IPAC2013 - List of Keywords (betatron)

Paper	Title	Other Keywords	Page
MOODB202	Simulations and Measurements of Cleaning with 100 MJ Beams in the LHC	simulation, proton, collimation, beam-losses	52
	R. Bruce, R.W. Aßmann, V. Boccone, C. Bracco, M. Cauchi, F. Cerutti, D. Deboy, A. Ferrari, L. Lari, A. Marsili, A. Mereghetti, E. Quaranta, S. Redaelli, G. Robert-Demolaize, A. Rossi, B. Salvachua, E. Skordis, G. Valentino, V. Vlachoudis, Th. Weiler, D. Wollmann CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain E. Quaranta Politecnico/Milano, Milano, Italy G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The CERN Large Hadron Collider is routinely storing proton beam intensities of more than 100 MJ, which puts extraordinary demands on the control of beam losses to avoid quenches of the superconducting magnets. Therefore, a detailed understanding of the LHC beam cleaning is required. We present tracking and shower simulations of the LHC's multi-stage collimation system and compare with measured beam losses, which allow us to conclude on the predictive power of the simulations.
	Slides MOODB202 [6.343 MB]

MOPME042	A PRELIMINARY SIMULATION OF BPM SIGNAL DIODE DETECTOR FOR HLS II TUNE MEASUREMENT SYSTEM*	simulation, storage-ring, pick-up, synchrotron	565
	J.J. Zheng, P. Lu, T.J. Ma, B.G. Sun, Y.L. Yang, J.Y. Zou USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Supported by National Natural Science Foundation of China (11105141, 11175173) and the Fundamental Research Funds for the Central Universities (WK2310000015) A high sensitivity BPM signal detection front-end electronics has been designed for HLS II tune measurement system according to the HLS II upgrade requirements. Classical tune measurement systems filter out just one or a few of these betatron sidebands frequency. As a consequence, most of the betatron energy is dropped and only a very small energy remains for further processing. A new method, referred to as Direct Diode Detection (3D) by LHC[1], improves the situation. In this paper, the HLS II BPM signals have been calculated out in time domain and frequency domain. Basing on the characteristics of HLS II BPM signal, a preliminary simulation is performed to test and verify the feasibility of diode detector for HLS II tune measurement system. The simulation results clearly show that the technique of diode-based circuit can be applied to HLS II tune measurement.

MOPWO019	An IDE for Spin-orbit Dynamics Simulation	simulation, lattice, controls, optics	921
	A.N. Ivanov, N.V. Kulabukhova St. Petersburg State University, St. Petersburg, Russia
	In this paper a prototype of an IDE for simulation of spin-orbit motion is described. It is based on the component software development and provides a flexible graphic user interface. One of the main parts of it is numerical methods for ordinary differential equations integration. For numerical simulation it is possible use either the matrix map algorithm or traditional step-by-step methods. This workflow allows choosing one of numerical algorithms and to provide necessary computational experiments. It is also contains both a visual designer of an accelerator lattice and additional tools for control parameters of the model. There is also exists possibility for code generation in different programming languages and computation on high-performance systems.

MOPWO037	SixTrack Simulation of Off-momentum Cleaning in LHC	simulation, radiation, synchrotron, synchrotron-radiation	972
	E. Quaranta, R. Bruce, S. Redaelli CERN, Geneva, Switzerland
	In the LHC, high-amplitude particles are cleaned by either betatron collimators or momentum collimators. Previously, betatron losses have been considered more important, but measurements during the first years of operation show high losses also in the off-momentum cleaning insertion. This causes a significant radiation dose to warm magnets downstream of the collimators. Our work in this paper aims at simulating with SixTrack the off-momentum particles, driven into the momentum collimators by radiation damping outside the RF system acceptance. The results are an important ingredient in assessing the effectiveness of new passive absorbers to protect the warm magnets.

MOPWO048	Cleaning Performance of the LHC Collimation System up to 4 TeV	alignment, collimation, insertion, beam-losses	1002
	B. Salvachua, R.W. Aßmann, R. Bruce, M. Cauchi, D. Deboy, L. Lari, A. Marsili, D. Mirarchi, E. Quaranta, S. Redaelli, A. Rossi, G. Valentino CERN, Geneva, Switzerland M. Cauchi UoM, Msida, Malta L. Lari IFIC, Valencia, Spain D. Mirarchi The Imperial College of Science, Technology and Medicine, London, United Kingdom G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	Funding: Research supported by EU FP7 HiLumi LHC (Grant agreement 284404) In this paper we review the performance of the LHC collimation system during 2012 and compare it with previous years. During 2012, the so-called tight settings were deployed for a better cleaning and improved beta-star reach. As a result, a record cleaning efficiency below a few 0.0001 was achieved in the cold regions where the highest beam losses occur. The cleaning in other cold locations is typically a factor of 10 better. No quenches were observed during regular operation with up to 140 MJ stored beam energy. The system stability during the year, monitored regularly to ensure the system functionality for all machine configurations, and the performance of the alignment tools are also reviewed.

MOPWO050	Comparison of LHC Beam Loss Maps using the Transverse Damper Blow up and Tune Resonance Crossing Methods	collimation, injection, resonance, background	1008
	V. Moens, R. Bruce, S. Redaelli, B. Salvachua, G. Valentino CERN, Geneva, Switzerland V. Moens EPFL, Lausanne, Switzerland G. Valentino University of Malta, Information and Communication Technology, Msida, Malta
	The LHC collimator settings are qualified regularly via beam loss maps. In this procedure, the beam is artificially excited to create abnormal loss rates. The transverse damper blow up and tune resonance crossing methods are used to increase the betatron amplitude of particles and verify the efficiency of the collimation cleaning and the collimator hierarchy. This paper presents a quantitative comparison of the methods, based on measurements done at different phases of the LHC machine cycle. The analysis is done using Beam Loss Monitor (BLM) with integration times of 1.3 s and 80 ms. The use of the faster BLM data to study the time evolution of the losses in IR3 and IR7 during off-momentum loss maps is also presented.

MOPWO051	Estimate of Warm Magnets Lifetime in the Betatron and Momentum Cleaning Insertions of the LHC	luminosity, insertion, collimation, radiation	1011
	B. Salvachua, R. Bruce, M. Brugger, F. Cerutti, S. Redaelli CERN, Geneva, Switzerland
	The CERN LHC collimation system is designed to perform momentum and betatron cleaning in different insertions, respectively IR3 and IR7. The insertions are not perfectly decoupled because the dispersion in IR7 is not null and the beta function in IR3 is not zero. The detailed sharing of losses between the two insertions depends on the relative collimator settings as observed by the change between 2011 and 2012 LHC operation. In this report, using the beam loss measurements at the primary collimators of IR3 and IR7, the total BLM losses in the two insertions are calculated and compared to each other. These studies are also used to quantify the total dose to warm magnets in those IRs with the aim to understand better their lifetime and the implications of the radiation to electronics. This will be of particular importance in view of LHC operating at nominal performance after several years of operation.

