. The TR24 cyclotron manufactured and commercialized by ACSI delivers a 16-25 MeV proton beam with intensity from few nA up to 500 microA. The TR24 is a separated-sector isochronous cyclotron with normal-conducting magnet and stripper foil. It is a challenge to fit the high intensity proton beam used for target irradiation to radiobiology and analytical applications due to requirements on beam quality and energy resolution. Field distribution in the region of the extraction performed with OPERA 3D as well as beam dynamics related with stripping are analysed. 3D calculation model and hypothesis about geometry and beam are described. Our goal is to evaluate the extraction efficiency and the beam characteristics in the focusing plane outside the cyclotron which will serve as inputs for the design of future beam lines and enable beam matching conditions. Therefore, different issues are discussed: energy dispersion, transverse dynamics and orbit separation.

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THPAK034

Practical Betatron Tune Behavior During Acceleration in Scaling FFAG Rings at KURNS

booster, acceleration, proton, extraction

3287

Y. Ishi, Y. Fuwa, Y. Kuriyama, Y. Mori, H. Okita, T. Uesugi
Kyoto University, Research Reactor Institute, Osaka, Japan
J.-B. Lagrange
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

In scaling FFAG* accelerators, ideally, betatron tunes are fixed for each closed orbit concerned with the certain beam energy. Therefore, they should not vary during the acceleration. However, it is not the case since practical implementations of the magnetic field can not provide perfect scaling conditions. There are two types of radial scaling FFAG ring at Kyoto University Research Reactor Institute: one has no return yokes so called 'yoke free type' adopted by MAIN RING which has a large tune variations causing non negligible beam losses; the other has return yokes and filed clamps adopted by BOOSTER RING which has smaller tune variations compared with MAIN RING. We report the tune measurements and calculations based on 3-d magnetic field calculations about these two types of ring and discuss the scaling conditions in FFAG accelerators.
FFAG* : FFAG stands for fixed filed alternating gradient. It describes one the focusing scheme in the circular accelerator.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK034

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THPAK036

Accurate Modeling of Fringe Field Effects on Nonlinear Integrable Optics in IOTA

optics, quadrupole, octupole, lattice

3294

C.E. Mitchell, R.D. Ryne
LBNL, Berkeley, California, USA
F.H. O'Shea
RadiaBeam, Santa Monica, California, USA

Funding: This work is supported by the U.S. Department of Energy, Office of High Energy Physics.
The Integrable Optics Test Accelerator (IOTA) is a novel storage ring under commissioning at Fermi National Accelerator Laboratory designed to investigate the dynamics of beams with large transverse tune spread in the presence of strongly nonlinear integrable optics. Uncontrolled nonlinear effects resulting from magnetic fringe fields can affect the integrability of particle motion, and long-term numerical tracking requires an accurate representation of these effects. Surface fitting algorithms provide a robust and reliable method for extracting this information from 3-dimensional magnetic field data provided on a grid. These algorithms are applied to investigate the unique nonlinear magnetic insert of the IOTA ring, and consequences of the fringe fields to the long-term dynamics of the beam are discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK036

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THPAK118

Beam Dynamics Studies for a Strong-Focusing Cyclotron

cavity, dipole, focusing, cyclotron

3522

J. Gerity, S. Assadi, P.M. McIntyre, A. Sattarov
Texas A&M University, College Station, USA

Results are presented from end-to-end simulation of a 100 MeV strong focusing cyclotron (SFC). The develop-ment of the high-current SFC is motivated by applica-tions for production of medical isotopes and for a proton driver for subcritical fission. It uses a novel superconducting cavity to provide suffi-cient energy gain to fully separate all turns. An arc-contour F-D doublet, trim dipole winding, and sextupole are located along each turn within the aperture of each sector dipole to control the betatron and synchrotron motion and to stabilize non-linear dynamics with high-current operation. The phase space evolution of a proton bunch in the SFC was simulated using both the code OPAL and an ad hoc Runge-Kutta tracker. Iterative optimization of the dipole, quadrupole, and sextupole fields was used to provide precise isochronicity, favorable betatron phase advance, and cancellation of dispersion in each cell.

