Keyword: alignment
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MOXA03 Sirius Commissioning Results and Operation Status MMI, storage-ring, injection, operation 13
 
  • L. Liu, M.B. Alves, A.C.S. Oliveira, X.R. Resende, F.H. de Sá
    LNLS, Campinas, Brazil
  
  Sirius is a 4th generation 3 GeV synchrotron light source that has just finalized the first commissioning phase at the Brazilian Center for Research in Energy and Materials (CNPEM) campus in Campinas, Brazil. This paper describes the main Accelerator Physics issues faced during the storage ring commissioning, methods that were used to work them out and the current operation status of the machine.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOXA03  
About • paper received ※ 20 May 2021       paper accepted ※ 10 June 2021       issue date ※ 16 August 2021  
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MOPAB023 Experimental Test of a New Method to Verify Retraction Margins Between Dump Absorbers and Tertiary Collimators at the LHC experiment, beam-losses, emittance, operation 115
 
  • C. Wiesner, W. Bartmann, C. Bracco, R. Bruce, J. Molson, M. Schaumann, C. Staufenbiel, J.A. Uythoven, M. Valette, J. Wenninger, D. Wollmann, M. Zerlauth
    CERN, Meyrin, Switzerland
  
  The protection of the tertiary collimators (TCTs) and the LHC triplet aperture in case of a so-called asynchronous beam dump relies on the correct retraction between the TCTs and the dump region absorbers. A new method to validate this retraction has been proposed, and a proof-of-principle experiment was performed at the LHC. The method uses a long orbit bump to mimic the change of the beam trajectory caused by an asynchronous firing of the extraction kickers. It can, thus, be performed with circulating beam. This paper reports on the performed beam measurements, compares them with expectations and discusses the potential benefits of the new method for machine protection.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB023  
About • paper received ※ 19 May 2021       paper accepted ※ 25 August 2021       issue date ※ 24 August 2021  
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MOPAB038 Robustness Studies and First Commissioning Simulations for the SOLEIL Upgrade Lattice lattice, sextupole, MMI, simulation 171
 
  • D. Amorim, A. Loulergue, L.S. Nadolski, R. Nagaoka
    SOLEIL, Gif-sur-Yvette, France
  
  Diffraction limited light sources will use very strong focusing elements to achieve their emittance goal. The beam will therefore be more sensitive to magnet field and alignment errors. Impact of errors on the lattice proposed for the SOLEIL upgrade was studied with the Accelerator Toolbox (AT) code. The performance achieved with the imperfect lattice will be presented. In particular the effect of girders misalignment was also accounted for. As the lattice uses a large number of permanent magnets for the beam bending as well as the focusing, challenges arise in terms of beam correction. The correctors and BPMs location and number will be investigated to maximize their efficiency, and corrector magnet strength required to obtain a closed orbit will be studied. The commissioning strategy, and in particular the method used to achieve the first turns and a stored beam in the machine will also be exposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB038  
About • paper received ※ 19 May 2021       paper accepted ※ 31 May 2021       issue date ※ 16 August 2021  
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MOPAB137 Interaction Region Design for DWA Experiments at FACET-II electron, experiment, radiation, diagnostics 478
 
  • O. Williams, G. Andonian, A. Fukasawa, W.J. Lynn, N. Majernik, P. Manwani, B. Naranjo, J.B. Rosenzweig, Y. Sakai, M. Yadav, Y. Zhuang
    UCLA, Los Angeles, California, USA
  • C.I. Clarke, M.J. Hogan, B.D. O’Shea, D.W. Storey, V. Yakimenko
    SLAC, Menlo Park, California, USA
  • M. Ruelas
    RadiaBeam, Santa Monica, California, USA
  • M. Yadav
    The University of Liverpool, Liverpool, United Kingdom
  
  Funding: DOE HEP Grant DE-SC0009914
The extremely intense beam generated at FACET-II provides the unique opportunity to investigate the effects of beam-driven GV/m fields in dielectrics exceeding meter-long interaction lengths. The diverse range of phenomena to be explored, such as material response in the terahertz regime, suppression of high-field pulse damping effects, advanced geometry structures, and methods for beam break up (BBU) mitigation, all within a single UHV vacuum vessel, requires flexibility and precision in the experimental layout. We present here details of the experimental design for the dielectric program at FACET-II. Specifically, consideration is given to the alignment of the dielectric structures due to the extreme fields associated with the electron beam, as well as implementation of electron beam and Cherenkov radiation-based diagnostics. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB137  
About • paper received ※ 19 May 2021       paper accepted ※ 17 August 2021       issue date ※ 29 August 2021  
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MOPAB231 Tunability Study of the Ultra-Low β* Optics at ATF2 with New Octupole Setup and Tuning Knobs octupole, optics, simulation, quadrupole 752
 
