IPAC2015 - List of Keywords (collider)

Paper	Title	Other Keywords	Page
MOBC1	Towards Ultra-Low β^* in ATF2	optics, octupole, multipole, linear-collider	38
	M. Patecki, A.V. Aloev, D.R. Bett, M. Modena, R. Tomás CERN, Geneva, Switzerland K. Kubo, T. Okugi, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan E. Marín, G.R. White SLAC, Menlo Park, California, USA
	The Accelerator Test Facility 2 (ATF2) has already demonstrated the feasibility of Final Focus Systems based on the local chromaticity correction scheme and its focusing capabilities by reaching a vertical beam size at the virtual Interaction Point (IP) of less than 50 nm. The value of the chromaticity in ATF2 is comparable with the expected chromaticity in ILC, but 4 times lower than in a design of CLIC. ATF2 gives the unique possibility to test operation at CLIC chromaticity values by reducing the vertical beta function at the IP by a factor of 4 (the inverse proportionality of chromaticity with beta function value at IP is assumed). The experience collected in this way would be beneficial for both ILC and CLIC projects. Simulations show that the multipolar errors and Final Doublet fringe fields spoil the IP beam sizes at ATF2. Either increasing a value of the horizontal beta function or installing a pair of octupole magnets mitigate the impact of these aberrations. This paper summarizes the studies towards the realization of the ultra-low β^* optics in ATF2 and reports on the progress of the construction of the octupoles.
	Slides MOBC1 [1.566 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOBC1
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MOPWA005	Comparison between Digital Filters and Singular Value Decomposition to Reduce Noise in LHC Orbits used for Action and Phase Jump Analysis	simulation, quadrupole, resonance, hadron	83
	A.C. García-Bonilla, J.F. Cardona UNAL, Bogota D.C, Colombia
	Funding: Fundación Para la Promoción de la Investigación y la Tecnología del Banco de la República and DIB (División de Investigación de Bogotá). One of the initial difficulties to apply the Action and Phase Jump (APJ) analysis to LHC orbits was the high level of noise present in the BPM measurements. On the other hand, the unprecedented number of turns for LHC allows us to use all sort of filters. In this paper, we evaluate the effectiveness of digital filters like the band-pass filter and compare them with a filter based on Singular Value Decomposition, when magnetic error estimations are made using a recent version of the APJ method. First, mainly results on simulated orbits with noise are presented, and then, plots and results are shown for the filters effect on experimental data. The analysis indicates that a combination of filters leads to measurements with the least uncertainty.
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MOPWA050	Beam Dynamics Studies to Develop a High-energy Luminosity Model for the LHC	simulation, luminosity, beam-beam-effects, emittance	233
	G. Campogiani Rome University La Sapienza, Roma, Italy Y. Papaphilippou CERN, Geneva, Switzerland
	Funding: support provided by the EPS-AG through the EPS-AG student grant program Luminosity, the key figure of merit of a collider as the LHC, depends on the brightness of the colliding beams. This makes the intensity dependent beam-beam effect the dominant performance limiting factor at collision. The parasitic interactions due to the electromagnetic mutual influence of the beams in the interaction region of a collider induce a diffusive behaviour in the tails of the beam. The evolution of charge density distribution is studied to model the beam tails evolution in order to characterize beam lifetime and luminosity. To achieve this, tools are developed for tracking distributions of arbitrary number of single particles interacting with the opposing strong-beam, to analyse the halo formation processes due to the combined effect of beam-beam and machine non-linearities. This paper presents preliminary results of the simulations, both for the LHC Run I and nominal LHC parameters. The former will be used to benchmark simulations while the latter aims at supporting luminosity estimate for the Run II.
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MOPWA059	Dynamic Aperture Studies for the FCC-ee	lattice, sextupole, synchrotron, radiation	258
	L.E. Medina Medrano DCI-UG, León, Mexico R. Martin, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland R. Martin Humboldt University Berlin, Berlin, Germany
	Funding: Work supported by the Beam Project (CONACYT, Mexico). Dynamic aperture (DA) studies have been conducted on the latest Future Circular Collider - ee (FCC-ee) lattices as a function of momentum deviation. Two different schemes for the interaction region are used, which are connected to the main arcs: the crab waist approach, developed by BINP, and an update to the CERN design where the use of crab cavities is envisioned. The results presented show an improvement in the performance of both designs.
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MOPWA062	Optimization of the Momentum Bandwidth for Final Focus System in CEPC	sextupole, factory, luminosity, simulation	269
	S. Bai, T.J. Bian, J. Gao, H. Geng, D. Wang, Y. Wang, M. Xiao IHEP, Beijing, People's Republic of China F. Su Institute of High Energy Physics (IHEP), People's Republic of China
	With the discovery of the higgs boson at around 125GeV, a circular higgs factory design with high luminosity (L ~ 10³⁴ cm^-2s^-1) is becoming more popular in the accelerator world. To achieve such high luminosity, a final focus system in non-local chromaticity correction scheme with very low β functions at the interaction point is designed. The narrow momentum bandwidth is a crucial problem of this kind of design. It is shown that by introducing additional sextupoles the momentum acceptance of the CEPC final focus system can be increased by about a factor of four.
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MOPWA067	Theory of Transverse Ionization Cooling in a Linear Channel	emittance, lattice, quadrupole, scattering	279
	M. Xiao, J. Gao, Y. Yue IHEP, Beijing, People's Republic of China
	Ionization cooling is the most hopeful method to reduce the emittance of muon beams, which plays an important role in neutrino factory and muon collider. Within the moment-equation approach, I present a way to derive the formulae of emittance in transverse under linear channel. All heating and coupling terms are reserved in the deriving process. From my formulae, it is a way to achieve a small emittance by designing the cooling channel compact to make the beta function changing sharply.
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MOPJE023	3D Computer Simulations of the Ultrarelativistic Beam Dynamics in Super Colliders	simulation, focusing, experiment, plasma	326
	M.A. Boronina, V.A. Vshivkov ICM&MG SB RAS, Novosibirsk, Russia G. Dudnikova ICT SB RAS, Novosibirsk, Russia
	Funding: The work is supported by RFBR Grants 14-01-31088, 14-01-00392, 14-07-00241. The problem of numerical modeling of beam-beam interaction with high relativistic factor (~10⁴) is considered. We present 3D a self-consistent simulation model based on particle-in-cell method. The mixed Euler-Lagrangian decomposition is used in parallel algorithm for achieving good load balancing and reducing communication cost. Stable regimes of beam dynamics, depending on the beams configuration (beta-function, emittance, energy, currents and relative offset) can be found on the base of the model. In the calculations we used 10⁸ particles on the grid 100x100x100, the number of processors depends highly on the beam shape. The Lomonosov Super Computer and Siberian Supercomputer Centre cluster were used to perform the presented simulations.
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MOPJE029	A Linear Accelerator Simulation Framework	simulation, framework, ground-motion, lattice	341
	J. Snuverink JAI, Egham, Surrey, United Kingdom N. Fuster-Martínez IFIC, Valencia, Spain J. Pfingstner CERN, Geneva, Switzerland J. Pfingstner University of Oslo, Oslo, Norway
	Many good tracking tools are available for simulations for linear accelerators. However, several simple tasks need to be performed repeatedly, like lattice definitions, beam setup, output storage, etc. In addition, complex simulations can become unmanageable quite easily. A high level layer would therefore be beneficial. We propose LinSim, a linear accelerator framework with the codes PLACET and Guinea-Pig. It provides a documented well-debugged high level layer of functionality. Users only need to provide the input settings and essential code and/or use some of the many implemented imperfections and algorithms. It can be especially useful for first-time users. Currently the following accelerators are implemented: ATF2, ILC, CLIC and FACET. This paper discusses the framework design and shows its strength in some condensed examples.
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MOPJE055	Design of an Intense Muon Source with a Carbon and Mercury Target	target, proton, factory, solenoid	423
	D. Stratakis, J.S. Berg BNL, Upton, Long Island, New York, USA X.P. Ding UCLA, Los Angeles, California, USA D.V. Neuffer Fermilab, Batavia, Illinois, USA
	Funding: Authored by employees of Brookhaven Science Associates LLC under Contract DE-SC0012704 and with Fermi Research Alliance LLC under Contract DE-AC02-07CH11359 with the United States Department of Energy In high-intensity sources, muons are produced by firing high energy protons onto a target to produce pions. The pions decay to muons which are captured and accelerated. In the present study, we examine the performance of the channel for two different target scenarios: one based on liquid mercury and another one based on a solid carbon target. We produce distributions with the two different target materials and discuss differences in particle spectrum near the sources. We then propagate the distributions through our capture system and compare the full system performance for the two target types.
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MOPJE062	Testing Aspects of Advanced Coherent Electron Cooling Technique	electron, hadron, bunching, FEL	445
	V. Litvinenko, Y.C. Jing, I. Pinayev, G. Wang BNL, Upton, Long Island, New York, USA D.F. Ratner SLAC, Menlo Park, California, USA V. Samulyak SBU, Stony Brook, USA
	An advanced version of the coherent-electron cooling based on the microbunching instability was proposed in . This approach promised to significantly increase the bandwidth of the system and, therefore, significantly shorter cooling time in high energy hadron colliders. In this paper we present our plans of simulating and testing the key aspects of this proposed technique using the set-up of the coherent-electron-cooling proof-of-principle experiment at BNL. D.F. Ratner, Phys. Rev. Lett. 111, 084802 (2013)
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MOPJE073	The Extreme Beams Initiative in EuCARD-2	polarization, linac, hadron, diagnostics	483
	G. Franchetti, J. Struckmeier GSI, Darmstadt, Germany K. Aulenbacher IKP, Mainz, Germany F. Zimmermann CERN, Geneva, Switzerland
	EuCARD-2 is an Integration Activity on accelerator R&D co-funded within the European Union’s 7th Framework Programme. The Extreme Beams (XBEAM) network of EuCARD-2 extends, and goes beyond the scope of, the previous Networking Activities of CARE-HHH and EuCARD(-1) EuroLumi. XBEAM addresses, and pushes, all accelerator frontiers: luminosity, energy, beam power, beam intensity, and polarization. This is realized through five tasks: Coordination and Communication, Extreme Colliders (XCOL)m Extreme Performance Rings (XRING), Extreme SC Linacs (XLINAC), and Extreme Polarization (XPOL), respectively. In the first two years of EuCARD-2, XBEAM (co-)organised more than 15 topical workshops: the upgrade of KEKB in Japan, crystal channelling, the advancement of the CERN facilities, e.g. LHC upgrades and the Future Circular Collider, magnet optimization, space-charge effects, the commissioning of proton linacs, with emphasis on the ESS, key questions for lepton spin polarization, storage rings for measuring the electric dipole moment of electrons or protons. This presentation reports the major achievements of the XBEAM activity from 2013 to 2015, and outlines the further plans through 2017.
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MOPJE078	Beam Delivery Simulation - Recent Developments and Optimization	simulation, background, toolkit, linear-collider	499
	J. Snuverink, S.T. Boogert, H. Garcia Morales, S.M. Gibson, R. Kwee-Hinzmann, L.J. Nevay JAI, Egham, Surrey, United Kingdom L.C. Deacon UCL, London, United Kingdom
	Funding: Research supported by FP7 HiLumi LHC - grant agreement 284404 and by the STFC via the JAI3 grant Beam Delivery Simulation (BDSIM) is a particle tracking code that simulates the passage of particles through both the magnetic accelerator lattice as well as their interaction with the material of the accelerator itself. The Geant4 toolkit is used to give a full range of physics processes needed to simulate both the interaction of primary particles and the production and subsequent propagation of secondaries. BDSIM has already been used to simulate linear accelerators such as the International Linear Collider (ILC) and the Compact Linear Collider (CLIC), but it has recently been adapted to simulate circular accelerators as well, producing loss maps for the Large Hadron Collider (LHC). In this paper the most recent developments, which extend BDSIM's functionality as well as improve its efficiency are presented. Improvement and refactorisation of the tracking algorithms are presented alongside improved automatic geometry construction for increased particle tracking speed.
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MOPJE082	Analytical Approach to the Beam-Beam Interaction with the Hourglass Effect	luminosity, coupling, detector, framework	510
	M.P. Crouch, R.B. Appleby UMAN, Manchester, United Kingdom B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: STFC HL-LHC The HL-LHC upgrade will allow higher luminosities to be reached in the LHC. To achieve higher luminosities the β-function at the IP is decreased, which in turn will result in the hourglass effect becoming more prominent as the transverse bunch sizes become comparable to the length of the bunch. This effect reduces the luminosity since not all particles in the bunch will collide at the minimum IP. The standard derivation of the electric and magnetic fields of the beam-beam interaction is that undertaken by Bassetti and Erskine. The derivation by Bassetti Erskine does not include a coupling between bunch planes. When the transverse bunch sizes are comparable to the length of the bunch the magnitude of the transverse kick will be dependent on the longitudinal position. Currently only numerical methods are available to evaluate this effect. Here a theoretical framework is outlined that provides an analytical approach to derive the electric field for the beam-beam interaction with a coupling between the transverse and longitudinal planes.
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MOPMA022	Numerical Analysis of Parasitic Crossing Compensation with Wires in DAΦNE	positron, luminosity, beam-beam-effects, experiment	589
	A. Valishev Fermilab, Batavia, Illinois, USA C. Milardi, M. Zobov INFN/LNF, Frascati (Roma), Italy D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	Funding: This work was partially supported by the US LARP. The HiLumi LHC Design Study is partially funded by the European Commission Grant Agreement 284404. Current bearing wire compensators were successfully used in the 2005-2006 running of the DAΦNE collider to mitigate the detrimental effects of parasitic beam-beam interactions. A marked improvement of the positron beam lifetime was observed in machine operation with the KLOE detector. In view of the possible application of wire beam-beam compensators for the High Luminosity LHC upgrade, we revisit the DAΦNE experiments. We use an improved model of the accelerator with the goal to validate the modern simulation tools and provide valuable input for the LHC upgrade project.
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MOPMN007	An Alternate Ring-Ring Design for eRHIC	electron, ion, proton, linac	713
	Y. Zhang JLab, Newport News, Virginia, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and No. DE-AC02-06CH11357 I present here a new ring-ring design of eRHIC. It utilizes high repetition rate colliding beams and is likely able to deliver the performance to meet the requirements of the science program with low technical risk and modest accelerator R&D. The expected performance includes high luminosities over multiple collision points and a broad CM energy range with a maximum value up to 2×1034 cm^-2s⁻¹ per detector, and polarization higher than 70% for the colliding electron and light ion beams. This new design calls for reuse of decommissioned facilities in the US, namely, the PEP-II high energy ring and one section of the SLAC linac as a full energy injector.
