Keyword: dipole
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MOB2CO03 Collider in the Sea: Vision for a 500 TeV World Laboratory ion, collider, luminosity, hadron 13
 
  • P.M. McIntyre, S.P. Bannert, J. Breitschopf, J. Gerity, J.N. Kellams, A. Sattarov
    Texas A&M University, College Station, USA
  • S. Assadi
    HiTek ESE LLC, Madison, USA
  • D. Chavez
    DCI-UG, León, Mexico
  • N. Pogue
    LLNL, Livermore, California, USA
  
  A design is presented for a hadron collider in which the magnetic storage ring is configured as a circular pipeline, supported in neutral buoyancy in the sea at a depth of ~100 m. Each collider detector is housed in a bathysphere the size of the CMS hall at LHC, also neutral-buoyant. Each half-cell of the collider lattice is ~300 m long, housed in a single pipe that contains one dipole, one quadrupole, a correction package, and all umbilical connections. A choice of ~4 T dipole field, 2000 km circumference provides a collision energy of 700 TeV. Beam dynamics is dominated by synchrotron radiation damping, which sustains luminosity for >10 hours. Issues of radiation shielding and abort can be accommodated inexpensively. There are at least ten sites world-wide where the collider could be located, all near major urban centers. The paper summarizes several key issues; how to connect and disconnect half-cell segments of the pipeline at-depth using remote submersibles; how to maintain the lattice in the required alignment; provisions for the injector sequence.  
slides icon Slides MOB2CO03 [3.440 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOB2CO03  
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MOPOB16 Higher Order Modes Analysis of Fermilab's Recycler Cavity impedance, cavity, ion, HOM 106
 
  • M.H. Awida, J.E. Dey, T.N. Khabiboulline, V.A. Lebedev, R.L. Madrak
    Fermilab, Batavia, Illinois, USA
  
  Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
Two recycler cavities are being employed in Fermilab's Recycler Ring for the purpose of slip stacking proton bunches, where 6 batches of 8 GeV protons coming from the Booster are stacked on top of 6 circulating batches. Slip stacking requires two RF cavities operating at 52.809 and 51.545 MHz. In this paper, we report on the analysis of higher order modes in the Recycler cavity, presenting the values for R/Q and shunt impedances. Knowing the frequencies and properties of higher order modes is particularly critical for beam physics and avoidance of beam instabilities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB16  
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MOPOB30 Development and Comparison of Mechanical Structures for FNAL 15 T Nb3Sn Dipole Demonstrator ion, operation, collider, controls 137
 
  • A.V. Zlobin, I. Novitski
    Fermilab, Batavia, Illinois, USA
  
  Funding: *Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
Main design challenges for 15 T accelerator magnets are large Lorentz forces at this field level. The large Lorentz forces generate high stresses in the coil and mechanical structure and, thus, need stress control to maintain them at the acceptable level for brittle Nb3Sn coils and other elements of magnet mechanical structure. To provide these conditions and achieve the design field in the FNAL 15 T dipole demonstrator, several mechanical structures have been developed and analysed. The possibilities and limitations of these designs are discussed in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB30  
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MOPOB40 Quench Training Analysis of Nb3Sn Accelerator Magnets ion, quadrupole, operation, magnet-design 155
 
  • S. Stoynev, K.H. Riemer, A.V. Zlobin
    Fermilab, Batavia, Illinois, USA
  
  Funding: This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Nb3Sn accelerator magnet technology has made significant progress during the past decades. Thanks to that 11-12 T Nb3Sn dipoles and quadrupoles are planned to be used in accelerators such as LHC in near future for the luminosity upgrade and in longer term for the LHC energy upgrade or a future Very High Energy pp Collider. However, all the state of the art Nb3Sn accelerator magnets show quite long training. This specific feature significantly raises the required design margin or limit the nominal operation field of Nb3Sn accelerator magnets and, thus, increases their cost. To resolve this problem Fermilab has launched a study aiming to analyze the relatively large amount of Nb3Sn magnet training data accumulated at Fermilab magnet test facility. The ultimate goal is to correlate magnet design and manufacturing features and magnet material properties with training performance parameters which will eventually allow us to optimize both the magnet design, fabrication and the training processes. This paper describes the general strategy of the analysis and presents the first results based on partial data processing. Conclusions and further steps are also outlined and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB40  
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MOPOB41 Field Quality Measurements in the FNAL Twin-Aperture 11 T Dipole for LHC Upgrades ion, quadrupole, magnet-design, ion-effects 158
 