TUPFI032	Observation of Instabilities in the LHC due to Missing Head-on Beam-beam Interactions	damping, octupole, luminosity, beam-beam-effects	1412
	W. Herr, G. Arduini, R. Giachino, E. Métral, G. Papotti, T. Pieloni CERN, Geneva, Switzerland X. Buffat, N. Mounet EPFL, Lausanne, Switzerland
	We report the observation of coherent instabilities on individual bunches out of the LHC bunch train. These instabilities occured spontaneously after several hours of stable beam while in other cases they were related to the application of a small transverse beam separation during a luminosity optimization. Only few bunches were affected, depending on there collision scheme and following various tests we interprete these instabilities as a sudden loss of Landau damping when the tune spread from the beam-beam interaction became insufficient.

TUPFI034	Observations of Two-beam Instabilities during the 2012 LHC Physics Run	octupole, damping, impedance, luminosity	1418
	T. Pieloni EPFL, Lausanne, Switzerland G. Arduini, X. Buffat, R. Giachino, W. Herr, M. Lamont, N. Mounet, E. Métral, G. Papotti, B. Salvant, J. Wenninger CERN, Geneva, Switzerland S.M. White BNL, Upton, Long Island, New York, USA
	During the 2012 run coherent beam instabilities have been observed in the LHC at 4 TeV, during the betatron squeeze and in collision for special filling patterns. Several studies to characterize these instabilities have been carried out during operation and in special dedicated experiments. In this paper we summarize the observations collected for different machine parameters and the present understanding of the origin of these instabilities.

TUPFI038	Operation of the Betatron Squeeze at the LHC	optics, luminosity, proton, injection	1430
	S. Redaelli, X. Buffat, M. Lamont, G.J. Müller, M. Solfaroli Camillocci, R. Tomás, J. Wenninger CERN, Geneva, Switzerland G.J. Müller TU Dresden, Dresden, Germany
	The betatron squeeze is one of the most delicate operational phases at the large Hadron collider as it entails changes of optics performed at top energy, with full intensities. Appropriate software was developed to handle the squeeze, which ensured an efficient commissioning down to a β^* of 60 cm and a smooth operation. Several optics configurations could be commissioned and put in operation for physics. The operational experience of the LHC runs from 2010 until 2012 is presented and the overall performance reviewed.

TUPME016	Crosstalk Between Beam-beam Interaction and Lattice Nonlinearities in the SuperKEKB	simulation, luminosity, lattice, resonance	1601
	D. Zhou, K. Ohmi, Y. Ohnishi, K. Oide, H. Sugimoto KEK, Ibaraki, Japan
	Momentum-dependent lattice nonlinearities have been proven to be important for the luminosity performance in the KEKB B-factory. As an upgrade of KEKB, the SuperKEKB adopts nano-beam scheme, in which the colliding beams are squeezed to extremely small sizes at the interaction point. Consequently, the lattice nonlinearities in SuperKEKB become more stronger than in KEKB. Using two codes, SAD and BBWS, we did various simulations to study the crosstalk between beam-beam interaction and lattice nonlinearities. It is found that lattice nonlinearities can cause remarkable luminosity loss in the SuperKEKB.

TUPME028	RF Orbit Separation for CPT-Test Experiment at VEPP-4M	electron, positron, closed-orbit, beam-beam-effects	1634
	V.E. Blinov, E.A. Bekhtenev, G.V. Karpov, V.A. Kiselev, S.A. Krutikhin, G.Y. Kurkin, E.B. Levichev, O.I. Meshkov, S.I. Mishnev, V.V. Neyfeld, S.A. Nikitin, I.B. Nikolaev, D.N. Shatilov, G.M. Tumaikin BINP SB RAS, Novosibirsk, Russia A.P. Chabanov, O.P. Gordeev, A.I. Mickailov Budker INP & NSU, Novosibirsk, Russia
	Funding: This work was supported by the Ministry of Education and Science of the Russian federation and the Russian Foundation for Basis Research (grant 11-02-01422-a) In a special program of experiments which is under development in a background regime at the VEPP-4M storage ring we set an aim to realize a potential possibility to make the CPT invariance test with the accuracy better than 10^-8. The test will be based on a precise comparison of the spin precession frequencies of simultaneously stored electrons and positrons. To exclude the presence of static electric fields increasing a systematic error we have developed and tested a special RF system driven at the half revolution frequency to subsitute for the electrostatic orbit separation system. The latter is needed for the electron and positron orbit separation at the parasitic interaction point where the beam-beam effects drastically cut the beam currents.

TUPME045	Turn-by-turn Measurements in the KEK-ATF	synchrotron, damping, injection, emittance	1664
	Y. Renier, Y. Papaphilippou, R. Tomás, M. Wendt CERN, Geneva, Switzerland N. Eddy Fermilab, Batavia, USA K. Kubo, S. Kuroda, T. Naito, T. Okugi, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	The ATF damping ring has been upgraded with new read-out electronics for the beam position monitors (BPM), capable to acquire the beam orbits on a turn-by-turn basis, as well as in a high resolution averaging mode. The new BPM system allows to improve optic corrections and to achieve an even smaller vertical emittance (<2pm). Experimental results are presented based on turn-by-turn beam orbit measurements in the ring, for estimating the beta functions and dispersion along the lattice. A fast method to measure spectral line amplitude in a few turns is also presented, including the evaluation of chromaticity.

TUPWA009	Bunch by Bunch Intra-Bunch Feedback System for Curing Transverse Beam Instabilities at the J-PARC MR	feedback, impedance, injection, kicker	1739
	O. A. Konstantinova, Y.H. Chin, Y. Kurimoto, T. Obina, M. Okada, K. Takata, M. Tobiyama, T. Toyama KEK, Ibaraki, Japan Y. Shobuda JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	At the J-PARC Main Ring (MR), transverse instabilities have been observed during the injection and at the onset of acceleration with large particle losses. The present bunch by bunch feedback system, operating in a narrowband mode, has been effectively suppressing these instabilities, allowing the beam power to reach 230kW with only 400W of particle losses. The observed beam signals show that bunches are still executing complicated intra-bunch oscillations even if the narrowband feedback system is on, though they are not imposing significant particle losses at present. The new and more advanced broadband feedback system has been developed for control of the intra-bunch oscillations and further reduction of particle losses. The elaborate analysis code has been also developed on the MATLAB platform to analyse effects of the broadband feedback system on intra-bunch oscillations. This paper describes the development of these advanced instruments and presents the analysis of the latest beam test results using the MATLAB code.

TUPWA021	Multi-Pass, Multi-Bunch Beam Breakup of ERLs with 9-cell Tesla Cavities	HOM, cavity, dipole, simulation	1769
	S. Chen, J.E. Chen, L.W. Feng, S. Huang, Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu PKU, Beijing, People's Republic of China
	Funding: Supported by the Major State Basic Research Development Program of China under Grant No. 2011CB808303 and No. 2011CB808304 In this paper, multi-pass, multi-bunch beam break-up of some small-scale Energy Recovery Linac(ERL) configuration using 9-cell Tesla cavity is discussed. The threshold currents of different cases are investigated and some factors that influence the threshold currents are discussed.