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MOPMN027	Optimization of Dynamic Aperture for Hadron Lattices in eRHIC	sextupole, lattice, hadron, storage-ring	757
	Y.C. Jing, V. Litvinenko, D. Trbojevic BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The potential upgrade of the Relativistic Heavy Ion Collider (RHIC) to an electron ion collider (eRHIC) involves numerous extensive changes to the existing collider complex. The expected very high luminosity is planned to be achieved at eRHIC with the help of squeezing the beta function of the hadron ring at the IP to a few cm, causing a large rise of the natural chromaticities and thus bringing with it challenges for the beam long term stability (Dynamic aperture). We present our effort to expand the DA by carefully tuning the nonlinear magnets thus controlling the size of the footprints in tune space and all lower order resonance driving terms. We show a reasonably large DA through particle tracking over millions of turns of beam revolution.
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MOPTY053	Electromagnetic Design and Optimization of Directivity of Stripline Beam Position Monitors for the High Luminosity Large Hadron Collider	luminosity, simulation, impedance, hadron	1051
	D. Draskovic, C.B. Boccard, O.R. Jones, T. Lefèvre, M. Wendt CERN, Geneva, Switzerland
	This paper presents the preliminary electromagnetic design of a stripline Beam Position Monitor (BPM) for the High Luminosity program of the Large Hadron Collider (HL-LHC) at CERN. The design is fitted into a new octagonal shielded Beam Screen for the low-beta triplets and is optimized for high directivity. It also includes internal Tungsten absorbers, required to reduce the energy deposition in the superconducting magnets. The achieved broadband directivity in wakefield solver simulations presents significant improvement over the directivity of the current stripline BPMs installed in the LHC.
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MOPTY084	Design, Testing and Performance Results of a High-resolution, Broad-band, Low-latency Stripline Beam Position Monitor System	electron, operation, laser, FPGA	1136
	P. Burrows, D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich, G.B. Christian, M.R. Davis, C. Perry JAI, Oxford, United Kingdom D.R. Bett CERN, Geneva, Switzerland
	A high-resolution, low-latency beam position monitor (BPM) system has been developed for use in particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. The fast analogue front-end signal processor is based on a single-stage RF down-mixer. The processor latency is 15.6 ± 0.1 ns. A position resolution below 300 nm has been demonstrated for beam intensities of around 1 nC, with single-pass beam.
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TUYB3	Progress on the Design of the Polarized Medium-energy Electron Ion Collider at JLab	ion, electron, polarization, luminosity	1302
	F. Lin, S.A. Bogacz, P.D. Brindza, A. Camsonne, E. Daly, Y.S. Derbenev, D. Douglas, R. Ent, D. Gaskell, R.L. Geng, J.M. Grames, J. Guo, L. Harwood, A. Hutton, K. Jordan, A.J. Kimber, G.A. Krafft, R. Li, T.J. Michalski, V.S. Morozov, P. Nadel-Turonski, F.C. Pilat, M. Poelker, R.A. Rimmer, Y. Roblin, T. Satogata, M. Spata, R. Suleiman, A.V. Sy, C. Tennant, H. Wang, S. Wang, H. Zhang, Y. Zhang, Z.W. Zhao JLab, Newport News, Virginia, USA S. Abeyratne, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA D.P. Barber DESY, Hamburg, Germany Y. Cai, Y. Nosochkov, M.K. Sullivan, M.-H. Wang, U. Wienands SLAC, Menlo Park, California, USA A. Castilla, J.R. Delayen ODU, Norfolk, Virginia, USA Y. Filatov JINR, Dubna, Russia J. Gerity, T.L. Mann, P.M. McIntyre, N. Pogue, A. Sattarov Texas A&M University, College Station, Texas, USA C. Hyde, K. Park Old Dominion University, Norfolk, Virginia, USA A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia P.N. Ostroumov ANL, Argonne, Illinois, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. The Medium-energy Electron Ion Collider (MEIC) at JLab is designed to provide high luminosity and high polarization needed to reach new frontiers in the exploration of nuclear structure. The luminosity, exceeding 1033 cm^-2s⁻¹ in a broad range of the center-of-mass (CM) energy and maximum luminosity above 1034 cm^-2s⁻¹, is achieved by high-rate collisions of short small-emittance low-charge bunches made possible by high-energy electron cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, 3He) can be easily preserved and manipulated due to the unique figure-8 shape of the collider rings. A fully consistent set of parameters have been developed considering the balance of machine performance, required technical development and cost. This paper reports recent progress on the MEIC accelerator design including electron and ion complexes, integrated interaction region design, figure-8-ring-based electron and ion polarization schemes, RF/SRF systems and ERL-based high-energy electron cooling. Luminosity performance is also presented for the MEIC baseline design.
	Slides TUYB3 [6.245 MB]
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TUBD2	Final Cooling For a High-luminosity High-energy Lepton Collider	emittance, luminosity, solenoid, linac	1384
	D.V. Neuffer Fermilab, Batavia, Illinois, USA T.L. Hart, D.J. Summers UMiss, University, Mississippi, USA H. K. Sayed BNL, Upton, Long Island, New York, USA
	Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the U. S. Department of Energy. The final cooling system for a high-energy high-luminosity muon collider requires reduction of the transverse emittance by an order of magnitude to ~0.00003 m (rms, N), while allowing longitudinal emittance increase to ~0.1m. In the present baseline approach, this is obtained by transverse cooling of low-energy muons within a sequence of high field solenoids with low-frequency rf systems. Recent studies of such systems are presented. Since the final cooling steps are actually emittance exchange a variant form of that final system can be obtained by a round to flat transform in x-y, with transverse slicing of the enlarged flat transverse dimension followed by longitudinal recombination of the sliced bunchlets. Development of final exchange following lowest-emittance cooling is discussed.
	Slides TUBD2 [1.976 MB]
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TUPTY004	Tracking Simulation for Beam Loss Studies with Application to FCC	simulation, lattice, scattering, detector	2004
	M. Boscolo INFN/LNF, Frascati (Roma), Italy H. Burkhardt CERN, Geneva, Switzerland
	We present an implementation of a tracking simulation tool used to evaluate the main particle loss effects for Flavor Factories with the aim of applying these studies also to FCC. We describe the interface of the Monte Carlo tracking code with MAD-X, showing first simulations of the Touschek effect for the FCC-ee at the Z. We plan to use this approach also for multi-turn simulations of particles scattered by radiative Bhabha, beam-gas and eventually Beamstrahlung effects.
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TUPTY010	The Luminosity Reduction with Hourglass Effect and Crossing Angle in an e-p Collider	luminosity, electron, proton, acceleration	2016
	Y.M. Peng IHEP, Beijing, People's Republic of China Y. Zhang JLab, Newport News, Virginia, USA
	This paper derived the luminosity reduction caused by crossing angle and hourglass effect in an asymmetric collision. Here, we gave the general expressions of the geometrical reduction factor of luminosity for the asymmetric case caused by crossing angle and hourglass effect, for tri-Gaussian bunches colliding. We also gave it simple expression in some special cases to recover the earlier results, such as the formulas for only hour-glass effect exist and only crossing angle exist. The expressions used in e-p collider are also analysed in detail.
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TUPTY017	Ion Polarization Control in the MPD and SPD Detectors of the NICA Collider	polarization, solenoid, detector, proton	2031
	A.D. Kovalenko, A.V. Butenko, V.D. Kekelidze, V.A. Mikhaylov JINR, Dubna, Moscow Region, Russia Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Two solenoid Siberian snakes are placed in the opposite collider’s straight sections are used to control deuteron’s and proton’s polarization in the NICA collider. Solenoid snakes substantially reconstruct beam’s orbital motion. The change of the polarization direction in the vertical plane of MPD and SPD detectors occurs due to insertion of polarization control (PC) solenoids in the magnetic lattice of the collider. The solenoids rotating particle’s spin by small angels practically do not influence on the beam’s orbital motion parameters. The dynamic of the polarization vector as function of the orbit length for cases of longitudinal and vertical polarization in the MPD and SPD detectors are presented.
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TUPTY018	Interaction region for crab waist scheme of the Future Electron-Positron Collider (CERN)	sextupole, quadrupole, luminosity, lattice	2034
	A.V. Bogomyagkov, E.B. Levichev BINP SB RAS, Novosibirsk, Russia
	Funding: Work is supported by the Ministry of Education and Science of the Russian Federation Design study of the accelerator that would fit 80-100~km tunnel called Future Circular Colliders (FCC) includes high-luminosity e⁺e^- collider (FCC-ee) with center-of-mass energy from 90 to 350~GeV to study Higgs boson properties and perform precise measurements at the electroweak scale. Crab waist interaction region provides collisions with luminosity higher than 2×10³⁶~cm^-2sec^-1 at beam energy of 45~GeV. The small values of the beta functions at the interaction point and distant final focus lenses are the reasons for high nonlinear chromaticity limiting energy acceptance of the whole ring. The paper describes interaction region for crab waist collision scheme in the FCC-ee, principles of tuning the chromaticity correction section in order to provide large energy acceptance.
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TUPTY023	Lessons Learned From the First Long Shutdown of the Lhc and Its Injector Chain	operation, radiation, superconducting-magnet, hardware	2050
	K. Foraz, M.B.M. Barberan Marin, M. Bernardini, J. Coupard, N. Gilbert, D. Hay, S. Mataguez, D.J. Mcfarlane, E. Vergara Fernandez CERN, Geneva, Switzerland
	The First Long Shutdown (LS1) of the LHC and its Injector chain, which started in February 2013, was completed by the first quarter 2015. A huge number of activities have been performed; this paper reviews the process of the coordination of LS1 from the preparatory phase to the testing phase. The preparatory phase is a very important process: an accurate view of what is to be done, and what can be done is essential. But reality is always different, the differences between what was planned and what was done will be described. The paper will recall the coordination, reporting and decisional processes, highlighting points of success and points to be improved in terms of general coordination, in-situ coordination, safety coordination, logistics and resource management.
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TUPTY033	Civil Engineering Optimisation Tool for the Study of CERN's Future Circular Colliders	alignment, civil-engineering, hadron, database	2079
	C. Cook, B. Goddard, P. Lebrun, J.A. Osborne, Y. Robert CERN, Geneva, Switzerland
	Funding: CERN The feasibility of Future Circular Colliders (FCC), possible successors to the Large Hadron Collider (LHC), is currently under investigation at CERN. This paper describes how CERN’s civil engineering team are utilising an interactive tool containing a 3D geological model of the Geneva basin. This tool will be used to investigate the optimal position of the proposed 80km-100km tunnel. The benefits of using digital modelling during the feasibility stage are discussed and some early results of the process are presented.
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TUPTY042	Non-linear Coupling Studies in the LHC	coupling, octupole, hadron, simulation	2105
	T. Persson, Y.I. Levinsen, E.H. Maclean, R. Tomás CERN, Geneva, Switzerland E.H. Maclean JAI, Oxford, United Kingdom
	The amplitude detuning has been observed to decrease significantly as the horizontal and vertical tunes are approaching each other. This effect is potentially harmful since it might cause a loss of Landau damping, hence giving rise to instabilities. The measured tune split (Qx-Qy) versus amplitude is several times bigger than what can be explained with linear coupling. In this paper we present studies performed to identify the dominant sources of the non-linear coupling observed in the LHC.
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TUPTY047	ERL with Non-Scaling Fixed Field Alternating Gradient Lattice for eRHIC	electron, linac, hadron, ion	2120
	D. Trbojevic, J.S. Berg, S.J. Brooks, Y. Hao, V. Litvinenko, C. Liu, F. Méot, M.G. Minty, V. Ptitsyn, T. Roser, P. Thieberger, N. Tsoupas BNL, Upton, Long Island, New York, USA
	Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy. The proposed eRHIC electron-hadron collider uses a "non-scaling FFAG" lattice to recirculate 16 turns of different energy through just two beamlines located in the RHIC tunnel. This paper presents lattices for these two FFAGs that are optimised for low magnet field and to minimise total synchrotron radiation across the energy range. The higher number of recirculations in the FFAG allows a shorter linac (1.322GeV) to be used, drastically reducing cost, while still achieving a 21.2GeV maximum energy to collide with one of the existing RHIC hadron rings at up to 250GeV. eRHIC uses many cost-saving measures in addition to the FFAG: the linac operates in energy recovery mode, so the beams also decelerate via the same FFAG loops and energy is recovered from the interacted beam. All magnets will constructed from NdFeB permanent magnet material, meaning chillers and large magnet power supplies are not needed. This paper also describes a smaller prototype ERL-FFAG accelerator that will test all of these technologies in combination to reduce technical risk for eRHIC.
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TUPTY050	Considerations for the Beam Dump System of a 100 TeV Centre-of-mass FCC hh Collider	extraction, kicker, septum, optics	2132
	T. Kramer, M.G. Atanasov, M.J. Barnes, W. Bartmann, J. Borburgh, E. Carlier, F. Cerutti, L. Ducimetière, B. Goddard, A. Lechner, R. Losito, G.E. Steele, L.S. Stoel, J.A. Uythoven, F.M. Velotti CERN, Geneva, Switzerland
	A 100 TeV centre-of-mass energy frontier proton collider in a new tunnel of 80–100 km circumference is a central part of CERN’s Future Circular Colliders (FCC) design study. One of the major challenges for such a machine will be the beam dump system, which for each ring will have to reliably abort proton beams with stored energies in the range of 8 Gigajoule, more than an order of magnitude higher than planned for HL-LHC. The transverse proton beam energy densities are even more extreme, a factor of 100 above that of the presently operating LHC. The requirements for the beam dump subsystems are outlined, and the present technological limitations are described. First concepts for the beam dump system are presented and the feasibility is discussed, highlighting in particular the areas in which major technological progress will be needed. The potential implications on the overall machine and other key subsystems are described, including constraints on filling patterns, interlocking, beam intercepting devices and insertion design.
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TUPTY054	RF Design of the CLIC Structure Prototype Optimized for Manufacturing from Two Halves	linac, multipole, wakefield, simulation	2147
	H. Zha, A. Grudiev CERN, Geneva, Switzerland V.A. Dolgashev SLAC, Menlo Park, California, USA
	We present the RF design of a 12GHz Compact Linear Collider (CLIC) main linac accelerating structure prototype. The structure is made from two longitudinally symmetric halves. The main manufacturing process of each half is precision milling. The structure uses the same iris dimensions as the CLIC-G structure but the cell shape is optimized for milling. The geometry is optimized to reduce the surface electric and magnetic fields and the modified Poynting vector. This design can potentially reduce fabrication cost.
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TUPTY055	Optimization of the RF Design of the CLIC Main Linac Accelerating Structure	wakefield, linac, simulation, cavity	2150
	H. Zha, A. Grudiev CERN, Geneva, Switzerland
	We present a new optimized design of the accelerating structure for the main linac of CLIC (Compact Linear Collider). The new structure has lower surface magnetic fields and a significantly smaller transverse size compared to the baseline design described in the CLIC Concept Design Report (CDR). This new design should reach higher accelerating gradients and have a reduced manufacturing cost. The details of the RF design procedure and the obtained results are presented in this paper.