  • T. Strauss, G. Apollinari, E.Z. Barzi, G. Chlachidze, J. DiMarco, A. Nobrega, I. Novitski, S. Stoynev, D. Turrioni, G. Velev, A.V. Zlobin
    Fermilab, Batavia, Illinois, USA
  • B. Auchmann, S. Izquierdo Bermudez, M. Karppinen, L. Rossi, F. Savary, D. Smekens
    CERN, Geneva, Switzerland
  
  Funding: *Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy and European Commission under FP7 project HiLumi LHC, GA no.284404
FNAL and CERN magnet groups are developing a twin-aperture Nb3Sn 11 T dipole suitable for installation in the LHC to provide room for additional collimators in the dispersion suppressor (DS) areas. Two of these magnets with a collimator in between will replace one regular MB dipole. A single-aperture 2-m long dipole demonstrator and two 1-m long dipole models have been assembled and tested at FNAL in 2012-2014. The 1 m long collared coils were then assembled into the twin-aperture configuration and tested in 2015. The first magnet test was focused on the quench performance of twin-aperture magnet configuration including magnet training, ramp rate sensitivity and temperature dependence of magnet quench current. In the second test performed in July 2016 field quality in one of the two magnet apertures has been measured and compared with the data for the single-aperture models. These results are reported and discussed in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB41  
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MOPOB49 Persistent Current Effects in RHIC Arc Dipole Magnets Operated at Low Currents ion, operation, ion-effects, detector 170
 
  • X. Wang, S. Caspi, S.A. Gourlay, G.L. Sabbi
    LBNL, Berkeley, California, USA
  • A.K. Ghosh, R.C. Gupta, A.K. Jain, P. Wanderer
    BNL, Upton, Long Island, New York, USA
  
  Funding: BNL work was supported by Brookhaven Science Associates, LLC under Contract# DESC0012704 with the U.S. DOE. LBNL work was supported by the U.S. DOE under Contract# DEAC02- 05CH11231.
The Relativistic Heavy Ion Collider (RHIC) arc dipoles at Brookhaven National Laboratory are operated at low field for low energy Au-Au studies. Indications of strong nonlinear magnetic fields have been observed at these low currents due to the persistent current effects of superconducting NbTi filaments. We report the details of the measurement and calculation of the field errors due to persistent current effect. The persistent current induced field errors calculated with a model based on the strand magnetization data agree well with the measurements of a spare arc dipole magnet. The dependence of the persistent current effects on the park current is calculated based on the validated model. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB49  
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MOPOB54 Superferric Arc Dipoles for the Ion Ring and Booster of JLEIC ion, multipole, quadrupole, collider 184
 
  • P.M. McIntyre, J. Breitschopf, T. Elliott, R. Garrison, J. Gerity, J.N. Kellams, A. Sattarov
    Texas A&M University, College Station, USA
  • D. Chavez
    DCI-UG, León, Mexico
  
  Funding: This work was supported by a grant from the NP Division of the US Dept. of Energy.
The JLEIC project requires 3 T superferric dipoles and quadrupoles for the half-cell arcs of its Ion Ring and Booster. A superferric design using NbTi cable-in-conduit conductor is being developed. A mockup winding has been completed, with the objectives to develop and evaluate the coil structure and the winding tooling and methods, and to measure errors in the position of each cable turn in the dipole body. The results of the mockup winding study are presented. The CIC design is now ready for construction and testing of a first model dipole. 		 
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB54  
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MOPOB55 Room Temperature Magnets in FRIB Driver Linac ion, linac, quadrupole, alignment 188
 
  • Y. Yamazaki, N.K. Bultman, E.E. Burkhardt, F. Feyzi, K. Holland, A. Hussain, M. Ikegami, F. Marti, S.J. Miller, T. Russo, J. Wei, Q. Zhao
    FRIB, East Lansing, USA
  • W.J. Yang, Q.G. Yao
    IMP/CAS, Lanzhou, People's Republic of China
  
  Funding: Work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 and the National Science Foundation under Cooperative Agreement PHY-1102511.
The FRIB Driver Linac* is to accelerate all the stable ions beyond 200 MeV/nucleon with a beam power of 400 kW. The linac is unique, being compactly folded twice. In this report, the room temperature magnets, amounting 147 in total, after Front End with a 0.5-MeV RFQ, are detailed, emphasizing the rotating coil field measurements and fiducialization.
*E. Pozdeyev et al., "Status of FRIB" in this conference.
T. Xu, "Superconducting Cryomodule Development and Production for the FRIB Linac" in this conference. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-MOPOB55  
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MOPOB59 Magnet Design for the Splitter/Combiner Regions of CBETA, the Cornell-Brookhaven Energy-Recovery-Linac Test Accelerator ion, quadrupole, linac, magnet-design 201
 
