IPAC2018 - List of Keywords (alignment)

Paper	Title	Other Keywords	Page
MOPMF024	Dipole Field Quality and Dynamic Aperture for FCC-hh	dipole, injection, dynamic-aperture, optics	137
	B. Dalena CEA/IRFU, Gif-sur-Yvette, France D. Boutin, A. Chancé CEA/DRF/IRFU, Gif-sur-Yvette, France B.J. Holzer, S. Izquierdo Bermudez, D. Schoerling, D. Schulte CERN, Geneva, Switzerland
	Funding: This Research and Innovation Action project submitted to call H2020-INFRADEV-1-2014-1 receives funding from the European Union's H2020 Framework Program under grant agreement No. 654305. The Nb₃Sn dipole design for the hadron machine option of the Future Circular Colliders enters in an intense and long R&D phase. As a result, more realistic dipole field quality evaluations are available for beam dynamics studies. The paper discusses the impact of the main dipole field quality on the first and second order design of the hadron machine and on its dynamic aperture.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF024
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MOPMF057	FCC-ee Dynamic Aperture Studies and Frequency Map Analysis	dynamic-aperture, emittance, resonance, sextupole	244
	T. Tydecks, S. Aumon, T.K. Charles, B. Härer, B.J. Holzer, K. Oide, Y. Papaphilippou, J. Wenninger CERN, Geneva, Switzerland
	The FCC-ee Lepton Collider will provide e⁺e⁻ collisions in the beam energy range of 45.6 GeV to 182.5 GeV. FCC-ee will be a precision measurement tool for Z, W, H and t physics with expected luminosities of 2.07× 10³⁶ cm^-2 s^-1 at the Z-pole and 1.3 × 10³⁴ cm^-2 s^-1 at the tt^- threshold. In order to achieve the foreseen luminosities, a vertical β^* of 1 mm to 2 mm is mandatory. Dynamic aperture and frequency map analysis for the 97.75 km machine with such a squeezed accelerator optics are studied. Furthermore, effects of machine misalignments on dynamic and momentum aperture are presented and estimations for the required tolerances are given
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF057
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MOPML035	Betatron Frequencies in Cotangential Trajectory Accelerator for Proton Beam Therapy	betatron, cyclotron, resonance, extraction	485
	T. Aoki, F. Ebina, C. Hori, Y. Nakashima, T. Seki Hitachi Ltd., Ibaraki-ken, Japan T. Hae Hitachi Ltd., Hitachi Research Laboratory, Ibaraki-ken, Japan
	It is important that downsizing of an accelerator for spreading proton beam therapy. The synchrotron is the solution of accelerator of proton beam therapy system which can vary energy of extracted beam in the range of from 70 MeV to 235 MeV with a merit of requiring no energy selection system. In order to downsize accelerator with above merit, we suggested smaller variable energy accelerator which have cotangential trajectories. This new type accelerator is expected to realize variability of beam energy with static main magnetic field. One of technological problems of this new type accelerator is stability of betatron oscillation. We plan to utilize week focusing field as main magnetic field, which is decreasing on the radial direction outward and uniform in longitudinal direction, of this new type accelerator. We found the main magnetic field which realizes stable betaron oscillations in the range of from 70 MeV to 235 MeV as the result of estimating the betaron oscillations in this main field by numerical calculation. We report new type accelerator concept and results of analysis of betatron oscillation in cotangential trajectories.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML035
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TUPAF052	Effects of Electrostatic Septum Alignment on Particle Loss During Slow Extraction at CERN SPS	extraction, simulation, operation, septum	826
	J. Prieto, Y. Dutheil, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel, F.M. Velotti CERN, Geneva, Switzerland M.A. Kagan SLAC, Menlo Park, California, USA
	Slow extraction is an intrinsically lossy process that splits the beam with an electrostatic septum (ES), employing a thin-wire array to delimit the high electric field region that deflects the beam into the extraction channel. At CERN's Super Proton Synchrotron (SPS) the ES is over 16 m long and composed of 5 separate units containing separate wire-arrays that can be moved independently. The tanks are all mounted on a single support structure that can move the ensemble coherently. As a result, the large number of positional degrees of freedom complicates the alignment procedure in operation. Obtaining and maintaining accurate alignment of the ES with the beam is therefore crucial for minimising beam loss. In this paper, we investigate the alignment procedure for different operational scenarios using particle tracking simulations to understand the beam loss along the extraction straight as a function of the relative positions of each of the 5 separate ES units. An important aspect of the study was to understand the required alignment tolerance to achieve optimum extraction efficiency for a given configuration of wire-array thicknesses.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF052
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TUPAF055	Progress Toward a Dynamic Extraction Bump for Slow Extraction in the CERN SPS	extraction, simulation, septum, closed-orbit	838
	L.S. Stoel, M. Benedikt, M.A. Fraser, B. Goddard, J. Prieto, F.M. Velotti CERN, Geneva, Switzerland
	The possibility of reducing the angular spread of slow extracted particles with a time-dependent extraction bump at the CERN Super Proton Synchrotron (SPS) is under investigation. In order to create this so-called dynamic bump, two orthogonal knobs were designed to enable independent movements of the beam in position and angle at the upstream end of the electrostatic extraction septum (ES). With the present slow extraction scheme, simulations show that the use of a dynamic bump can reduce the angular spread at the ES by roughly a factor two and reduce beam loss on the ES. A reduction in the angular spread is also a prerequisite to exploit the full potential of other loss reduction techniques being considered for implementation at the SPS, like the active or passive diffusers planned for installation upstream of the ES in 2018. In this paper, the simulated loss reduction with a dynamic bump alone or in combination with other loss reduction techniques will be assessed, the first beam-based tests of the dynamic bump presented, the details of its implementation examined and its potential for future operation at the SPS discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF055
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TUPAF056	The CERN-ELENA Electron Cooler Magnetic System	solenoid, electron, gun, proton	842
	G. Tranquille, L.V. Jørgensen CERN, Geneva, Switzerland D. Luckin, R.J. Warner Tesla Engineering Limited, West-Sussex, United Kingdom
	Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler the performance of which is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the efficient recuperation of the electrons in the collector and the quality of the guiding magnetic field ensure an optimal performance of the cooler. The ELENA cooler is a compact device incorporating an adiabatic expansion to reduce the electron beam temperature as well as electrostatic bending plates for efficient collection of the electron beam. The transverse components of the longitudinal field in the cooling section must be kept small (Bt/Bl ≤ 5x10-4) to ensure a minimal perturbation to the electron beam transverse temperature. The longitudinal field itself needs to be as low as possible such that the distortion to the closed orbit of the circulating ion beam due to the short 90° toroids is kept as small as possible. We present the solutions chosen to design and construct a magnetic system within the above constraints as well as the setup used to measure and optimise the magnetic field components.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF056
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TUPAF067	Beam Physics Analysis of the ESS RFQ Non-Conformities	rfq, emittance, ion-source, radio-frequency-quadrupole	886
	A. Ponton ESS, Lund, Sweden
	During the fabrication of an RFQ, deviation from the perfect geometry will occur during assembling, brazing and machining the different parts. These geometrical defects will also impact the theoretical inter-vane voltage, given by the beam dynamics, even if tuners can correct partially the effect of the manufacturing. The combination of geometrical and voltage errors will alter the electro-magnetic field in the axis region leading to a degradation of the beam quality. The study proposes to expand the method to treat the voltage errors presented in * , in which the deviation from the theoretical parameters is represented by a sum of periodic functions of z, to the machining errors and to include positioning and alignment errors. The results of the error study will be presented. Then, using the results of the fabrication control by metrology, we will analyze the impact of the real RFQ geometry on the beam transport and compare the results will the prediction from the error study. * A. Ponton et al., "Voltage errors studies in the ESS RFQ", presented at the 7th Int. Particle Accelerator Conf. (IPAC'16), Busan, Korea, May 2016, paper THPMB039.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF067
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TUPAF079	Scaled Alvarez-Cavity Model Investigations for the UNILAC Upgrade	DTL, cavity, simulation, pick-up	916
	M. Heilmann, X. Du, L. Groening, M. Kaiser, S. Mickat, M. Vossberg GSI, Darmstadt, Germany A. Seibel IAP, Frankfurt am Main, Germany