  • A. Pastushenko, R. Tomás García
    CERN, Geneva, Switzerland
  • A. Faus-Golfe
    Université Paris-Saclay, CNRS/IN2P3, IJCLab, Orsay, France
  • K. Kubo, S. Kuroda, T. Naito, T. Okugi, N. Terunuma, R.J. Yang
    KEK, Ibaraki, Japan
  
  The main goal of the Accelerator Test Facility 2 (ATF2) is to demonstrate the feasibility of future linear colliders’ final focus systems. The Ultra-low β* optics of ATF2 is designed to have the same chromaticity level as CLIC. To ease the tuning procedure, a pair of octupoles was installed in ATF2 in 2017. This paper reports the optimizations performed to the octupoles’ setup for Ultra-low β* optics including the new alignment technique, based on the waist shift and the new tunning knobs constructed for this optics. The full tuning procedure including the static errors is simulated for this setup.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB231  
About • paper received ※ 19 May 2021       paper accepted ※ 28 July 2021       issue date ※ 12 August 2021  
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MOPAB261 NSLS-II Storage Ring Lattice Analysis using Response Matrices lattice, quadrupole, storage-ring, sextupole 829
 
  • J. Choi
    BNL, Upton, New York, USA
  
  Funding: Work supported by the U.S. Department of Energy (DOE) under contract No. DE-SC0012704.
Affected from various sources, the NSLS-II storage ring lattice is slightly changing operation to operation and, for the operational performance, we are continually optimizing the lattice and maintaining the response matrices for the feedback and lattice analysis. Because not all sources are identified, we are investing efforts to identify as many as possible. As one of such efforts, we also study the measured response matrices. In this paper, we present the results of lattice studies using a pair of recently measured response matrices. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB261  
About • paper received ※ 20 May 2021       paper accepted ※ 02 June 2021       issue date ※ 19 August 2021  
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MOPAB320 The CMS ECAL Enfourneur: A Gigantic Machine with a Soft Touch operation, controls, insertion, experiment 986
 
  • V. Pettinacci
    INFN-Roma, Roma, Italy
  
  The electromagnetic calorimeter (ECAL) of the CMS experiment at the LHC is composed of 75848 scintillating lead tungstate crystals arranged in a barrel section and two endcaps. The barrel part is made of 36 supermodules (SM), 2.7 tons each, and is installed inside the CMS magnet. There are 18 SMs on each side of CMS, with each SM containing 1700 crystals. During Long Shutdown 3, all ECAL SMs must be extracted to refurbish the electronics in preparation for HL-LHC. A dedicated machine called the "Enfourneur" is used to extract and re-insert the SMs inside CMS, with a required accuracy of about 1mm. In order to speed up the extraction and insertion process, two Enfourneurs will be employed, operating in parallel on both sides. In view of the purchase of the second Enfourneur, the design has been improved, starting from the feedback of past operations. The improvements to the new Enfourneur design include increased space for the operators, optimization of the operations and the controls with the use of electric motors, and an updated alignment system. Handling plans inside the CMS cavern have been defined in order to be compliant with the rest of CMS structures and procedures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB320  
About • paper received ※ 11 May 2021       paper accepted ※ 17 August 2021       issue date ※ 20 August 2021  
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MOPAB350 RF Buncher Cavity for Polarized He-3 Beam at BNL cavity, simulation, insertion, booster 1090
 
  • T. Kanesue, S.M. Trabocchi
    BNL, Upton, New York, USA
  • A. Murata
    TIT, Tokyo, Japan
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-SC0012704 with the U.S. Department of Energy.
A 100.625 MHz quarter wave resonator type rf buncher cavity was fabricated for polarized He-3 spin rotator beam line at BNL. This cavity will be installed in the existing EBIS-To-Booster beam line to provide effective voltage of more than 40 kV for 2 MeV/u 3He2+ beam. This cavity has a large drift tube inner diameter of 80 mm and small gap length of 5 mm. The buncher consists of 3 sections, which are a cavity main body including drift tube, stem, and inner wall, a lid with a power coupler, and a lid with an inductive tuner. The main body was machined from a bulk copper only by CNC machining. The result of low power test agreed well with rf simulation without any alignment. The difference between measured and calculated resonant frequency was <0.1 %, and measured Q value was 92 % of that in simulation. The cavity rf design and test results will be shown. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB350  
About • paper received ※ 26 May 2021       paper accepted ※ 28 May 2021       issue date ※ 12 August 2021  
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TUPAB003 Final Focus Solenoids Beam-Based Positioning Tests solenoid, collider, lattice, positron 1330
 