  • J.A. Crittenden, D.C. Burke, Y.L.P. Fuentes, C.E. Mayes, K.W. Smolenski
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Supported by NSF award DMR-0807731, DOE grant DE-AC02-76SF00515, and New York State.
The Cornell-Brookhaven Energy-Recovery-Linac Test Accelerator (CBETA) will provide a 150-MeV electron beam using four acceleration and four deceleration passes through the Cornell Main Linac Cryomodule housing six 1.3-GHz superconducting RF cavities. The return path of this 76-m-circumference accelerator will be provided by 106 fixed-field alternating-gradient (FFAG) cells which carry the four beams of 42, 78, 114 and 150-MeV. Here we describe magnet designs for the splitter and combiner regions which serve to match the on-axis linac beam to the off-axis beams in the FFAG cells, providing the path-length adjustment necessary to energy recovery for each of the four beams. The path lengths of the four beamlines in each of the splitter and combiner regions are designed to be adapted to 1-, 2-, 3-, and 4-pass staged operations. Design specifications and modeling for the 24 dipole and 32 quadrupole electromagnets in each region are presented. The CBETA project will serve as the first demonstration of multi-pass energy recovery using superconducting RF cavities with FFAG cell optics for the return loop. 		 
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TUPOA57 Using High­ Precision Beam Position Monitors at the Cornell Electron Storage Ring (CESR) to Measure the One­ Way Speed of Light Anisotropy ion, electron, positron, simulation 399
 
  • W.F. Bergan, M.J. Forster, N.T. Rider, D. L. Rubin, D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • B.A. Schmookler
    MIT, Cambridge, Massachusetts, USA
  • B. Wojtsekhowski
    CMU, Pittsburgh, Pennsylvania, USA
  
  Funding: NSF PHY-1416318 NSF DGE-1144153
The Cornell Electron Storage Ring (CESR) has been equipped with a number of high-precision beam position monitors which are capable of measuring the orbit of a circulating beam with a precision of a few microns. This technology will enable a precision measurement of deviations in the one-way speed of light. An anisotropic speed of light will alter the beam momentum as it travels around the ring, resulting in a change of orbit over the course of a sidereal day. Using counter-circulating electron and positron beams, we will be able to suppress many of the systematics such as those relating to variations in RF voltage or magnet strength. We show here initial feasibility studies to measure the stability of our beam position monitors and the various systematic effects which may hide our signal and discuss ways in which we can minimize their impact. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOA57  
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TUPOB04 A More Compact Design for the JLEIC Ion Pre-Booster Ring ion, booster, injection, linac 483
 
  • B. Mustapha, P.N. Ostroumov
    ANL, Argonne, USA
  • B. Erdelyi
    Northern Illinois University, DeKalb, Illinois, USA
  
  Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 for ANL
The original design of the JLEIC pre-booster was a 3-GeV figure-8 shaped synchrotron with a circumference of about 240 m. In the current baseline design, the 3-GeV pre-booster was converted into an 8-GeV booster of the same shape and size but using super-ferric magnets with fields up to 3 Tesla. In order to limit the foot-print of the JLEIC ion complex and reduce its total cost, we have designed a more compact and cost-effective octagonal 3-GeV ring about half the size of the original one. At 3 GeV, the figure-8 shape is not required to preserve ion polarization; Siberian snakes with reasonable magnetic fields can be used for spin correction. As the ion collider ring requires an injection energy of at least 8 GeV, we propose to use the existing electron storage ring, which is part of the electron complex, as a large booster for the ions up to 11 GeV. The design optimization of the pre-booster ring will be presented leading to the final octagonal ring design. Preliminary beam simulations will also be presented and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB04  
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TUPOB22 Dependence of the Coupling of Dipole Motion From Bunch to Bunch Caused by Electron Clouds at CesrTA Due to Variations in Bunch Length and Chromaticity ion, electron, damping, positron 538
 
  • M.G. Billing, L.Y. Bartnik, M.J. Forster, N.T. Rider, J.P. Shanks, M.B. Spiegel, S. Wang
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • R. Holtzapple
    CalPoly, San Luis Obispo, California, USA
  • E.C. Runburg
    University of Notre Dame, Indiana, USA
  
  The Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) has been utilized to probe the interaction of the electron cloud with a 2.1 GeV stored positron beam. Recent experiments have characterized any dependence of beam'electron cloud (EC) interactions on the bunch length (or synchrotron tune) and the vertical chromaticity. The measurements were performed on a 30-bunch positron train with 14 nsec spacing between bunches, at a fixed current of 0.75 mA/bunch. The dynamics of the stored beam, in the presence of the EC, was quantified using 20 turn-by-turn beam position monitors in CESR to measure the correlated bunch-by-bunch dipole motion. In this paper we report on the observations from these experiments and analyze the coupling of di-pole motion from bunches within the train to subsequent bunches, caused by the EC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB22  
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TUPOB31 Compensation of Chromaticity in the JLEIC Electron Collider Ring ion, sextupole, emittance, electron 561
 