TUPWA050	Effect of Transverse Coupling on Asymmetric Cooling in Compton Rings	emittance, laser, coupling, electron	1823
	E.V. Bulyak NSC/KIPT, Kharkov, Ukraine J. Urakawa KEK, Ibaraki, Japan F. Zimmermann CERN, Geneva, Switzerland
	Fast cooling of bunches circulating in a Compton ring is achieved by placing the collision point between electron bunches and laser pulses in a dispersive section and by, in addition, introducing a transverse offset between the laser pulse and the electron-beam closed orbit. Growth of the emittance in the dispersive transversal direction due to the additional excitation of betatron oscillations limits this type of cooling. Here we present the results of further studies on the fast cooling process, looking at the effect of the coupling of the transverse (betatron) oscillations. We first show theoretically that the transverse betatron coupling shortens the cooling time and hence reduces the steady-state energy spread of the electron beam, as well as the quantum losses. The theoretical estimates are then validated by simulations. Finally, a proof-of-principle experiment at the KEK ATF Damping Ring is proposed.

TUPWO010	Optimal Twiss Parameters for Emittance Measurement in Periodic Transport Channels	emittance, simulation, beam-transport, focusing	1898
	N. Golubeva, V. Balandin, W. Decking DESY, Hamburg, Germany
	From the point of view of the optimality criteria introduced in , we study in this paper the procedure of emittance measurement in periodic beam transport channels. V.Balandin, W.Decking, N.Golubeva. “Invariant Criteria for the Design of Multiple Beam Profile Emittance and Twiss Parameters Measurement Sections”, These Proceedings.

TUPWO011	Invariant Criterion for the Design of Multiple Beam Profile Emittance and Twiss Parameters Measurement Sections	emittance, coupling, simulation, optics	1901
	V. Balandin, W. Decking, N. Golubeva DESY, Hamburg, Germany
	By studying errors in the reconstructed beam parameters as functions of the errors in the beam size measurements, we introduce an optimality criteria which can be used for the design and comparison of multiple beam profile emittance and Twiss parameters measurement sections and which is independent from the position of the reconstruction point.

TUPWO015	Off-Energy Injection Into Newsubaru	injection, lattice, septum, synchrotron	1913
	Y. Shoji LASTI, Hyogo, Japan Y. Minagawa, Y. Takemura JASRI/SPring-8, Hyogo-ken, Japan
	NewSUBARU is temporarily operated in non-achromatic mode for the research using chromaticity modulation. At this special mode, a normal injection scheme does not work because of the larger stored beam size and smaller ring acceptance. In order to obtain good injection efficiency, which enables top-up operation, the injected beam energy is displaced from the ring energy. The finite dispersion of 1.1 m at the injection point and the energy displacement of 0.7% reduce the betatron oscillation amplitude of the injected beam. A trade off is a synchrotron oscillation produced by the energy mismatch. Using this technique, it became possible to inject new beam using a closed fast injection bump and also a top-up operation. Although it is not possible to inject beam to a normal achromatic lattice using a closed bump. Especially in non-achromatic quasi-isochronous ring, it would be possible that the energy mismatch is reduced by the betatron amplitude dependent shift of the equilibrium energy.

TUPWO049	Automatic Correction of Betatron Coupling in the LHC using Injection Oscillations	coupling, injection, controls, quadrupole	1979
	T. Persson, T. Bach, D. Jacquet, V. Kain, Y.I. Levinsen, E.H. Maclean, M.J. McAteer, P.K. Skowroński, R. Tomás, G. Vanbavinckhove CERN, Geneva, Switzerland R. Miyamoto ESS, Lund, Sweden
	The control of the betatron coupling at injection and during the energy ramp is critical for the safe operation of the tune feedback and for the dynamic aperture. In the LHC every fill is preceded by the injection of a pilot bunch with low intensity. Using the injection oscillations from the pilot bunch we are able to measure the coupling at each individual BPM. The measurement is used to calculate a global coupling correction. The correction is based on the use of two orthogonal knobs which correct the real and imaginary part of the difference resonance term f1001, respectively. This method to correct the betatron coupling has been proven successful during the normal operation of the LHC. This paper presents the method used to calculate the corrections and its performance.

TUPWO054	Recent Results from the EMMA Experiment	acceleration, simulation, synchrotron, closed-orbit	1988
	B.D. Muratori, J.K. Jones STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R. Appleby, J.M. Garland, H.L. Owen UMAN, Manchester, United Kingdom J.S. Berg, F. Méot BNL, Upton, Long Island, New York, USA C.S. Edmonds, J.K. Jones, I.W. Kirkman, B.D. Muratori, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom C.S. Edmonds, I.W. Kirkman, A. Wolski The University of Liverpool, Liverpool, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom J. Pasternak STFC/RAL, Chilton, Didcot, Oxon, United Kingdom J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom
	EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. After a recent demonstration of acceleration in the serpentine channel, the injected EMMA beam was further studied. This entails the continuation of the exploration of the large transverse and longitudinal acceptance and the effects of slower integer tune crossing on the betatron amplitude. A single closed orbit correction that is effective at multiple momenta (and hence over a significant range in tune space) was implemented. A comparison with a detailed model based on measured field maps, and the experimental mapping of the machine by relating the initial and final phase space coordinates was also done. These recent results together with more practical improvements such as injection orbit matching with real-time monitoring of the coordinates in the transverse phase space will be reported in this paper.

TUPWO073	Precision Tune, Phase and Beta Function Measurement by Frequency Analysis in RHIC	optics, dipole, kicker, booster	2027
	C. Liu, R.L. Hulsart, A. Marusic, R.J. Michnoff, M.G. Minty, P. Thieberger BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The high quality of the RHIC turn-by-turn (TbT) data obtained from the beam position monitor (BPM) system was fully exploited by using two analysis approaches. One is a time domain least square fitting technique and the other one is a frequency domain interpolated Fourier Transform technique. Both methods were applied to 1024-turn data from kicked beam and from continuous coherent excitation experiments. The betatron phase precisions obtained with both methods were ~0.1 degree for the continuous excitation and ~0.2 degree for the impulse excitation. The algorithms of these two analyses and comparison of their results will be presented in this report.

WEPEA003	Dipole Fringe Field Effects in the ThomX Ring	dipole, quadrupole, sextupole, closed-orbit	2504
	J.F. Zhang LAL, Orsay, France A. Loulergue SOLEIL, Gif-sur-Yvette, France
	Thom-X is a 50 MeV compact ring based on the Compton back-scattering which is being built in LAL, France. With a very short bend radius of 0.352 m, the nonlinear effects of the dipole fringe fields become critical to the beam dynamic . This paper compares the modelings of the dipole fringe field using four popular codes: MadX, Elegant, BETA, and Tracy3, and then discuss the proper model to have consistent results between the analytical calculation and the symplectic tracking of the Thom-X ring.