	The 1:3 scaled aluminum model of an Alvarez-type cavity with 10 gaps was used for comparison of simulation with measurement for the frequency and the electric field on axis. The scaled frequency is 325.224 MHz and an Alvarez cavity has a small frequency tuning range. With this scaled model it was possible to apply different stem configurations for each drift tube to damp parasitic modes and to increase the field stability. The new drift tubes have an optimized free-formed profile on the end plates in order to increase the shunt impedance. In special the assembly, positioning and alignment of the drift tubes can be tested and the frequency change can be investigated in this respect.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF079
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TUPAL075	Mechanical Design and Error Analysis of a 325 MHz IH-DTL Test Cavity	DTL, cavity, simulation, linac	1186
	R. Tang, C.T. Du, X. Guan, K.D. Man, C.-X. Tang, X.W. Wang, Q.Z. Xing, S.X. Zheng TUB, Beijing, People's Republic of China J. Li NUCTECH, Beijing, People's Republic of China
	A 325 MHz interdigital H-mode drift tube linac (IH-DTL) test cavity with a modified KONUS beam dynamics is under fabrication at Tsinghua University. The inner diameter of the tank increases from 196.8 to 232.6 mm. The mechanical design is considered carefully because of its small geometry. A three-piece design has been adopted in the mechanical design. The error analysis is carried out to determine the error requirement of machining and alignment. The details of mechanical design and error analysis is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL075
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TUPMF006	Pulsed Wire Measurements of a High Field Gradient Quadrupole Wiggler	quadrupole, wiggler, laser, wakefield	1257
	M. Kasa, A. Zholents ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Alignment of the quadrupoles in a quadrupole wiggler to sub micrometer precision is required for the collinear wakefield accelerator that is under consideration at Argonne National Laboratory for a compact Free-Electron Laser [1]. The pulsed wire measurement method is the only technique that we are aware of that allows for sub micrometer precision and the ability to distinguish between the various quadrupoles within the wiggler. A one period prototype wiggler was manufactured and subsequently measured using the pulsed wire technique. The goal of the measurements was to verify that the magnetic centers of each quadrupole could be located and aligned to each other within the required precision. The method and results are described. [1] A. Zholents, et al., "A preliminary design of the collinear dielectric wakefield accelerator", Nucl. Instrum. Meth. A829 (2016) 190-193.
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TUPMF040	Alignment of Current Strips at the Canadian Light Source	closed-orbit, undulator, electron, vacuum	1342
	W.A. Wurtz CLS, Saskatoon, Saskatchewan, Canada Q.L. Zhang SINAP, Shanghai, People's Republic of China
	The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source will employ a 180 mm period elliptically polarizing undulator (EPU180), which will have significant impacts on beam dynamics with large tune shifts and reductions in dynamic aperture. Current strips mounted to the vacuum chamber are intended to mitigate the effects of EPU180 with each strip powered by an independent power supply. It is important to accurately model the current strips in order to calculate the required compensation. We model the current strips as straight wires, parallel to the electron beam, with small horizontal and vertical displacements from their nominal positions. As the real current strips are not completely straight, this is an effective model, but justified as we are mostly interested in the magnetic field integrated along the strips. By activating two strips and measuring the ratio of the two currents needed to minimize closed orbit distortion in the horizontal and vertical planes, we can find the effective horizontal and vertical displacements of the straight wires in the model. Our goal is to create an effective model of the strips from beam-based measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF040
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TUPML078	Fast Quadrupole Beam Based Alignment Using AC Corrector Excitations	quadrupole, closed-orbit, optics, synchrotron	1727
	Z. Martí, G. Benedetti, U. Iriso ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	A novel method to perform Beam Based Alignment has been tested at ALBA using the 10kHz fast acquisition BPMs together with an AC excitation of the corrector magnets allowing to speed up the beam based alignment process. The former approach relies on software synchronization and tango device servers to execute a series of DC corrector magnets and quadrupoles settings designed to avoid the quadrupole hysteresis effects. The approach that we present here is simpler, gives the same level of accuracy and precision and speeds up the measurement by a factor 10. The total measurement time has changed from 5 hours to 10 minutes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML078
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WEPAF066	The New CLIC Main Linac Installation and Alignment Strategy	target, quadrupole, linac, collider	1979
	H. Mainaud Durand, J. Gayde, J. Jaros, M. Sosin, A. P. Zemanek CERN, Geneva, Switzerland V. Rude ESGT-CNAM, Le Mans, France
	A complete solution has been proposed for the pre-alignment of the CLIC main linac in 2012 for the Conceptual Design Report. Two recent studies provide new perspectives for such a pre-alignment. First in a study on Particle Accelerator Components' Metrology and Alignment to the Nanometre scale (PACMAN), new solutions to fiducialise and align different types of components within a micrometric accuracy on the same support were proposed and validated, using a stretched wire. Secondly, a 5 degree of freedom adjustment platform with plug-in motors showed a very accurate and efficient way to adjust remotely components. By combining the results of both studies, two scenarios of installation and alignment for the CLIC main linac are proposed, providing micrometric and automatized solutions of micrometric assembly, fiducialisation and alignment in metrological labs or in the tunnel. In this paper, the outcome of the two studies are presented; the two scenarios of installation and alignment are then detailed and discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF066
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WEPAF067	Alignment and Monitoring Systems for Accelerators and Experiments Based on BCAM - First Results and Benefits of Systems Developed for ATLAS, LHCb and HIE-ISOLDE	detector, monitoring, ISOL, target	1983
	J. Gayde, B. Di Girolamo, Y. Kadi, G. Kautzmann, F. Klumb, R. Lindner, D. Mergelkuhl, L. Pontecorvo, M. Raymond, P. Sainvitu, E. Thomas CERN, Geneva, Switzerland F. Blanc, P. Stefko EPFL, Lausanne, Switzerland
	In the last few years alignment and monitoring systems based on BCAM* cameras active sensors, or their HBCAM evolution, have been developed at the request of the Technical Coordination of LHC experiments and HIE-ISOLDE facility Project Leader. ADEPO (ATLAS DEtector POsition) has been designed to speed up the precise closure - 0.3 mm - of large detector parts representing in total ~2500 tons. For LHCb a system has been studied and installed to monitor the positions of the Inner Tracker stations during the LHCb dipole magnet cycles. The MATHILDE (Monitoring and Alignment Tracking for HIE-ISOLDE) system has been developed to fulfil the alignment and monitoring needs for components of the LINAC enclosed in successive Cryo-Modules. These systems have been in each case configured and adapted to the objectives and environmental conditions: low space for integration; presence of magnetic fields; exposure to non-standard environmental conditions such as high vacuum and cryogenic temperatures. After a short description of the different systems and of the environmental constraints, this paper summarizes their first results, performances and their added value. * BCAM: Brandeis CCD Angle Monitor, http://alignment.hep.brandeis.edu/Devices/BCAM/
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WEPAF069	Evaluation of Frequency Scanning Interferometer Performances for Surveying, Alignment and Monitoring of Physics Instrumentation	laser, target, luminosity, cavity	1990
	J. Gayde, S.W. Kamugasa CERN, Geneva, Switzerland
	During the last three years, the performance of Frequency Scanning Interferometry, accurate to a few micrometres, has been evaluated at CERN in the frame of the PACMAN project. Improvements have been studied and tested to make it better suited for typical alignment and survey conditions in accelerators and experiments. The results of these developments and tests, coupled with the multi-channel capability of the system, and its compactness which eases its integration in the area to be surveyed, offer a wide scope of possible applications for in-situ large scale metrology for physics equipment and facility elements. Furthermore, the fact that the system electronics can be placed far away from the position to be measured, allows the system to be used in confined and hazardous spaces. This paper briefly describes the system and its improvements. It gives the precision obtained for distance measurements and for the 3D point reconstruction based on FSI observations in the case of CLIC component fiducialisation.
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WEPAF080	Beam Size Measurements Based on Movable Quadrupolar Pick-ups	pick-up, emittance, embedded, quadrupole	2028