  • D.B. Shwartz
    BINP SB RAS, Novosibirsk, Russia
  • D.B. Shwartz
    NSU, Novosibirsk, Russia
  
  The final focusing at the VEPP-2000 electron-positron collider is done by 13 T superconducting solenoids. The misalignment of solenoids not only provides closed orbit distortions but also harmful for dynamic aperture reduction due to strong nonlinear fringe fields. The final beam-based alignment of solenoids was foreseen but turned out to be not a trivial procedure. Here we present the test study of solenoids positioning reconstruction procedure based on circulating beam orbit responses.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB003  
About • paper received ※ 22 May 2021       paper accepted ※ 02 June 2021       issue date ※ 28 August 2021  
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TUPAB005 Emittance Estimates for the Future Circular Collider emittance, quadrupole, simulation, sextupole 1338
 
  • L. van Riesen-Haupt, T.K. Charles, R. Tomás García, F. Zimmermann
    CERN, Meyrin, Switzerland
  • T.K. Charles
    The University of Liverpool, Liverpool, United Kingdom
  
  The alignment strategy of the FCC-ee has a large impact on its luminosity. Larger alignment tolerances result in increased coupling and a subsequently higher vertical emittance. At the same time, tighter alignment tolerances around the 100 km ring are a major cost driver. This paper applies analytical emittance estimate methods to the FCC-ee and compares their predictions to data from simulations with different alignment tolerances. These methods can be used to help understand the impact of misalignments of certain magnet groups and to come up with an efficient alignment strategy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB005  
About • paper received ※ 16 May 2021       paper accepted ※ 14 June 2021       issue date ※ 26 August 2021  
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TUPAB007 A Correction Scheme for the Magnet Imperfection on the CEPC Collider Ring lattice, quadrupole, emittance, optics 1346
 
  • B. Wang, Y. Wang, Y. Wei, C.H. Yu, Y. Zhang
    IHEP, Beijing, People’s Republic of China
  
  This paper describes the error correction scheme for the CEPC CDR lattice in Higgs mode, which has a small beta function at the interaction point. The low emittance optics has an enhanced sensitivity to the magnet misalignments and field errors, especially for the final focus quadrupole misalignment. The magnet imperfection will cause the closed orbit distortion and optics distortion. The correction scheme for these magnet imperfections includes the closed orbit correction, the dispersion correction, the beta function correction and the betatron coupling correction. The resulting performance and the dynamic aperture for the corrected lattice are studied.  
poster icon Poster TUPAB007 [1.075 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB007  
About • paper received ※ 14 May 2021       paper accepted ※ 09 June 2021       issue date ※ 14 August 2021  
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TUPAB129 Beam Based Alignment in a Compact THz-FEL Facility quadrupole, FEL, linac, undulator 1692
 
  • Q.S. Chen, T. Hu, K.F. Liu, B. Qin, Y.Q. Xiong
    HUST, Wuhan, People’s Republic of China
  
  In this paper, we presented the beam based alignment results in a compact THz-FEL facility. The alignment was divided into two sections, the transport line and the optical line. In the transport line, all the five quadrupoles upstream of the undulator were adjusted one by one to fit the electron beam from the traveling wave linac. In the optical line, a set of auxiliary coils were winded on the yokes of the quadrupole downstream of the double bend achromat (DBA) to produce a vertical steering force. Another combined steering magnet, together with the auxiliary coils, corrected the beam orbit in the optical line. With the dispersion free test, the displacement between the magnetic centers of the quads and the beam orbit was less than 0.1mm.  
poster icon Poster TUPAB129 [0.673 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB129  
About • paper received ※ 18 May 2021       paper accepted ※ 17 June 2021       issue date ※ 27 August 2021  
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TUPAB134 Linac-to-Booster Optimization Procedure Towards High Transmission for the Alba Injector linac, booster, quadrupole, operation 1703
 