WEPEA027	Nonlinear Model Calibration in Electron Storage Rings via Frequency Analysis	radiation, sextupole, storage-ring, damping	2558
	G. Liu, W. Li, L. Wang, K. Xuan USTC/NSRL, Hefei, Anhui, People's Republic of China
	Frequency analysis of turn-by-turn BPM data is a very useful numerical method for analysing the detrimental effect of the nonlinear resonances in storage rings, and which has been widely used for nonlinear resonances measurement and correction. We applied this method in this paper for calibrating the nonlinear model by numerical fitting of the sextupole components with the effect of radiation damping and decoherence of the betatron oscillation in HLSII storage ring.

WEPEA036	Spin Tune Decoherence Effects in Electro- and Magnetostatic Structures	sextupole, acceleration, emittance, synchrotron	2579
	Y. Senichev, R. Maier, D. Zyuzin FZJ, Jülich, Germany N.V. Kulabukhova St. Petersburg State University, St. Petersburg, Russia
	In Electric Dipole Moment search experiments with polarized beams the coherence of spin oscillations of particles has a crucial role. The decoherent effects arise due to spin tune dependence on particle energy and particle trajectory in focusing-deflecting fields. They are described through the n-th order spin tune aberrations. Since the first order is suppressed by RF field, the second order plays crucial role. It depends on the orbit lengthening and on the odd order field components. We consider the spin decoherence effects and methods of their compensation in different channels, electrostatic, magnetostatic linking the decoherence effects with common characteristics such as the momentum compaction factor, the chromaticity and others.

WEPEA067	Beam Optics Measurements through Turn by turn Beam Position Data in the SLS	storage-ring, optics, luminosity, positron	2663
	P. Zisopoulos, Y. Papaphilippou CERN, Geneva, Switzerland A. Streun PSI, Villigen PSI, Switzerland V.G. Ziemann Uppsala University, Uppsala, Sweden
	Refined Fourier analysis of turn-by-turn (TBT) transverse position data measurements can be used for determining several beam properties of a ring, such as transverse tunes, optics functions, phases, chromatic properties and coupling. In particular, the Numerical Analysis of Fundamental Frequencies (NAFF) algorithm is used to analyze TBT data from the Swiss Light Source (SLS) storage ring in order to estimate on and off-momentum beam characteristics. Of particular interest is the potential of using the full position information within one turn in order to measure beam optics properties.

WEPEA072	Experimental Studies of Resonance Crossing in Linear Non-scaling FFAGs With the S-POD Plasma Trap	resonance, dipole, ion, focusing	2675
	S.L. Sheehy, D.J. Kelliher, S. Machida, C.R. Prior STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom K. Fukushima, K. Ito, K. Moriya, H. Okamoto HU/AdSM, Higashi-Hiroshima, Japan
	In a linear non-scaling FFAG the betatron tunes vary over a wide range during acceleration. This naturally leads to resonance crossing including first order integer resonances. The S-POD (Simulator for Particle Orbit Dynamics) plasma trap apparatus at Hiroshima University represents a physically equivalent system to a charged particle beam travelling in a strong focusing accelerator lattice. The S-POD system can be used as an ‘experimental simulation’ to investigate the effects of resonance crossing and its dependence on dipole errors, tune crossing speed and other factors. Recent developments and experiments are discussed.

WEPEA081	Local 3Qy Betatron Resonance Correction in the 2012 RHIC 250 GeV Run	sextupole, resonance, dynamic-aperture, proton	2696
	Y. Luo, W. Fischer, T. Roser, V. Schoefer, C.M. Zimmer 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. In this article we performed numerical simulations to correct the local vertical third order betatron resonance 3Q_y in the interaction regions in the Yellow ring for the 2012 RHIC 250~GeV polarized proton run. Considering the main sources of skew sextupoles are located in the interaction regions, we used local bump methods to minimize their contributions to the global 3Q_y resonance driving term. Two kinds of correction orbit bumps are tested and the dynamic apertures with these correction strengths are calculated and compared.

WEPME003	Determination of Optics Transfer between the Kicker and BPMs for Transverse Feedback System	kicker, feedback, optics, synchrotron	2923
	M. Alhumaidi, A.M. Zoubir TU Darmstadt, Darmstadt, Germany J. Grieser TU Darmstadt, RTR, Darmstadt, Germany
	The knowledge of the transfer optics between the positions of the Kicker and the BPMs is required for the calculation of the correction signal in transverse feedback systems. Therefore, using nominal values of the transfer optics with uncertainties leads to feedback quality degradation, and thus beam disturbances. In this work, we propose a method for measuring the phase advances and amplitude scaling between the positions of the kicker and the BPMs. Directly after applying a kick on the beam by means of the kicker, we record the BPM signals. Consequently, we use the Second-Order Blind Identification (SOBI) algorithm to decompose the noised recorded signals into independent sources mixture. Finally, we determine the required optics parameters by identifying and analyzing the betatron oscillation sourced from the kick based on its mixing and temporal patterns. Results for the heavy ions synchrotron SIS 18 at the GSI are shown.

WEPME011	Beam Tests and Plans for the CERN PS Transverse Damper System	emittance, damping, injection, kicker	2947
	A. Blas, S.S. Gilardoni, G. Sterbini CERN, Geneva, Switzerland
	The CERN Proton Synchrotron (CPS) has been running without any transverse damping equipment since 1998, thanks to the stabilizing effect of the linear coupling applied between horizontal and vertical planes. Lately, the demand for an active damper strongly emerged for two main reasons: to avoid restrictions as imposed on the betatron tune settings by the linear coupling and to cure instabilities appearing with high intensity beams, especially at the extraction energy. Late in 2012, two electronic prototype units, newly developed for the CPS one-turn-feedback, were programmed with a firmware designed to satisfy the transverse feedback (TFB) requirements in both planes. The main achievements were to automatically adapt the loop delay to the particles' time-of-flight variation within a nanosecond precision and to compensate the changing betatron phase advance between pick-up and kicker during the entire accelerating cycle. With the power equipment limited to the modest bandwidth of 23 MHz and 2 x 800 W per plane, encouraging results were obtained such as fast damping of injection oscillations caused by injection errors, reduction of beam losses along the cycle and damping of instabilities at all CPS energies.

