IPAC2017 - List of Keywords (betatron)

Paper	Title	Other Keywords	Page
MOPAB003	Energy Deposition in the Betatron Collimation Insertion of the 100 TeV Future Circular Collider	dipole, insertion, proton, simulation	68
	M.I. Besana, C. Bahamonde Castro, A. Bertarelli, R. Bruce, F. Carra, F. Cerutti, A. Ferrari, M. Fiascaris, A. Lechner, A. Mereghetti, S. Redaelli, E. Skordis, V. Vlachoudis CERN, Geneva, Switzerland
	The FCC proton beam is designed to carry a total energy of about 8500 MJ, a factor of 20 above the LHC. In this context, the collimation system has to deal with extremely tight requirements to prevent quenches and material damage. A first layout of the betatron cleaning insertion was conceived, adapting the present LHC collimation system to the FCC lattice. A crucial ingredient to assess its performance, in particular to estimate the robustness of the protection devices and the load on the downstream elements, is represented by the simulation of the particle shower generated at the collimators, allowing detailed energy deposition estimations. This paper presents the first results of the simulation chain starting from the proton losses generated with the Sixtrack-FLUKA coupling, as currently done for the present LHC and for its upgrade. Expectations in terms of total power, peak power density and integrated dose on the different accelerator components are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB003
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MOPAB009	Decomposition of Beam Losses at LHC	beam-losses, proton, distributed, collimation	88
	B. Salvachua, D. Mirarchi, M. Pojer, S. Redaelli, R. Rossi, G. Valentino, M. Wyszynski CERN, Geneva, Switzerland
	The LHC collimation system provides betatron cleaning and off-momentum cleaning in two different locations of the LHC ring. In the betatron cleaning area, three primary collimators cut the primary halo in horizontal, vertical and skew planes. The beam loss monitors located downstream each of these collimators can be used to diagnose the main plane of loss. We present here a method to identify these beam losses at the LHC and decompose them as a linear combination of loss scenarios using singular value decomposition to calculate Moore-Penrose pseudoinverse of the scenario matrix. This matrix has been used to evaluate the type of beam losses in different stages of the LHC cycle.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB009
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MOPAB014	Generating Low Beta Regions With Quadrupoles for Final Muon Cooling	emittance, quadrupole, simulation, collider	107
	J.G. Acosta, L.M. Cremaldi, T.L. Hart, S.J. Oliveros, D.J. Summers UMiss, University, Mississippi, USA D.V. Neuffer Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359 Muon beams and colliders are rich sources of new physics, if muons can be cooled. A normalized rms transverse muon emittance of 280 microns has been achieved in simulation with short solenoids and a betatron function of 3 cm. Here we use ICOOL, G4beamline, and MAD-X to explore using a 400 MeV/c muon beam and strong focusing quadrupoles to approach a normalized transverse emittance of 100 microns and finish 6D muon cooling. The low beta regions produced by the quadrupoles are occupied by dense, low Z absorbers, such as lithium hydride or beryllium, that cool the beam. Equilibrium transverse emittance is linearly proportional to the beta function. Reverse emittance exchange with septa and/or wedges is then used to decrease transverse emittance from 100 to 25 microns at the expense of longitudinal emittance for a high energy lepton collider. Work remains to be done on chromaticity correction.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB014
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MOPAB122	Fast Bunch by Bunch Tune Measurements at the CERN PS	injection, proton, synchrotron, operation	415
	P. Zisopoulos, M. Gąsior, M. Serluca, G. Sterbini CERN, Geneva, Switzerland
	The CERN Proton Synchrotron (PS) is a crucial component of the Large Hadron Collider (LHC) injector complex. The PS role is to provide beams of high brightness and with the required time structure. In this paper, we present the results of bunch-by-bunch tune measurements by using turn-by-turn transverse beam position monitors (BPMs). The data from different BPMs are combined together to allow fast and accurate tune measurements for each bunch. The obtained results are compared with the present PS tune-meter system and the specific advantages and limits of this technique are commented and exemplified.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB122
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MOPAB151	Techniques for Transparent Lattice Measurement and Correction	lattice, feedback, operation, storage-ring	483
	W.X. Cheng, K. Ha, Y. Li BNL, Upton, Long Island, New York, USA
	Funding: Work supported by DOE contract No: DE-SC0012704 NSLS-II storage ring started top off operation since Oct 2015. It has been noticed during the user operation that machine lattice was affected by insertion devices (ID). The storage ring coupling, emittance and lifetime vary when ID gap changes. Lattice characterization was typically carried out with dedicated machine study time with low storage current. Due to collective effect, the lattice at high operation current is different. To characterize the machine lattice during normal user operation with little disturbance, a small portion of beam (~1%) filled in the ion gap can be excited by the bunch by bunch feedback system near betatron frequency. Recent development on BPM electronics enables the gate function to detect partial beam motion in the ring. With the gated BPM turn by turn data from excited bunches, storage ring lattice can be measured and corrected with the well-developed tools. We present in the paper preliminary test results with these tools to characterize the lattice and how it improves the machine performance during user operation.
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MOPIK066	COBEA - Optical Parameters From Response Matrices without Knowledge of Magnet Strengths	storage-ring, optics, lattice, closed-orbit	676
	B. Riemann, S. Khan, S. Koetter, T. Weis DELTA, Dortmund, Germany