  • R. Muñoz Horta, D. Lanaia, E. Marín, F. Pérez
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  
  ALBA is a third generation synchrotron light source that consists of 3 accelerators (Linac, Booster and Storage ring) and two transfer lines, Linac-to-Booster (LTB) and Booster-to-Storage (BTS). The ALBA accelerators team has defined a robust procedure that optimizes the beam performance from Linac to Booster in terms of transmission and stability. The implemented beam-based alignment and global orbit correction techniques have been investigated first in simulations and afterwards successfully implemented in the machine.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB134  
About • paper received ※ 18 May 2021       paper accepted ※ 26 May 2021       issue date ※ 16 August 2021  
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TUPAB173 ESS Drift Tube Linac Manufacturing, Assembly and Tuning DTL, linac, cavity, emittance 1797
 
  • F. Grespan, L. Antoniazzi, A. Baldo, C. Baltador, A. Battistello, L. Bellan, P. Bottin, M. Comunian, D. Conventi, E. Fagotti, L. Ferrari, A. Palmieri, R. Panizzolo, A. Pisent, D. Scarpa
    INFN/LNL, Legnaro (PD), Italy
  • R.A. Baron
    ESS, Lund, Sweden
  • T. Bencivenga, P. Mereu, C. Mingioni, M. Nenni, E. Nicoletti
    INFN-Torino, Torino, Italy
  • A.G. Colombo
    INFN- Sez. di Padova, Padova, Italy
  • B. Jones
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  
  The Drift Tube Linac (DTL) for the ESS Linac will accelerate H+-beams of up to 62.5 mA peak current from 3.62 to 90 MeV. The structure consists of five cavities. The first cavity (DTL1) is a 7.6 m long tank containing 60 drift tubes, 23 fixed tuners, 3 movable tuners and 24 post-couplers, operating at a frequency of 352.21 MHz and an average accelerating field of 3.0 MV/m. The cavity is now assembled at ESS, the results of alignment and tuning are here presented. The DTL1 "as-built" as been analyzed from the beam dynamics point of view. The manufacturing of DTL4 and DTL3 is completed and they are now under assembly at ESS. DTL2 and DTL5 manufacturing will be completed within 2021. The paper describes the production and assembly stages, with a focus on the statistics of quality check in terms of metrology, alignment, leak tests.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB173  
About • paper received ※ 19 May 2021       paper accepted ※ 27 May 2021       issue date ※ 14 August 2021  
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TUPAB308 Mechanical Consolidation of the LHC Inner Triplet Magnet Supporting System for Remote Alignment vacuum, GUI, quadrupole, ECR 2207
 
  • F. Micolon, N. Bourcey, J-B. Deschamps, A. Herty, S. Le Naour, T. Mikkola, V. Parma, D. Ramos, V. Rude, M. Sosin
    CERN, Meyrin, Switzerland
  
  Given the high radiation area and the tight alignment tolerances, the LHC inner triplet magnets were designed to be realigned remotely using motorized supporting jacks. However, during run 2 the LHC triplet realignment system started to show an unexpected behavior with erratic load variations on the magnet supporting jacks when operated. It was then decided to freeze any further realignment of the LHC triplet magnet for the remainder of the run. Subsequently, a project team was set up at CERN to understand better the conditions leading to such unexpected behavior and to study and propose a technical consolidation for the realignment system of the LHC triplet magnet. A fully instrumented magnet string using LHC triplet spare magnets was assembled and used at CERN to provide a realistic test bench for this study. This paper reports on the work undertaken to study the triplet magnet overall realignment kinematic, the findings on the readjustment system malfunction and details the consolidation solution implemented for the next LHC run  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB308  
About • paper received ※ 18 May 2021       paper accepted ※ 07 June 2021       issue date ※ 18 August 2021  
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TUPAB309 Alignment Verification and Monitoring Strategies for the Sirius Light Source network, monitoring, radiation, survey 2210
 
  • R. Oliveira Neto, R. Junqueira Leão, L.R. Leão
    CNPEM, Campinas, SP, Brazil
  
  The approach for the alignment of Sirius is the use of portable coordinate metrology instruments in a common reference, via a network of stable points previously surveyed. This type of network is composed of a dense distribution of points materialized in the form of embedded target holders on the special slab and radiation shielding. Phenomena such as ground movements, temperature gradients and vibrations could lead to misalignment of the components, possibly causing a degradation in machine performance. Therefore, the relative positions of the accelerator magnets need to be periodically verified along with the structures surrounding it to ensure a good reference to future alignment operations. This paper will present the status of Sirius monitoring systems, including data from the first months of operation of the hydrostatic levelling sensors. Also, possibilities with simplified network measurements for detecting structural deformations and assessing its stability will be presented, along with a proposal of a photogrammetric reconstruction of the alignment profile of the storage ring. Finally, it will be shown a compilation of analysis on the deformation of the Sirius facilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB309  
About • paper received ※ 20 May 2021       paper accepted ※ 01 July 2021       issue date ※ 27 August 2021  
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TUPAB310 Establishing a Metrological Reference Network for the Alignment of Sirius network, survey, controls, laser 2214
 