THOBB102	Beam Coupling Impedance Localization Technique Validation and Measurements in the CERN Machines	impedance, kicker, quadrupole, lattice	3106
	N. Biancacci, G. Arduini, T. Argyropoulos, H. Bartosik, R. Calaga, K. Cornelis, S.S. Gilardoni, N. Mounet, E. Métral, Y. Papaphilippou, S. Persichelli, G. Rumolo, B. Salvant, G. Sterbini, R. Tomás, R. Wasef CERN, Geneva, Switzerland M. Migliorati, L. Palumbo URLS, Rome, Italy
	The beam coupling impedance could lead to limitations in beam brightness and quality, and therefore it needs accurate quantification and continuous monitoring in order to detect and mitigate high impedance sources. In the CERN machines, for example, kickers and collimators are expected to be the main contributors to the total imaginary part of the transverse impedance. In order to detect the other sources, a beam based measurement was developed: from the variation of betatron phase beating with intensity, it is possible to detect the locations of main impedance sources. In this work we present the application of the method with beam measurements in the CERN PS, SPS and LHC.
	Slides THOBB102 [7.224 MB]

Paper

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Other Keywords

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MOODB202

Simulations and Measurements of Cleaning with 100 MJ Beams in the LHC

simulation, proton, collimation, beam-losses

52

R. Bruce, R.W. Aßmann, V. Boccone, C. Bracco, M. Cauchi, F. Cerutti, D. Deboy, A. Ferrari, L. Lari, A. Marsili, A. Mereghetti, E. Quaranta, S. Redaelli, G. Robert-Demolaize, A. Rossi, B. Salvachua, E. Skordis, G. Valentino, V. Vlachoudis, Th. Weiler, D. Wollmann
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain
E. Quaranta
Politecnico/Milano, Milano, Italy
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The CERN Large Hadron Collider is routinely storing proton beam intensities of more than 100 MJ, which puts extraordinary demands on the control of beam losses to avoid quenches of the superconducting magnets. Therefore, a detailed understanding of the LHC beam cleaning is required. We present tracking and shower simulations of the LHC's multi-stage collimation system and compare with measured beam losses, which allow us to conclude on the predictive power of the simulations.

Slides MOODB202 [6.343 MB]

MOPME042

A PRELIMINARY SIMULATION OF BPM SIGNAL DIODE DETECTOR FOR HLS II TUNE MEASUREMENT SYSTEM*

simulation, storage-ring, pick-up, synchrotron

565

J.J. Zheng, P. Lu, T.J. Ma, B.G. Sun, Y.L. Yang, J.Y. Zou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by National Natural Science Foundation of China (11105141, 11175173) and the Fundamental Research Funds for the Central Universities (WK2310000015)
A high sensitivity BPM signal detection front-end electronics has been designed for HLS II tune measurement system according to the HLS II upgrade requirements. Classical tune measurement systems filter out just one or a few of these betatron sidebands frequency. As a consequence, most of the betatron energy is dropped and only a very small energy remains for further processing. A new method, referred to as Direct Diode Detection (3D) by LHC[1], improves the situation. In this paper, the HLS II BPM signals have been calculated out in time domain and frequency domain. Basing on the characteristics of HLS II BPM signal, a preliminary simulation is performed to test and verify the feasibility of diode detector for HLS II tune measurement system. The simulation results clearly show that the technique of diode-based circuit can be applied to HLS II tune measurement.

MOPWO019

An IDE for Spin-orbit Dynamics Simulation

simulation, lattice, controls, optics

921

A.N. Ivanov, N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia

In this paper a prototype of an IDE for simulation of spin-orbit motion is described. It is based on the component software development and provides a flexible graphic user interface. One of the main parts of it is numerical methods for ordinary differential equations integration. For numerical simulation it is possible use either the matrix map algorithm or traditional step-by-step methods. This workflow allows choosing one of numerical algorithms and to provide necessary computational experiments. It is also contains both a visual designer of an accelerator lattice and additional tools for control parameters of the model. There is also exists possibility for code generation in different programming languages and computation on high-performance systems.

MOPWO037

SixTrack Simulation of Off-momentum Cleaning in LHC

simulation, radiation, synchrotron, synchrotron-radiation

972

E. Quaranta, R. Bruce, S. Redaelli
CERN, Geneva, Switzerland

In the LHC, high-amplitude particles are cleaned by either betatron collimators or momentum collimators. Previously, betatron losses have been considered more important, but measurements during the first years of operation show high losses also in the off-momentum cleaning insertion. This causes a significant radiation dose to warm magnets downstream of the collimators. Our work in this paper aims at simulating with SixTrack the off-momentum particles, driven into the momentum collimators by radiation damping outside the RF system acceptance. The results are an important ingredient in assessing the effectiveness of new passive absorbers to protect the warm magnets.

MOPWO048

Cleaning Performance of the LHC Collimation System up to 4 TeV

alignment, collimation, insertion, beam-losses

1002

B. Salvachua, R.W. Aßmann, R. Bruce, M. Cauchi, D. Deboy, L. Lari, A. Marsili, D. Mirarchi, E. Quaranta, S. Redaelli, A. Rossi, G. Valentino
CERN, Geneva, Switzerland
M. Cauchi
UoM, Msida, Malta
L. Lari
IFIC, Valencia, Spain
D. Mirarchi
The Imperial College of Science, Technology and Medicine, London, United Kingdom
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

Funding: Research supported by EU FP7 HiLumi LHC (Grant agreement 284404)
In this paper we review the performance of the LHC collimation system during 2012 and compare it with previous years. During 2012, the so-called tight settings were deployed for a better cleaning and improved beta-star reach. As a result, a record cleaning efficiency below a few 0.0001 was achieved in the cold regions where the highest beam losses occur. The cleaning in other cold locations is typically a factor of 10 better. No quenches were observed during regular operation with up to 140 MJ stored beam energy. The system stability during the year, monitored regularly to ensure the system functionality for all machine configurations, and the performance of the alignment tools are also reviewed.

MOPWO050

Comparison of LHC Beam Loss Maps using the Transverse Damper Blow up and Tune Resonance Crossing Methods

collimation, injection, resonance, background

1008

V. Moens, R. Bruce, S. Redaelli, B. Salvachua, G. Valentino
CERN, Geneva, Switzerland
V. Moens
EPFL, Lausanne, Switzerland
G. Valentino
University of Malta, Information and Communication Technology, Msida, Malta

The LHC collimator settings are qualified regularly via beam loss maps. In this procedure, the beam is artificially excited to create abnormal loss rates. The transverse damper blow up and tune resonance crossing methods are used to increase the betatron amplitude of particles and verify the efficiency of the collimation cleaning and the collimator hierarchy. This paper presents a quantitative comparison of the methods, based on measurements done at different phases of the LHC machine cycle. The analysis is done using Beam Loss Monitor (BLM) with integration times of 1.3 s and 80 ms. The use of the faster BLM data to study the time evolution of the losses in IR3 and IR7 during off-momentum loss maps is also presented.

MOPWO051

Estimate of Warm Magnets Lifetime in the Betatron and Momentum Cleaning Insertions of the LHC

luminosity, insertion, collimation, radiation

1011

B. Salvachua, R. Bruce, M. Brugger, F. Cerutti, S. Redaelli
CERN, Geneva, Switzerland

The CERN LHC collimation system is designed to perform momentum and betatron cleaning in different insertions, respectively IR3 and IR7. The insertions are not perfectly decoupled because the dispersion in IR7 is not null and the beta function in IR3 is not zero. The detailed sharing of losses between the two insertions depends on the relative collimator settings as observed by the change between 2011 and 2012 LHC operation. In this report, using the beam loss measurements at the primary collimators of IR3 and IR7, the total BLM losses in the two insertions are calculated and compared to each other. These studies are also used to quantify the total dose to warm magnets in those IRs with the aim to understand better their lifetime and the implications of the radiation to electronics. This will be of particular importance in view of LHC operating at nominal performance after several years of operation.