	This paper presents some results of Closed-Orbit Bilinear-Exponential Analysis (COBEA), an algorithm designed to decompose (coupled) response matrices into betatron tunes and other optical parameters at beam position monitor and corrector positions. The only additional information strictly required by the algorithm is the ordering of monitors and correctors along the storage ring beam path. The presented method is largely lattice-independent, as no magnet strengths or dimensions are needed, and converges in a reasonable time interval due to usage of gradient-based optimization. After describing key features of the algorithm, a set of COBEA results is compared to LOCO results for the storage rings of MLS and BESSY II. The paper is concluded by a brief discussion of further applications, limits and further development of the COBEA algorithm.
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MOPIK069	Approximate Matrices for Modeling the Focusing of the Undulator Periods and Undulator End Fields	undulator, focusing, dipole, laser	686
	V. Balandin, N. Golubeva DESY, Hamburg, Germany
	We describe procedure for constructing approximate matrices for modeling the focusing of the undulator periods and undulator end fields and discuss applicability of these matrices to the European XFEL undulators.
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MOPIK070	Notes on Relations between Slice and Projected Beam Parameters	emittance, FEL	689
	V. Balandin, N. Golubeva DESY, Hamburg, Germany
	We consider some aspects of the relations between slice and projected beam parameters.
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MOPIK124	A New Method to Tune the Nonlinear Lattice Online	lattice, sextupole, focusing, injection	828
	W. Guo, Y. Hidaka, X. Yang BNL, Upton, Long Island, New York, USA
	Most nonlinear lattice tuning methods use only part of the optimization constraints, for example, part of the driving terms, nonlinear detuning, lifetime or injection efficiency. Even though some of the nonlinear properties can be improved, it is not guaranteed the nonlinear lattice is fully optimized. In this paper we propose to optimize the nonlinear lattice by correcting the betatron phase advance and detuning of the off-orbit lattices. It is shown that all the leading order optimization constraints are restored in this approach. One advantage of this new method is that the measurement is independent of BPM calibration errors. We succeed in both simulation and experiment in identifying the intentionally added sextupole errors.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK124
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TUPIK095	Possibilities for Transverse Feedback Phase Adjustment by Means of Digital Filters	pick-up, feedback, kicker, damping	1924
	G. Kotzian CERN, Geneva, Switzerland
	In transverse feedback systems a phase adjustment is generally required to convert a beam position signal from a pick-up into a momentum correction signal used by a transverse kicker. In this paper we outline several possibilities for phase adjustments using only single pick-ups or the vector combination of two pick-ups. Analytical expressions are given as a function of the fractional tune and the betatron phase advance between the pick-up location and the kicker. The shortest possible digital filter is formulated, including a notch for closed orbit suppression and a free parameter to adjust for betatron phase. We introduce a novel, fully parametrized digital filter with the feature to be insensitive to variations in fractional tune. Examples are given for the SPS transverse feedback system and compared with measurements.
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TUPVA031	Impact of Incoherent Effects on the Landau Stability Diagram at the LHC	octupole, damping, coupling, simulation	2125
	C. Tambasco, J. Barranco García, X. Buffat, T. Pieloni CERN, Geneva, Switzerland J. Barranco García, X. Buffat, T. Pieloni EPFL, Lausanne, Switzerland
	Instability thresholds are explored at the Large Hadron Collider (LHC) by means of the computation of the Landau Stability Diagrams (SD). In the presence of diffusive mechanisms, caused by resonance excitations or noise, the SD can be reduced due to the modification of the particle distribution inside the beam. This effect can lead to a possible lack of Landau damping of the coherent modes previously damped by lying within the unperturbed SD area. The limitations deriving from coherent instabilities in the LHC is crucial in view of future projects that aim to increase the performance of the LHC such as the High-Luminosity upgrade (HL-LHC). Simulation tools for the computation of the SD have been extended in order to take into account the incoherent effects from long tracking through the detailed model of the accelerator machine. The model includes among others beam-beam interactions and octupoles and the interplay between both is addressed. Finally the simulation results are compared to the Beam Transfer Function (BTF) measurements in the LHC.
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TUPVA088	Observing Suppression of Syncrotron Oscillation Amplitudes	synchrotron, acceleration, dipole, cavity	2284
	K. Jimbo Kyoto University, Kyoto, Japan
	We proposed a method to reduce loosing particles in acceleration stage of synchrotrons. A slowly varying horizontal electrostatic field may be useful to de-excite synchrotron oscillations. Then we have to somehow observe the damping of amplitudes of synchrotron oscillations to confirm the effect. We assume that the synchrotron component of rationalized Hamiltonian in acceleration stage is kept constant. Our experimental results did not contradict with this assumption. Taking advantage of this assumption, we can easily confirm the damping of synchrotron oscillation amplitudes experimentally through the increase of synchrotron frequencies. jimbo@iae.kyoto-u.ac.jp
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TUPVA112	Acceleration of Polarized Proton and Deuteron Beams in Nuclotron at JINR	resonance, proton, acceleration, polarization	2349