  • Y.M. Nosochkov, Y. Cai, M.K. Sullivan
    SLAC, Menlo Park, California, USA
  • Y.S. Derbenev, F. Lin, V.S. Morozov, F.C. Pilat, G.H. Wei, Y. Zhang
    JLab, Newport News, Virginia, USA
  • M.-H. Wang
    Self Employment, Private address, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported by the US DOE Contract DE-AC02-76SF00515.
The Jefferson Lab Electron-Ion Collider (JLEIC) is being designed to achieve a high luminosity of up to 1034 1/(cm2*sec). The latter requires a small beam size at the interaction point demanding a strong final focus (FF) quadrupole system. The strong beam focusing in the FF unavoidably creates a large chromaticity which has to be compensated in order to avoid a severe degradation of momentum acceptance. This has to be done while preserving sufficient dynamic aperture. An additional design requirement for the chromaticity compensation optics in the electron ring is preservation of the low beam emittance. This paper reviews the development and selection of a chromaticity correction scheme for the electron collider ring. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB31  
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TUPOB37 Diffusion Measurement From Transverse Echoes ion, quadrupole, simulation, octupole 572
 
  • Y.S. Li
    Carleton College, Northfield, Minnesota, USA
  
  Beam diffusion is an important measure of stability in high intensity beams. Traditional methods of diffusion characterization (e.g. beam scraping) can be very time-consuming. In this study, we investigate the transverse beam echo as a novel technique for measuring beam diffusion. Numerical analysis of maximum echo amplitude was compared with theoretical predictions with and without diffusion. We succeeded in performing a self-consistent measurement of the linear diffusion coefficient via a parameter scan over delay time. We also demonstrated the effectiveness of pulsed quadrupoles as a means to boost echo amplitude. Finally, multi-echo sequences were also briefly investigated. Results from this study will support planned experiments at the IOTA proton ring under construction at Fermilab.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB37  
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TUPOB41 Bi-Complex Toolbox Applied to Gyromagnetic Beam Break-Up ion, polarization, experiment, linac 585
 
  • A.V. Smirnov
    RadiaBeam, Santa Monica, California, USA
  
  Transverse instability of a multi-bunch beam in the presence of a longitudinal magnetostatic field and hybrid dipole modes is considered analytically within a single-section model. It incorporates resonant interaction with beam harmonics and eigenmodes, degenerated waves of different polarizations, and the Lorentz RF force contribution. The analysis is performed in a very compact form using a bi-complex i,j-space including four-component collective frequency of the instability. Rotating polarization of the collective field is determined by ImiImj part of the bi-complex collective frequency in agreement with available data. The other three components represent detuning of the collective frequency ReiRej, the left-hand, and right-hand increments ImiRej±ReiImj of the gyro-magnetic BBU effect. The scalar hyper-complex toolbox can be applied to designing of non-ferrite non-reciprocal devices, spin transport, and for characterization of complex transverse dynamics in gyro-devices such as Gyro-TWTs.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB41  
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TUPOB43 Magnetic Cloaking of Charged Particle Beams ion, electron, detector, superconducting-magnet 588
 
  • K.G. Capobianco-Hogan, A.A. Adhyatman, G. Arrowsmith-Kron, G. Bello Portmann, D.B. Bhatti, R. Cervantes, B.D. Coe, A. Deshpande, N. Feege, S.P. Jeffas, T.C. Krahulik, J.J. LaBounty, T.M. LaByer, A. Oliveira, H.A. Powers, R.S. Sekelsky, V.D. Shethna, N. Ward, H.J. van Nieuwenhuizen
    Stony Brook University, Stony Brook, USA
  • R. Cervantes
    University of Washington, CENPA, Seattle, USA
  • B.D. Coe
    BNL, Upton, Long Island, New York, USA
  
  In order to measure the momentum of particles produced by asymmetric collisions in the proposed Electron Ion Collider, a magnetic field should be introduced perpendicular to the path of the beam to increase momentum resolution without bending or depolarizing it. A magnetic cloak consisting of a superconducting magnetic shield surrounded by a ferromagnetic layer is capable of shielding the interior from a magnetic field – thereby protecting the beam – without distorting the field outside of the cloak – permitting detector coverage at high pseudorapidity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB43  
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TUPOB56 The eRHIC Ring-Ring Design ion, electron, proton, luminosity 616
 