TUPFI032

Observation of Instabilities in the LHC due to Missing Head-on Beam-beam Interactions

damping, octupole, luminosity, beam-beam-effects

1412

W. Herr, G. Arduini, R. Giachino, E. Métral, G. Papotti, T. Pieloni
CERN, Geneva, Switzerland
X. Buffat, N. Mounet
EPFL, Lausanne, Switzerland

We report the observation of coherent instabilities on individual bunches out of the LHC bunch train. These instabilities occured spontaneously after several hours of stable beam while in other cases they were related to the application of a small transverse beam separation during a luminosity optimization. Only few bunches were affected, depending on there collision scheme and following various tests we interprete these instabilities as a sudden loss of Landau damping when the tune spread from the beam-beam interaction became insufficient.

TUPFI034

Observations of Two-beam Instabilities during the 2012 LHC Physics Run

octupole, damping, impedance, luminosity

1418

T. Pieloni
EPFL, Lausanne, Switzerland
G. Arduini, X. Buffat, R. Giachino, W. Herr, M. Lamont, N. Mounet, E. Métral, G. Papotti, B. Salvant, J. Wenninger
CERN, Geneva, Switzerland
S.M. White
BNL, Upton, Long Island, New York, USA

During the 2012 run coherent beam instabilities have been observed in the LHC at 4 TeV, during the betatron squeeze and in collision for special filling patterns. Several studies to characterize these instabilities have been carried out during operation and in special dedicated experiments. In this paper we summarize the observations collected for different machine parameters and the present understanding of the origin of these instabilities.

TUPFI038

Operation of the Betatron Squeeze at the LHC

optics, luminosity, proton, injection

1430

S. Redaelli, X. Buffat, M. Lamont, G.J. Müller, M. Solfaroli Camillocci, R. Tomás, J. Wenninger
CERN, Geneva, Switzerland
G.J. Müller
TU Dresden, Dresden, Germany

The betatron squeeze is one of the most delicate operational phases at the large Hadron collider as it entails changes of optics performed at top energy, with full intensities. Appropriate software was developed to handle the squeeze, which ensured an efficient commissioning down to a β^* of 60 cm and a smooth operation. Several optics configurations could be commissioned and put in operation for physics. The operational experience of the LHC runs from 2010 until 2012 is presented and the overall performance reviewed.

TUPME016

Crosstalk Between Beam-beam Interaction and Lattice Nonlinearities in the SuperKEKB

simulation, luminosity, lattice, resonance

1601

D. Zhou, K. Ohmi, Y. Ohnishi, K. Oide, H. Sugimoto
KEK, Ibaraki, Japan

Momentum-dependent lattice nonlinearities have been proven to be important for the luminosity performance in the KEKB B-factory. As an upgrade of KEKB, the SuperKEKB adopts nano-beam scheme, in which the colliding beams are squeezed to extremely small sizes at the interaction point. Consequently, the lattice nonlinearities in SuperKEKB become more stronger than in KEKB. Using two codes, SAD and BBWS, we did various simulations to study the crosstalk between beam-beam interaction and lattice nonlinearities. It is found that lattice nonlinearities can cause remarkable luminosity loss in the SuperKEKB.

TUPME028

RF Orbit Separation for CPT-Test Experiment at VEPP-4M

electron, positron, closed-orbit, beam-beam-effects

1634

V.E. Blinov, E.A. Bekhtenev, G.V. Karpov, V.A. Kiselev, S.A. Krutikhin, G.Y. Kurkin, E.B. Levichev, O.I. Meshkov, S.I. Mishnev, V.V. Neyfeld, S.A. Nikitin, I.B. Nikolaev, D.N. Shatilov, G.M. Tumaikin
BINP SB RAS, Novosibirsk, Russia
A.P. Chabanov, O.P. Gordeev, A.I. Mickailov
Budker INP & NSU, Novosibirsk, Russia

Funding: This work was supported by the Ministry of Education and Science of the Russian federation and the Russian Foundation for Basis Research (grant 11-02-01422-a)
In a special program of experiments which is under development in a background regime at the VEPP-4M storage ring we set an aim to realize a potential possibility to make the CPT invariance test with the accuracy better than 10^-8. The test will be based on a precise comparison of the spin precession frequencies of simultaneously stored electrons and positrons. To exclude the presence of static electric fields increasing a systematic error we have developed and tested a special RF system driven at the half revolution frequency to subsitute for the electrostatic orbit separation system. The latter is needed for the electron and positron orbit separation at the parasitic interaction point where the beam-beam effects drastically cut the beam currents.

TUPME045

Turn-by-turn Measurements in the KEK-ATF

synchrotron, damping, injection, emittance

1664

Y. Renier, Y. Papaphilippou, R. Tomás, M. Wendt
CERN, Geneva, Switzerland
N. Eddy
Fermilab, Batavia, USA
K. Kubo, S. Kuroda, T. Naito, T. Okugi, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

The ATF damping ring has been upgraded with new read-out electronics for the beam position monitors (BPM), capable to acquire the beam orbits on a turn-by-turn basis, as well as in a high resolution averaging mode. The new BPM system allows to improve optic corrections and to achieve an even smaller vertical emittance (<2pm). Experimental results are presented based on turn-by-turn beam orbit measurements in the ring, for estimating the beta functions and dispersion along the lattice. A fast method to measure spectral line amplitude in a few turns is also presented, including the evaluation of chromaticity.

TUPWA009

Bunch by Bunch Intra-Bunch Feedback System for Curing Transverse Beam Instabilities at the J-PARC MR

feedback, impedance, injection, kicker

1739

O. A. Konstantinova, Y.H. Chin, Y. Kurimoto, T. Obina, M. Okada, K. Takata, M. Tobiyama, T. Toyama
KEK, Ibaraki, Japan
Y. Shobuda
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

At the J-PARC Main Ring (MR), transverse instabilities have been observed during the injection and at the onset of acceleration with large particle losses. The present bunch by bunch feedback system, operating in a narrowband mode, has been effectively suppressing these instabilities, allowing the beam power to reach 230kW with only 400W of particle losses. The observed beam signals show that bunches are still executing complicated intra-bunch oscillations even if the narrowband feedback system is on, though they are not imposing significant particle losses at present. The new and more advanced broadband feedback system has been developed for control of the intra-bunch oscillations and further reduction of particle losses. The elaborate analysis code has been also developed on the MATLAB platform to analyse effects of the broadband feedback system on intra-bunch oscillations. This paper describes the development of these advanced instruments and presents the analysis of the latest beam test results using the MATLAB code.