	Y. Filatov, A.V. Butenko, A.D. Kovalenko, V.A. Mikhaylov JINR, Dubna, Moscow Region, Russia Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	The superconducting synchrotron Nuclotron allows one to accelerate proton and deuteron beams up to 13.5 GeV/c. The beam depolarization occurs at the crossing of spin resonances. For deuterons, the vertical polarization is preserved almost to the maximum momentum. Tens of spin resonances are crossing during the proton acceleration. The proton polarization will be preserved by a solenoidal 5% snake up to 3.4 GeV/c at the field ramp rate of 1 T/s. It is planned to use a partial 50% snake to eliminate the resonant depolarization of the proton beam in the total momentum range of the accelerator. The results of simulations and experimental data are presented.
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WEPAB011	High Order Magnetic Field Components and Non-Linear Optics at the ANKA Storage Ring	wiggler, octupole, resonance, sextupole	2586
	A.I. Papash, E. Blomley, J. Gethmann, E. Huttel, A.-S. Müller, M. Schuh KIT, Eggenstein-Leopoldshafen, Germany
	The Karlsruhe Institute of technology operates the 2.5 GeV electron storage ring ANKA as an accelerator test facility and synchrotron radiation source. A superconducting wiggler is installed in a short straight section of the ring where vertical beta-function is large (13 m). The life time of the electron beam was reduced from 15 to 12 hours at a high field level of the wiggler (2.5 T) even though the coherent shift of vertical tune was compensated locally. Computer simulations show the non-linear nature of the effect. The ANKA storage ring operates with strong sextupoles at a positive chromaticity of +2/+6. Even residual octupole components of the wiggler field, set at the tolerance limit of fabrication conditions, could reduce the dynamic aperture for off-momentum particles providing the betatron tune is located in the vicinity of a weak octupole resonance and the chromaticity is high. Also the vertical betatron tune is close to the sextupole resonance Qy=8/3. Large resonance stop-band and proximity of sextupole resonance affect the life time as well. Betatron tunes of ANKA have been shifted away of suspected high-order resonances and beam life time was essentially improved.
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WEPAB131	Layout of the MICE Demonstration of Muon Ionization Cooling	emittance, detector, lattice, solenoid	2881
	C. Hunt, J.-B. Lagrange, J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	Funding: STFC, DOE, NSF, INFN, CHIPP and more Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams necessary to elucidate the physics of flavour at the Neutrino Factory and to provide lepton-antilepton collisions up to several TeV at the Muon Collider. The international Muon Ionization Cooling Experiment (MICE) will demonstrate muon ionization cooling, the technique proposed to reduce the phase-space volume occupied by the muon beam at such facilities. In an ionization-cooling channel, the muon beam traverses a material (the absorber) loosing energy, which is replaced using RF cavities. The combined effect is to reduce the transverse emittance of the beam (transverse cooling). The configuration of MICE required to deliver the demonstration of ionization cooling is presently being prepared in parallel to the execution of a programme designed to measure the cooling properties of liquid-hydrogen and lithium hydride (Step IV). The design of this final cooling demonstration will be presented together with a summary of the performance of each of its components and the cooling performance of the experiment. submitted by the Speakers Bureau of the collaboration, in charge of finding later a member to prepare and present the contribution
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WEPIK052	Energy Acceptance and on Momentum Aperture Optimization for the Sirius Project	lattice, storage-ring, resonance, dynamic-aperture	3041
	P.S. Dester, L. Liu, F.H. de Sá LNLS, Campinas, Brazil
	A fast objective function to calculate Touschek lifetime and on momentum aperture is essential to explore the vast search space of strength of quadrupole and sextupole families in Sirius. Touschek lifetime is estimated by using the energy aperture (dynamic and physical), rf system parameters and driving terms. Non-linear induced betatron oscillations are considered to determine the energy aperture. On momentum aperture is estimated by using a chaos indicator and resonance crossing considerations. Touschek lifetime and on momentum aperture constitute the objective function, which was used in a multi-objective genetic algorithm to perform an optimization for Sirius.
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WEPIK070	Nonlinear Lattice Optimization for the SPring-8 Upgrade	sextupole, lattice, injection, octupole	3091
	K. Soutome, H. Tanaka RIKEN SPring-8 Center, Hyogo, Japan Y. Shimosaki, M. Takao JASRI/SPring-8, Hyogo-ken, Japan
	The SPring-8 upgrade project has adopted the hybrid MBA lattice to achieve the emittance of about 100 pmrad at 6 GeV with damping effects by insertion devices. This optics has two dispersion bumps in one unit cell where chromaticity-correcting sextupoles locate. The horizontal and vertical betatron phases between these bumps are tuned to be 3PI and PI, respectively, to cancel the low order contributions of nonlinear kicks due to sextupoles. However, it is not easy to obtain a sufficiently large dynamic aperture (DA) since (i) the cancellation is incomplete due to a nested arrangement, (ii) sextupoles are very strong, and (iii) the number of tuning knobs is limited. The DA is quite small due to the leakage of nonlinear kicks by nested sextupoles. We hence proposed to install additional weak sextupoles between the dispersion bumps to suppress the leakage kick further. Simulations show that this simple scheme is very effective for suppressing ADTS and for enlarging DA. We present details of this scheme and some numerical examples together with a newly developed fourth-order formula of ADTS for describing and controlling the lattice nonlinearity.
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WEPIK071	Resistive-Wall Impedance Effects for the New KEK Light Source	impedance, vacuum, feedback, storage-ring	3095
	N. Nakamura KEK, Ibaraki, Japan