  • H. Geraissate, G.R. Rovigatti de Oliveira
    LNLS, Campinas, Brazil
  • R. Junqueira Leão
    CNPEM, Campinas, SP, Brazil
  
  Sirius is the Brazilian 4th generation synchrotron light source. It consists of three electron accelerators and it has room for up to 38 beamlines. To make the alignment of Sirius components possible, there is a need for a network of points comprising the installation volume, allowing the location of portable coordinate instruments on a common reference frame. This work describes the development of such networks for the whole Sirius facility. The layout of the networks is presented together with the survey strategies. Details are given on how the calculations combined laser trackers and optical level measurements data and how the Earth curvature compensation was performed. A novel laser tracker orientation technique applied for linking networks on different environments is also presented. Finally, the uncertainty estimation for the resulting network and its deformation history is shown.  
poster icon Poster TUPAB310 [4.084 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB310  
About • paper received ※ 20 May 2021       paper accepted ※ 07 June 2021       issue date ※ 21 August 2021  
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TUPAB313 Arrangement Optimization of Quadrupoles and Correctors for Beam Alignment quadrupole, focusing, electron, FEL 2221
 
  • L. Xu, Q.M. Zhang
    Xi’an Jiaotong University, People’s Republic of China
  • H.X. Deng
    SARI-CAS, Pudong, Shanghai, People’s Republic of China
  • N. Huang
    UCAS, Beijing, People’s Republic of China
  • N. Huang
    SINAP, Shanghai, People’s Republic of China
  
  In the X-ray free-electron laser (XFEL), the alignment and stability of beam orbit have a great impact on power and qualities of the generated X-ray pulses. Currently, the beam-based alignment (BBA) is the most widely used technique in beam alignment. In order to find the best arrangement of quadrupoles and correctors, a mathematical model is established based on the transmission matrix method. With this model, several simple arrangements of quadrupoles and correctors are selected to simulate the beam alignment process. It is found that when two correctors adjust two quadrupoles, the beam can pass through the center of quadrupoles approximately collimated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB313  
About • paper received ※ 16 May 2021       paper accepted ※ 31 August 2021       issue date ※ 16 August 2021  
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TUPAB372 Status of the Quadrupole Doublet Module Series Manfacturing quadrupole, cryogenics, site, synchrotron 2388
 
  • T. Winkler, A. Bleile, L.H.J. Bozyk, V.I. Datskov, J. Ketter, P. Kowina, J.P. Meier, N. Pyka, C. Roux, P.J. Spiller, K. Sugita, A. Waldt, St. Wilfert
    GSI, Darmstadt, Germany
  
  The 83 Quadrupole Doublet Modules (QDM) for the heavy-ion-synchrotron SIS100 of the FAIR project at GSI are highly integrated cryogenic modules containing multiple magnets. Each of eleven different QDM types consists of two units, where one unit consists of one quadrupole magnet as well as corrector magnets depending on the modules position in the accelerator Ion-Optical Lattice. Additionally, the QDMs contain cryogenic collimators, beam diagnostics, as well as cryogenic UHV beam pipes. The modules contain parts from multiple suppliers increasing the logistics behinds the QDMs design further. We present the process of the module integration, give details on the current integration status and present an outlook on the timeline for the QDM integration planning.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB372  
About • paper received ※ 18 May 2021       paper accepted ※ 02 June 2021       issue date ※ 21 August 2021  
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WEPAB011 Update on the Low Emittance Tuning of the e+/e- Future Circular Collider emittance, sextupole, quadrupole, lattice 2601
 
  • T.K. Charles
    The University of Liverpool, Liverpool, United Kingdom
  • B.J. Holzer, F. Zimmermann
    CERN, Geneva, Switzerland
  • K. Oide
    KEK, Ibaraki, Japan
  