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TUPTY057	Scenarios for Circular Gamma-Gamma Higgs Factories	laser, luminosity, electron, factory	2156
	F. Zimmermann, Y. Papaphilippou CERN, Geneva, Switzerland R. Aleksan CEA/DSM/IRFU, France A. Apyan NU, Evanston, Illinois, USA
	Funding: The research leading to these results has received partial funding from the European Commission under the FP7 Research Infrastructures project EuCARD-2, grant agreement no.312453. The Higgs boson can be produced directly in gamma-gamma collisions generated by laser Compton back scattering off 80-90 GeV electron or positron beams. We discuss options for realizing a gamma-gamma Higgs factory using a high-energy circular e⁺e⁻ collider, such as FCC-ee or CEPC, and/or its top-up injector ring, and compare the parameters and advantages of such a facility, including the expected performance, with those for a Higgs factory based on a recirculating linac, such as SAPPHiRE.
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TUPTY058	Mitigating Performance Limitations of Single Beam-pipe Circular e⁺e⁻ Colliders	luminosity, electron, synchrotron, operation	2160
	M. Koratzinos DPNC, Genève, Switzerland F. Zimmermann CERN, Geneva, Switzerland
	Renewed interest in circular e⁺e⁻ colliders has spurred designs of single beam-pipe machines, like the CEPC in China, and double beam pipe ones, such as the FCC-ee effort at CERN. Single beam-pipe designs profit from lower costs but are limited by the number of bunches that can be accommodated in the machine. We analyse these performance limitations and propose a solution that can accommodate O(1000) bunches while keeping more than 90% of the ring with a single beam pipe.
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TUPTY059	First Considerations on Beam Optics and Lattice Design for the Future Electron-Positron Collider FCC-ee	emittance, optics, lattice, operation	2162
	B. Härer, B.J. Holzer, F. Zimmermann CERN, Geneva, Switzerland A.V. Bogomyagkov BINP SB RAS, Novosibirsk, Russia
	The Future Circular Collider (FCC) study includes the design of a 100-km electron positron collider (FCC-ee) with collision energies between 90 GeV and 350 GeV. This paper describes first aspects of the design and the optics of the FCC-ee collider, optimised for four different beam energies. Special emphasis is put on the need for a highly flexible magnet lattice in order to achieve the required beam emittances in each case and on the layout of the interaction region that will have to combine an advanced mini-beta concept, an effective beam separation scheme and a local chromaticity control to optimise the momentum acceptance and dynamic aperture of the ring.
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TUPTY060	The FCC-ee Study: Progress and Challenges	interaction-region, synchrotron, radiation, optics	2165
	M. Koratzinos DPNC, Genève, Switzerland S. Aumon, C. Cook, A. Doblhammer, B. Härer, B.J. Holzer, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland A.V. Bogomyagkov, E.B. Levichev, D.N. Shatilov BINP SB RAS, Novosibirsk, Russia M. Boscolo INFN/LNF, Frascati (Roma), Italy L.E. Medina Medrano UGTO, Leon, Mexico U. Wienands SLAC, Menlo Park, California, USA
	The FCC (future circular collider) study represents a vision for the next large project in high energy physics, comprising a 80-100 km tunnel that can house a future 100TeV hadron collider. The study also includes a high luminosity e⁺e⁻ collider operating in the centre-of-mass energy range of 90-350 GeV as a possible intermediate step, the FCC-ee. The FCC-ee aims at definitive electro-weak precision measurements of the Z, W, H and top particles, and search for rare phenomena. Although FCC-ee is based on known technology, the goal performance in luminosity and energy calibration make it quite challenging. During 2014 the study went through an exploration phase and during the next three years a conceptual design report will be prepared.
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TUPTY061	Combined Operation and Staging Scenarios for the FCC-ee Lepton Collider	emittance, luminosity, optics, operation	2169
	M. Benedikt, B.J. Holzer, E. Jensen, R. Tomás, J. Wenninger, F. Zimmermann CERN, Geneva, Switzerland A.V. Bogomyagkov, E.B. Levichev, D.N. Shatilov BINP SB RAS, Novosibirsk, Russia K. Ohmi, K. Oide KEK, Ibaraki, Japan U. Wienands SLAC, Menlo Park, California, USA
	FCC-ee is a proposed high-energy electron positron circular collider that would initially occupy the 100-km FCC tunnel that will eventually house the 100 TeV FCC-hh hadron collider. The parameter range for the e⁺/e⁻ collider is large, operating at a cm energy from 90 GeV (Z-pole) to 350 GeV (t-tbar production) with the maximum beam current ranging from 1.5 A to 6 mA for each beam, corresponding to a synchrotron radiation power of 50 MW and a radiative energy loss varying from ~30 MeV/turn to ~7500 MeV/turn. This presents challenges for the rf system due to the varying rf voltage requirements and beam loading conditions. In this paper we present a possible gradual evolution of the FCC-ee complex by step-wise expansion, and possibly reconfiguration, of the superconducting RF system. The performance attainable at each step is discussed, along with the possible advantages and drawbacks.
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TUPTY074	Muon Beam Emittance Evolution in the Helical Ionization Cooling Channel for Bright Muon Sources	plasma, emittance, space-charge, simulation	2203
	K. Yonehara, C.Y. Yoshikawa Fermilab, Batavia, Illinois, USA C.M. Ankenbrandt, R.P. Johnson, S.A. Kahn Muons, Inc, Illinois, USA M. Chung UNIST, Ulsan, Republic of Korea Y.S. Derbenev, A.V. Sy JLab, Newport News, Virginia, USA B.T. Freemire IIT, Chicago, Illinois, USA
	The six-dimensional ionization cooling is essential to design a bright muon source. A geometry constraint is a challenge issue in a compact helical cooling channel (HCC). Especially, the HCC requires a large bore helical magnet and a compact helical RF system to incorporate the RF into the magnet chamber. A new emittance evolution has been designed to mitigate the geometry constraint. The HCC was functionally separated into three parts sections. The lattice at the initial section provides a large transverse acceptance by using a strong helical focus magnet. Once the transverse beam size is small enough to get into the compact RF the HCC lattice in the middle section generates a large longitudinal beta tune to dominate the longitudinal cooling. Consequently, the longitudinal emittance becomes smaller than the transverse one at the end of middle section. In the final section, the magnetic field strength is gradually reduced to match out the helical channel to the straight solenoid. As a result, the emittance exchange takes place and the final transverse emittance becomes smaller than the longitudinal one. The new emittance evolution scenario will be discussed in this presentation.
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TUPTY078	Fixed-energy Cooling and Stacking for an Electron Ion Collider	electron, ion, ECR, space-charge	2214
	P.M. McIntyre, S. Assadi, J. Gerity, A. Sattarov Texas A&M University, College Station, Texas, USA
	The proposed designs for polarized-beam electron-ion colliders require cooling of the ion beam to achieve and sustain high luminosity. One attractive approach is to make a fixed-energy storage ring in which ions are con-tinuously cooled and stacked during a collider store, then transferred to the collider and accelerated for a new store when the luminosity decreases. An example design is reported for a 6 GeV/u superferric storage ring, and for a d.c. electron cooling system in which electron space charge is fully neutralized so that high-current magnetized e-cooling can be used to best advantage.
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TUPTY081	Design of a 6 TeV Muon Collider	sextupole, dynamic-aperture, quadrupole, octupole	2226
	M.-H. Wang, Y. Cai, Y. Nosochkov SLAC, Menlo Park, California, USA M.A. Palmer Fermilab, Batavia, Illinois, USA
	Funding: Work supported by the US Department of Energy contract DE-AC02-76SF00515 A design of a muon collider ring with the center of mass energy of 6 TeV is presented. The ring circumference is about 6.3 km, and the beta functions at collision point are 1 cm in both planes. The ring linear optics, the non-linear chromaticity correction scheme in the Interaction Region (IR), and the additional non-linear field orthogonal knobs are described in detail. The IR magnet specifications are based on the maximum pole tip field of 20 T in dipoles and 15 T in quadrupoles. The results of the beam dynamics optimization for maximum dynamic aperture are presented.
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TUPTY082	Scanning Synchronization of Colliding Bunches for MEIC Project	cavity, ion, controls, electron	2229
	Y.S. Derbenev, V.P. Popov JLab, Newport News, Virginia, USA Y.D. Chernousov ICKC, Novosibirsk, Russia G.M. Kazakevich Euclid TechLabs, LLC, Solon, Ohio, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Synchronization of colliding beams is one of the major issues of an electron-ion collider (EIC) design because of sensitivity of ion revolution frequency to beam energy. A conventional solution for this trouble is insertion of bent chicanes in the arcs space. In our report we consider a method to provide space coincidence of encountering bunches in the crab-crossing orbits Interaction Region (IR) while repetition rates of two beams do not coincide. The method utilizes pair of fast kickers realizing a bypass for the electron bunches as the way to equalize positions of the colliding bunches at the Interaction Point (IP). A dipole-mode warm or SRF cavities fed by the magnetron transmitters are used as fast kickers, allowing a broad-band phase and amplitude control. The proposed scanning synchronization method implies stabilization of luminosity at a maximum via a feedback loop. This synchronization method is evaluated as perspective for the Medium Energy Electron-Ion collider (MEIC) project of JLab with its very high bunch repetition rate.
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TUPTY084	Update on the MEIC Electron Collider Ring Design	electron, dipole, quadrupole, optics	2236
	F. Lin, Y.S. Derbenev, L. Harwood, A. Hutton, V.S. Morozov, F.C. Pilat, Y. Zhang JLab, Newport News, Virginia, USA Y. Cai, Y. Nosochkov, M.K. Sullivan, M.-H. Wang, U. Wienands SLAC, Menlo Park, California, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work also supported by the U.S. DOE Contract No. DE-AC02-76SF00515. The electron collider ring of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab is designed to accumulate and store a high-current polarized electron beam for collisions with an ion beam. We consider a design of the electron collider ring based on reusing PEP-II components, such as magnets, power supplies, vacuum system, etc. This has the potential to significantly reduce the cost and engineering effort needed to bring the project to fruition. This paper reports on an electron ring optics design considering the balance of PEP-II hardware parameters (such as dipole sagitta, magnet field strengths and acceptable synchrotron radiation power) and electron beam quality in terms of equilibrium emittances.
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TUPWI029	Baseline Scheme for Polarization Preservation and Control in the MEIC Ion Complex	polarization, ion, controls, solenoid	2301
	V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang JLab, Newport News, Virginia, USA Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. The scheme for preservation and control of the ion polarization in the Medium-energy Electron-Ion Collider (MEIC) has been under active development in recent years. The figure-8 configuration of the ion rings provides a unique capability to control the polarization of any ion species including deuterons by means of "weak" solenoids rotating the particle spins by small angles. Insertion of "weak" solenoids into the magnetic lattices of the booster and collider rings solves the problem of polarization preservation during acceleration of the ion beam. Universal 3D spin rotators designed on the basis of "weak" solenoids allow one to obtain any polarization orientation at an interaction point of MEIC. This paper presents the baseline scheme for polarization preservation and control in the MEIC ion complex.
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TUPWI030	Numerical Calculation of the Ion Polarization in MEIC	polarization, controls, solenoid, proton	2304
	V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang JLab, Newport News, Virginia, USA Y. Filatov MIPT, Dolgoprudniy, Moscow Region, Russia A.M. Kondratenko, M.A. Kondratenko Science and Technique Laboratory Zaryad, Novosibirsk, Russia
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Ion polarization in the Medium-energy Electron-Ion Collider (MEIC) is controlled by means of universal 3D spin rotators designed on the basis of “weak” solenoids. We use numerical calculations to demonstrate that the 3D rotators have negligible effect on the orbital properties of the ring. We present calculations of the polarization dynamics along the collider’s orbit for both longitudinal and transverse polarization directions at a beam interaction point. We calculate the degree of depolarization due to the longitudinal and transverse beam emittances in case when the zero-integer spin resonance is compensated.
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TUPWI031	Status of the MEIC Ion Collider Ring Design	ion, electron, dipole, optics	2307
	V.S. Morozov, Y.S. Derbenev, L. Harwood, A. Hutton, F. Lin, F.C. Pilat, Y. Zhang JLab, Newport News, Virginia, USA Y. Cai, Y. Nosochkov, M.K. Sullivan, M.-H. Wang, U. Wienands SLAC, Menlo Park, California, USA J. Gerity, T.L. Mann, P.M. McIntyre, N. Pogue, A. Sattarov Texas A&M University, College Station, Texas, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported in part by the US DOE Contract No. DE-AC02-76SF00515. We present an update on the design of the ion collider ring of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The design is based on the use of super-ferric magnets. It provides the necessary momentum range of 8 to 100 GeV/c for protons and ions, matches the electron collider ring design using PEP-II components, fits readily on the JLab site, offers a straightforward path for a future full-energy upgrade by replacing the magnets with higher-field ones in the same tunnel, and is more cost effective than using presently available current-dominated super-conducting magnets. We describe complete ion collider optics including an independently-designed modular detector region.
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TUPWI033	Matching into the Helical Bunch Coalescing Channel for a High Luminosity Muon Collider	emittance, acceleration, simulation, luminosity	2315
	A.V. Sy, Y.S. Derbenev, V.S. Morozov JLab, Newport News, Virginia, USA C.M. Ankenbrandt, R.P. Johnson Muons, Inc, Illinois, USA D.V. Neuffer, K. Yonehara, C.Y. Yoshikawa Fermilab, Batavia, Illinois, USA
	Funding: This work was supported in part by U.S. DOE STTR Grant DE-SC0007634. This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. For high luminosity in a muon collider, muon bunches that have been cooled in the six-dimensional helical cooling channel (HCC) must be merged into a single bunch and further cooled in preparation for acceleration and transport to the collider ring. The helical bunch coalescing channel has been previously simulated [, ] and provides the most natural match from helical upstream and downstream subsystems. This work focuses on the matching from the exit of the multiple bunch HCC into the start of the helical bunch coalescing channel. The simulated helical matching section simultaneously matches the helical spatial period λ in addition to providing the necessary acceleration for efficient bunch coalescing. Previous studies assumed that the acceleration of muon bunches from p=209.15 MeV/c to 286.816 MeV/c and matching of λ from 0.5 m to 1.0 m could be accomplished with zero particle losses and zero emittance growth in the individual bunches. This study demonstrates nonzero values for both particle loss and emittance growth, and provides considerations for reducing these adverse effects to best preserve high luminosity. C. Yoshikawa, et al., “Bunch Coalescing in a Helical Channel,” MAP-doc-4302-v2. **C. Yoshikawa, et al., “Bunch Coalescing in a Helical Channel,” IPAC12 TUPPD013, New Orleans, Louisiana, USA.
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TUPWI034	Capture, Acceleration and Bunching RF Systems for the MEIC Booster and Storage Rings	ion, cavity, electron, bunching	2318