	KEK Light Source (KEK-LS) is a 3-GeV storage ring of 20-cell HMBA (Hybrid Multi-Bend Achromat) lattice, which is planned to be constructed as a successor of the two existing Photon Factory storage rings (PF ring and PF-AR) in the KEK Tsukuba Campus. In this ring, a lot of in-vacuum undulators with a small magnetic gap (4 mm at minimum) will be installed and the vacuum pipe of a small aperture (25 mm in diameter) will be used. In addition, NEG coating, having a low electric conductivity, will be utilized for the vacuum pipe to ensure a sufficient beam lifetime early in the machine commissioning. In this paper, the heating power due to the longitudinal RW impedance and the growth rate of coupled-bunch instability caused by the transverse RW impedance are calculated and the effects of the RW impedance on KEK-LS are presented. K. Harada et al., Proc. of IPAC2016, Busan, Korea, pp.3251-3253; K. Harada et al., these proceedings.
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WEPIK074	Twiss Parameter Measurement and Application to Space Charge Dynamics	resonance, space-charge, emittance, lattice	3101
	K. Ohmi, S. Igarashi, T. Toyama KEK, Ibaraki, Japan H. Harada, S. Hatakeyama JAEA/J-PARC, Tokai-mura, Japan N. Kuroo UTTAC, Tsukuba, Ibaraki, Japan Y. Sato J-PARC, KEK & JAEA, Ibaraki-ken, Japan R. Tomás, A. Wegscheider CERN, Geneva, Switzerland
	We are looking for feasible and quantitative method to evaluate space charge induced beam loss in J-PARC MR. One possible way is space charge simulation and theory based on measured Twiss parameter. Twiss parameter measurement using turn-by-turn monitors is presented. Resonance strengths of lattice magnets and space charge force are estimated by the measured Twiss parameters. Emittance growth and beam loss under the resonance strengths are discussed.
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THPAB022	Ion Instability in SuperKEKB Phase I Commissioning	ion, simulation, feedback, vacuum	3741
	K. Ohmi, H. Fukuma, Y. Suetsugu, M. Tobiyama KEK, Ibaraki, Japan
	Ion instability has been observed in SuperKEKB phase I commissioning. Unstable modes, their growth rates, tune shift were measured. Frequency of the unstable modes is slower than theoretical prediction and the growth rate is also slower. We discuss possible model to explain the measurements.
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THPVA012	Transverse Impedance Measurement in SuperKEKB	damping, impedance, operation, storage-ring	4442
	N. Kuroo UTTAC, Tsukuba, Ibaraki, Japan T. Ishibashi, T. Mimashi, K. Ohmi, Y. Ohnishi, K. Shibata, Y. Suetsugu, S. Terui, M. Tobiyama, D. Zhou KEK, Ibaraki, Japan
	In KEK(Japan), SuperKEKB project is progressing toward upgrade. This project aims improvement luminosity (8×10³⁵ cm^-2s- 1) which is 40 times of the performance of the KEKB accelerator. In Phase 1 of this project, a performance test as storage ring was carried out. Understanding of ring Impedance/wake is an important subject in phase I. Measurement of Head Tail Damping using Turn by Turn monitor was performed to evaluate impedance/wake. Betatron motion is excited by kicker and its damping is measured for several parameters sets of bunch current and chromaticity in both HER and LER. The wake field was calculated from the decrement of betatron amplitude. We present the wake field which is cross-checked with tune shift based on the current dependence.
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THPVA074	Upgrade Study of the MedAustron Ion Beam Center	extraction, ion, quadrupole, synchrotron	4619
	A. De Franco, T.T. Böhlen, F. Farinon, G. Kowarik, M. Kronberger, C. Kurfürst, S. Nowak, F. Osmić, M.T.F. Pivi, C. Schmitzer, P. Urschütz, A. Wastl EBG MedAustron, Wr. Neustadt, Austria
	Funding: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk'odowska-Curie grant agreement No 675265. MedAustron is a synchrotron-based ion beam therapy center allowing the treatment of tumours with protons and other light ion species, in particular C⁶⁺. Commissioning of the first irradiation room for clinical therapy with proton beams has been completed and in parallel to the commissioning of the remaining two irradiation rooms, a facility upgrade study has started. Our analysis includes considerations for the possibility to introduce different extraction mechanisms, new diagnostic tools, optimization of the accelerator cycle time, ripples mitigation for more accurate active beam stabilization and other improvements for hardware reliability. We present the concept, the main benefits, also in terms of treatment time reduction, and the challenges for implementation. Each option will be investigated including a detailed assessment on resources demand, impact and risk analysis.
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THPVA075	Beam Measurements in the MedAustron Synchrotron With Slow Extraction and Off-Momentum Operation	emittance, synchrotron, extraction, pick-up	4623
	C. Kurfürst, A. De Franco, F. Farinon, M. Kronberger, S. Myalski, S. Nowak, F. Osmić, M.T.F. Pivi, C. Schmitzer, P. Urschütz, A. Wastl EBG MedAustron, Wr. Neustadt, Austria A. Garonna TERA, Novara, Italy T.K.D. Kulenkampff CERN, Geneva, Switzerland L.C. Penescu Abstract Landscapes, Montpellier, France
	The MedAustron Ion Therapy Center is a medical accelerator facility for hadron therapy cancer treatment using protons and carbon ions. The facility features 4 irradiation rooms, three of which are dedicated to clinical operation and a fourth one dedicated to non-clinical research. The latter was handed over to researchers in autumn 2016. A 7 MeV/n injector feeds a 77 m circumference synchrotron which provides beams for treatment and research. Routine verification measurements in the synchrotron involve beam emittance, dispersion as well as tunes and chromaticity. The horizontal and vertical emittance are measured using scraping plates and a direct current transformer. The dispersion function in the ring is determined by sweeping the synchrotron RF frequency while measuring the beam position in the shoe-box pick-ups. The horizontal and vertical betatron tune and chromaticity are measured with Direct Diode Detection electronics, developed at CERN, while changing the beam position with the RF radial loop. The beam is kept off-momentum, thus in dispersive regions the closed orbit is largely offset from the central orbit. Methods for beam measurements in the synchrotron are presented.
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Paper