  The FCC-ee project studies the design of a future 100 km e+/e circular collider for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 1035 cm-2 s−1. To achieve ultra-low vertical emittance a highly effective emittance tuning scheme is required. In this paper, we describe a comprehensive correction strategy used for the low emittance tuning. The strategy includes Dispersion Free Steering, linear coupling compensation based on Resonant Driving Terms and beta beat correction utilising response matrices.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB011  
About • paper received ※ 18 May 2021       paper accepted ※ 23 June 2021       issue date ※ 02 September 2021  
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WEPAB238 Modeling Short Range Wakefield Effects in a High Gradient Linac wakefield, linac, space-charge, dipole 3185
 
  • F. Bosco, M. Carillo, L. Faillace, L. Giuliano, M. Migliorati, A. Mostacci, L. Palumbo
    Sapienza University of Rome, Rome, Italy
  • M. Behtouei, L. Faillace, A. Giribono, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati, Italy
  • F. Bosco, M. Migliorati
    INFN-Roma1, Rome, Italy
  • L. Giuliano, A. Mostacci, L. Palumbo
    INFN-Roma, Roma, Italy
  • J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  
  Funding: This work is supported by DARPA GRIT under contract no. 20204571 and partially by INFN National committee V through the ARYA project.
The interaction of charged beams with the surrounding accelerating structures requires a thorough investigation due to potential negative effects on the phase space quality. Indeed, the wakefields acting back on the beam are responsible for emittance dilution and instabilities, such as the beam break-up, which limit the performances of electron-based radiation sources and linear colliders. Here we introduce a new tracking code which is meant to investigate the effects of short-range transverse wakefields in linear accelerators. The tracking is based on quasi-analytical models for the beam dynamics which, in addition to the basic optics specified by the applied fields, include dipole wakefield forces and a simple approach to account for space-charge effects. Such features provide a reliable tool which easily allows to inspect the performances of a linac. To validate the model, a parallel analysis for a reference case is performed with well-known beam dynamics codes, and comparisons are shown. As an illustrative application, we discuss a study on alignment tolerances evaluating the emittance growth induced by misaligned accelerating sections. 		 
poster icon Poster WEPAB238 [1.747 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB238  
About • paper received ※ 18 May 2021       paper accepted ※ 07 July 2021       issue date ※ 01 September 2021  
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WEPAB356 Proposal of an Alignment System for HALF: The Reference Network of Alignment monitoring, real-time, simulation, network 3533
 
  • X. Li, J.X. Chen, X.Y. He, W. Wang, Z.Y. Wang
    USTC/NSRL, Hefei, Anhui, People’s Republic of China
  • J.X. Chen, T. Luo
    IHEP CSNS, Guangdong Province, People’s Republic of China
  
  As a fourth-generation light source based on the diffraction-limited storage ring, Hefei Advanced Light Facility (HALF) has higher requirements for magnets alignment in accuracy, efficiency, and reliability. In this paper, the Reference Network of Alignment (RNA) system is proposed to improve the magnetic axis alignment accuracy on the radial direction of the beamline. Herein, we mainly introduce the concept design and the theoretical analysis of the RNA system, which center on the novel fusion method of sensors. A simulation result shows that it is credible to assume the RNA system can achieve an alignment installation accuracy of 20 µm and a displacement monitoring accuracy of 10 µm.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB356  
About • paper received ※ 16 May 2021       paper accepted ※ 21 June 2021       issue date ※ 31 August 2021  
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WEPAB361 New Generation CERN LHC Injection Dump - Assembly and Installation (TDIS) vacuum, injection, radiation, operation 3548
 
  • D. Carbajo Perez, E. Berthomé, C. Bertone, N. Biancacci, C. Bracco, G. Bregliozzi, B. Bulat, C. Cadiou, M. Calviani, G. Cattenoz, A. Cherif, P. Costa Pinto, A. Dallocchio, M. Di Castro, P. Fessia, M.I. Frankl, R. Franqueira Ximenes, J.-F. Fuchs, H. Garcia Gavela, J.-M. Geisser, L. Gentini, S.S. Gilardoni, M.A. Gonzalez De La Aleja Cabana, J.L. Grenard, J.M. Heredia, S. Joly, A. Lechner, J. Lendaro, J. Maestre, E. Page, M. Perez Ornedo, A. Perillo-Marcone, D. Pugnat, E. Rigutto, B. Salvant, A. Sapountzis, K. Scibor, R. Seidenbinder, J. Sola Merino, M. Taborelli, E. Urrutia, A. Vieille, C. Vollinger, C. Yin Vallgren
    CERN, Meyrin, Switzerland
  