	A. Sounas, M. Gąsior, T. Lefèvre, A. Mereghetti, J. Olexa, S. Redaelli, G. Valentino CERN, Geneva, Switzerland
	Measurements with quadrupolar pick-ups (PU) have attracted particular interest as non-intercepting diagnostics for determining the transverse beam size. They are based on processing the signals of an electromagnetic PU for the extraction of the second-order moment, which contains information about the beam size. Despite the simplicity of the concept, quadrupololar measurements have always been highly challenging in reality. This comes from the fact that the quadrupolar moment constitutes only a very small part of the total PU signal dominated by the intensity and the position signals. Therefore, the beam size information can easily be lost due to small imperfections in the signal processing chain, such as asymmetries in the electronics and cables. In this paper, we present a new method for quadrupolar measurements using movable PUs. Through position and aperture scans, our technique minimizes the parasitic beam position signal and takes into account imperfections of the PU, cables and electronics, thus enabling an efficient auto-calibration of the measurement system. Preliminary studies, using collimators with embedded electrostatic PUs in the LHC at CERN, have shown very promising results.
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WEPAL070	HLS System to Measure the Location Changes in Real Time of PAL-XFEL Devices	FEL, linac, real-time, survey	2345
	H. J. Choi, J.H. Han, H.-S. Kang, S.H. Kim, H.-G. Lee, S.B. Lee PAL, Pohang, Kyungbuk, Republic of Korea
	All components of PAL-XFEL (Pohang Accelerator Laboratory's X-ray free-electron laser) were completely installed in December 2015, and Hard X-ray 0.1nm lasing achieved through its beam commissioning test and machine study on March 16, 2017. The beam line users has been performing various tests including pump-probe X-ray scattering, time-resolved x-ray liquidography, etc in the hard x-ray beam line since March 22. The energy and flux of x-ray photon beam generated from XFEL and synchronization timing should be stable to ensure successful time-resolved tests. Several parts that comprise the large scientific equipment should be installed and operated at precise three-dimensional location coordinates X, Y, and Z through survey and alignment to ensure their optimal performance. As time goes by, however, the ground goes through uplift and subsidence, which consequently changes the coordinates of installed components and leads to alignment errors ΔX, ΔY, and ΔZ. As a result, the system parameters change, and the performance of the large scientific equipment deteriorates accordingly. Measuring the change in locations of systems comprising the large scientific equipment in real time would make it possible to predict alignment errors, locate any region with greater changes, realign components in the region fast, and shorten the time of survey and alignment. For this purpose, a HLS's (hydrostatic leveling sensor) with 0.2um of resolution are installed and operated in a waterpipe of total length 1km in the PAL-XFEL building. This paper is designed to introduce the operating principle of the HLS, the installation and operation of the HLS system, and how to utilize the HLS system in order to ensure beam stabilization.
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WEPMF066	Fabrication of Split-Section X-band Structure Using Elastic Averaging	vacuum, coupling, electron, gun	2521
	P. Borchard, S.A. Appert, J.S. Hoh Dymenso LLC, San Francisco, USA
	Conventional accelerator structures are manufactured using axial stacks of cylindrical components which, when brazed together, form the accelerator cell structure. Splitting the accelerator structure into two sections along the beam axis allows for a significant reduction in part count and vacuum joint length. The resultant single and coplanar vacuum joint between the two split sections allows for joining techniques such as electron beam welding or brazing of the parts to form the accelerator vacuum envelope. High precision alignment of the two sections is achieved through an elastic averaging interface coupling where improved accuracy is derived from the averaging of errors over a large number of relatively compliant contacting members. The monoblock split sections allow for highly optimized cooling configurations with enhanced heat removal in high heat flux regions, reducing vacuum wall thermal stresses and enabling higher power operation. This paper describes the engineering and manufacturing of four generations of brazed and electron beam welded X-band accelerator structures at both 9.3 GHz and 11.4 GHz frequencies.
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WEPMF078	Assembly of the DQW Crab Cavity Cryomodule for SPS Test	cavity, cryomodule, vacuum, controls	2561
	M. Garlaschè, K. Artoos, R. Calaga, O. Capatina, T. Capelli, N. El Kbiri, D. Lombard, P.F. Marcillac, P. Minginette, M. Narduzzi, L.R.A. Renaglia, J. Roch, J.S. Swieszek CERN, Geneva, Switzerland A. Krawczyk, B. Prochal IFJ-PAN, Kraków, Poland
	RF Crab Cavities are an essential part of the High Luminosity Upgrade of the LHC accelerating complex. Two concepts of such superconducting systems are being developed: the Double Quarter Wave (DQW) and the RF Dipole (RFD). A prototype cryomodule - hosting two DQW cavities - has been fabricated and assembled for validation tests to be carried out in the Super Proton Synchrotron (SPS) at CERN. An overview of the main cryomodule components is presented, together with the system features and main fabrication requirements. The preparatory measures for cryomodule assembly, the execution and lessons learned are also discussed.
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WEPML073	Research on Magnetic Center Measurement of Quadrupole and Sextupole Using Vibrating Wire Alignment Technique in HEPS-TF	sextupole, quadrupole, background, multipole	2860
	L. Wu, C. H. Li, H. Qu, H. Wang, X.L. Wang IHEP, Beijing, People's Republic of China H.Y. Zhu Institute of High Energy Physics (IHEP), People's Republic of China
	In order to meet the extremely low emittance re-quirement, the magnets in the storage ring of High Energy Photon Source(HEPS) need to have a stable support and precise positioning. Vibrating wire align-ment technique can be used to pre-align the quadru-poles and sextupoles on one girder with high preci-sion. Research of vibrating wire alignment technique is one important project of HEPS Test Facility (HEPS-TF). In HEPS-TF, the key and difficult technologies of HEPS should be researched and developed. This paper introduces the principle of the vibrating wire align-ment technique and the measurement system in brief. The magnetic center measurement of quadrupole and sextupole using vibrating wire will be introduced in detail. It concludes the measurement procedure, mag-netic field distribution, measurement repeatability, sag correction and magnet adjustment measurement. The research of vibrating wire has get a better precision than the aim. The magnetic center measurement preci-sion reach to ±3μm and the magnet adjustment error is less than 6μm.
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WEPML075	Test of Magnet Girder Prototypes for HEPS-TF	coupling, HOM, photon, site	2863
	H. Wang, C. H. Li, S.J. Li, J. Liu, H. Qu, Z. Wang, L. Wu IHEP, Beijing, People's Republic of China H.Y. Zhu Institute of High Energy Physics (IHEP), People's Republic of China
	Auto-tuning magnet girder is one of the key technolo-gies to be solved for HEPS-TF (Test Facility of High Ener-gy Photon Source). The girder should have high adjusting accuracy, high stability and can be beam-based aligned, to obtain the stability requirements of beam orbit. There are two girders developed, and the tests have been done. The accuracy of girder motion is within 10 microns while the adjusting range is 1 mm and the resolution is better than 1 microns, the natural frequency is higher than 24 Hz.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML075
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THPAF039	IP Orbit Correction Update for HL-LHC	quadrupole, optics, dipole, cavity	3048
	D. Gamba, R. De Maria CERN, Geneva, Switzerland
	Funding: Research supported by the HL-LHC project. The HL-LHC design foresees a substantial modification of the LHC layout next to the low beta Interaction Points (IPs), namely IP1 and IP5. The inner triplets will be replaced by larger aperture ones to achieve lower beta at the IPs and crab cavities (CCs) will be installed. This will add new constraints to the orbit control, which required a careful choice of location and strength of the new orbit correctors to be installed in the area. The new orbit correction system will need to correct for the unavoidable imperfections, but also provide the necessary flexibility for implementing and optimising the crossing scheme. Detailed studies of the HL-LHC layout versions HLLHCV1.0 and HLLHCV1.1 were already performed. This paper is the continuation of these works and is based on the latest layout HLLHCV1.3. A simplification of the previous analysis is proposed that helps to identify the dominant imperfections. The expected performance and tolerances of the present layout are presented.
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THPAL017	From design to alignment of ThomX quadrupoles	quadrupole, simulation, multipole, HOM	3660
	C. Vallerand, R. Marie, H. Monard LAL, Orsay, France J. Campmany, J. Marcos, V. Massana ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain J. Chavanne, G. Le Bec ESRF, Grenoble, France M.-E. Couprie, A. Lestrade, A. Loulergue, F. Marteau, M. Ros SOLEIL, Gif-sur-Yvette, France