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MOPAB003

Energy Deposition in the Betatron Collimation Insertion of the 100 TeV Future Circular Collider

dipole, insertion, proton, simulation

68

M.I. Besana, C. Bahamonde Castro, A. Bertarelli, R. Bruce, F. Carra, F. Cerutti, A. Ferrari, M. Fiascaris, A. Lechner, A. Mereghetti, S. Redaelli, E. Skordis, V. Vlachoudis
CERN, Geneva, Switzerland

The FCC proton beam is designed to carry a total energy of about 8500 MJ, a factor of 20 above the LHC. In this context, the collimation system has to deal with extremely tight requirements to prevent quenches and material damage. A first layout of the betatron cleaning insertion was conceived, adapting the present LHC collimation system to the FCC lattice. A crucial ingredient to assess its performance, in particular to estimate the robustness of the protection devices and the load on the downstream elements, is represented by the simulation of the particle shower generated at the collimators, allowing detailed energy deposition estimations. This paper presents the first results of the simulation chain starting from the proton losses generated with the Sixtrack-FLUKA coupling, as currently done for the present LHC and for its upgrade. Expectations in terms of total power, peak power density and integrated dose on the different accelerator components are presented.

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MOPAB009

Decomposition of Beam Losses at LHC

beam-losses, proton, distributed, collimation

88

B. Salvachua, D. Mirarchi, M. Pojer, S. Redaelli, R. Rossi, G. Valentino, M. Wyszynski
CERN, Geneva, Switzerland

The LHC collimation system provides betatron cleaning and off-momentum cleaning in two different locations of the LHC ring. In the betatron cleaning area, three primary collimators cut the primary halo in horizontal, vertical and skew planes. The beam loss monitors located downstream each of these collimators can be used to diagnose the main plane of loss. We present here a method to identify these beam losses at the LHC and decompose them as a linear combination of loss scenarios using singular value decomposition to calculate Moore-Penrose pseudoinverse of the scenario matrix. This matrix has been used to evaluate the type of beam losses in different stages of the LHC cycle.

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MOPAB014

Generating Low Beta Regions With Quadrupoles for Final Muon Cooling

emittance, quadrupole, simulation, collider

107

J.G. Acosta, L.M. Cremaldi, T.L. Hart, S.J. Oliveros, D.J. Summers
UMiss, University, Mississippi, USA
D.V. Neuffer
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359
Muon beams and colliders are rich sources of new physics, if muons can be cooled. A normalized rms transverse muon emittance of 280 microns has been achieved in simulation with short solenoids and a betatron function of 3 cm. Here we use ICOOL, G4beamline, and MAD-X to explore using a 400 MeV/c muon beam and strong focusing quadrupoles to approach a normalized transverse emittance of 100 microns and finish 6D muon cooling. The low beta regions produced by the quadrupoles are occupied by dense, low Z absorbers, such as lithium hydride or beryllium, that cool the beam. Equilibrium transverse emittance is linearly proportional to the beta function. Reverse emittance exchange with septa and/or wedges is then used to decrease transverse emittance from 100 to 25 microns at the expense of longitudinal emittance for a high energy lepton collider. Work remains to be done on chromaticity correction.

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MOPAB122

Fast Bunch by Bunch Tune Measurements at the CERN PS

injection, proton, synchrotron, operation

415

P. Zisopoulos, M. Gąsior, M. Serluca, G. Sterbini
CERN, Geneva, Switzerland

The CERN Proton Synchrotron (PS) is a crucial component of the Large Hadron Collider (LHC) injector complex. The PS role is to provide beams of high brightness and with the required time structure. In this paper, we present the results of bunch-by-bunch tune measurements by using turn-by-turn transverse beam position monitors (BPMs). The data from different BPMs are combined together to allow fast and accurate tune measurements for each bunch. The obtained results are compared with the present PS tune-meter system and the specific advantages and limits of this technique are commented and exemplified.

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MOPAB151

Techniques for Transparent Lattice Measurement and Correction

lattice, feedback, operation, storage-ring

483

W.X. Cheng, K. Ha, Y. Li
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract No: DE-SC0012704
NSLS-II storage ring started top off operation since Oct 2015. It has been noticed during the user operation that machine lattice was affected by insertion devices (ID). The storage ring coupling, emittance and lifetime vary when ID gap changes. Lattice characterization was typically carried out with dedicated machine study time with low storage current. Due to collective effect, the lattice at high operation current is different. To characterize the machine lattice during normal user operation with little disturbance, a small portion of beam (~1%) filled in the ion gap can be excited by the bunch by bunch feedback system near betatron frequency. Recent development on BPM electronics enables the gate function to detect partial beam motion in the ring. With the gated BPM turn by turn data from excited bunches, storage ring lattice can be measured and corrected with the well-developed tools. We present in the paper preliminary test results with these tools to characterize the lattice and how it improves the machine performance during user operation.

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MOPIK066

COBEA - Optical Parameters From Response Matrices without Knowledge of Magnet Strengths

storage-ring, optics, lattice, closed-orbit

676

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

This paper presents some results of Closed-Orbit Bilinear-Exponential Analysis (COBEA), an algorithm designed to decompose (coupled) response matrices into betatron tunes and other optical parameters at beam position monitor and corrector positions. The only additional information strictly required by the algorithm is the ordering of monitors and correctors along the storage ring beam path. The presented method is largely lattice-independent, as no magnet strengths or dimensions are needed, and converges in a reasonable time interval due to usage of gradient-based optimization. After describing key features of the algorithm, a set of COBEA results is compared to LOCO results for the storage rings of MLS and BESSY II. The paper is concluded by a brief discussion of further applications, limits and further development of the COBEA algorithm.