	S. Wang, J. Guo, F. Lin, V.S. Morozov, R.A. Rimmer, H. Wang, Y. Zhang JLab, Newport News, Virginia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 The MEIC, proposed by Jefferson Lab, consists of a series of accelerators. The electron collider ring accepts electrons from CEBAF at energies from 3 to 12 GeV. Protons and ions are delivered to a booster and captured in a long bunch before ramping and transfer to the ion collider ring. The ion collider ring accelerates a small number of long ion bunches to colliding energy before they are re-bunched into a high frequency train of very short bunches for colliding. Two sets of low frequency RF systems are needed for the long ion bunch energy ramping in the booster and ion collider ring. Another two sets of high frequency RF cavities are needed for re-bunching in the ion collider ring and compensating synchrotron radiation energy loss in the electron collider ring. The requirements from energy ramping, ion beam bunching, electron beam energy compensation, collective effects, beam loading and feedback capability, RF power capability, etc. are presented. The preliminary designs of these RF systems are presented. Concepts for the baseline cavity and RF station configurations are described, as well as some options that may allow more flexible injection and acceleration schemes.
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TUPWI035	MEIC Proton Beam Formation with a Low Energy Linac	booster, ion, linac, proton	2322
	Y. Zhang JLab, Newport News, Virginia, USA
	The MIEC proton and ion beams are generated, accumulated, accelerated and cooled in a new green-field ion injector complex designed specifically to support its high luminosity goal. This injector consists of sources, a linac and a small booster ring. In this paper we explore feasibility of a short ion linac that injects low energy protons and ions into the booster ring.
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TUPWI038	A High Energy e-p/A Collider Based on CepC-SppC	proton, electron, luminosity, ion	2329
	Y. Zhang JLab, Newport News, Virginia, USA Y.M. Peng IHEP, Beijing, People's Republic of China
	Construction of CepC and SppC, the proposed future energy frontier circular e⁺e⁻ and pp colliders in China, provides an opportunity to realize e-p or e-A collisions in a CM energy range up to 4.1 TeV. This paper presents a preliminary conceptual design of this e-p/A collider. The design parameters and anticipated luminosities will be given. We also discuss staging approaches to realize this collider with a low cost and at an earlier time.
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TUPWI039	Modeling Crabbing Dynamics in an Electron-Ion Collider	electron, proton, betatron, ion	2333
	A. Castilla, J.R. Delayen, T. Satogata ODU, Norfolk, Virginia, USA A. Castilla, J.R. Delayen, V.S. Morozov, T. Satogata JLab, Newport News, Virginia, USA A. Castilla DCI-UG, León, Mexico
	Funding: *Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. A local crabbing scheme requires π/2 (mod π) horizontal betatron phase advances from an interaction point (IP) to the crab cavities on each side of it. However, realistic phase advances generated by sets of quadrupoles, or Final Focusing Blocks (FFB), between the crab cavities located in the expanded beam regions and the IP differ slightly from π/2. To understand the effect of crabbing on the beam dynamics in this case, a simple model of the optics of the Medium Energy Electron-Ion Collider (MEIC) including local crabbing was developed using linear matrices and then studied numerically over multiple turns (1000 passes) of both electron and proton bunches. The same model was applied to both local and global crabbing schemes to determine the linear-order dynamical effects of the synchro-betatron coupling induced by crabbing.
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TUPWI040	End-to-End Simulation of Bunch Merging for a Muon Collider	solenoid, kicker, emittance, simulation	2336
	Y. Bao, G.G. Hanson UCR, Riverside, California, USA R.B. Palmer, D. Stratakis BNL, Upton, Long Island, New York, USA
	Muon accelerator beams are commonly produced indirectly through pion decay by interaction of a charged particle beam with a target. Efficient muon capture requires the muons to be first phase-rotated by rf cavities into a train of 21 bunches with much reduced energy spread. Since luminosity is proportional to the square of the number of muons per bunch, it is crucial for a Muon Collider to use relatively few bunches with many muons per bunch. In this paper we will describe a bunch merging scheme that should achieve this goal. We present for the first time a complete end-to-end simulation of a 6D bunch merger for a Muon Collider. The 21 bunches arising from the phase-rotator, after some initial cooling, are merged in longitudinal phase space into 7 bunches, which then go through 7 paths with different lengths and reach at the final collecting ”funnel” at the same time. The final single bunch has a transverse and a longitudinal emittance that matches well with the subsequent 6D rectilinear cooling scheme.
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TUPWI043	Chromatic Effects in Long Periodic Transport Channels	emittance, lattice, linac, linear-collider	2342
	V. Litvinenko Stony Brook University, Stony Brook, USA Y. Hao, Y.C. Jing BNL, Upton, Long Island, New York, USA
	Long periodic transport channels are frequently used in accelerator complexes and suggested for using in high-energy ERLs for electron-hadron colliders. Without proper chromaticity compensation, such transport channels exhibit high sensitivity to the random orbit errors causing significant emittance growth. Such emittance growth can come from both the correlated and the uncorrelated energy spread. In this paper we present results of our theoretical and numerical studies of such effects and develop a criteria for acceptable chromaticity in such channels
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TUPWI044	Final Muon Emittance Exchange in Vacuum for a Collider	quadrupole, emittance, betatron, focusing	2346
	D.J. Summers, J.G. Acosta, L.M. Cremaldi, T.L. Hart, S.J. Oliveros, L.P. Perera, W. Wu UMiss, University, Mississippi, USA D.V. Neuffer Fermilab, Batavia, Illinois, USA
	Funding: Work supported by NSF Award 0969770 We outline a plan for final muon ionization cooling with quadrupole doublets focusing onto short absorbers followed by emittance exchange in vacuum to achieve the small transverse beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized xyz emittances of (0.071, 0.141, 2.4) mm-rad are exchanged into (0.025, 0.025, 70) mm-rad. Thin electrostatic septa efficiently slice the bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 microseconds, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87%.
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TUPWI045	Consequences of Bounds on Longitudinal Emittance Growth for the Design of Recirculating Linear Accelerators	linac, emittance, quadrupole, dipole	2350
	J.S. Berg BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Recirculating linear accelerators (RLAs) are a cost-effective method for the acceleration of muons for a muon collider in energy ranges from a couple GeV to a few 10s of GeV. Muon beams generally have longitudinal emittances that are large for the RF frequency that is used, and it is important to limit the growth of that longitudinal emittance. This has particular consequences for the arc design of the RLAs. I estimate the longitudinal emittance growth in an RLA arising from the RF nonlinearity. Given an emittance growth limitation and other design parameters, one can then compute the maximum momentum compaction in the arcs. I describe how to obtain an approximate arc design satisfying these requirements based on the deisgn in Bogacz (2005). Longitudinal dynamics also determine the energy spread in the beam, and this has consequences on the transverse phase advance in the linac. This in turn has consequences for the arc design due to the need to match beta functions. I combine these considerations to discuss design parameters for the acceleration of muons for a collider in an RLA from 5 to 63 GeV. Bogacz, S. A. 2005. Low energy stages - 'dogbone' muon RLA. Nucl. Phys. B (Proc. Supp.) 149:309-312.
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TUPWI054	9-D Polarized Proton Transport in the MEIC "Figure-8" Collider Ring - First Steps	dipole, lattice, polarization, quadrupole	2375
	F. Méot BNL, Upton, Long Island, New York, USA V.S. Morozov JLab, Newport News, Virginia, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Spin tracking studies in the MEIC figure-8 collider ion ring are presented, based on a preliminary design of the lattice. They provide numerical illustrations of some of the aspects of the figure-8 concept, including spin-rotator based spin control, and lay out the path towards complete spin tracking simulations.
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WEAB1	Compensating Tune Spread Induced by Space Charge in Bunched Beams	hadron, electron, space-charge, proton	2450
	V. Litvinenko Stony Brook University, Stony Brook, USA G. Wang BNL, Upton, Long Island, New York, USA
	The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Several schemes were proposed to compensate for space charge effects in a coasting (e.g., continuous) hadron beam, and some have been tested. Using an appropriate transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But none of these methods address the issue of compensating space-charge induced tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present several practical examples of such a system.
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WEBB2	First Considerations on Beam Optics and Lattice Design for the Future Hadron-Hadron Collider FCC-hh	dipole, quadrupole, optics, injection	2466
	B. Dalena CEA/IRFU, Gif-sur-Yvette, France R. Alemany-Fernández, B.J. Holzer, D. Schulte CERN, Geneva, Switzerland A. Chancé, J. Payet CEA, Gif-sur-Yvette, France
	The main emphasis of the Future Circular Collider study is the design of a 100~TeV proton-proton collider in a new tunnel of about 100 km circumference. This paper presents the first optics design of the future hadron collider (FCC-hh). The basic layout follows a quasi-circular geometry ‘‘quasi racetrack'' with 8 arcs and 8 straight sections, four of which designed as interaction points. Assuming 16~T dipole magnets, a first version of the ring geometry and magnet lattice is presented, including the optics of the foreseen high luminosity regions and of the other straight sections dedicated to the installation of injection/extraction lines, beam dump etc., and an arc structure with optimized dipole fill factor to reach the target center-of-mass energy of 100~TeV.
	Slides WEBB2 [4.622 MB]
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WEAD3	Quantum Efficiency Improvement of Polarized Electron Source using Strain Compensated Super Lattice Photocathode	electron, laser, gun, polarization	2479
	N. Yamamoto, M. Hosaka, A. Mano, T. Miyauchi, Y. Takashima, Y. Takeda Nagoya University, Nagoya, Japan X.J. Jin, M. Yamamoto KEK, Ibaraki, Japan
	Polarized electron beam is essential for future electron-positron colliders and electron-ion colliders. Improving the quantum efficiency is an important subject to realize those proposed applications. Recently we have developed the strain compensated superlattice (SL) photocathode. In the strain compensated SLs, the equivalent compressive and tensile strains introduced in the well and barrier SL layers so that strain relaxation is effectively suppressed with increasing the SL layer thickness and high crystal quality can be expected. In this study, we fabricated the GaAs/GaAsP strain compensated SLs with the thickness up to 90-pair SL layers. Up to now, the electron spin polarization of 92 % and the quantum efficiency of 1.6 % were simultaneously achieved from 24-pair sample. In the presentation, we show the effect of the superlattice thickness on the photocathode performances and discuss the photocathode physics.
	Slides WEAD3 [3.064 MB]
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WEPWA057	Design Concepts for Muon-Based Accelerators	factory, simulation, target, proton	2633
	R.D. Ryne LBNL, Berkeley, California, USA Y.I. Alexahin, A.D. Bross, K. E. Gollwitzer, N.V. Mokhov, D.V. Neuffer, M.A. Palmer, K. Yonehara Fermilab, Batavia, Illinois, USA J.S. Berg, H.G. Kirk, R.B. Palmer, D. Stratakis BNL, Upton, Long Island, New York, USA S.A. Bogacz JLab, Newport News, Virginia, USA J.-P. Delahaye SLAC, Menlo Park, California, USA T.J. Roberts Muons, Inc, Illinois, USA P. Snopok Illinois Institute of Technology, Chicago, Illinois, USA
	Muon-based accelerators have the potential to enable facilities at both the Intensity and the Energy Frontiers. Muon storage rings can serve as high precision neutrino sources, and a muon collider is an ideal technology for a TeV or multi-TeV collider. Progress in muon accelerator designs has advanced steadily in recent years. In regard to 6D muon cooling, detailed and realistic designs now exist that provide more than 5 order-of-magnitude emittance reduction. Furthermore, detector performance studies indicate that with suitable pixelation and timing resolution, backgrounds in the collider detectors can be significantly reduced thus enabling high quality physics results. Thanks to these and other advances in design & simulation of muon systems, technology development, and systems demonstrations, muon storage-ring-based neutrino sources and a muon collider appear more feasible than ever before. A muon collider is now arguably among the most compelling approaches to a multi-TeV lepton collider. This paper summarizes the current status of design concepts for muon-based accelerators for neutrino factories and a muon collider.
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WEPJE010	Particle Production of a Graphite Target System for the Intensity Frontier	target, proton, emittance, factory	2692
	X.P. Ding UCLA, Los Angeles, California, USA H.G. Kirk BNL, Upton, Long Island, New York, USA K.T. McDonald PU, Princeton, New Jersey, USA
	A solid graphite target system is considered for an intense muon and/or neutrino source in support of physics at the intensity frontier. We previously optimized the geometric parameters of the beam and target to maximize particle production at low energies by incoming protons with kinetic energy of 6.75 GeV and an rms geometric emittance of 5 mm-mrad using the MARS15(2014) code. In this study, we ran MARS15 with ROOT-based geometry and also considered a mercury-jet target as an upgrade operation. The optimization was extended to focused proton beams with transverse emittances from 5 to 50 mm-mrad, showing that the particle production decreases slowly with increasing emittance. We also studied the beam dump configuration to suppress the rate of undesirable higher-energy secondary particles in the beam.
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WEPMN003	The Magnetic Measurement for Low Magnetic Field Stability of Dipole Magnet for CEPC	collimation, positron, dipole, electron	2917
	Z. Zhang, F.S. Chen, H. Geng, B. Yin IHEP, Beijing, People's Republic of China
	The CEPC (China Electron-Positron Collider) project is in the pre-research stage. When the beam energy of booster is 120 GeV, the magnetic field of deflection magnet is 640 G. In order to save funds for scientific research, we are ready to select the injection energy for 6 GeV, this corresponds to a magnetic field about 32 G. In such a low magnetic field, the effects of earth's magnetic field and ambient temperature variations cannot be ignored. In this paper, first written the collection procedures for magnetic field value and ambient temperature values by Labview software, then used a one-dimensional probe to measure the background magnetic field for three directions (Bx, By, Bz) and the value of the ambient temperature values, the time of data collection for each direction are more than 24 hours (every minute collecting a set of values). Finally, plus the different currents (3A, 6A.. 15A) to the dipole magnet, the time of measured and the data collected by over 24 hours. Based on the results of the analysis of large amounts of data, summarized and analyzed the effect of Earth's magnetic field and ambient temperature for dipole magnet in a low magnetic field.
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WEPHA003	Measurement of NEG Coating Performance Variation in the LHC after the First Long Shutdown	vacuum, simulation, injection, hadron	3100
	V. Bencini, V. Baglin, G. Bregliozzi, P. Chiggiato, R. Kersevan, C. Yin Vallgren CERN, Geneva, Switzerland
	During the Long Shutdown 1 (LS1) of the Large Hadron Collider, 90% of the Non-Evaporable Getter (NEG) coated beam pipes in the Long Straight Sections (LSS) were vented to undertake the planned upgrade and consolidation programmes. After each intervention, an additional bake-out and NEG activation were performed to reach the vacuum requirements. An analysis of the coating performance variation after the additional activation cycle has been carried out by using ultimate pressure and pressure build-up measurements. In addition, laboratory measurements have been carried out to mimic the LHC coated beam pipe behaviour. The experimental data have been compared with calculation obtained by Molflow+.