	Quadrupoles for Thomx Facility have been carefully designed and measured due to high constraints of the storage ring. The need of a compact accelerator, 70 m2 on floor, as well as a beam life time of 20 ms, led to the following requirements for the quadrupole : a gradient of 5 T/m with 20.5 mm radius bore, harmonic content better than few 1.10^-3 at the reference radius of 18 mm, no cross-talk with sextupole placed within 5 cm and a precision of the magnetic axis of 100 μm and the roll angle of 300 μrad for measurements and alignment. Total of 41 quadrupoles have been built and all measured by a rotating coil at ALBA and SOLEIL, providing multipole components, transfer function and magnetic center. Cross-check measurements have also been carried out with a versatile stretched wire from ESRF at LAL. This paper mainly describes results of simulations with OPERA and RADIA and provides the results of measurements with these three benches. These results will be compared and highlighted important points for the alignment and installation of quadrupoles in an accelerator.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL017
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THPAL022	Precision Magnet Measurements for Deuteron Beam Transport	quadrupole, dipole, multipole, neutron	3670
	R.A. Marsh, D.J. Gibson, B. Rusnak LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. A versatile 4 MeV and 7 MeV deuteron beam transport line is being developed at Lawrence Livermore National Laboratory in support of an accelerator-driven source for fast neutron imaging. The beamline design requires precise alignment and high quality quadrupole magnets to transport a low emittance beam to the target through diagnostics, a bending dipole, and a differential pumping line with minimum beam loss and emittance growth. Vector magnetic field measurements of these magnets have been completed using a mobile version of an existing magnet mapping capability. This magnet mapping system is being used to ensure the delivered magnets meet the field uniformity specification, and that the mountings are aligned and capable of reaching the specified alignment tolerances. Details of the magnet measurement and calibration process that enable accurate field measurements to represent the intrinsic magnet field quality and not the systematic error of the measurement setup are presented.
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THPAL158	Development of an Half-Cell Accelerating Structure in Tsinghua	cavity, simulation, GUI, radiation	4023
	M.M. Peng, W. Gai, J. Shi, Z.H. Wang, H. Zha TUB, Beijing, People's Republic of China
	The half-cell high gradient accelerating structure is attractive for its easy manufacturing and good alignment. A structure with 12 cells has been designed for the frequency of 11.424 GHz and a cold test will be conducted. Two different mechanical factory manufacture with same machining drawing and the results will be compared.
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THPMF001	Beam Dynamics Studies for Beam Focusing and Solenoid Alignment at SINBAD	solenoid, emittance, linac, gun	4026
	S. Yamin, R.W. Aßmann, B. Marchetti, J. Zhu DESY, Hamburg, Germany
	SINBAD (Short INnovative Bunches and Accelerators at DESY) facility under construction at DESY plans to host several experiments for the production of ultra-short bunches and will be a test facility for high-gradient compact novel acceleration techniques. The ARES (Accelerator Research Experiment at SINBAD) linac is foreseen to produce ultra-short bunches to be injected e.g. into Novel Dielectric Laser Acceleration structures or Laser Wake-Field Acceleration experiments. The work presented in this paper is based on optimization of the focusing system consisting of solenoids for the ARES, which have been studied earlier in detail but is revisited for updated beamline. Moreover tolerances for the possible misalignment of solenoids are presented investigating the effect on the beam properties during the gun commissioning. * J. Zhu, R. Assmann, U. Dorda, B. Marchetti, "Matching sub-fs electron bunches for laser-driven plasma acceleration at SINBAD", Nucl. Instrum. Methods Phys. Res., Sect. A 829, 229 (2016)
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THPMF054	Beam Performance Simulation with Error Effects and Correction on HEPS Design	multipole, optics, sextupole, emittance	4186
	D. Ji, X. Cui, Z. Duan, Y. Jiao, Y. Wei, Y.L. Zhao IHEP, Beijing, People's Republic of China
	The High Energy Photon Source (HEPS) is a 6-GeV, ul-tralow-emittance kilometre-scale storage ring light source to be built in China. In this paper, the progress of the error and correction effect study on HEPS over the past one year will be presented, including error requirement and correction progress update. And beam performance eval-uation with static error and correction on orbit, optics, emittance and dynamic aperture will be presented.
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THPMF064	Beam Based Alignment of SRF Cavities in an Electron Injector Linac	cavity, linac, emittance, electron	4219
	F. Hug KPH, Mainz, Germany M. Arnold, T. Bahlo, J. Pforr, N. Pietralla TU Darmstadt, Darmstadt, Germany
	Funding: Funded by DFG through Cluster of Excellence EXC 1098/2014 "PRISMA" and RTG 2128 "AccelencE" and by the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871 Proper alignment of accelerating cavities is an important issue concerning beam quality of accelerators. In particular SRF cavities of injector linacs using high accelerating gradients on low beta electron beams can affect the beam quality significantly when not aligned perfectly. On the other hand knowing the exact position of every cavity after several cool-down cycles of a cryomodule can be difficult depending on the cryomodule design. We will report on operational experience on the SC injector of the Darmstadt superconducting linac and ERL (S-DALINAC) showing unexpected effects on beam dynamics and beam quality. Operators could observe transverse beam deflections by changing accelerating phases of the injector SRF-cavities while a growth of tranverse emittance occurred at the same time. As beam currents in the S-DALINAC injector do never exceed 100 μA and the effects could even be observed at nA beam currents space-charge effects could be eliminated to be the reason for these observations. In this work we will report on the possibility to align SRF cavities after cooldown by measuring the transverse deflection of the beam and compare results with beam dynamics simulations.
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THPMK020	Beam-Based Alignment Procedures for Small Gap in-Vacuum Undulators at the Taiwan Photon Source	photon, undulator, MMI, electron	4342
	Y.-C. Liu, J.C. Huang, F.H. Tseng NSRRC, Hsinchu, Taiwan
	We have developed a beam-based alignment procedure for small gap IVUs (In-vacuum undulators) at TPS, which allow us to measure the field center and mechanical canter of IVUs with 0.1 mm accuracy. The measurement method and results are presented in this paper.
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THPML081	Beam-Based Measurements of the ISAC-II Superconducting Heavy Ion Linac	cavity, linac, ISAC, TRIUMF	4841
	S. Kiy, R.E. Laxdal, M. Marchetto, S.D. Rädel, O. Shelbaya TRIUMF, Vancouver, Canada
	Preparation for experiments, which typically run for one to two weeks in the ISAC-II facility at TRIUMF, requires some amount of overhead, limiting the efficiency of the facility. Efforts are underway to improve the ISAC-II linac model to reduce this overhead while also improving the quality of the delivered ion beam. This can be accomplished with beam-based measurements and corrections of alignment, cavity gradients, focal strengths, and more. A review of the present state of the linac will be given, including measured mis-alignments and other factors that affect the reproducibility of tunes. The outlook on expected improvements will also be summarized, including progress on the automatic phasing of cavities with a focus on integration to the High Level Application platform being developed at TRIUMF. Lastly, a summary will be given on the expected paradigm shift in the tuning approach taken: moving from re-active tuning by operators or beam delivery experts to pro-active measurements and investigations, version-controlled tunes, and continuous feedback from beam physicists.
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THPML127	Alignment and Installation for the FELiChEM project	FEL, laser, network, controls	4977
	W. Wang, Zhang, H.T. H.T, X.Y. He, D.R. Xu USTC/NSRL, Hefei, Anhui, People's Republic of China
	Funding: Work supported by National Natural Science Foundation of China (11705199) and China Postdoctoral Science Foundation (2017M622024) FELiChEM is a new experimental facility under construction at the University of Science and Technology of China. There are more than one hundred important devices to construct it, which core device is two free electron laser oscillators generating middle-infrared and far-infrared laser and covering the spectral range of 25-200μm. The optical cavity is an important component of oscillator which very sensitive to misalignment errors of the mirror, due to its near-concentric and symmetric structure. High precision alignment and installation is necessary to ensure the smooth implementation of the FELiChEM project. Laser tracker and Level are used to install this devices according to the alignment control network. An efficient and high-precision alignment method based on autocollimator and photoelectric auto-collimator is used to align optical cavity of oscillator. This methods is proven to be effective and meet the tolerances by multiple means.
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Paper