  Funding: Work supported by the Hilumi Project
During CERN’s LS2, several upgrades were performed to beam intercepting devices in the framework of the HL-LHC Project. Upgraded equipment includes two internal beam dumps (TDIS) intended for machine protection located at the injection points from the SPS to the LHC. These two devices have been assembled, tested, and installed around LHC Point 2 and Point 8 and are currently ready to get commissioned with the beam. They are 5.8m-long, three-module-segmented vacuum chambers, with large aperture to accommodate the injected and circulating beam and equipped with absorbing materials, These comprise graphite and higher Z alloys that are embedded on sub-assemblies reinforced with back-stiffeners made of TZM. The current contribution covers three main matters. First, it details the TDIS design and its key technical features. The second topic discussed is the outcome of an experiment where a prototype module was tested under high-energy beam impacts at CERN’s HiRadMat facility. To conclude it is presented the return of experience from the pre-series construction, validation and installation in the LHC tunnel. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB361  
About • paper received ※ 18 May 2021       paper accepted ※ 11 June 2021       issue date ※ 17 August 2021  
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WEPAB380 Measurements of Field Emission Induced Optical Spectra radiation, site, experiment, electron 3602
 
  • R.C. Peacock, G. Burt
    Lancaster University, Lancaster, United Kingdom
  • S. Calatroni, W. Wuensch
    CERN, Meyrin, Switzerland
  
  Field emission induced optical spectra in a dc electrode system have been measured using a spectrometer and CCD camera system in order to gain insight into the nature of field emissions sites. Spectra were measured from between 2 ridged parallel copper electrodes with a gap ranging from 60µm to 100µm and a bias voltage of up to 8000V under high vacuum conditions. A strong correlation between the light intensity of the spectra and the measured field emitted current was observed as a function of applied voltage. A characteristic broadband spectrum ranging from 550nm and 850nm wavelength was observed but there were important features which varied as a function of observation angle, polarity, and conditioning state and also with time. Possible causes of the optical spectra being considered include black body radiation, optical transition radiation and cathode luminescence of copper. Further experiments are ongoing with an improved optical setup to increase optical alignment for measurements with different materials of electrodes, developing further understanding of the cause of the optical spectra, to provide understanding into characteristics and evolution of emission sites.  
poster icon Poster WEPAB380 [1.158 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB380  
About • paper received ※ 11 May 2021       paper accepted ※ 24 June 2021       issue date ※ 24 August 2021  
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THXB06 Results of the First Alignment Run for Sirius network, laser, operation, survey 3728
 
  • R. Junqueira Leão, R. Oliveira Neto
    CNPEM, Campinas, SP, Brazil
  • H. Geraissate, F. Rodrigues, G.R. Rovigatti de Oliveira
    LNLS, Campinas, Brazil
  
  It is widely known that the position of particle accelerator components is critical for its performance. For the latest generation light sources, whose magnetic lattice is optimized for achieving very low emittance, the tolerable misalignments are in the order of a few dozen micrometers. Due to the perimeter of these machines, the requirements push the limits of large-volume dimensional metrology and associated instruments and techniques. Recently a fine alignment campaign of the Sirius accelerators was conducted following the pre-alignment performed during the installation phase. To conform with the strict relative positioning demands, measurement good practices were followed, and several 3D metrology procedures were developed. Also, to improve positioning resolution, high rigidity translation devices were produced. Finally, the special target holders designed as removable fiducials for the magnets were revisited to assure maximum reliability. Data processing algorithms were implemented to evaluate the alignment results in a robust and agile manner. This paper will present the final positioning errors for Sirius magnets with an expression of the estimated uncertainty.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THXB06  
About • paper received ※ 20 May 2021       paper accepted ※ 02 July 2021       issue date ※ 01 September 2021  
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THPAB066 Ground Diffusion Measurement and Its Effect on APS-U Orbit Stability ground-motion, electron, simulation, quadrupole 3907
 
  • V. Sajaev
    ANL, Lemont, Illinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Spatial and temporal ground diffusion can be approximately described by the ATL law*,**. Ground diffusion can have an important effect on the long-term stability of the accelerator alignment. To estimate the possible consequences of the ground diffusion on the APS Upgrade performance, the ground diffusion constant of the existing APS tunnel was measured using historical data of the orbit correction effort and then used to estimate the ground diffusion effect on the orbit stability of the APS Upgrade. In this paper, we will describe the diffusion constant measurement and present the estimations of the expected APS-U alignment and orbit stability.
* B.A. Baklakov et. al., Technical Physics, v.38(10), pp.894-898(1993)
** V. Shiltsev, Physical Review Letters, 104(23), p.238501 (2010). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB066  
About • paper received ※ 12 May 2021       paper accepted ※ 13 July 2021       issue date ※ 24 August 2021  
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THPAB104 Magnetic Error Effects of the Storage Ring for the Southern Advanced Photon Source lattice, closed-orbit, quadrupole, optics 3980
 