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MOPIK069

Approximate Matrices for Modeling the Focusing of the Undulator Periods and Undulator End Fields

undulator, focusing, dipole, laser

686

V. Balandin, N. Golubeva
DESY, Hamburg, Germany

We describe procedure for constructing approximate matrices for modeling the focusing of the undulator periods and undulator end fields and discuss applicability of these matrices to the European XFEL undulators.

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MOPIK070

Notes on Relations between Slice and Projected Beam Parameters

emittance, FEL

689

V. Balandin, N. Golubeva
DESY, Hamburg, Germany

We consider some aspects of the relations between slice and projected beam parameters.

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MOPIK124

A New Method to Tune the Nonlinear Lattice Online

lattice, sextupole, focusing, injection

828

W. Guo, Y. Hidaka, X. Yang
BNL, Upton, Long Island, New York, USA

Most nonlinear lattice tuning methods use only part of the optimization constraints, for example, part of the driving terms, nonlinear detuning, lifetime or injection efficiency. Even though some of the nonlinear properties can be improved, it is not guaranteed the nonlinear lattice is fully optimized. In this paper we propose to optimize the nonlinear lattice by correcting the betatron phase advance and detuning of the off-orbit lattices. It is shown that all the leading order optimization constraints are restored in this approach. One advantage of this new method is that the measurement is independent of BPM calibration errors. We succeed in both simulation and experiment in identifying the intentionally added sextupole errors.

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TUPIK095

Possibilities for Transverse Feedback Phase Adjustment by Means of Digital Filters

pick-up, feedback, kicker, damping

1924

G. Kotzian
CERN, Geneva, Switzerland

In transverse feedback systems a phase adjustment is generally required to convert a beam position signal from a pick-up into a momentum correction signal used by a transverse kicker. In this paper we outline several possibilities for phase adjustments using only single pick-ups or the vector combination of two pick-ups. Analytical expressions are given as a function of the fractional tune and the betatron phase advance between the pick-up location and the kicker. The shortest possible digital filter is formulated, including a notch for closed orbit suppression and a free parameter to adjust for betatron phase. We introduce a novel, fully parametrized digital filter with the feature to be insensitive to variations in fractional tune. Examples are given for the SPS transverse feedback system and compared with measurements.

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TUPVA031

Impact of Incoherent Effects on the Landau Stability Diagram at the LHC

octupole, damping, coupling, simulation

2125

C. Tambasco, J. Barranco García, X. Buffat, T. Pieloni
CERN, Geneva, Switzerland
J. Barranco García, X. Buffat, T. Pieloni
EPFL, Lausanne, Switzerland

Instability thresholds are explored at the Large Hadron Collider (LHC) by means of the computation of the Landau Stability Diagrams (SD). In the presence of diffusive mechanisms, caused by resonance excitations or noise, the SD can be reduced due to the modification of the particle distribution inside the beam. This effect can lead to a possible lack of Landau damping of the coherent modes previously damped by lying within the unperturbed SD area. The limitations deriving from coherent instabilities in the LHC is crucial in view of future projects that aim to increase the performance of the LHC such as the High-Luminosity upgrade (HL-LHC). Simulation tools for the computation of the SD have been extended in order to take into account the incoherent effects from long tracking through the detailed model of the accelerator machine. The model includes among others beam-beam interactions and octupoles and the interplay between both is addressed. Finally the simulation results are compared to the Beam Transfer Function (BTF) measurements in the LHC.

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TUPVA088

Observing Suppression of Syncrotron Oscillation Amplitudes

synchrotron, acceleration, dipole, cavity

2284

K. Jimbo
Kyoto University, Kyoto, Japan

We proposed a method to reduce loosing particles in acceleration stage of synchrotrons. A slowly varying horizontal electrostatic field may be useful to de-excite synchrotron oscillations. Then we have to somehow observe the damping of amplitudes of synchrotron oscillations to confirm the effect. We assume that the synchrotron component of rationalized Hamiltonian in acceleration stage is kept constant. Our experimental results did not contradict with this assumption. Taking advantage of this assumption, we can easily confirm the damping of synchrotron oscillation amplitudes experimentally through the increase of synchrotron frequencies.
jimbo@iae.kyoto-u.ac.jp

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TUPVA112

Acceleration of Polarized Proton and Deuteron Beams in Nuclotron at JINR

resonance, proton, acceleration, polarization

2349

Y. Filatov, A.V. Butenko, A.D. Kovalenko, V.A. Mikhaylov
JINR, Dubna, Moscow Region, Russia
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

The superconducting synchrotron Nuclotron allows one to accelerate proton and deuteron beams up to 13.5 GeV/c. The beam depolarization occurs at the crossing of spin resonances. For deuterons, the vertical polarization is preserved almost to the maximum momentum. Tens of spin resonances are crossing during the proton acceleration. The proton polarization will be preserved by a solenoidal 5% snake up to 3.4 GeV/c at the field ramp rate of 1 T/s. It is planned to use a partial 50% snake to eliminate the resonant depolarization of the proton beam in the total momentum range of the accelerator. The results of simulations and experimental data are presented.