Title

Other Keywords

Page

MOPMF024

Dipole Field Quality and Dynamic Aperture for FCC-hh

dipole, injection, dynamic-aperture, optics

137

B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
D. Boutin, A. Chancé
CEA/DRF/IRFU, Gif-sur-Yvette, France
B.J. Holzer, S. Izquierdo Bermudez, D. Schoerling, D. Schulte
CERN, Geneva, Switzerland

Funding: This Research and Innovation Action project submitted to call H2020-INFRADEV-1-2014-1 receives funding from the European Union's H2020 Framework Program under grant agreement No. 654305.
The Nb₃Sn dipole design for the hadron machine option of the Future Circular Colliders enters in an intense and long R&D phase. As a result, more realistic dipole field quality evaluations are available for beam dynamics studies. The paper discusses the impact of the main dipole field quality on the first and second order design of the hadron machine and on its dynamic aperture.

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MOPMF057

FCC-ee Dynamic Aperture Studies and Frequency Map Analysis

dynamic-aperture, emittance, resonance, sextupole

244

T. Tydecks, S. Aumon, T.K. Charles, B. Härer, B.J. Holzer, K. Oide, Y. Papaphilippou, J. Wenninger
CERN, Geneva, Switzerland

The FCC-ee Lepton Collider will provide e⁺e⁻ collisions in the beam energy range of 45.6 GeV to 182.5 GeV. FCC-ee will be a precision measurement tool for Z, W, H and t physics with expected luminosities of 2.07× 10³⁶ cm^-2 s^-1 at the Z-pole and 1.3 × 10³⁴ cm^-2 s^-1 at the tt^- threshold. In order to achieve the foreseen luminosities, a vertical β^* of 1 mm to 2 mm is mandatory. Dynamic aperture and frequency map analysis for the 97.75 km machine with such a squeezed accelerator optics are studied. Furthermore, effects of machine misalignments on dynamic and momentum aperture are presented and estimations for the required tolerances are given

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MOPML035

Betatron Frequencies in Cotangential Trajectory Accelerator for Proton Beam Therapy

betatron, cyclotron, resonance, extraction

485

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

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

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TUPAF052

Effects of Electrostatic Septum Alignment on Particle Loss During Slow Extraction at CERN SPS

extraction, simulation, operation, septum

826

J. Prieto, Y. Dutheil, M.A. Fraser, B. Goddard, V. Kain, L.S. Stoel, F.M. Velotti
CERN, Geneva, Switzerland
M.A. Kagan
SLAC, Menlo Park, California, USA

Slow extraction is an intrinsically lossy process that splits the beam with an electrostatic septum (ES), employing a thin-wire array to delimit the high electric field region that deflects the beam into the extraction channel. At CERN's Super Proton Synchrotron (SPS) the ES is over 16 m long and composed of 5 separate units containing separate wire-arrays that can be moved independently. The tanks are all mounted on a single support structure that can move the ensemble coherently. As a result, the large number of positional degrees of freedom complicates the alignment procedure in operation. Obtaining and maintaining accurate alignment of the ES with the beam is therefore crucial for minimising beam loss. In this paper, we investigate the alignment procedure for different operational scenarios using particle tracking simulations to understand the beam loss along the extraction straight as a function of the relative positions of each of the 5 separate ES units. An important aspect of the study was to understand the required alignment tolerance to achieve optimum extraction efficiency for a given configuration of wire-array thicknesses.

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TUPAF055

Progress Toward a Dynamic Extraction Bump for Slow Extraction in the CERN SPS

extraction, simulation, septum, closed-orbit

838

L.S. Stoel, M. Benedikt, M.A. Fraser, B. Goddard, J. Prieto, F.M. Velotti
CERN, Geneva, Switzerland

The possibility of reducing the angular spread of slow extracted particles with a time-dependent extraction bump at the CERN Super Proton Synchrotron (SPS) is under investigation. In order to create this so-called dynamic bump, two orthogonal knobs were designed to enable independent movements of the beam in position and angle at the upstream end of the electrostatic extraction septum (ES). With the present slow extraction scheme, simulations show that the use of a dynamic bump can reduce the angular spread at the ES by roughly a factor two and reduce beam loss on the ES. A reduction in the angular spread is also a prerequisite to exploit the full potential of other loss reduction techniques being considered for implementation at the SPS, like the active or passive diffusers planned for installation upstream of the ES in 2018. In this paper, the simulated loss reduction with a dynamic bump alone or in combination with other loss reduction techniques will be assessed, the first beam-based tests of the dynamic bump presented, the details of its implementation examined and its potential for future operation at the SPS discussed.

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TUPAF056

The CERN-ELENA Electron Cooler Magnetic System

solenoid, electron, gun, proton

842

G. Tranquille, L.V. Jørgensen
CERN, Geneva, Switzerland
D. Luckin, R.J. Warner
Tesla Engineering Limited, West-Sussex, United Kingdom

Phase space compression of the antiproton beam in ELENA will be performed by a new electron cooler the performance of which is greatly influenced by the properties of the electron beam. Careful design of the electron gun electrodes, the efficient recuperation of the electrons in the collector and the quality of the guiding magnetic field ensure an optimal performance of the cooler. The ELENA cooler is a compact device incorporating an adiabatic expansion to reduce the electron beam temperature as well as electrostatic bending plates for efficient collection of the electron beam. The transverse components of the longitudinal field in the cooling section must be kept small (Bt/Bl ≤ 5x10-4) to ensure a minimal perturbation to the electron beam transverse temperature. The longitudinal field itself needs to be as low as possible such that the distortion to the closed orbit of the circulating ion beam due to the short 90° toroids is kept as small as possible. We present the solutions chosen to design and construct a magnetic system within the above constraints as well as the setup used to measure and optimise the magnetic field components.

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TUPAF067

Beam Physics Analysis of the ESS RFQ Non-Conformities

rfq, emittance, ion-source, radio-frequency-quadrupole

886

A. Ponton
ESS, Lund, Sweden

During the fabrication of an RFQ, deviation from the perfect geometry will occur during assembling, brazing and machining the different parts. These geometrical defects will also impact the theoretical inter-vane voltage, given by the beam dynamics, even if tuners can correct partially the effect of the manufacturing. The combination of geometrical and voltage errors will alter the electro-magnetic field in the axis region leading to a degradation of the beam quality. The study proposes to expand the method to treat the voltage errors presented in * , in which the deviation from the theoretical parameters is represented by a sum of periodic functions of z, to the machining errors and to include positioning and alignment errors. The results of the error study will be presented. Then, using the results of the fabrication control by metrology, we will analyze the impact of the real RFQ geometry on the beam transport and compare the results will the prediction from the error study.
* A. Ponton et al., "Voltage errors studies in the ESS RFQ", presented at the 7th Int. Particle Accelerator Conf. (IPAC'16), Busan, Korea, May 2016, paper THPMB039.

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TUPAF079

Scaled Alvarez-Cavity Model Investigations for the UNILAC Upgrade

DTL, cavity, simulation, pick-up

916

M. Heilmann, X. Du, L. Groening, M. Kaiser, S. Mickat, M. Vossberg
GSI, Darmstadt, Germany
A. Seibel
IAP, Frankfurt am Main, Germany

The 1:3 scaled aluminum model of an Alvarez-type cavity with 10 gaps was used for comparison of simulation with measurement for the frequency and the electric field on axis. The scaled frequency is 325.224 MHz and an Alvarez cavity has a small frequency tuning range. With this scaled model it was possible to apply different stem configurations for each drift tube to damp parasitic modes and to increase the field stability. The new drift tubes have an optimized free-formed profile on the end plates in order to increase the shunt impedance. In special the assembly, positioning and alignment of the drift tubes can be tested and the frequency change can be investigated in this respect.