  • J. Chen, Y. Jiao, X. Liu, S. Wang
    IHEP, Beijing, People’s Republic of China
  • Y. Zhao
    IHEP CSNS, Guangdong Province, People’s Republic of China
  
  There are various magnetic errors in the actual accelerator, which will significantly affect the beam quality and machine performance. The diffraction-limited storage ring (DLSR) of Southern Advanced Photon Source (SAPS) will use a large number of ultra-high gradient quadrupoles and sextupoles, which, in turn, leads to the tight tolerance of beam parameters to magnetic errors. Based on a preliminary designed storage ring lattice of the SAPS, the influence of various magnetic errors on lattice parameters has been evaluated.  
poster icon Poster THPAB104 [0.588 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB104  
About • paper received ※ 17 May 2021       paper accepted ※ 23 June 2021       issue date ※ 18 August 2021  
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THPAB191 Physics-Enhanced Reinforcement Learning for Optimal Control network, lattice, controls, simulation 4150
 
  • A.N. Ivanov, I.V. Agapov, A. Eichler, S. Tomin
    DESY, Hamburg, Germany
  
  We propose an approach for incorporating accelerator physics models into reinforcement learning agents. The proposed approach is based on the Taylor mapping technique for simulation of the particle dynamics. The resulting computational graph is represented as a polynomial neural network and embedded into the traditional reinforcement learning agents. The application of the model is demonstrated in a nonlinear simulation model of beam transmission. The comparison of the approach with the traditional numerical optimization as well as neural networks based agents demonstrates better convergence of the proposed technique.  
poster icon Poster THPAB191 [0.846 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB191  
About • paper received ※ 11 May 2021       paper accepted ※ 29 July 2021       issue date ※ 24 August 2021  
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THPAB332 Development of a Pair of 182 GHz Two-Half Power Extractor and Accelerator for Short Pulse RF Breakdown Study acceleration, GUI, electron, wakefield 4435
 
  • J.H. Shao, J.G. Power
    ANL, Lemont, Illinois, USA
  • R.B. Agustsson, S.V. Kutsaev, A.Yu. Smirnov
    RadiaBeam, Santa Monica, California, USA
  
  High-frequency structures are favorable in structure wakefield acceleration for their strong beam-structure interaction. Recent progress of advanced fabrication technologies, such as high-precision two-half milling and additive machining, has enabled experimental research of mm-wave/THz structures. In this work, we have designed a pair of 182 GHz two-half copper power extractor and accelerator for short pulse RF breakdown study. When driven by a 182 GHz 4-bunch train with 4 nC total charge and 0.3 mm rms bunch length, the power extractor will generate 0.4 ns ~8 MW RF pulses and the corresponding gradient in the single-cell accelerator will reach ~460 MV/m. RF and mechanical design of the proof-of-concept structures will be reported in this manuscript.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB332  
About • paper received ※ 26 May 2021       paper accepted ※ 19 July 2021       issue date ※ 26 August 2021  
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THPAB352 Computer Vision Techniques Used to Monitor the Alignment of Cavities and Solenoids in the PIP-II Prototype SSR1 Cryomodule cavity, solenoid, target, cryomodule 4485
 
  • S. Zorzetti, J. Bernardini, D. Passarelli
    Fermilab, Batavia, Illinois, USA
  
  The alignment of the SRF PIP-II string components is studied as the acceptable beam deflection, offset and defocusing, which may otherwise cause beam loss. Simulations and measurements established that the maximum deviation of the beam pipe from the reference orbit should not exceed a small fraction of the beam aperture. To observe the translations and rotations of each single component within the cryomodule, optical instruments (H-BCAM) surveying highly reflective targets, installed in the internal assembly of the module were used. The alignment monitoring concept for the PIP II SSR1 prototype cryomodule, along with relevant measurements of the components’ position monitoring during coldmass cooldown is presented in this contribution. This development paves the way to new computer vision applications in the field of cryomodule assemblies in cleanroom environment, in which robotically-assisted operations have the potential to dramatically reduce the risk of chemical and particulate contamination.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB352  
About • paper received ※ 19 May 2021       paper accepted ※ 02 August 2021       issue date ※ 31 August 2021  
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