TUPWA021

Multi-Pass, Multi-Bunch Beam Breakup of ERLs with 9-cell Tesla Cavities

HOM, cavity, dipole, simulation

1769

S. Chen, J.E. Chen, L.W. Feng, S. Huang, Y.M. Li, K.X. Liu, S.W. Quan, F. Zhu
PKU, Beijing, People's Republic of China

Funding: Supported by the Major State Basic Research Development Program of China under Grant No. 2011CB808303 and No. 2011CB808304
In this paper, multi-pass, multi-bunch beam break-up of some small-scale Energy Recovery Linac(ERL) configuration using 9-cell Tesla cavity is discussed. The threshold currents of different cases are investigated and some factors that influence the threshold currents are discussed.

TUPWA050

Effect of Transverse Coupling on Asymmetric Cooling in Compton Rings

emittance, laser, coupling, electron

1823

E.V. Bulyak
NSC/KIPT, Kharkov, Ukraine
J. Urakawa
KEK, Ibaraki, Japan
F. Zimmermann
CERN, Geneva, Switzerland

Fast cooling of bunches circulating in a Compton ring is achieved by placing the collision point between electron bunches and laser pulses in a dispersive section and by, in addition, introducing a transverse offset between the laser pulse and the electron-beam closed orbit. Growth of the emittance in the dispersive transversal direction due to the additional excitation of betatron oscillations limits this type of cooling. Here we present the results of further studies on the fast cooling process, looking at the effect of the coupling of the transverse (betatron) oscillations. We first show theoretically that the transverse betatron coupling shortens the cooling time and hence reduces the steady-state energy spread of the electron beam, as well as the quantum losses. The theoretical estimates are then validated by simulations. Finally, a proof-of-principle experiment at the KEK ATF Damping Ring is proposed.

TUPWO010

Optimal Twiss Parameters for Emittance Measurement in Periodic Transport Channels

emittance, simulation, beam-transport, focusing

1898

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

From the point of view of the optimality criteria introduced in *, we study in this paper the procedure of emittance measurement in periodic beam transport channels.
* V.Balandin, W.Decking, N.Golubeva. “Invariant Criteria for the Design of Multiple Beam Profile Emittance and Twiss Parameters Measurement Sections”, These Proceedings.

TUPWO011

Invariant Criterion for the Design of Multiple Beam Profile Emittance and Twiss Parameters Measurement Sections

emittance, coupling, simulation, optics

1901

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

By studying errors in the reconstructed beam parameters as functions of the errors in the beam size measurements, we introduce an optimality criteria which can be used for the design and comparison of multiple beam profile emittance and Twiss parameters measurement sections and which is independent from the position of the reconstruction point.

TUPWO015

Off-Energy Injection Into Newsubaru

injection, lattice, septum, synchrotron

1913

Y. Shoji
LASTI, Hyogo, Japan
Y. Minagawa, Y. Takemura
JASRI/SPring-8, Hyogo-ken, Japan

NewSUBARU is temporarily operated in non-achromatic mode for the research using chromaticity modulation. At this special mode, a normal injection scheme does not work because of the larger stored beam size and smaller ring acceptance. In order to obtain good injection efficiency, which enables top-up operation, the injected beam energy is displaced from the ring energy. The finite dispersion of 1.1 m at the injection point and the energy displacement of 0.7% reduce the betatron oscillation amplitude of the injected beam. A trade off is a synchrotron oscillation produced by the energy mismatch. Using this technique, it became possible to inject new beam using a closed fast injection bump and also a top-up operation. Although it is not possible to inject beam to a normal achromatic lattice using a closed bump. Especially in non-achromatic quasi-isochronous ring, it would be possible that the energy mismatch is reduced by the betatron amplitude dependent shift of the equilibrium energy.

TUPWO049

Automatic Correction of Betatron Coupling in the LHC using Injection Oscillations

coupling, injection, controls, quadrupole

1979

T. Persson, T. Bach, D. Jacquet, V. Kain, Y.I. Levinsen, E.H. Maclean, M.J. McAteer, P.K. Skowroński, R. Tomás, G. Vanbavinckhove
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

The control of the betatron coupling at injection and during the energy ramp is critical for the safe operation of the tune feedback and for the dynamic aperture. In the LHC every fill is preceded by the injection of a pilot bunch with low intensity. Using the injection oscillations from the pilot bunch we are able to measure the coupling at each individual BPM. The measurement is used to calculate a global coupling correction. The correction is based on the use of two orthogonal knobs which correct the real and imaginary part of the difference resonance term f1001, respectively. This method to correct the betatron coupling has been proven successful during the normal operation of the LHC. This paper presents the method used to calculate the corrections and its performance.

TUPWO054

Recent Results from the EMMA Experiment

acceleration, simulation, synchrotron, closed-orbit

1988

B.D. Muratori, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Appleby, J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
J.S. Berg, F. Méot
BNL, Upton, Long Island, New York, USA
C.S. Edmonds, J.K. Jones, I.W. Kirkman, B.D. Muratori, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.S. Edmonds, I.W. Kirkman, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. After a recent demonstration of acceleration in the serpentine channel, the injected EMMA beam was further studied. This entails the continuation of the exploration of the large transverse and longitudinal acceptance and the effects of slower integer tune crossing on the betatron amplitude. A single closed orbit correction that is effective at multiple momenta (and hence over a significant range in tune space) was implemented. A comparison with a detailed model based on measured field maps, and the experimental mapping of the machine by relating the initial and final phase space coordinates was also done. These recent results together with more practical improvements such as injection orbit matching with real-time monitoring of the coordinates in the transverse phase space will be reported in this paper.

TUPWO073

Precision Tune, Phase and Beta Function Measurement by Frequency Analysis in RHIC

optics, dipole, kicker, booster

2027

C. Liu, R.L. Hulsart, A. Marusic, R.J. Michnoff, M.G. Minty, P. Thieberger
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The high quality of the RHIC turn-by-turn (TbT) data obtained from the beam position monitor (BPM) system was fully exploited by using two analysis approaches. One is a time domain least square fitting technique and the other one is a frequency domain interpolated Fourier Transform technique. Both methods were applied to 1024-turn data from kicked beam and from continuous coherent excitation experiments. The betatron phase precisions obtained with both methods were ~0.1 degree for the continuous excitation and ~0.2 degree for the impulse excitation. The algorithms of these two analyses and comparison of their results will be presented in this report.

WEPEA003

Dipole Fringe Field Effects in the ThomX Ring

dipole, quadrupole, sextupole, closed-orbit

2504

J.F. Zhang
LAL, Orsay, France
A. Loulergue
SOLEIL, Gif-sur-Yvette, France

Thom-X is a 50 MeV compact ring based on the Compton back-scattering which is being built in LAL, France. With a very short bend radius of 0.352 m, the nonlinear effects of the dipole fringe fields become critical to the beam dynamic . This paper compares the modelings of the dipole fringe field using four popular codes: MadX, Elegant, BETA, and Tracy3, and then discuss the proper model to have consistent results between the analytical calculation and the symplectic tracking of the Thom-X ring.