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TUPAL075

Mechanical Design and Error Analysis of a 325 MHz IH-DTL Test Cavity

DTL, cavity, simulation, linac

1186

R. Tang, C.T. Du, X. Guan, K.D. Man, C.-X. Tang, X.W. Wang, Q.Z. Xing, S.X. Zheng
TUB, Beijing, People's Republic of China
J. Li
NUCTECH, Beijing, People's Republic of China

A 325 MHz interdigital H-mode drift tube linac (IH-DTL) test cavity with a modified KONUS beam dynamics is under fabrication at Tsinghua University. The inner diameter of the tank increases from 196.8 to 232.6 mm. The mechanical design is considered carefully because of its small geometry. A three-piece design has been adopted in the mechanical design. The error analysis is carried out to determine the error requirement of machining and alignment. The details of mechanical design and error analysis is presented.

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TUPMF006

Pulsed Wire Measurements of a High Field Gradient Quadrupole Wiggler

quadrupole, wiggler, laser, wakefield

1257

M. Kasa, A. Zholents
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Alignment of the quadrupoles in a quadrupole wiggler to sub micrometer precision is required for the collinear wakefield accelerator that is under consideration at Argonne National Laboratory for a compact Free-Electron Laser [1]. The pulsed wire measurement method is the only technique that we are aware of that allows for sub micrometer precision and the ability to distinguish between the various quadrupoles within the wiggler. A one period prototype wiggler was manufactured and subsequently measured using the pulsed wire technique. The goal of the measurements was to verify that the magnetic centers of each quadrupole could be located and aligned to each other within the required precision. The method and results are described.
[1] A. Zholents, et al., "A preliminary design of the collinear dielectric wakefield accelerator", Nucl. Instrum. Meth. A829 (2016) 190-193.

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TUPMF040

Alignment of Current Strips at the Canadian Light Source

closed-orbit, undulator, electron, vacuum

1342

W.A. Wurtz
CLS, Saskatoon, Saskatchewan, Canada
Q.L. Zhang
SINAP, Shanghai, People's Republic of China

The Quantum Materials Spectroscopy Centre beamline at the Canadian Light Source will employ a 180 mm period elliptically polarizing undulator (EPU180), which will have significant impacts on beam dynamics with large tune shifts and reductions in dynamic aperture. Current strips mounted to the vacuum chamber are intended to mitigate the effects of EPU180 with each strip powered by an independent power supply. It is important to accurately model the current strips in order to calculate the required compensation. We model the current strips as straight wires, parallel to the electron beam, with small horizontal and vertical displacements from their nominal positions. As the real current strips are not completely straight, this is an effective model, but justified as we are mostly interested in the magnetic field integrated along the strips. By activating two strips and measuring the ratio of the two currents needed to minimize closed orbit distortion in the horizontal and vertical planes, we can find the effective horizontal and vertical displacements of the straight wires in the model. Our goal is to create an effective model of the strips from beam-based measurements.

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TUPML078

Fast Quadrupole Beam Based Alignment Using AC Corrector Excitations

quadrupole, closed-orbit, optics, synchrotron

1727

Z. Martí, G. Benedetti, U. Iriso
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

A novel method to perform Beam Based Alignment has been tested at ALBA using the 10kHz fast acquisition BPMs together with an AC excitation of the corrector magnets allowing to speed up the beam based alignment process. The former approach relies on software synchronization and tango device servers to execute a series of DC corrector magnets and quadrupoles settings designed to avoid the quadrupole hysteresis effects. The approach that we present here is simpler, gives the same level of accuracy and precision and speeds up the measurement by a factor 10. The total measurement time has changed from 5 hours to 10 minutes.

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WEPAF066

The New CLIC Main Linac Installation and Alignment Strategy

target, quadrupole, linac, collider

1979

H. Mainaud Durand, J. Gayde, J. Jaros, M. Sosin, A. P. Zemanek
CERN, Geneva, Switzerland
V. Rude
ESGT-CNAM, Le Mans, France

A complete solution has been proposed for the pre-alignment of the CLIC main linac in 2012 for the Conceptual Design Report. Two recent studies provide new perspectives for such a pre-alignment. First in a study on Particle Accelerator Components' Metrology and Alignment to the Nanometre scale (PACMAN), new solutions to fiducialise and align different types of components within a micrometric accuracy on the same support were proposed and validated, using a stretched wire. Secondly, a 5 degree of freedom adjustment platform with plug-in motors showed a very accurate and efficient way to adjust remotely components. By combining the results of both studies, two scenarios of installation and alignment for the CLIC main linac are proposed, providing micrometric and automatized solutions of micrometric assembly, fiducialisation and alignment in metrological labs or in the tunnel. In this paper, the outcome of the two studies are presented; the two scenarios of installation and alignment are then detailed and discussed.

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WEPAF067

Alignment and Monitoring Systems for Accelerators and Experiments Based on BCAM - First Results and Benefits of Systems Developed for ATLAS, LHCb and HIE-ISOLDE

detector, monitoring, ISOL, target

1983

J. Gayde, B. Di Girolamo, Y. Kadi, G. Kautzmann, F. Klumb, R. Lindner, D. Mergelkuhl, L. Pontecorvo, M. Raymond, P. Sainvitu, E. Thomas
CERN, Geneva, Switzerland
F. Blanc, P. Stefko
EPFL, Lausanne, Switzerland

In the last few years alignment and monitoring systems based on BCAM* cameras active sensors, or their HBCAM evolution, have been developed at the request of the Technical Coordination of LHC experiments and HIE-ISOLDE facility Project Leader. ADEPO (ATLAS DEtector POsition) has been designed to speed up the precise closure - 0.3 mm - of large detector parts representing in total ~2500 tons. For LHCb a system has been studied and installed to monitor the positions of the Inner Tracker stations during the LHCb dipole magnet cycles. The MATHILDE (Monitoring and Alignment Tracking for HIE-ISOLDE) system has been developed to fulfil the alignment and monitoring needs for components of the LINAC enclosed in successive Cryo-Modules. These systems have been in each case configured and adapted to the objectives and environmental conditions: low space for integration; presence of magnetic fields; exposure to non-standard environmental conditions such as high vacuum and cryogenic temperatures. After a short description of the different systems and of the environmental constraints, this paper summarizes their first results, performances and their added value.
* BCAM: Brandeis CCD Angle Monitor, http://alignment.hep.brandeis.edu/Devices/BCAM/

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WEPAF069

Evaluation of Frequency Scanning Interferometer Performances for Surveying, Alignment and Monitoring of Physics Instrumentation

laser, target, luminosity, cavity

1990

J. Gayde, S.W. Kamugasa
CERN, Geneva, Switzerland

During the last three years, the performance of Frequency Scanning Interferometry, accurate to a few micrometres, has been evaluated at CERN in the frame of the PACMAN project. Improvements have been studied and tested to make it better suited for typical alignment and survey conditions in accelerators and experiments. The results of these developments and tests, coupled with the multi-channel capability of the system, and its compactness which eases its integration in the area to be surveyed, offer a wide scope of possible applications for in-situ large scale metrology for physics equipment and facility elements. Furthermore, the fact that the system electronics can be placed far away from the position to be measured, allows the system to be used in confined and hazardous spaces. This paper briefly describes the system and its improvements. It gives the precision obtained for distance measurements and for the 3D point reconstruction based on FSI observations in the case of CLIC component fiducialisation.