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WEPTY041	DESIGN CONCEPT AND PARAMETERS OF A 15 T Nb3Sn DIPOLE DEMONSTRATOR FOR A 100 TEV HADRON COLLIDER	dipole, hadron, controls, magnet-design	3365
	A.V. Zlobin, N. Andreev, E.Z. Barzi, V.V. Kashikhin, 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 Hadron Colliders (HC) are the most powerful discovery tools in modern high energy physics. A 100 TeV HC in a ~100 km tunnel with a nominal operation field of ~15 T is being considered for the post-LHC era. The choice of a 15 T nominal field requires using the Nb3Sn technology. Practical demonstration of this field level in an accelerator-quality magnet and substantial reduction of magnet costs are key conditions for the realization of such a machine. FNAL has started the development of a 15 T Nb3Sn dipole demonstrator for a 100 TeV HC. As a first step in this direction, the existing 11 T dipole magnet, developed for LHC upgrades, will be modified by adding two layers to achieve the nominal field of 15 T in a 60 mm aperture. As the next step, to increase the field margin the innermost 2-layer coil will be replaced with an optimized coil using the conductor grading approach. This paper describes the design concept and parameters of the 15 T Nb3Sn dipole demonstrators. Magnetic, mechanical and quench protection issues are discussed.
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WEPTY043	Short Pulse Marx Modulator	high-voltage, controls, flattop, network	3370
	R.A. Phillips, M.P.J. Gaudreau, M.K. Kempkes, B.E. Simpson Diversified Technologies, Inc., Bedford, Massachusetts, USA J.A. Casey Rockfield Research Inc., Las Vegas, Nevada, USA
	Funding: DE-SC0004251 High energy, short-pulse modulators are being re-examined for the Compact Linear Collider (CLIC) and numerous X-Band accelerator designs. At the very high voltages required for these systems, all of the existing designs are based on pulse transformers, which significantly limit their performance and efficiency. There is not a fully optimized, transformer-less modulator design capable of meeting the demanding requirements of very high voltage pulses at short pulse widths. Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) has completed development of a short pulse, solid-state Marx modulator. The modulator is designed for high efficiency in the 100 kV to 500 kV range, for currents up to 250 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort were modularity and scalability, combined with low cost and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are not available with hard switch or transformer-coupled topologies.
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WEPTY047	Thermal and Lorentz Force Analysis of Beryllium Windows for the Rectilinear Muon Cooling Channel	cavity, Windows, simulation, emittance	3381
	T.H. Luo, D. Li, S.P. Virostek LBNL, Berkeley, California, USA D.L. Bowring Fermilab, Batavia, Illinois, USA R.B. Palmer, D. Stratakis BNL, Upton, Long Island, New York, USA
	Reduction of the 6-dimensional phase-space of a muon beam by several orders of magnitude is a key requirement for a Muon Collider. Recently, a 12-stage rectilinear ionization cooling channel has been proposed to achieve that goal. The channel consists of a series of low frequency (325 MHz-650 MHz) normal conducting pillbox cavities, which are enclosed within thin beryllium windows (foils) to increase shunt impedance and give a higher field on-axis for a given amount of power. These windows are subject to ohmic heating from RF currents and Lorentz force from the EM field in the cavity, both of which will produce out of plane displacements that can detune the cavity frequency. In this study, using the TEM3P code, we report on a detailed thermal and mechanical analysis for the actual Be windows used on a 325 MHz cavity in a vacuum ionization cooling rectilinear channel for a Muon Collider.
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WEPTY050	Low Powered RF Measurements of Dielectric Materials for use in High Pressure Gas Filled RF Cavities	cavity, simulation, radio-frequency, factory	3387
	B.T. Freemire IIT, Chicago, Illinois, USA G. Arriaga Northern Illinois Univerity, Dekalb, Illinois, USA D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, A.V. Tollestrup, Y. Torun, K. Yonehara Fermilab, Batavia, Illinois, USA H.D. Phan McDaniel College, Westminster, USA Y. Torun Illinois Institute of Technology, Chicago, Illlinois, USA
	The Helical Cooling Channel scheme envisioned for a Muon Collider or Neutrino Factory requires high pressure gas filled radio frequency cavities to operate in superconducting magnets. One method to shrink the radii of the cavities is to load them with a dielectric material. The dielectric constant, loss tangent, and dielectric strength are important in determining the most suitable material. Low powered RF measurements of the dielectric constant and loss tangent were taken for multiple purities of alumina and magnesium calcium titanate, as well as cordierite, forsterite, and aluminum nitride. Measurements of alumina were consistent with previously reported results. The results were used to design an insert for a high powered RF test that included sending beam through the cavity.
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WEPWI006	Dither Coils for the SuperKEKB Fast Collision Feedback System	vacuum, feedback, coupling, multipole	3500
	U. Wienands, S.D. Anderson, S.M. Gierman, M. Kosovsky, C.M. Spencer, M.K. Sullivan SLAC, Menlo Park, California, USA Y. Funakoshi, M. Masuzawa, T. Oki KEK, Ibaraki, Japan
	Funding: Work supported in part by US DOE and in part by the US-Japan collaboration agreement. The collision feedback system for the SuperKEKB electron-positron collider at KEK will employ a dither feedback with a roughly 100 Hz excitation frequency to generate a signal proportional to the offset of the two beams. The excitation will be provided by a local bump across the interaction point (IP) that is generated by a set of eight air-core solid-wire magnet coil assemblies, each of which provides a horizontal and/or vertical deflection of the beam, to be installed around the vacuum system of the SuperKEKB Low Energy Ring. The design of the coils was challenging as large antechambers had to be accommodated and a 0.1% relative field uniformity across a good-field region of ±1 cm was aimed for, while keeping reasonable dimensions of the coils. This led to non-symmetric, non-flat designs of the coils. The paper describes the magnetic design and the method used to calculate the magnetic field of the coils, the mechanical design and the field measurement results. Tracking in the lattice model has indicated acceptable performance.
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WEPWI022	RF System Requirements for a Medium-Energy Electron-Ion Collider (MEIC) at JLab	ion, electron, booster, SRF	3536
	R.A. Rimmer, J. Guo, J. Henry, H. Wang, S. Wang JLab, Newport News, Virginia, USA Y.L. Huang IMP/CAS, Lanzhou, People's Republic of China
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 JLab is studying options for a medium energy electron-ion collider that could fit on the JLab site and use CEBAF as a full-energy electron injector. A new ion source, linac and booster would be required, together with collider storage rings for the ions and electrons. In order to achieve the maximum luminosity these will be high current storage rings with many bunches. We present the high level RF system requirements for the storage rings, ion booster ring and high-energy ion beam cooling system, and describe the technology options under consideration to meet them. We also present options for staging that might reduce the initial capital cost while providing a smooth upgrade path to a higher final energy. The technologies under consideration may also be useful for other proposed storage ring colliders or ultimate light sources.
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WEPWI053	HTS/lTS Hybrid High Field Superconducting Magnet Designs for the Proposed 100 TeV Proton Colliders	dipole, proton, superconductivity, magnet-design	3609
	R.C. Gupta, M. Anerella, A.K. Ghosh, W. Sampson, J. Schmalzle BNL, Upton, Long Island, New York, USA J. Kolonko, D. Larson, R.M. Scanlan, R.J. Weggel, E. Willen Particle Beam Lasers, Inc., Northridge, California, USA C.M. Rey e2P, Knoxville, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under contract Number DE-SC0012704, with the U.S. Department of Energy and STTR contract DOE Grant Number DE-SC0011348. Proposed proton-proton colliders with a center-of-mass energy up to 100 TeV in a tunnel of desired size require the dipole magnets to be of very high field–20 teslas in some proposals. This field is beyond the limit of present conventional Low Temperature Superconductors (LTS) and requires using High Temperature Superconductors (HTS). The preliminary magnetic design presented in this paper is an HTS/LTS hybrid design with high strength HTS tape used in higher field regions and less expensive LTS in lower field regions, with a goal of optimizing the performance while reducing the cost. A major concern in the magnets built with the HTS tape is the large field errors associated with the conductor magnetization. The strategy presented here aims to reduce those errors considerably. This paper also presents a proof-of-principle design and program to experimentally evaluate that concept.
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WEPWI056	A Number of Upgrades on RHIC Power Supply System	power-supply, controls, operation, superconducting-magnet	3618
	C. Mi, D. Bruno, A. Di Lieto, J. Drozd, G. Heppner, T. Nolan, F. Orsatti, T. Samms, J. Sandberg, C. Schultheiss, R. Zapasek BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. This year marks the 15th run for the Relativistic Heavy Ion Collider (RHIC). Operation of a reliable superconducting magnet power supply system is a key factor of accelerator’s performance. Over the past 15 of years, the RHIC power supply system has been made many improvements to increase the machine availability and reduce failures. During these past 15 years of operating RHIC a lot of problems have been solved or addressed. In this paper some of the essential upgrades/improvements are discussed.
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THXB2	Crab Cavities: Past, Present, and Future of a Challenging Device	cavity, luminosity, HOM, operation	3643
	Q. Wu BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with LARP and the U.S. Department of Energy and EU FP7 HiLumi LHC - Grant Agreement 284404 In two-ring facilities operating with a crossing angle collision scheme, the luminosity can be limited due to incomplete overlap of the colliding bunches. Crab cavities are introduced to restore head-on collisions by providing destined opposite deflection to the head and tail of the bunch. Luminosity increase has been demonstrated at KEKB with global crab crossing, and the Large Hardron Collider (LHC) at CERN is currently designing local crab crossing for the Hi-Lumi upgrade. Future colliders may investigate both approaches. This paper reviews the challenges in the technology and implementation of crab cavities, discusses experience in past colliders, ongoing R&D and proposed implementations for future facilities such as HL-LHC, CLIC, ILC, and eRHIC/MEIC.
	Slides THXB2 [4.307 MB]
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THPF089	Beam Transfer to the FCC-hh Collider from a 3.3 TeV Booster in the LHC Tunnel	injection, kicker, septum, optics	3901
	W. Bartmann, M.J. Barnes, M.A. Fraser, B. Goddard, W. Herr, J. Holma, V. Kain, T. Kramer, M. Meddahi, A. Milanese, R. Ostojić, L.S. Stoel, J.A. Uythoven, F.M. Velotti CERN, Geneva, Switzerland
	Transfer of the high brightness 3.3 TeV proton beams from the High Energy Booster (HEB) to the 100 TeV centre-of-mass proton collider in a new tunnel of 80–100 km circumference will be a major challenge. The extremely high stored beam energy means that machine protection considerations will constrain the functional design of the transfer, for instance in the amount of beam transferred, the kicker rise and fall times and hence the collider filling pattern. In addition the transfer lines may need dedicated insertions for passive protection devices. The requirements and constraints are described, and a first concept for the 3.3 TeV beam transfer between the machines is outlined. The resulting implications on the parameters and design of the various kicker systems are explored, in the context of the available technology. The general features of the transfer lines between the machines are described, with the expected constraints on the collider layout and insertion lengths.
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THPF094	Possible Reuse of the LHC as a 3.3 TeV High Energy Booster for Hadron Injection into the FCC-hh Collider	injection, extraction, dipole, insertion	3919
	B. Goddard, W. Bartmann, M. Benedikt, W. Herr, M. Lamont, P. Lebrun, M. Meddahi, A. Milanese, M. Solfaroli Camillocci, L.S. Stoel CERN, Geneva, Switzerland
	One option for the injector into a 100 TeV centre-of-mass energy frontier proton collider (FCC-hh) in a new tunnel of 80–100 km circumference is to reuse a suitably modified LHC as 3.3 TeV High Energy Booster (HEB). The changes that would be required to the existing LHC insertions are described, including the types and numbers of new magnets and circuits. The limitations on the maximum LHC ramp rate and minimum cycle time discussed. The key question of the minimum FCC filling time achievable with technically possible upgrades is examined, together with the issues of decommissioning for the elements which would need to be removed from the machine. The potential performance reach of the modified LHC as 3.3 TeV HEB is quantified, and implications for FCC-hh discussed.
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THPF122	The Status of MICE Step IV	solenoid, emittance, experiment, detector	4000
	D. Rajaram Fermilab, Batavia, Illinois, USA V.C. Palladino INFN-Napoli, Napoli, Italy
	Funding: SFTC, DOE, NSF, INFN, CHIPP and more Muon (μ) beams of low emittance provide the basis for the intense, well-characterised neutrino beams of the Neutrino Factory and for lepton-antilepton collisions at energies of up to several TeV at the Muon Collider. The International Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling; the technique by which it is proposed to reduce the μ phase-space volume. In a cooling channel, the μ beam traverses a material (the absorber) in which it looses energy, then replaced longitudinally by RF cavities. The net effect is to reduce transverse emittance(transverse cooling). MICE is being constructed in a series of Steps. At Step IV, MICE will study the properties of liquid hydrogen and lithium hydride that affect cooling. A solenoidal spectrometer will measure emittance up and downstream of the absorber vessel, where a focusing coil will focus muons. The construction of Step IV at RAL is well advanced towards scheduled completion early in 2015. Its status will be described together with a summary of the performance of the principal components. Plans for the commissioning and operation and the Step IV measurement programme will be described.
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THPF133	Textured-Powder BI-2212 Ag Wire Technology Development	interface, dipole, hadron, electron	4030
	P.M. McIntyre, J.N. Kellams, J.M. Vandergrifft Texas A&M University, College Station, Texas, USA K.C. Damborsky Oxford Instruments, Semiconductor Systems, Carteret, New Jersey, USA L. Motowidlo SupraMagnetics, Inc., Plantsville, Connecticut, USA N. Pogue PSI, Villigen, Villigen, Switzerland
	Progress is reported in developing textured-powder Bi-2212 cores as a new approach to Bi-2212/Ag wire tech-nology. The process builds upon earlier work in which Bi-2212 fine powder can be highly textured in its a-b plane orientation and fabricated into square-cross-section bars. The current work concerns an Enhanced Textured Powder (ETP) process, in which silver nanopowder is homogeneously mixed with the Bi-2212 powder. We report studies of the effect of the addition on the phase dynamics near melt temperature. ETP cores are being prepared for compounding into a billet to fabricate multi-filament wire.
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THPF134	Magnet Design and Synchrotron Damping Considerations for a 100 TeV Hadron Collider	dipole, synchrotron, radiation, luminosity	4034
	P.M. McIntyre, S. Assadi, J. Gerity, T.L. Mann, A. Sattarov Texas A&M University, College Station, Texas, USA D. Chavez DCI-UG, León, Mexico N. Pogue PSI, Villigen, Villigen, Switzerland M. Tomsic Hypertech Research, Inc., Columbus, USA
	A conceptual design is presented for a 100 TeV hadron collider based upon a 4.5 T NbTi cable-in-conduit dipole technology. It incorporates a side radiation channel to extract synchrotron radiation from the beam channel so that it does not produce limitations from heating on a beam liner or gas load limits on collider performance. Synchrotron damping can be used to support ‘bottom-up’ stacking to sustain maximum luminosity in the collisions.
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Paper