WEPEA027

Nonlinear Model Calibration in Electron Storage Rings via Frequency Analysis

radiation, sextupole, storage-ring, damping

2558

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

Frequency analysis of turn-by-turn BPM data is a very useful numerical method for analysing the detrimental effect of the nonlinear resonances in storage rings, and which has been widely used for nonlinear resonances measurement and correction. We applied this method in this paper for calibrating the nonlinear model by numerical fitting of the sextupole components with the effect of radiation damping and decoherence of the betatron oscillation in HLSII storage ring.

WEPEA036

Spin Tune Decoherence Effects in Electro- and Magnetostatic Structures

sextupole, acceleration, emittance, synchrotron

2579

Y. Senichev, R. Maier, D. Zyuzin
FZJ, Jülich, Germany
N.V. Kulabukhova
St. Petersburg State University, St. Petersburg, Russia

In Electric Dipole Moment search experiments with polarized beams the coherence of spin oscillations of particles has a crucial role. The decoherent effects arise due to spin tune dependence on particle energy and particle trajectory in focusing-deflecting fields. They are described through the n-th order spin tune aberrations. Since the first order is suppressed by RF field, the second order plays crucial role. It depends on the orbit lengthening and on the odd order field components. We consider the spin decoherence effects and methods of their compensation in different channels, electrostatic, magnetostatic linking the decoherence effects with common characteristics such as the momentum compaction factor, the chromaticity and others.

WEPEA067

Beam Optics Measurements through Turn by turn Beam Position Data in the SLS

storage-ring, optics, luminosity, positron

2663

P. Zisopoulos, Y. Papaphilippou
CERN, Geneva, Switzerland
A. Streun
PSI, Villigen PSI, Switzerland
V.G. Ziemann
Uppsala University, Uppsala, Sweden

Refined Fourier analysis of turn-by-turn (TBT) transverse position data measurements can be used for determining several beam properties of a ring, such as transverse tunes, optics functions, phases, chromatic properties and coupling. In particular, the Numerical Analysis of Fundamental Frequencies (NAFF) algorithm is used to analyze TBT data from the Swiss Light Source (SLS) storage ring in order to estimate on and off-momentum beam characteristics. Of particular interest is the potential of using the full position information within one turn in order to measure beam optics properties.

WEPEA072

Experimental Studies of Resonance Crossing in Linear Non-scaling FFAGs With the S-POD Plasma Trap

resonance, dipole, ion, focusing

2675

S.L. Sheehy, D.J. Kelliher, S. Machida, C.R. Prior
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
K. Fukushima, K. Ito, K. Moriya, H. Okamoto
HU/AdSM, Higashi-Hiroshima, Japan

In a linear non-scaling FFAG the betatron tunes vary over a wide range during acceleration. This naturally leads to resonance crossing including first order integer resonances. The S-POD (Simulator for Particle Orbit Dynamics) plasma trap apparatus at Hiroshima University represents a physically equivalent system to a charged particle beam travelling in a strong focusing accelerator lattice. The S-POD system can be used as an ‘experimental simulation’ to investigate the effects of resonance crossing and its dependence on dipole errors, tune crossing speed and other factors. Recent developments and experiments are discussed.

WEPEA081

Local 3Qy Betatron Resonance Correction in the 2012 RHIC 250 GeV Run

sextupole, resonance, dynamic-aperture, proton

2696

Y. Luo, W. Fischer, T. Roser, V. Schoefer, C.M. Zimmer
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.
In this article we performed numerical simulations to correct the local vertical third order betatron resonance 3Q_y in the interaction regions in the Yellow ring for the 2012 RHIC 250~GeV polarized proton run. Considering the main sources of skew sextupoles are located in the interaction regions, we used local bump methods to minimize their contributions to the global 3Q_y resonance driving term. Two kinds of correction orbit bumps are tested and the dynamic apertures with these correction strengths are calculated and compared.

WEPME003

Determination of Optics Transfer between the Kicker and BPMs for Transverse Feedback System

kicker, feedback, optics, synchrotron

2923

M. Alhumaidi, A.M. Zoubir
TU Darmstadt, Darmstadt, Germany
J. Grieser
TU Darmstadt, RTR, Darmstadt, Germany

The knowledge of the transfer optics between the positions of the Kicker and the BPMs is required for the calculation of the correction signal in transverse feedback systems. Therefore, using nominal values of the transfer optics with uncertainties leads to feedback quality degradation, and thus beam disturbances. In this work, we propose a method for measuring the phase advances and amplitude scaling between the positions of the kicker and the BPMs. Directly after applying a kick on the beam by means of the kicker, we record the BPM signals. Consequently, we use the Second-Order Blind Identification (SOBI) algorithm to decompose the noised recorded signals into independent sources mixture. Finally, we determine the required optics parameters by identifying and analyzing the betatron oscillation sourced from the kick based on its mixing and temporal patterns. Results for the heavy ions synchrotron SIS 18 at the GSI are shown.

WEPME011

Beam Tests and Plans for the CERN PS Transverse Damper System

emittance, damping, injection, kicker

2947

A. Blas, S.S. Gilardoni, G. Sterbini
CERN, Geneva, Switzerland

The CERN Proton Synchrotron (CPS) has been running without any transverse damping equipment since 1998, thanks to the stabilizing effect of the linear coupling applied between horizontal and vertical planes. Lately, the demand for an active damper strongly emerged for two main reasons: to avoid restrictions as imposed on the betatron tune settings by the linear coupling and to cure instabilities appearing with high intensity beams, especially at the extraction energy. Late in 2012, two electronic prototype units, newly developed for the CPS one-turn-feedback, were programmed with a firmware designed to satisfy the transverse feedback (TFB) requirements in both planes. The main achievements were to automatically adapt the loop delay to the particles' time-of-flight variation within a nanosecond precision and to compensate the changing betatron phase advance between pick-up and kicker during the entire accelerating cycle. With the power equipment limited to the modest bandwidth of 23 MHz and 2 x 800 W per plane, encouraging results were obtained such as fast damping of injection oscillations caused by injection errors, reduction of beam losses along the cycle and damping of instabilities at all CPS energies.

THOBB102

Beam Coupling Impedance Localization Technique Validation and Measurements in the CERN Machines

impedance, kicker, quadrupole, lattice

3106

N. Biancacci, G. Arduini, T. Argyropoulos, H. Bartosik, R. Calaga, K. Cornelis, S.S. Gilardoni, N. Mounet, E. Métral, Y. Papaphilippou, S. Persichelli, G. Rumolo, B. Salvant, G. Sterbini, R. Tomás, R. Wasef
CERN, Geneva, Switzerland
M. Migliorati, L. Palumbo
URLS, Rome, Italy

The beam coupling impedance could lead to limitations in beam brightness and quality, and therefore it needs accurate quantification and continuous monitoring in order to detect and mitigate high impedance sources. In the CERN machines, for example, kickers and collimators are expected to be the main contributors to the total imaginary part of the transverse impedance. In order to detect the other sources, a beam based measurement was developed: from the variation of betatron phase beating with intensity, it is possible to detect the locations of main impedance sources. In this work we present the application of the method with beam measurements in the CERN PS, SPS and LHC.

Slides THOBB102 [7.224 MB]