  • C. Montag, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A.V. Fedotov, W. Fischer, Y. Hao, A. Hershcovitch, Y. Luo, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, S. Seletskiy, T.V. Shaftan, V.V. Smaluk, S. Tepikian, F.J. Willeke, H. Witte, Q. Wu
    BNL, Upton, Long Island, New York, USA
  
  The ring-ring version of the eRHIC electron-ion collider design aims at providing electron-proton collisions with a center-of-mass energy ranging from 32 to 141 GeV at a luminosity reaching 1033 cm-2 sec-1. This design of the double-ring collider also supports electron-ion collisions with similar electron-nucleon luminosities, and is upgradeable to 1034 cm-2 sec-1 using bunched beam electron cooling of the hadron beam. The baseline luminosities are achievable using existing technologies and beam parameters that have been routinely achieved at RHIC in hadron-hadron collisions or elsewhere in e+e− collisions. This minimizes the risk associated with the challenging luminosity goal and is keeping the technical risk of the e-RHIC electron-ion collider low. The latest design status will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB56  
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TUPOB60 Permanent Magnets for High Energy Nuclear Physics Accelerators ion, quadrupole, electron, permanent-magnet 622
 
  • N. Tsoupas, S.J. Brooks, A.K. Jain, F. Méot, V. Ptitsyn, D. Trbojevic
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by the US Department of Energy
The proposed eRHIC accelerator1 will collide 20 GeV polarized electrons with 250 GeV polarized protons or 100 GeV/n polarized 3He ions or other unpolarized heavy ions. The electron accelerator of the eRHIC will be based on a 1.665 GeV Energy Recovery Linac (ERL) placed in the RHIC tunnel and two Fixed Field Alternating Gradient (FFAG) recirculating rings placed alongside the RHIC accelerator. The electron bunches reach the 20 GeV energy after passing 12 times through the ERL by recirculation in the FFAG rings. The FFAG rings consist of FODO cells comprised of one focusing and one defocusing quadrupoles made of permanent magnet material. Similarly other sections of the electron accelerator will utilize permanent magnets. In this presentation we will discuss details on the design of these magnets and their advantages over the current-excited magnets.
1. <http://arxiv.org/ftp/arxiv/papers/1409/1409.1633.pdf> 		 
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TUPOB63 POSINST Simulation on Fermilab Main Injector and Recycler Ring ion, electron, simulation, proton 632
 
  • Y. Ji
    IIT, Chicago, Illinois, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
  • R.M. Zwaska
    Fermilab, Batavia, Illinois, USA
  
  The Fermilab accelerator complex is currently undergoing an upgrade from 400kW to 700kW. This intensity could push operations into the region where electron cloud (e-cloud) generation could be observed and even cause instabilities. The POSINST simulation code was used to study how in- creasing beam intensities will affect electron cloud genera- tion. Threshold simulations show how the e-cloud density depend on the beam intensity and secondary electron yield (SEY) in the Main Injector (MI) and Recycler Ring (RR).  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-TUPOB63  
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WEA2CO03 Incoherent Vertical Emittance Growth from Electron Cloud at CesrTA ion, simulation, electron, positron 672
 
  • S. Poprocki, J.A. Crittenden, S.N. Hearth, J.D. Perrin, D. L. Rubin, S. Wang
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Work supported by the US National Science Foundation PHY-1416318, PHY-0734867, and PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538.
We report on measurements of electron cloud (EC) induced tune shifts and emittance growth at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) with comparison to tracking simulation predictions. Experiments were performed with 2.1 GeV positrons in a 30 bunch train with 14 ns bunch spacing and 9 mm bunch length, plus a witness bunch at varying distance from the train to probe the cloud as it decays. Complementary data with an electron beam were obtained to distinguish EC effects from other sources of tune shifts and emittance growth. High resolution electric field maps are computed with EC buildup simulation codes (ECLOUD) in the small region around the beam as the bunch passes through the cloud. These time-sliced field maps are input to a tracking simulation based on a weak-strong model of the interaction of the positron beam (weak) with the electron cloud (strong). Tracking through the full lattice over multiple radiation damping times with electron cloud elements in the dipole and field-free regions predict vertical emittance growth, and tune shifts in agreement with the measurements. 		 
slides icon Slides WEA2CO03 [1.227 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEA2CO03  
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WEB2IO02 Compact Crabbing Cavity Systems for Particle Colliders cavity, ion, HOM, collider 679
 