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Other Keywords

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MOBC1

Towards Ultra-Low β^* in ATF2

optics, octupole, multipole, linear-collider

38

M. Patecki, A.V. Aloev, D.R. Bett, M. Modena, R. Tomás
CERN, Geneva, Switzerland
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
E. Marín, G.R. White
SLAC, Menlo Park, California, USA

The Accelerator Test Facility 2 (ATF2) has already demonstrated the feasibility of Final Focus Systems based on the local chromaticity correction scheme and its focusing capabilities by reaching a vertical beam size at the virtual Interaction Point (IP) of less than 50 nm. The value of the chromaticity in ATF2 is comparable with the expected chromaticity in ILC, but 4 times lower than in a design of CLIC. ATF2 gives the unique possibility to test operation at CLIC chromaticity values by reducing the vertical beta function at the IP by a factor of 4 (the inverse proportionality of chromaticity with beta function value at IP is assumed). The experience collected in this way would be beneficial for both ILC and CLIC projects. Simulations show that the multipolar errors and Final Doublet fringe fields spoil the IP beam sizes at ATF2. Either increasing a value of the horizontal beta function or installing a pair of octupole magnets mitigate the impact of these aberrations. This paper summarizes the studies towards the realization of the ultra-low β^* optics in ATF2 and reports on the progress of the construction of the octupoles.

Slides MOBC1 [1.566 MB]

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MOPWA005

Comparison between Digital Filters and Singular Value Decomposition to Reduce Noise in LHC Orbits used for Action and Phase Jump Analysis

simulation, quadrupole, resonance, hadron

83

A.C. García-Bonilla, J.F. Cardona
UNAL, Bogota D.C, Colombia

Funding: Fundación Para la Promoción de la Investigación y la Tecnología del Banco de la República and DIB (División de Investigación de Bogotá).
One of the initial difficulties to apply the Action and Phase Jump (APJ) analysis to LHC orbits was the high level of noise present in the BPM measurements. On the other hand, the unprecedented number of turns for LHC allows us to use all sort of filters. In this paper, we evaluate the effectiveness of digital filters like the band-pass filter and compare them with a filter based on Singular Value Decomposition, when magnetic error estimations are made using a recent version of the APJ method. First, mainly results on simulated orbits with noise are presented, and then, plots and results are shown for the filters effect on experimental data. The analysis indicates that a combination of filters leads to measurements with the least uncertainty.

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MOPWA050

Beam Dynamics Studies to Develop a High-energy Luminosity Model for the LHC

simulation, luminosity, beam-beam-effects, emittance

233

G. Campogiani
Rome University La Sapienza, Roma, Italy
Y. Papaphilippou
CERN, Geneva, Switzerland

Funding: support provided by the EPS-AG through the EPS-AG student grant program
Luminosity, the key figure of merit of a collider as the LHC, depends on the brightness of the colliding beams. This makes the intensity dependent beam-beam effect the dominant performance limiting factor at collision. The parasitic interactions due to the electromagnetic mutual influence of the beams in the interaction region of a collider induce a diffusive behaviour in the tails of the beam. The evolution of charge density distribution is studied to model the beam tails evolution in order to characterize beam lifetime and luminosity. To achieve this, tools are developed for tracking distributions of arbitrary number of single particles interacting with the opposing strong-beam, to analyse the halo formation processes due to the combined effect of beam-beam and machine non-linearities. This paper presents preliminary results of the simulations, both for the LHC Run I and nominal LHC parameters. The former will be used to benchmark simulations while the latter aims at supporting luminosity estimate for the Run II.

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MOPWA059

Dynamic Aperture Studies for the FCC-ee

lattice, sextupole, synchrotron, radiation

258

L.E. Medina Medrano
DCI-UG, León, Mexico
R. Martin, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
R. Martin
Humboldt University Berlin, Berlin, Germany

Funding: Work supported by the Beam Project (CONACYT, Mexico).
Dynamic aperture (DA) studies have been conducted on the latest Future Circular Collider - ee (FCC-ee) lattices as a function of momentum deviation. Two different schemes for the interaction region are used, which are connected to the main arcs: the crab waist approach, developed by BINP, and an update to the CERN design where the use of crab cavities is envisioned. The results presented show an improvement in the performance of both designs.

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MOPWA062

Optimization of the Momentum Bandwidth for Final Focus System in CEPC

sextupole, factory, luminosity, simulation

269

S. Bai, T.J. Bian, J. Gao, H. Geng, D. Wang, Y. Wang, M. Xiao
IHEP, Beijing, People's Republic of China
F. Su
Institute of High Energy Physics (IHEP), People's Republic of China

With the discovery of the higgs boson at around 125GeV, a circular higgs factory design with high luminosity (L ~ 10³⁴ cm^-2s^-1) is becoming more popular in the accelerator world. To achieve such high luminosity, a final focus system in non-local chromaticity correction scheme with very low β functions at the interaction point is designed. The narrow momentum bandwidth is a crucial problem of this kind of design. It is shown that by introducing additional sextupoles the momentum acceptance of the CEPC final focus system can be increased by about a factor of four.

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MOPWA067

Theory of Transverse Ionization Cooling in a Linear Channel

emittance, lattice, quadrupole, scattering

279

M. Xiao, J. Gao, Y. Yue
IHEP, Beijing, People's Republic of China

Ionization cooling is the most hopeful method to reduce the emittance of muon beams, which plays an important role in neutrino factory and muon collider. Within the moment-equation approach, I present a way to derive the formulae of emittance in transverse under linear channel. All heating and coupling terms are reserved in the deriving process. From my formulae, it is a way to achieve a small emittance by designing the cooling channel compact to make the beta function changing sharply.

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MOPJE023

3D Computer Simulations of the Ultrarelativistic Beam Dynamics in Super Colliders

simulation, focusing, experiment, plasma

326

M.A. Boronina, V.A. Vshivkov
ICM&MG SB RAS, Novosibirsk, Russia
G. Dudnikova
ICT SB RAS, Novosibirsk, Russia

Funding: The work is supported by RFBR Grants 14-01-31088, 14-01-00392, 14-07-00241.
The problem of numerical modeling of beam-beam interaction with high relativistic factor (~10⁴) is considered. We present 3D a self-consistent simulation model based on particle-in-cell method. The mixed Euler-Lagrangian decomposition is used in parallel algorithm for achieving good load balancing and reducing communication cost. Stable regimes of beam dynamics, depending on the beams configuration (beta-function, emittance, energy, currents and relative offset) can be found on the base of the model. In the calculations we used 10⁸ particles on the grid 100x100x100, the number of processors depends highly on the beam shape. The Lomonosov Super Computer and Siberian Supercomputer Centre cluster were used to perform the presented simulations.

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MOPJE029

A Linear Accelerator Simulation Framework

simulation, framework, ground-motion, lattice

341

J. Snuverink
JAI, Egham, Surrey, United Kingdom
N. Fuster-Martínez
IFIC, Valencia, Spain
J. Pfingstner
CERN, Geneva, Switzerland
J. Pfingstner
University of Oslo, Oslo, Norway

Many good tracking tools are available for simulations for linear accelerators. However, several simple tasks need to be performed repeatedly, like lattice definitions, beam setup, output storage, etc. In addition, complex simulations can become unmanageable quite easily. A high level layer would therefore be beneficial. We propose LinSim, a linear accelerator framework with the codes PLACET and Guinea-Pig. It provides a documented well-debugged high level layer of functionality. Users only need to provide the input settings and essential code and/or use some of the many implemented imperfections and algorithms. It can be especially useful for first-time users. Currently the following accelerators are implemented: ATF2, ILC, CLIC and FACET. This paper discusses the framework design and shows its strength in some condensed examples.

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MOPJE055

Design of an Intense Muon Source with a Carbon and Mercury Target

target, proton, factory, solenoid

423

D. Stratakis, J.S. Berg
BNL, Upton, Long Island, New York, USA
X.P. Ding
UCLA, Los Angeles, California, USA
D.V. Neuffer
Fermilab, Batavia, Illinois, USA

Funding: Authored by employees of Brookhaven Science Associates LLC under Contract DE-SC0012704 and with Fermi Research Alliance LLC under Contract DE-AC02-07CH11359 with the United States Department of Energy
In high-intensity sources, muons are produced by firing high energy protons onto a target to produce pions. The pions decay to muons which are captured and accelerated. In the present study, we examine the performance of the channel for two different target scenarios: one based on liquid mercury and another one based on a solid carbon target. We produce distributions with the two different target materials and discuss differences in particle spectrum near the sources. We then propagate the distributions through our capture system and compare the full system performance for the two target types.