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WEPAB011

High Order Magnetic Field Components and Non-Linear Optics at the ANKA Storage Ring

wiggler, octupole, resonance, sextupole

2586

A.I. Papash, E. Blomley, J. Gethmann, E. Huttel, A.-S. Müller, M. Schuh
KIT, Eggenstein-Leopoldshafen, Germany

The Karlsruhe Institute of technology operates the 2.5 GeV electron storage ring ANKA as an accelerator test facility and synchrotron radiation source. A superconducting wiggler is installed in a short straight section of the ring where vertical beta-function is large (13 m). The life time of the electron beam was reduced from 15 to 12 hours at a high field level of the wiggler (2.5 T) even though the coherent shift of vertical tune was compensated locally. Computer simulations show the non-linear nature of the effect. The ANKA storage ring operates with strong sextupoles at a positive chromaticity of +2/+6. Even residual octupole components of the wiggler field, set at the tolerance limit of fabrication conditions, could reduce the dynamic aperture for off-momentum particles providing the betatron tune is located in the vicinity of a weak octupole resonance and the chromaticity is high. Also the vertical betatron tune is close to the sextupole resonance Qy=8/3. Large resonance stop-band and proximity of sextupole resonance affect the life time as well. Betatron tunes of ANKA have been shifted away of suspected high-order resonances and beam life time was essentially improved.

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WEPAB131

Layout of the MICE Demonstration of Muon Ionization Cooling

emittance, detector, lattice, solenoid

2881

C. Hunt, J.-B. Lagrange, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

Funding: STFC, DOE, NSF, INFN, CHIPP and more
Muon beams of low emittance provide the basis for the intense, well-characterised neutrino beams necessary to elucidate the physics of flavour at the Neutrino Factory and to provide lepton-antilepton collisions up to several TeV at the Muon Collider. The international Muon Ionization Cooling Experiment (MICE) will demonstrate muon ionization cooling, the technique proposed to reduce the phase-space volume occupied by the muon beam at such facilities. In an ionization-cooling channel, the muon beam traverses a material (the absorber) loosing energy, which is replaced using RF cavities. The combined effect is to reduce the transverse emittance of the beam (transverse cooling). The configuration of MICE required to deliver the demonstration of ionization cooling is presently being prepared in parallel to the execution of a programme designed to measure the cooling properties of liquid-hydrogen and lithium hydride (Step IV). The design of this final cooling demonstration will be presented together with a summary of the performance of each of its components and the cooling performance of the experiment.
submitted by the Speakers Bureau of the collaboration, in charge of
finding later a member to prepare and present the contribution

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WEPIK052

Energy Acceptance and on Momentum Aperture Optimization for the Sirius Project

lattice, storage-ring, resonance, dynamic-aperture

3041

P.S. Dester, L. Liu, F.H. de Sá
LNLS, Campinas, Brazil

A fast objective function to calculate Touschek lifetime and on momentum aperture is essential to explore the vast search space of strength of quadrupole and sextupole families in Sirius. Touschek lifetime is estimated by using the energy aperture (dynamic and physical), rf system parameters and driving terms. Non-linear induced betatron oscillations are considered to determine the energy aperture. On momentum aperture is estimated by using a chaos indicator and resonance crossing considerations. Touschek lifetime and on momentum aperture constitute the objective function, which was used in a multi-objective genetic algorithm to perform an optimization for Sirius.

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WEPIK070

Nonlinear Lattice Optimization for the SPring-8 Upgrade

sextupole, lattice, injection, octupole

3091

K. Soutome, H. Tanaka
RIKEN SPring-8 Center, Hyogo, Japan
Y. Shimosaki, M. Takao
JASRI/SPring-8, Hyogo-ken, Japan

The SPring-8 upgrade project has adopted the hybrid MBA lattice to achieve the emittance of about 100 pmrad at 6 GeV with damping effects by insertion devices. This optics has two dispersion bumps in one unit cell where chromaticity-correcting sextupoles locate. The horizontal and vertical betatron phases between these bumps are tuned to be 3PI and PI, respectively, to cancel the low order contributions of nonlinear kicks due to sextupoles. However, it is not easy to obtain a sufficiently large dynamic aperture (DA) since (i) the cancellation is incomplete due to a nested arrangement, (ii) sextupoles are very strong, and (iii) the number of tuning knobs is limited. The DA is quite small due to the leakage of nonlinear kicks by nested sextupoles. We hence proposed to install additional weak sextupoles between the dispersion bumps to suppress the leakage kick further. Simulations show that this simple scheme is very effective for suppressing ADTS and for enlarging DA. We present details of this scheme and some numerical examples together with a newly developed fourth-order formula of ADTS for describing and controlling the lattice nonlinearity.

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WEPIK071

Resistive-Wall Impedance Effects for the New KEK Light Source

impedance, vacuum, feedback, storage-ring

3095

N. Nakamura
KEK, Ibaraki, Japan

KEK Light Source (KEK-LS) is a 3-GeV storage ring of 20-cell HMBA (Hybrid Multi-Bend Achromat) lattice*, which is planned to be constructed as a successor of the two existing Photon Factory storage rings (PF ring and PF-AR) in the KEK Tsukuba Campus. In this ring, a lot of in-vacuum undulators with a small magnetic gap (4 mm at minimum) will be installed and the vacuum pipe of a small aperture (25 mm in diameter) will be used. In addition, NEG coating, having a low electric conductivity, will be utilized for the vacuum pipe to ensure a sufficient beam lifetime early in the machine commissioning. In this paper, the heating power due to the longitudinal RW impedance and the growth rate of coupled-bunch instability caused by the transverse RW impedance are calculated and the effects of the RW impedance on KEK-LS are presented.
* K. Harada et al., Proc. of IPAC2016, Busan, Korea, pp.3251-3253; K. Harada et al., these proceedings.