  • S.U. De Silva
    ODU, Norfolk, Virginia, USA
  
  In circular or ring-based particle colliders, crabbing cavities are used to increase the luminosity. The first superconducting crabbing cavity system was successfully implemented at KEKB electron-positron collider that have demonstrated the luminosity increase with overlapping bunches. Crabbing systems are an essential component in the future colliders with intense beams, such as the LHC high luminosity upgrade and proposed electron-ion colliders. Novel compact superconducting cavity designs with improved rf properties, at low operating frequencies have been prototyped successfully that can deliver high operating voltages. We present single cavity and multi-cell crabbing cavities proposed for future particle colliders and addresses the challenges in those cavity systems.  
slides icon Slides WEB2IO02 [13.985 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB2IO02  
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WEB3IO02 First Test Results of the 150 mm Aperture IR Quadrupole Models for the High Luminosity LHC ion, quadrupole, luminosity, alignment 853
 
  • G. Ambrosio, G. Chlachidze
    Fermilab, Batavia, Illinois, USA
  • P. Ferracin
    CERN, Geneva, Switzerland
  • G.L. Sabbi
    LBNL, Berkeley, California, USA
  • P. Wanderer
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP) and by the High Luminosity LHC project at CERN.
The High Luminosity upgrade of the LHC at CERN will use large aperture (150 mm) quadrupole magnets to focus the beams at the interaction points. The high field in the coils requires Nb3Sn superconductor technology, which has been brought to maturity by the LHC Accelerator Research Program (LARP) over the last 10 years. The key design targets for the new IR quadrupoles were established in 2012, and fabrication of model magnets started in 2014. This paper discusses the results from the first single short coil test and from the first short quadrupole model test. Remaining challenges and plans to address them are also presented and discussed. 		 
slides icon Slides WEB3IO02 [15.312 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEB3IO02  
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WEPOB62 Absolute Energy Measurement of the LEReC Electron Beam ion, simulation, electron, HOM 1033
 
  • S. Seletskiy, M. Blaskiewicz, A.V. Fedotov, D. Kayran, J. Kewisch, T.A. Miller, P. Thieberger
    BNL, Upton, Long Island, New York, USA
  
  The goal of future operation of the low energy RHIC Electron Cooling (LEReC) accelerator is to cool the RHIC ion beams. To provide successful cooling, the velocities of the RHIC ion beam and the LEReC electron beam must be matched with 10-4 accuracy. While the energy of ions will be known with the required accuracy, the e-beam energy can have an initial offset as large as 5%. The final setting of the e-beam energy will be performed by observing either the Schottky spectrum of debunched ions co-traveling with the e-beam or the recombination signal. Yet, to start observing such signals one has to set the absolute energy of the electron beam with an accuracy better than 10-2, preferably better than 5·10-3. In this paper we discuss how such accuracy can be reached by utilizing the LEReC 180 degree bend as a spectrometer.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-WEPOB62  
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THA1CO04 Persistent Current Effect in 15-16 T Nb3Sn Accelerator Dipoles and its Correction ion, ion-effects, sextupole, collider 1061
 
  • A.V. Zlobin, V.V. Kashikhin
    Fermilab, Batavia, Illinois, USA
  
  Funding: * This work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
Nb3Sn magnets with operating fields of 15-16 T are considered for the LHC Energy Doubler and a future Very High Energy pp Collider. Due to large coil volume, high critical current density and large superconducting (SC) filament size the persistent current effect is very large in Nb3Sn dipoles al low fields. This paper presents the results of analysis of the persistent current effect in the 15 T Nb3Sn dipole demonstrator being developed at FNAL, and describes different possibilities of its correction including passive SC wires, iron shims and coil geometry. 		 
slides icon Slides THA1CO04 [3.440 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THA1CO04  
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THPOA06 CSR-Immune Arc Compressors for Recirculating Accelerators Driving High Brightness Electron Beams ion, optics, emittance, sextupole 1108
 
  • S. Di Mitri, M. Cornacchia
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  
  The advent of short electron bunches in high brightness linear accelerators has raised the awareness of the accelerator community to the degradation of the beam transverse emittance by coherent synchrotron radiation (CSR) emitted in magnetic bunch length compressors, transfer lines and turnaround arcs. We reformulate the concept of CSR-driven beam optics balance, and apply it to the general case of varying bunch length in an achromatic cell*. The dependence of the CSR-perturbed emittance to beam optics, mean energy, and bunch charge is shown. The analytical findings are compared with particle tracking results**. Practical considerations on CSR-induced energy loss and nonlinear particle dynamics are included. As a result, we identify the range of parameters that allows feasibility of an arc compressor in a recirculating accelerator driving, for example, a free electron laser or a linear collider.
*S. Di Mitri and M. Cornacchia, EPL, 109 (2015) 62002
**S. Di Mitri, NIM A 806 (2016) 184'192 		 
poster icon Poster THPOA06 [0.616 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA06  
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THPOA13 Modeling of Dipole and Quadrupole Fringe-Field Effects for the Advanced Photon Source Upgrade Lattice ion, quadrupole, lattice, multipole 1119
 