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WEPAF080

Beam Size Measurements Based on Movable Quadrupolar Pick-ups

pick-up, emittance, embedded, quadrupole

2028

A. Sounas, M. Gąsior, T. Lefèvre, A. Mereghetti, J. Olexa, S. Redaelli, G. Valentino
CERN, Geneva, Switzerland

Measurements with quadrupolar pick-ups (PU) have attracted particular interest as non-intercepting diagnostics for determining the transverse beam size. They are based on processing the signals of an electromagnetic PU for the extraction of the second-order moment, which contains information about the beam size. Despite the simplicity of the concept, quadrupololar measurements have always been highly challenging in reality. This comes from the fact that the quadrupolar moment constitutes only a very small part of the total PU signal dominated by the intensity and the position signals. Therefore, the beam size information can easily be lost due to small imperfections in the signal processing chain, such as asymmetries in the electronics and cables. In this paper, we present a new method for quadrupolar measurements using movable PUs. Through position and aperture scans, our technique minimizes the parasitic beam position signal and takes into account imperfections of the PU, cables and electronics, thus enabling an efficient auto-calibration of the measurement system. Preliminary studies, using collimators with embedded electrostatic PUs in the LHC at CERN, have shown very promising results.

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WEPAL070

HLS System to Measure the Location Changes in Real Time of PAL-XFEL Devices

FEL, linac, real-time, survey

2345

H. J. Choi, J.H. Han, H.-S. Kang, S.H. Kim, H.-G. Lee, S.B. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

All components of PAL-XFEL (Pohang Accelerator Laboratory's X-ray free-electron laser) were completely installed in December 2015, and Hard X-ray 0.1nm lasing achieved through its beam commissioning test and machine study on March 16, 2017. The beam line users has been performing various tests including pump-probe X-ray scattering, time-resolved x-ray liquidography, etc in the hard x-ray beam line since March 22. The energy and flux of x-ray photon beam generated from XFEL and synchronization timing should be stable to ensure successful time-resolved tests. Several parts that comprise the large scientific equipment should be installed and operated at precise three-dimensional location coordinates X, Y, and Z through survey and alignment to ensure their optimal performance. As time goes by, however, the ground goes through uplift and subsidence, which consequently changes the coordinates of installed components and leads to alignment errors ΔX, ΔY, and ΔZ. As a result, the system parameters change, and the performance of the large scientific equipment deteriorates accordingly. Measuring the change in locations of systems comprising the large scientific equipment in real time would make it possible to predict alignment errors, locate any region with greater changes, realign components in the region fast, and shorten the time of survey and alignment. For this purpose, a HLS's (hydrostatic leveling sensor) with 0.2um of resolution are installed and operated in a waterpipe of total length 1km in the PAL-XFEL building. This paper is designed to introduce the operating principle of the HLS, the installation and operation of the HLS system, and how to utilize the HLS system in order to ensure beam stabilization.

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WEPMF066

Fabrication of Split-Section X-band Structure Using Elastic Averaging

vacuum, coupling, electron, gun

2521

P. Borchard, S.A. Appert, J.S. Hoh
Dymenso LLC, San Francisco, USA

Conventional accelerator structures are manufactured using axial stacks of cylindrical components which, when brazed together, form the accelerator cell structure. Splitting the accelerator structure into two sections along the beam axis allows for a significant reduction in part count and vacuum joint length. The resultant single and coplanar vacuum joint between the two split sections allows for joining techniques such as electron beam welding or brazing of the parts to form the accelerator vacuum envelope. High precision alignment of the two sections is achieved through an elastic averaging interface coupling where improved accuracy is derived from the averaging of errors over a large number of relatively compliant contacting members. The monoblock split sections allow for highly optimized cooling configurations with enhanced heat removal in high heat flux regions, reducing vacuum wall thermal stresses and enabling higher power operation. This paper describes the engineering and manufacturing of four generations of brazed and electron beam welded X-band accelerator structures at both 9.3 GHz and 11.4 GHz frequencies.

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WEPMF078

Assembly of the DQW Crab Cavity Cryomodule for SPS Test

cavity, cryomodule, vacuum, controls

2561

M. Garlaschè, K. Artoos, R. Calaga, O. Capatina, T. Capelli, N. El Kbiri, D. Lombard, P.F. Marcillac, P. Minginette, M. Narduzzi, L.R.A. Renaglia, J. Roch, J.S. Swieszek
CERN, Geneva, Switzerland
A. Krawczyk, B. Prochal
IFJ-PAN, Kraków, Poland

RF Crab Cavities are an essential part of the High Luminosity Upgrade of the LHC accelerating complex. Two concepts of such superconducting systems are being developed: the Double Quarter Wave (DQW) and the RF Dipole (RFD). A prototype cryomodule - hosting two DQW cavities - has been fabricated and assembled for validation tests to be carried out in the Super Proton Synchrotron (SPS) at CERN. An overview of the main cryomodule components is presented, together with the system features and main fabrication requirements. The preparatory measures for cryomodule assembly, the execution and lessons learned are also discussed.

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WEPML073

Research on Magnetic Center Measurement of Quadrupole and Sextupole Using Vibrating Wire Alignment Technique in HEPS-TF

sextupole, quadrupole, background, multipole

2860

L. Wu, C. H. Li, H. Qu, H. Wang, X.L. Wang
IHEP, Beijing, People's Republic of China
H.Y. Zhu
Institute of High Energy Physics (IHEP), People's Republic of China

In order to meet the extremely low emittance re-quirement, the magnets in the storage ring of High Energy Photon Source(HEPS) need to have a stable support and precise positioning. Vibrating wire align-ment technique can be used to pre-align the quadru-poles and sextupoles on one girder with high preci-sion. Research of vibrating wire alignment technique is one important project of HEPS Test Facility (HEPS-TF). In HEPS-TF, the key and difficult technologies of HEPS should be researched and developed. This paper introduces the principle of the vibrating wire align-ment technique and the measurement system in brief. The magnetic center measurement of quadrupole and sextupole using vibrating wire will be introduced in detail. It concludes the measurement procedure, mag-netic field distribution, measurement repeatability, sag correction and magnet adjustment measurement. The research of vibrating wire has get a better precision than the aim. The magnetic center measurement preci-sion reach to ±3μm and the magnet adjustment error is less than 6μm.

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WEPML075

Test of Magnet Girder Prototypes for HEPS-TF

coupling, HOM, photon, site

2863

H. Wang, C. H. Li, S.J. Li, J. Liu, H. Qu, Z. Wang, L. Wu
IHEP, Beijing, People's Republic of China
H.Y. Zhu
Institute of High Energy Physics (IHEP), People's Republic of China

Auto-tuning magnet girder is one of the key technolo-gies to be solved for HEPS-TF (Test Facility of High Ener-gy Photon Source). The girder should have high adjusting accuracy, high stability and can be beam-based aligned, to obtain the stability requirements of beam orbit. There are two girders developed, and the tests have been done. The accuracy of girder motion is within 10 microns while the adjusting range is 1 mm and the resolution is better than 1 microns, the natural frequency is higher than 24 Hz.

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THPAF039

IP Orbit Correction Update for HL-LHC

quadrupole, optics, dipole, cavity

3048

D. Gamba, R. De Maria
CERN, Geneva, Switzerland

Funding: Research supported by the HL-LHC project.
The HL-LHC design foresees a substantial modification of the LHC layout next to the low beta Interaction Points (IPs), namely IP1 and IP5. The inner triplets will be replaced by larger aperture ones to achieve lower beta at the IPs and crab cavities (CCs) will be installed. This will add new constraints to the orbit control, which required a careful choice of location and strength of the new orbit correctors to be installed in the area. The new orbit correction system will need to correct for the unavoidable imperfections, but also provide the necessary flexibility for implementing and optimising the crossing scheme. Detailed studies of the HL-LHC layout versions HLLHCV1.0 and HLLHCV1.1 were already performed. This paper is the continuation of these works and is based on the latest layout HLLHCV1.3. A simplification of the previous analysis is proposed that helps to identify the dominant imperfections. The expected performance and tolerances of the present layout are presented.