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MOPJE062

Testing Aspects of Advanced Coherent Electron Cooling Technique

electron, hadron, bunching, FEL

445

V. Litvinenko, Y.C. Jing, I. Pinayev, G. Wang
BNL, Upton, Long Island, New York, USA
D.F. Ratner
SLAC, Menlo Park, California, USA
V. Samulyak
SBU, Stony Brook, USA

An advanced version of the coherent-electron cooling based on the microbunching instability was proposed in *. This approach promised to significantly increase the bandwidth of the system and, therefore, significantly shorter cooling time in high energy hadron colliders. In this paper we present our plans of simulating and testing the key aspects of this proposed technique using the set-up of the coherent-electron-cooling proof-of-principle experiment at BNL.
* D.F. Ratner, Phys. Rev. Lett. 111, 084802 (2013)

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MOPJE073

The Extreme Beams Initiative in EuCARD-2

polarization, linac, hadron, diagnostics

483

G. Franchetti, J. Struckmeier
GSI, Darmstadt, Germany
K. Aulenbacher
IKP, Mainz, Germany
F. Zimmermann
CERN, Geneva, Switzerland

EuCARD-2 is an Integration Activity on accelerator R&D co-funded within the European Union’s 7th Framework Programme. The Extreme Beams (XBEAM) network of EuCARD-2 extends, and goes beyond the scope of, the previous Networking Activities of CARE-HHH and EuCARD(-1) EuroLumi. XBEAM addresses, and pushes, all accelerator frontiers: luminosity, energy, beam power, beam intensity, and polarization. This is realized through five tasks: Coordination and Communication, Extreme Colliders (XCOL)m Extreme Performance Rings (XRING), Extreme SC Linacs (XLINAC), and Extreme Polarization (XPOL), respectively. In the first two years of EuCARD-2, XBEAM (co-)organised more than 15 topical workshops: the upgrade of KEKB in Japan, crystal channelling, the advancement of the CERN facilities, e.g. LHC upgrades and the Future Circular Collider, magnet optimization, space-charge effects, the commissioning of proton linacs, with emphasis on the ESS, key questions for lepton spin polarization, storage rings for measuring the electric dipole moment of electrons or protons. This presentation reports the major achievements of the XBEAM activity from 2013 to 2015, and outlines the further plans through 2017.

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MOPJE078

Beam Delivery Simulation - Recent Developments and Optimization

simulation, background, toolkit, linear-collider

499

J. Snuverink, S.T. Boogert, H. Garcia Morales, S.M. Gibson, R. Kwee-Hinzmann, L.J. Nevay
JAI, Egham, Surrey, United Kingdom
L.C. Deacon
UCL, London, United Kingdom

Funding: Research supported by FP7 HiLumi LHC - grant agreement 284404 and by the STFC via the JAI3 grant
Beam Delivery Simulation (BDSIM) is a particle tracking code that simulates the passage of particles through both the magnetic accelerator lattice as well as their interaction with the material of the accelerator itself. The Geant4 toolkit is used to give a full range of physics processes needed to simulate both the interaction of primary particles and the production and subsequent propagation of secondaries. BDSIM has already been used to simulate linear accelerators such as the International Linear Collider (ILC) and the Compact Linear Collider (CLIC), but it has recently been adapted to simulate circular accelerators as well, producing loss maps for the Large Hadron Collider (LHC). In this paper the most recent developments, which extend BDSIM's functionality as well as improve its efficiency are presented. Improvement and refactorisation of the tracking algorithms are presented alongside improved automatic geometry construction for increased particle tracking speed.

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MOPJE082

Analytical Approach to the Beam-Beam Interaction with the Hourglass Effect

luminosity, coupling, detector, framework

510

M.P. Crouch, R.B. Appleby
UMAN, Manchester, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: STFC HL-LHC
The HL-LHC upgrade will allow higher luminosities to be reached in the LHC. To achieve higher luminosities the β-function at the IP is decreased, which in turn will result in the hourglass effect becoming more prominent as the transverse bunch sizes become comparable to the length of the bunch. This effect reduces the luminosity since not all particles in the bunch will collide at the minimum IP. The standard derivation of the electric and magnetic fields of the beam-beam interaction is that undertaken by Bassetti and Erskine. The derivation by Bassetti Erskine does not include a coupling between bunch planes. When the transverse bunch sizes are comparable to the length of the bunch the magnitude of the transverse kick will be dependent on the longitudinal position. Currently only numerical methods are available to evaluate this effect. Here a theoretical framework is outlined that provides an analytical approach to derive the electric field for the beam-beam interaction with a coupling between the transverse and longitudinal planes.

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MOPMA022

Numerical Analysis of Parasitic Crossing Compensation with Wires in DAΦNE

positron, luminosity, beam-beam-effects, experiment

589

A. Valishev
Fermilab, Batavia, Illinois, USA
C. Milardi, M. Zobov
INFN/LNF, Frascati (Roma), Italy
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

Funding: This work was partially supported by the US LARP. The HiLumi LHC Design Study is partially funded by the European Commission Grant Agreement 284404.
Current bearing wire compensators were successfully used in the 2005-2006 running of the DAΦNE collider to mitigate the detrimental effects of parasitic beam-beam interactions. A marked improvement of the positron beam lifetime was observed in machine operation with the KLOE detector. In view of the possible application of wire beam-beam compensators for the High Luminosity LHC upgrade, we revisit the DAΦNE experiments. We use an improved model of the accelerator with the goal to validate the modern simulation tools and provide valuable input for the LHC upgrade project.

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MOPMN007

An Alternate Ring-Ring Design for eRHIC

electron, ion, proton, linac

713

Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Work supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and No. DE-AC02-06CH11357
I present here a new ring-ring design of eRHIC. It utilizes high repetition rate colliding beams and is likely able to deliver the performance to meet the requirements of the science program with low technical risk and modest accelerator R&D. The expected performance includes high luminosities over multiple collision points and a broad CM energy range with a maximum value up to 2×1034 cm^-2s⁻¹ per detector, and polarization higher than 70% for the colliding electron and light ion beams. This new design calls for reuse of decommissioned facilities in the US, namely, the PEP-II high energy ring and one section of the SLAC linac as a full energy injector.

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MOPMN027

Optimization of Dynamic Aperture for Hadron Lattices in eRHIC

sextupole, lattice, hadron, storage-ring

757

Y.C. Jing, V. Litvinenko, D. Trbojevic
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The potential upgrade of the Relativistic Heavy Ion Collider (RHIC) to an electron ion collider (eRHIC) involves numerous extensive changes to the existing collider complex. The expected very high luminosity is planned to be achieved at eRHIC with the help of squeezing the beta function of the hadron ring at the IP to a few cm, causing a large rise of the natural chromaticities and thus bringing with it challenges for the beam long term stability (Dynamic aperture). We present our effort to expand the DA by carefully tuning the nonlinear magnets thus controlling the size of the footprints in tune space and all lower order resonance driving terms. We show a reasonably large DA through particle tracking over millions of turns of beam revolution.

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MOPTY053

Electromagnetic Design and Optimization of Directivity of Stripline Beam Position Monitors for the High Luminosity Large Hadron Collider

luminosity, simulation, impedance, hadron

1051

D. Draskovic, C.B. Boccard, O.R. Jones, T. Lefèvre, M. Wendt
CERN, Geneva, Switzerland

This paper presents the preliminary electromagnetic design of a stripline Beam Position Monitor (BPM) for the High Luminosity program of the Large Hadron Collider (HL-LHC) at CERN. The design is fitted into a new octagonal shielded Beam Screen for the low-beta triplets and is optimized for high directivity. It also includes internal Tungsten absorbers, required to reduce the energy deposition in the superconducting magnets. The achieved broadband directivity in wakefield solver simulations presents significant improvement over the directivity of the current stripline BPMs installed in the LHC.

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MOPTY084

Design, Testing and Performance Results of a High-resolution, Broad-band, Low-latency Stripline Beam Position Monitor System

electron, operation, laser, FPGA

1136

P. Burrows, D.R. Bett, N. Blaskovic Kraljevic, T. Bromwich, G.B. Christian, M.R. Davis, C. Perry
JAI, Oxford, United Kingdom
D.R. Bett
CERN, Geneva, Switzerland

A high-resolution, low-latency beam position monitor (BPM) system has been developed for use in particle accelerators and beamlines that operate with trains of particle bunches with bunch separations as low as several tens of nanoseconds, such as future linear electron-positron colliders and free-electron lasers. The system was tested with electron beams in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan. The fast analogue front-end signal processor is based on a single-stage RF down-mixer. The processor latency is 15.6 ± 0.1 ns. A position resolution below 300 nm has been demonstrated for beam intensities of around 1 nC, with single-pass beam.

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TUYB3

Progress on the Design of the Polarized Medium-energy Electron Ion Collider at JLab

ion, electron, polarization, luminosity

1302

F. Lin, S.A. Bogacz, P.D. Brindza, A. Camsonne, E. Daly, Y.S. Derbenev, D. Douglas, R. Ent, D. Gaskell, R.L. Geng, J.M. Grames, J. Guo, L. Harwood, A. Hutton, K. Jordan, A.J. Kimber, G.A. Krafft, R. Li, T.J. Michalski, V.S. Morozov, P. Nadel-Turonski, F.C. Pilat, M. Poelker, R.A. Rimmer, Y. Roblin, T. Satogata, M. Spata, R. Suleiman, A.V. Sy, C. Tennant, H. Wang, S. Wang, H. Zhang, Y. Zhang, Z.W. Zhao
JLab, Newport News, Virginia, USA
S. Abeyratne, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA
D.P. Barber
DESY, Hamburg, Germany
Y. Cai, Y. Nosochkov, M.K. Sullivan, M.-H. Wang, U. Wienands
SLAC, Menlo Park, California, USA
A. Castilla, J.R. Delayen
ODU, Norfolk, Virginia, USA
Y. Filatov
JINR, Dubna, Russia
J. Gerity, T.L. Mann, P.M. McIntyre, N. Pogue, A. Sattarov
Texas A&M University, College Station, Texas, USA
C. Hyde, K. Park
Old Dominion University, Norfolk, Virginia, USA
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia
P.N. Ostroumov
ANL, Argonne, Illinois, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The Medium-energy Electron Ion Collider (MEIC) at JLab is designed to provide high luminosity and high polarization needed to reach new frontiers in the exploration of nuclear structure. The luminosity, exceeding 1033 cm^-2s⁻¹ in a broad range of the center-of-mass (CM) energy and maximum luminosity above 1034 cm^-2s⁻¹, is achieved by high-rate collisions of short small-emittance low-charge bunches made possible by high-energy electron cooling of the ion beam and synchrotron radiation damping of the electron beam. The polarization of light ion species (p, d, 3He) can be easily preserved and manipulated due to the unique figure-8 shape of the collider rings. A fully consistent set of parameters have been developed considering the balance of machine performance, required technical development and cost. This paper reports recent progress on the MEIC accelerator design including electron and ion complexes, integrated interaction region design, figure-8-ring-based electron and ion polarization schemes, RF/SRF systems and ERL-based high-energy electron cooling. Luminosity performance is also presented for the MEIC baseline design.

Slides TUYB3 [6.245 MB]

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TUBD2

Final Cooling For a High-luminosity High-energy Lepton Collider

emittance, luminosity, solenoid, linac

1384

D.V. Neuffer
Fermilab, Batavia, Illinois, USA
T.L. Hart, D.J. Summers
UMiss, University, Mississippi, USA
H. K. Sayed
BNL, Upton, Long Island, New York, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. De-AC02-07CH11359 with the U. S. Department of Energy.
The final cooling system for a high-energy high-luminosity muon collider requires reduction of the transverse emittance by an order of magnitude to ~0.00003 m (rms, N), while allowing longitudinal emittance increase to ~0.1m. In the present baseline approach, this is obtained by transverse cooling of low-energy muons within a sequence of high field solenoids with low-frequency rf systems. Recent studies of such systems are presented. Since the final cooling steps are actually emittance exchange a variant form of that final system can be obtained by a round to flat transform in x-y, with transverse slicing of the enlarged flat transverse dimension followed by longitudinal recombination of the sliced bunchlets. Development of final exchange following lowest-emittance cooling is discussed.

Slides TUBD2 [1.976 MB]

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TUPTY004

Tracking Simulation for Beam Loss Studies with Application to FCC

simulation, lattice, scattering, detector

2004

M. Boscolo
INFN/LNF, Frascati (Roma), Italy
H. Burkhardt
CERN, Geneva, Switzerland

We present an implementation of a tracking simulation tool used to evaluate the main particle loss effects for Flavor Factories with the aim of applying these studies also to FCC. We describe the interface of the Monte Carlo tracking code with MAD-X, showing first simulations of the Touschek effect for the FCC-ee at the Z. We plan to use this approach also for multi-turn simulations of particles scattered by radiative Bhabha, beam-gas and eventually Beamstrahlung effects.

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TUPTY010

The Luminosity Reduction with Hourglass Effect and Crossing Angle in an e-p Collider

luminosity, electron, proton, acceleration

2016

Y.M. Peng
IHEP, Beijing, People's Republic of China
Y. Zhang
JLab, Newport News, Virginia, USA

This paper derived the luminosity reduction caused by crossing angle and hourglass effect in an asymmetric collision. Here, we gave the general expressions of the geometrical reduction factor of luminosity for the asymmetric case caused by crossing angle and hourglass effect, for tri-Gaussian bunches colliding. We also gave it simple expression in some special cases to recover the earlier results, such as the formulas for only hour-glass effect exist and only crossing angle exist. The expressions used in e-p collider are also analysed in detail.

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TUPTY017

Ion Polarization Control in the MPD and SPD Detectors of the NICA Collider

polarization, solenoid, detector, proton

2031

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

Two solenoid Siberian snakes are placed in the opposite collider’s straight sections are used to control deuteron’s and proton’s polarization in the NICA collider. Solenoid snakes substantially reconstruct beam’s orbital motion. The change of the polarization direction in the vertical plane of MPD and SPD detectors occurs due to insertion of polarization control (PC) solenoids in the magnetic lattice of the collider. The solenoids rotating particle’s spin by small angels practically do not influence on the beam’s orbital motion parameters. The dynamic of the polarization vector as function of the orbit length for cases of longitudinal and vertical polarization in the MPD and SPD detectors are presented.

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TUPTY018

Interaction region for crab waist scheme of the Future Electron-Positron Collider (CERN)

sextupole, quadrupole, luminosity, lattice

2034

A.V. Bogomyagkov, E.B. Levichev
BINP SB RAS, Novosibirsk, Russia

Funding: Work is supported by the Ministry of Education and Science of the Russian Federation
Design study of the accelerator that would fit 80-100~km tunnel called Future Circular Colliders (FCC) includes high-luminosity e⁺e^- collider (FCC-ee) with center-of-mass energy from 90 to 350~GeV to study Higgs boson properties and perform precise measurements at the electroweak scale. Crab waist interaction region provides collisions with luminosity higher than 2×10³⁶~cm^-2sec^-1 at beam energy of 45~GeV. The small values of the beta functions at the interaction point and distant final focus lenses are the reasons for high nonlinear chromaticity limiting energy acceptance of the whole ring. The paper describes interaction region for crab waist collision scheme in the FCC-ee, principles of tuning the chromaticity correction section in order to provide large energy acceptance.