  • M. Borland, R.R. Lindberg
    ANL, Argonne, 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.
The proposed upgrade of the Advanced Photon Source (APS) to a multibend-achromat lattice requires shorter and much stronger quadrupole magnets than are present in the existing ring. This results in longitudinal gradient profiles that differ significantly from a hard-edge model. Additionally, the lattice assumes the use of five-segment longitudinal gradient dipoles. Under these circumstances, the effects of fringe fields and detailed field distributions are of interest. We evaluated the effect of soft-edge fringe fields on the linear optics and chromaticity, finding that compensation for these effects is readily accomplished. In addition, we evaluated the reliability of standard methods of simulating hard-edge nonlinear fringe effects in quadrupoles. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA13  
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THPOA16 Gaseous H2-Filled Helical FOFO Snake for Initial 6D Ionization Cooling of Muons ion, solenoid, emittance, focusing 1129
 
  • Y.I. Alexahin
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work supported by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the U.S. DOE
H2 gas-filled channel for 6D ionization cooling of muons is described which consists of periodically inclined solenoids of alternating polarity with 325MHz RF cavities inside them. To provide sufficient longitudinal cooling LiH wedge absorbers are placed at the minima of transverse beta-function between the solenoids. An important feature of such channel (called Helical FOFO snake) is that it can cool simultaneously muons of both signs. Theoretical considerations as well as results of simulations with G4beamline are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA16  
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THPOA29 PIP-II Transfer Lines Design ion, booster, linac, optics 1161
 
  • A. Vivoli
    Fermilab, Batavia, Illinois, USA
  
  The U.S. Particle Physics Project Prioritization Panel (P5) report encouraged the realization of Fermilab's Proton Improvement Plan II (PIP-II) to support future neutrino programs in the United States. PIP-II aims at enhancing the capabilities of the Fermilab existing accelerator complex while simultaneously providing a flexible platform for its future upgrades. The central part of PIP-II project is the construction of a new 800 MeV H− Superconducting (SC) Linac together with upgrades of the Booster and Main Injector synchrotrons. New transfer lines will also be needed to deliver beam to the downstream accelerators and facilities. In this paper we present the recent development of the design of the transfer lines discussing the principles that guided their design, the constraints and requirements imposed by the existing accelerator complex and the following modifications implemented to comply with a better understanding of the limitations and further requirements that emerged during the development of the project.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA29  
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THPOA30 SCHARGEV 1.0 - Strong Space Charge Vlasov Solver ion, space-charge, impedance, feedback 1164
 
  • T. Zolkin, A.V. Burov
    Fermilab, Batavia, Illinois, USA
  
  The space charge (SC) is known to be one of the major limitations for the collective transverse beam stability. When space charge is strong, i.e. SC tune shift much greater than synchrotron tune, the problem allows an exact analytical solution. For that practically important case we present a fast and effective Vlasov solver SCHARGEV (Space CHARGE Vlasov) which calculates a complete eigensystem (spatial shapes of modes and frequency spectra) and therefore provides the growth rates and the thresholds of instabilities. SCHARGEV 1.0 includes driving and detuning wake forces, and, any feedback system (damper). In the next version we will include coupled bunch interaction and Landau damping. Numerical examples for FermiLab Recycler and CERN SPS are presented.  
poster icon Poster THPOA30 [1.493 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA30  
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THPOA31 Sector Magnets or Transverse Electromagnetic Fields in Cylindrical Coordinates ion, multipole, HOM, electromagnetic-fields 1167
 
  • T. Zolkin
    Fermilab, Batavia, Illinois, USA
  
  Laplace's equation in normalized cylindrical coordinates is considered for scalar and vector potentials describing electric or magnetic fields with invariance along the azimuthal coordinate (arXiv:1603.03451). A series of special functions are found which when expanded to lowest order in power series in radial and vertical coordinates (rho=1 and y=0) replicate harmonic homogeneous polynomials in two variables. These functions are based on radial harmonics found by Edwin M. McMillan forty years ago. In addition to McMillan's harmonics, a second family of radial harmonics is introduced to provide a symmetric description between electric and magnetic fields and to describe fields and potentials in terms of the same functions. Formulas are provided which relate any transverse fields specified by the coefficients in the power series expansion in radial or vertical planes in cylindrical coordinates with the set of new functions. This result is important for potential theory and for theoretical study, design and proper modeling of sector dipoles, combined function dipoles and any general sector element for accelerator physics and spectrometry.  
poster icon Poster THPOA31 [2.274 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA31  
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THPOA37 Study of 2D CSR Effects in a Compression Chicane ion, simulation, electron, FEL 1181
 