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WEPIK074

Twiss Parameter Measurement and Application to Space Charge Dynamics

resonance, space-charge, emittance, lattice

3101

K. Ohmi, S. Igarashi, T. Toyama
KEK, Ibaraki, Japan
H. Harada, S. Hatakeyama
JAEA/J-PARC, Tokai-mura, Japan
N. Kuroo
UTTAC, Tsukuba, Ibaraki, Japan
Y. Sato
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
R. Tomás, A. Wegscheider
CERN, Geneva, Switzerland

We are looking for feasible and quantitative method to evaluate space charge induced beam loss in J-PARC MR. One possible way is space charge simulation and theory based on measured Twiss parameter. Twiss parameter measurement using turn-by-turn monitors is presented. Resonance strengths of lattice magnets and space charge force are estimated by the measured Twiss parameters. Emittance growth and beam loss under the resonance strengths are discussed.

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THPAB022

Ion Instability in SuperKEKB Phase I Commissioning

ion, simulation, feedback, vacuum

3741

K. Ohmi, H. Fukuma, Y. Suetsugu, M. Tobiyama
KEK, Ibaraki, Japan

Ion instability has been observed in SuperKEKB phase I commissioning. Unstable modes, their growth rates, tune shift were measured. Frequency of the unstable modes is slower than theoretical prediction and the growth rate is also slower. We discuss possible model to explain the measurements.

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THPVA012

Transverse Impedance Measurement in SuperKEKB

damping, impedance, operation, storage-ring

4442

N. Kuroo
UTTAC, Tsukuba, Ibaraki, Japan
T. Ishibashi, T. Mimashi, K. Ohmi, Y. Ohnishi, K. Shibata, Y. Suetsugu, S. Terui, M. Tobiyama, D. Zhou
KEK, Ibaraki, Japan

In KEK(Japan), SuperKEKB project is progressing toward upgrade. This project aims improvement luminosity (8×10³⁵ cm^-2s- 1) which is 40 times of the performance of the KEKB accelerator. In Phase 1 of this project, a performance test as storage ring was carried out. Understanding of ring Impedance/wake is an important subject in phase I. Measurement of Head Tail Damping using Turn by Turn monitor was performed to evaluate impedance/wake. Betatron motion is excited by kicker and its damping is measured for several parameters sets of bunch current and chromaticity in both HER and LER. The wake field was calculated from the decrement of betatron amplitude. We present the wake field which is cross-checked with tune shift based on the current dependence.

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THPVA074

Upgrade Study of the MedAustron Ion Beam Center

extraction, ion, quadrupole, synchrotron

4619

A. De Franco, T.T. Böhlen, F. Farinon, G. Kowarik, M. Kronberger, C. Kurfürst, S. Nowak, F. Osmić, M.T.F. Pivi, C. Schmitzer, P. Urschütz, A. Wastl
EBG MedAustron, Wr. Neustadt, Austria

Funding: This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk'odowska-Curie grant agreement No 675265.
MedAustron is a synchrotron-based ion beam therapy center allowing the treatment of tumours with protons and other light ion species, in particular C⁶⁺. Commissioning of the first irradiation room for clinical therapy with proton beams has been completed and in parallel to the commissioning of the remaining two irradiation rooms, a facility upgrade study has started. Our analysis includes considerations for the possibility to introduce different extraction mechanisms, new diagnostic tools, optimization of the accelerator cycle time, ripples mitigation for more accurate active beam stabilization and other improvements for hardware reliability. We present the concept, the main benefits, also in terms of treatment time reduction, and the challenges for implementation. Each option will be investigated including a detailed assessment on resources demand, impact and risk analysis.

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THPVA075

Beam Measurements in the MedAustron Synchrotron With Slow Extraction and Off-Momentum Operation

emittance, synchrotron, extraction, pick-up

4623

C. Kurfürst, A. De Franco, F. Farinon, M. Kronberger, S. Myalski, S. Nowak, F. Osmić, M.T.F. Pivi, C. Schmitzer, P. Urschütz, A. Wastl
EBG MedAustron, Wr. Neustadt, Austria
A. Garonna
TERA, Novara, Italy
T.K.D. Kulenkampff
CERN, Geneva, Switzerland
L.C. Penescu
Abstract Landscapes, Montpellier, France

The MedAustron Ion Therapy Center is a medical accelerator facility for hadron therapy cancer treatment using protons and carbon ions. The facility features 4 irradiation rooms, three of which are dedicated to clinical operation and a fourth one dedicated to non-clinical research. The latter was handed over to researchers in autumn 2016. A 7 MeV/n injector feeds a 77 m circumference synchrotron which provides beams for treatment and research. Routine verification measurements in the synchrotron involve beam emittance, dispersion as well as tunes and chromaticity. The horizontal and vertical emittance are measured using scraping plates and a direct current transformer. The dispersion function in the ring is determined by sweeping the synchrotron RF frequency while measuring the beam position in the shoe-box pick-ups. The horizontal and vertical betatron tune and chromaticity are measured with Direct Diode Detection electronics, developed at CERN, while changing the beam position with the RF radial loop. The beam is kept off-momentum, thus in dispersive regions the closed orbit is largely offset from the central orbit. Methods for beam measurements in the synchrotron are presented.

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