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THPAK126

Revised Optics Design for the JLEIC Ion Booster

booster, lattice, sextupole, injection

3537

E.W. Nissen, T. Satogata
JLab, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE-AC05-06OR23177.
We outline the recently redesigned booster for the pro-posed Jefferson Lab Electron Ion Collider (JLEIC). This booster will inject protons (or ions of equivalent rigidity) at 280 MeV and accelerate them to 8 GeV kinetic energy. To avoid transition crossing, the booster uses flexible momentum compaction (FMC) lattices to raise the transi-tion gamma above the reach of the machine. We also include several families of sextupoles to simultaneously control the chromaticities, and nonlinear dispersions that were excited by the FMC cells.

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THPMF035

Numerical Analysis of Excitation Property of Pulse Picking by Resonant Excitation at BESSY II

synchrotron, kicker, emittance, radiation

4131

J.G. Hwang, M. Koopmans, R. Müller, M. Ries, A. Schälicke
HZB, Berlin, Germany

The pulse picking by resonant excitation (PPRE) method is applied at BESSY II to provide pseudo single bunch operation by separating the radiation from one horizontally enlarged bunch from the light of the multi-bunch filling. The bunch is enlarged by an excitation with an external signal close to the tune resonance. The variation of the beam size depends strongly on the frequency and amplitude of the excitation signal. In this paper we show the properties of the PPRE bunch studied by analytical modeling and numerical calculations using Elegant. The simulation results are compared with beam size measurements using a new interferometry beam size monitor at BESSY II.

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THPML072

Injection Comparison using Bunch-by-Bunch Beam Size Measurement System at SSRF

injection, damping, SRF, storage-ring

4811

H.J. Chen, J. Chen, B. Gao, Y.B. Leng
SINAP, Shanghai, People's Republic of China

Injection transient process happens every 5-10 minutes in storage ring during normal top-up operating mode at SSRF, which is a proper window for machine status and injection performance evaluation. In the recent year, a bunch-by-bunch beam size measurement system has been implemented at SSRF, which has the capability to offer transverse bunch-by-bunch position and size information and is a powerful tool for injection study. In this paper, we summarize three injection study results from July 2017 to April 2018, including betatron oscillation amplitude, spectrum, horizontal tune and damping time comparison. The oscillation amplitude and temporal behavior of recent injection are all better than results before contributed to the injection optimization work during maintenance in 2018 winter. In addition, the principal component analysis method is also applied to further study the injection behavior in turn-by-turn or bunch-by-bunch direction to the refilled bucket.

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THPML084

Validating the COBEA Algorithm at the DELTA Storage Ring

storage-ring, optics, closed-orbit, lattice

4851

B. Riemann, B.D. Isbarn, S. Khan, S. Koetter, T. Weis
DELTA, Dortmund, Germany

Closed-Orbit Bilinear-Exponential Analysis (COBEA) is an algorithm to decompose monitor-corrector response matrices into (scaled) beta optics values, phase advances, scaled dispersion and betatron tunes. No explicit magnetic lattice model is required for COBEA - only the sequence of monitors and correctors along the beam path (no lengths, no strengths approach). To obtain absolute beta values, the length of one drift space can be provided as optional input. In this work, the application of COBEA to the DELTA storage ring, operated by TU Dortmund University, is discussed, and its results for betatron tunes and scaled dispersion are compared with those of conventional, direct measurement methods. COBEA is also put in a historical perspective to other diagnostic algorithms. Improvements in the Python implementation of COBEA, which is available as free software, are presented. Due to COBEA being relatively modest regarding its requirements on input data respectively hardware, it should be applicable to the majority of existing storage rings.

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THPML111

Test of the Tune Measurement System Based on BBQ at HLS-II Storage Ring

storage-ring, ion-source, experiment, controls

4926

L.T. Huang, F.L. Gao, P. Lu, B.G. Sun, H.Q. Wang, J.G. Wang, Q. Wang, F.F. Wu, Y.L. Yang, T.Y. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by the National Science Foundation of China (Grant No. 11705203, 11575181)
The HLS-II storage ring is a crucial part of Hefei Light Source. Tune is one of the most important parameters of the electron storage ring, of which the tune measurement system is an integral component. In this paper, the design of a new tune measurement system based on BBQ (base band tune), is presented. Some experiments are performed to test this system. The new system is compared with the original system and the TBT (turn-by-turn) method respectively. The obtained results illustrate higher accuracy and higher stability for the new system. A new approach of calculating the betatron oscillation amplitude is proposed, and the betatron oscillation amplitudes in the normal running stage for the HLS-II storage ring are estimated at 95 nm (horizontal) and 60 nm (vertical).

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