  • C.C. Hall
    RadiaSoft LLC, Boulder, Colorado, USA
  • S. Biedron, S.V. Milton
    CSU, Fort Collins, Colorado, USA
  
  The study of coherent synchrotron radiation (CSR) has been an area of great interest because of its negative impact on FEL performance. The modeling of CSR is frequently performed using a 1D approximation*, as 2D and 3D models can become extremely computational intensive. While experimental evidence is lacking in this area most studies show reasonable agreement between 1D and 2D CSR models for beam parameters in existing accelerators. In this work we focus on 2D modeling of CSR in a four­-dipole chicane lattice based on the Jefferson Lab FEL. Comparison is shown between several models and measurement for energy loss due to CSR in the chicane. While good agreement is generally observed we also present investigation of several key differences observed in simulation. In particular, showing how the 1D and 2D CSR models deviate in regards to CSR and beam interaction within the drift spaces of the chicane and the downstream drift at the chicane end.
*E. Saldin, E. Schneidmiller, and M. Yurkov, Nucl. Instr. Meth. A398, 373 (1997). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA37  
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THPOA46 Benchmark of RF Photoinjector and Dipole Using ASTRA, GPT, and OPAL ion, simulation, gun, emittance 1194
 
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  • A. Adelmann
    PSI, Villigen PSI, Switzerland
  • G. Ha
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • C.J. Metzger-Kraus
    HZB, Berlin, Germany
  • N.R. Neveu, J.G. Power
    ANL, Argonne, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  • P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • S.J. Russell
    LANL, Los Alamos, New Mexico, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Funding: Grant no. DE-SC0015479, and contract No. DE-AC02-06CH11357.
With the rapid improvement in computing resources and codes in recent years, accelerator facilities can now achieve and rely on accurate beam dynamics simulations. These simulations include single particle effects (e.g. particle tracking in a magnetic field) as well as collective effects such as space charge (SC), and coherent synchrotron radiation (CSR). Using portions of the Argonne Wakefield Accelerator (AWA) as the benchmark model, we simulated beam dynamics with three particle tracking codes. The AWA rf photoinjector was benchmarked, primarily to study SC, in ASTRA, GPT, and OPAL-T using a 1 nC beam. A 20° dipole magnet was used to benchmark CSR effects in GPT and OPAL-T by bending a 1nC beam at energies between 2 MeV and 100 MeV. In this paper we present the results, and discuss the similarities and differences between the codes. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA46  
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THPOA48 Model of Electron Cloud Instability in Fermilab Recycler ion, electron, proton, simulation 1197
 
  • S. A. Antipov
    University of Chicago, Chicago, Illinois, USA
  • A.V. Burov, S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  
  An electron cloud instability might limit the intensity in the Fermilab Recycler after the PIP-II upgrade. A multibunch instability typically develops in the horizontal plane within a hundred turns and, in certain conditions, leads to beam loss. Recent studies have indicated that the instability is caused by an electron cloud, trapped in the Recycler index dipole magnets. We developed an analytical model of an electron cloud driven instability with the electrons trapped in combined function dipoles. The resulting instability growth rate of about 30 revolutions is consistent with experimental observations and qualitatively agrees with the simulation in the PEI code. The model allows an estimation of the instability rate for the future in-tensity upgrades.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA48  
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THPOA49 Electron Cloud Trapping in Recycler Combined Function Dipole Magnets ion, electron, proton, vacuum 1200
 
  • S. A. Antipov
    University of Chicago, Chicago, Illinois, USA
  • S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  
  Electron cloud can lead to a fast instability in intense proton and positron beams in circular accelerators. In the Fermilab Recycler the electron cloud is confined within its combined function magnets. We show that combined function magnets trap the electron cloud with their magnetic field, present the results of analytical estimates of trapping, and compare them to numerical simulations of electron cloud formation. The electron cloud in a combined function magnet is located at the beam center and up to 1% of the particles can be trapped by its magnetic field. Since the process of electron cloud build-up is exponential, once trapped this amount of electrons significantly increases the density of the cloud on the next revolution. In a Recycler combined function dipole this multi-turn accumulations allows the electron cloud reaching final intensities orders of magnitude greater than in a pure dipole. The multi-turn build-up can be stopped by injection of a single clearing bunch of 1*1010 p at any position in the ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-NAPAC2016-THPOA49  
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