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THPAL017

From design to alignment of ThomX quadrupoles

quadrupole, simulation, multipole, HOM

3660

C. Vallerand, R. Marie, H. Monard
LAL, Orsay, France
J. Campmany, J. Marcos, V. Massana
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
J. Chavanne, G. Le Bec
ESRF, Grenoble, France
M.-E. Couprie, A. Lestrade, A. Loulergue, F. Marteau, M. Ros
SOLEIL, Gif-sur-Yvette, France

Quadrupoles for Thomx Facility have been carefully designed and measured due to high constraints of the storage ring. The need of a compact accelerator, 70 m2 on floor, as well as a beam life time of 20 ms, led to the following requirements for the quadrupole : a gradient of 5 T/m with 20.5 mm radius bore, harmonic content better than few 1.10^-3 at the reference radius of 18 mm, no cross-talk with sextupole placed within 5 cm and a precision of the magnetic axis of 100 μm and the roll angle of 300 μrad for measurements and alignment. Total of 41 quadrupoles have been built and all measured by a rotating coil at ALBA and SOLEIL, providing multipole components, transfer function and magnetic center. Cross-check measurements have also been carried out with a versatile stretched wire from ESRF at LAL. This paper mainly describes results of simulations with OPERA and RADIA and provides the results of measurements with these three benches. These results will be compared and highlighted important points for the alignment and installation of quadrupoles in an accelerator.

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THPAL022

Precision Magnet Measurements for Deuteron Beam Transport

quadrupole, dipole, multipole, neutron

3670

R.A. Marsh, D.J. Gibson, B. Rusnak
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
A versatile 4 MeV and 7 MeV deuteron beam transport line is being developed at Lawrence Livermore National Laboratory in support of an accelerator-driven source for fast neutron imaging. The beamline design requires precise alignment and high quality quadrupole magnets to transport a low emittance beam to the target through diagnostics, a bending dipole, and a differential pumping line with minimum beam loss and emittance growth. Vector magnetic field measurements of these magnets have been completed using a mobile version of an existing magnet mapping capability. This magnet mapping system is being used to ensure the delivered magnets meet the field uniformity specification, and that the mountings are aligned and capable of reaching the specified alignment tolerances. Details of the magnet measurement and calibration process that enable accurate field measurements to represent the intrinsic magnet field quality and not the systematic error of the measurement setup are presented.

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THPAL158

Development of an Half-Cell Accelerating Structure in Tsinghua

cavity, simulation, GUI, radiation

4023

M.M. Peng, W. Gai, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

The half-cell high gradient accelerating structure is attractive for its easy manufacturing and good alignment. A structure with 12 cells has been designed for the frequency of 11.424 GHz and a cold test will be conducted. Two different mechanical factory manufacture with same machining drawing and the results will be compared.

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THPMF001

Beam Dynamics Studies for Beam Focusing and Solenoid Alignment at SINBAD

solenoid, emittance, linac, gun

4026

S. Yamin, R.W. Aßmann, B. Marchetti, J. Zhu
DESY, Hamburg, Germany

SINBAD (Short INnovative Bunches and Accelerators at DESY) facility under construction at DESY plans to host several experiments for the production of ultra-short bunches and will be a test facility for high-gradient compact novel acceleration techniques. The ARES (Accelerator Research Experiment at SINBAD) linac is foreseen to produce ultra-short bunches to be injected e.g. into Novel Dielectric Laser Acceleration structures or Laser Wake-Field Acceleration experiments. The work presented in this paper is based on optimization of the focusing system consisting of solenoids for the ARES, which have been studied earlier in detail but is revisited for updated beamline. Moreover tolerances for the possible misalignment of solenoids are presented investigating the effect on the beam properties during the gun commissioning.
* J. Zhu, R. Assmann, U. Dorda, B. Marchetti, "Matching sub-fs electron bunches for laser-driven plasma acceleration at SINBAD", Nucl. Instrum. Methods Phys. Res., Sect. A 829, 229 (2016)

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THPMF054

Beam Performance Simulation with Error Effects and Correction on HEPS Design

multipole, optics, sextupole, emittance

4186

D. Ji, X. Cui, Z. Duan, Y. Jiao, Y. Wei, Y.L. Zhao
IHEP, Beijing, People's Republic of China

The High Energy Photon Source (HEPS) is a 6-GeV, ul-tralow-emittance kilometre-scale storage ring light source to be built in China. In this paper, the progress of the error and correction effect study on HEPS over the past one year will be presented, including error requirement and correction progress update. And beam performance eval-uation with static error and correction on orbit, optics, emittance and dynamic aperture will be presented.

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THPMF064

Beam Based Alignment of SRF Cavities in an Electron Injector Linac

cavity, linac, emittance, electron

4219

F. Hug
KPH, Mainz, Germany
M. Arnold, T. Bahlo, J. Pforr, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: Funded by DFG through Cluster of Excellence EXC 1098/2014 "PRISMA" and RTG 2128 "AccelencE" and by the European Union's Horizon 2020 Research and Innovation programme under Grant Agreement No 730871
Proper alignment of accelerating cavities is an important issue concerning beam quality of accelerators. In particular SRF cavities of injector linacs using high accelerating gradients on low beta electron beams can affect the beam quality significantly when not aligned perfectly. On the other hand knowing the exact position of every cavity after several cool-down cycles of a cryomodule can be difficult depending on the cryomodule design. We will report on operational experience on the SC injector of the Darmstadt superconducting linac and ERL (S-DALINAC) showing unexpected effects on beam dynamics and beam quality. Operators could observe transverse beam deflections by changing accelerating phases of the injector SRF-cavities while a growth of tranverse emittance occurred at the same time. As beam currents in the S-DALINAC injector do never exceed 100 μA and the effects could even be observed at nA beam currents space-charge effects could be eliminated to be the reason for these observations. In this work we will report on the possibility to align SRF cavities after cooldown by measuring the transverse deflection of the beam and compare results with beam dynamics simulations.

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THPMK020

Beam-Based Alignment Procedures for Small Gap in-Vacuum Undulators at the Taiwan Photon Source

photon, undulator, MMI, electron

4342

Y.-C. Liu, J.C. Huang, F.H. Tseng
NSRRC, Hsinchu, Taiwan

We have developed a beam-based alignment procedure for small gap IVUs (In-vacuum undulators) at TPS, which allow us to measure the field center and mechanical canter of IVUs with 0.1 mm accuracy. The measurement method and results are presented in this paper.

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THPML081

Beam-Based Measurements of the ISAC-II Superconducting Heavy Ion Linac

cavity, linac, ISAC, TRIUMF

4841

S. Kiy, R.E. Laxdal, M. Marchetto, S.D. Rädel, O. Shelbaya
TRIUMF, Vancouver, Canada

Preparation for experiments, which typically run for one to two weeks in the ISAC-II facility at TRIUMF, requires some amount of overhead, limiting the efficiency of the facility. Efforts are underway to improve the ISAC-II linac model to reduce this overhead while also improving the quality of the delivered ion beam. This can be accomplished with beam-based measurements and corrections of alignment, cavity gradients, focal strengths, and more. A review of the present state of the linac will be given, including measured mis-alignments and other factors that affect the reproducibility of tunes. The outlook on expected improvements will also be summarized, including progress on the automatic phasing of cavities with a focus on integration to the High Level Application platform being developed at TRIUMF. Lastly, a summary will be given on the expected paradigm shift in the tuning approach taken: moving from re-active tuning by operators or beam delivery experts to pro-active measurements and investigations, version-controlled tunes, and continuous feedback from beam physicists.

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THPML127

Alignment and Installation for the FELiChEM project

FEL, laser, network, controls

4977

W. Wang, Zhang, H.T. H.T, X.Y. He, D.R. Xu
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (11705199) and China Postdoctoral Science Foundation (2017M622024)
FELiChEM is a new experimental facility under construction at the University of Science and Technology of China. There are more than one hundred important devices to construct it, which core device is two free electron laser oscillators generating middle-infrared and far-infrared laser and covering the spectral range of 25-200μm. The optical cavity is an important component of oscillator which very sensitive to misalignment errors of the mirror, due to its near-concentric and symmetric structure. High precision alignment and installation is necessary to ensure the smooth implementation of the FELiChEM project. Laser tracker and Level are used to install this devices according to the alignment control network. An efficient and high-precision alignment method based on autocollimator and photoelectric auto-collimator is used to align optical cavity of oscillator. This methods is proven to be effective and meet the tolerances by multiple means.

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