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TUPTY023

Lessons Learned From the First Long Shutdown of the Lhc and Its Injector Chain

operation, radiation, superconducting-magnet, hardware

2050

K. Foraz, M.B.M. Barberan Marin, M. Bernardini, J. Coupard, N. Gilbert, D. Hay, S. Mataguez, D.J. Mcfarlane, E. Vergara Fernandez
CERN, Geneva, Switzerland

The First Long Shutdown (LS1) of the LHC and its Injector chain, which started in February 2013, was completed by the first quarter 2015. A huge number of activities have been performed; this paper reviews the process of the coordination of LS1 from the preparatory phase to the testing phase. The preparatory phase is a very important process: an accurate view of what is to be done, and what can be done is essential. But reality is always different, the differences between what was planned and what was done will be described. The paper will recall the coordination, reporting and decisional processes, highlighting points of success and points to be improved in terms of general coordination, in-situ coordination, safety coordination, logistics and resource management.

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TUPTY033

Civil Engineering Optimisation Tool for the Study of CERN's Future Circular Colliders

alignment, civil-engineering, hadron, database

2079

C. Cook, B. Goddard, P. Lebrun, J.A. Osborne, Y. Robert
CERN, Geneva, Switzerland

Funding: CERN
The feasibility of Future Circular Colliders (FCC), possible successors to the Large Hadron Collider (LHC), is currently under investigation at CERN. This paper describes how CERN’s civil engineering team are utilising an interactive tool containing a 3D geological model of the Geneva basin. This tool will be used to investigate the optimal position of the proposed 80km-100km tunnel. The benefits of using digital modelling during the feasibility stage are discussed and some early results of the process are presented.

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TUPTY042

Non-linear Coupling Studies in the LHC

coupling, octupole, hadron, simulation

2105

T. Persson, Y.I. Levinsen, E.H. Maclean, R. Tomás
CERN, Geneva, Switzerland
E.H. Maclean
JAI, Oxford, United Kingdom

The amplitude detuning has been observed to decrease significantly as the horizontal and vertical tunes are approaching each other. This effect is potentially harmful since it might cause a loss of Landau damping, hence giving rise to instabilities. The measured tune split (Qx-Qy) versus amplitude is several times bigger than what can be explained with linear coupling. In this paper we present studies performed to identify the dominant sources of the non-linear coupling observed in the LHC.

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TUPTY047

ERL with Non-Scaling Fixed Field Alternating Gradient Lattice for eRHIC

electron, linac, hadron, ion

2120

D. Trbojevic, J.S. Berg, S.J. Brooks, Y. Hao, V. Litvinenko, C. Liu, F. Méot, M.G. Minty, V. Ptitsyn, T. Roser, P. Thieberger, N. Tsoupas
BNL, Upton, Long Island, New York, USA

Funding: Work performed under Contract Number DE-AC02-98CH10886 with the auspices of the US Department of Energy.
The proposed eRHIC electron-hadron collider uses a "non-scaling FFAG" lattice to recirculate 16 turns of different energy through just two beamlines located in the RHIC tunnel. This paper presents lattices for these two FFAGs that are optimised for low magnet field and to minimise total synchrotron radiation across the energy range. The higher number of recirculations in the FFAG allows a shorter linac (1.322GeV) to be used, drastically reducing cost, while still achieving a 21.2GeV maximum energy to collide with one of the existing RHIC hadron rings at up to 250GeV. eRHIC uses many cost-saving measures in addition to the FFAG: the linac operates in energy recovery mode, so the beams also decelerate via the same FFAG loops and energy is recovered from the interacted beam. All magnets will constructed from NdFeB permanent magnet material, meaning chillers and large magnet power supplies are not needed. This paper also describes a smaller prototype ERL-FFAG accelerator that will test all of these technologies in combination to reduce technical risk for eRHIC.

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TUPTY050

Considerations for the Beam Dump System of a 100 TeV Centre-of-mass FCC hh Collider

extraction, kicker, septum, optics

2132

T. Kramer, M.G. Atanasov, M.J. Barnes, W. Bartmann, J. Borburgh, E. Carlier, F. Cerutti, L. Ducimetière, B. Goddard, A. Lechner, R. Losito, G.E. Steele, L.S. Stoel, J.A. Uythoven, F.M. Velotti
CERN, Geneva, Switzerland

A 100 TeV centre-of-mass energy frontier proton collider in a new tunnel of 80–100 km circumference is a central part of CERN’s Future Circular Colliders (FCC) design study. One of the major challenges for such a machine will be the beam dump system, which for each ring will have to reliably abort proton beams with stored energies in the range of 8 Gigajoule, more than an order of magnitude higher than planned for HL-LHC. The transverse proton beam energy densities are even more extreme, a factor of 100 above that of the presently operating LHC. The requirements for the beam dump subsystems are outlined, and the present technological limitations are described. First concepts for the beam dump system are presented and the feasibility is discussed, highlighting in particular the areas in which major technological progress will be needed. The potential implications on the overall machine and other key subsystems are described, including constraints on filling patterns, interlocking, beam intercepting devices and insertion design.

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TUPTY054

RF Design of the CLIC Structure Prototype Optimized for Manufacturing from Two Halves

linac, multipole, wakefield, simulation

2147

H. Zha, A. Grudiev
CERN, Geneva, Switzerland
V.A. Dolgashev
SLAC, Menlo Park, California, USA

We present the RF design of a 12GHz Compact Linear Collider (CLIC) main linac accelerating structure prototype. The structure is made from two longitudinally symmetric halves. The main manufacturing process of each half is precision milling. The structure uses the same iris dimensions as the CLIC-G structure but the cell shape is optimized for milling. The geometry is optimized to reduce the surface electric and magnetic fields and the modified Poynting vector. This design can potentially reduce fabrication cost.

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TUPTY055

Optimization of the RF Design of the CLIC Main Linac Accelerating Structure

wakefield, linac, simulation, cavity

2150

H. Zha, A. Grudiev
CERN, Geneva, Switzerland

We present a new optimized design of the accelerating structure for the main linac of CLIC (Compact Linear Collider). The new structure has lower surface magnetic fields and a significantly smaller transverse size compared to the baseline design described in the CLIC Concept Design Report (CDR). This new design should reach higher accelerating gradients and have a reduced manufacturing cost. The details of the RF design procedure and the obtained results are presented in this paper.

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TUPTY057

Scenarios for Circular Gamma-Gamma Higgs Factories

laser, luminosity, electron, factory

2156

F. Zimmermann, Y. Papaphilippou
CERN, Geneva, Switzerland
R. Aleksan
CEA/DSM/IRFU, France
A. Apyan
NU, Evanston, Illinois, USA

Funding: The research leading to these results has received partial funding from the European Commission under the FP7 Research Infrastructures project EuCARD-2, grant agreement no.312453.
The Higgs boson can be produced directly in gamma-gamma collisions generated by laser Compton back scattering off 80-90 GeV electron or positron beams. We discuss options for realizing a gamma-gamma Higgs factory using a high-energy circular e⁺e⁻ collider, such as FCC-ee or CEPC, and/or its top-up injector ring, and compare the parameters and advantages of such a facility, including the expected performance, with those for a Higgs factory based on a recirculating linac, such as SAPPHiRE.

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TUPTY058

Mitigating Performance Limitations of Single Beam-pipe Circular e⁺e⁻ Colliders

luminosity, electron, synchrotron, operation

2160

M. Koratzinos
DPNC, Genève, Switzerland
F. Zimmermann
CERN, Geneva, Switzerland

Renewed interest in circular e⁺e⁻ colliders has spurred designs of single beam-pipe machines, like the CEPC in China, and double beam pipe ones, such as the FCC-ee effort at CERN. Single beam-pipe designs profit from lower costs but are limited by the number of bunches that can be accommodated in the machine. We analyse these performance limitations and propose a solution that can accommodate O(1000) bunches while keeping more than 90% of the ring with a single beam pipe.

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TUPTY059

First Considerations on Beam Optics and Lattice Design for the Future Electron-Positron Collider FCC-ee

emittance, optics, lattice, operation

2162

B. Härer, B.J. Holzer, F. Zimmermann
CERN, Geneva, Switzerland
A.V. Bogomyagkov
BINP SB RAS, Novosibirsk, Russia

The Future Circular Collider (FCC) study includes the design of a 100-km electron positron collider (FCC-ee) with collision energies between 90 GeV and 350 GeV. This paper describes first aspects of the design and the optics of the FCC-ee collider, optimised for four different beam energies. Special emphasis is put on the need for a highly flexible magnet lattice in order to achieve the required beam emittances in each case and on the layout of the interaction region that will have to combine an advanced mini-beta concept, an effective beam separation scheme and a local chromaticity control to optimise the momentum acceptance and dynamic aperture of the ring.

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TUPTY060

The FCC-ee Study: Progress and Challenges

interaction-region, synchrotron, radiation, optics

2165

M. Koratzinos
DPNC, Genève, Switzerland
S. Aumon, C. Cook, A. Doblhammer, B. Härer, B.J. Holzer, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
A.V. Bogomyagkov, E.B. Levichev, D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia
M. Boscolo
INFN/LNF, Frascati (Roma), Italy
L.E. Medina Medrano
UGTO, Leon, Mexico
U. Wienands
SLAC, Menlo Park, California, USA

The FCC (future circular collider) study represents a vision for the next large project in high energy physics, comprising a 80-100 km tunnel that can house a future 100TeV hadron collider. The study also includes a high luminosity e⁺e⁻ collider operating in the centre-of-mass energy range of 90-350 GeV as a possible intermediate step, the FCC-ee. The FCC-ee aims at definitive electro-weak precision measurements of the Z, W, H and top particles, and search for rare phenomena. Although FCC-ee is based on known technology, the goal performance in luminosity and energy calibration make it quite challenging. During 2014 the study went through an exploration phase and during the next three years a conceptual design report will be prepared.

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TUPTY061

Combined Operation and Staging Scenarios for the FCC-ee Lepton Collider

emittance, luminosity, optics, operation

2169

M. Benedikt, B.J. Holzer, E. Jensen, R. Tomás, J. Wenninger, F. Zimmermann
CERN, Geneva, Switzerland
A.V. Bogomyagkov, E.B. Levichev, D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia
K. Ohmi, K. Oide
KEK, Ibaraki, Japan
U. Wienands
SLAC, Menlo Park, California, USA

FCC-ee is a proposed high-energy electron positron circular collider that would initially occupy the 100-km FCC tunnel that will eventually house the 100 TeV FCC-hh hadron collider. The parameter range for the e⁺/e⁻ collider is large, operating at a cm energy from 90 GeV (Z-pole) to 350 GeV (t-tbar production) with the maximum beam current ranging from 1.5 A to 6 mA for each beam, corresponding to a synchrotron radiation power of 50 MW and a radiative energy loss varying from ~30 MeV/turn to ~7500 MeV/turn. This presents challenges for the rf system due to the varying rf voltage requirements and beam loading conditions. In this paper we present a possible gradual evolution of the FCC-ee complex by step-wise expansion, and possibly reconfiguration, of the superconducting RF system. The performance attainable at each step is discussed, along with the possible advantages and drawbacks.

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TUPTY074

Muon Beam Emittance Evolution in the Helical Ionization Cooling Channel for Bright Muon Sources

plasma, emittance, space-charge, simulation

2203

K. Yonehara, C.Y. Yoshikawa
Fermilab, Batavia, Illinois, USA
C.M. Ankenbrandt, R.P. Johnson, S.A. Kahn
Muons, Inc, Illinois, USA
M. Chung
UNIST, Ulsan, Republic of Korea
Y.S. Derbenev, A.V. Sy
JLab, Newport News, Virginia, USA
B.T. Freemire
IIT, Chicago, Illinois, USA

The six-dimensional ionization cooling is essential to design a bright muon source. A geometry constraint is a challenge issue in a compact helical cooling channel (HCC). Especially, the HCC requires a large bore helical magnet and a compact helical RF system to incorporate the RF into the magnet chamber. A new emittance evolution has been designed to mitigate the geometry constraint. The HCC was functionally separated into three parts sections. The lattice at the initial section provides a large transverse acceptance by using a strong helical focus magnet. Once the transverse beam size is small enough to get into the compact RF the HCC lattice in the middle section generates a large longitudinal beta tune to dominate the longitudinal cooling. Consequently, the longitudinal emittance becomes smaller than the transverse one at the end of middle section. In the final section, the magnetic field strength is gradually reduced to match out the helical channel to the straight solenoid. As a result, the emittance exchange takes place and the final transverse emittance becomes smaller than the longitudinal one. The new emittance evolution scenario will be discussed in this presentation.

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TUPTY078

Fixed-energy Cooling and Stacking for an Electron Ion Collider

electron, ion, ECR, space-charge

2214

P.M. McIntyre, S. Assadi, J. Gerity, A. Sattarov
Texas A&M University, College Station, Texas, USA

The proposed designs for polarized-beam electron-ion colliders require cooling of the ion beam to achieve and sustain high luminosity. One attractive approach is to make a fixed-energy storage ring in which ions are con-tinuously cooled and stacked during a collider store, then transferred to the collider and accelerated for a new store when the luminosity decreases. An example design is reported for a 6 GeV/u superferric storage ring, and for a d.c. electron cooling system in which electron space charge is fully neutralized so that high-current magnetized e-cooling can be used to best advantage.

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TUPTY081

Design of a 6 TeV Muon Collider

sextupole, dynamic-aperture, quadrupole, octupole

2226

M.-H. Wang, Y. Cai, Y. Nosochkov
SLAC, Menlo Park, California, USA
M.A. Palmer
Fermilab, Batavia, Illinois, USA

Funding: Work supported by the US Department of Energy contract DE-AC02-76SF00515
A design of a muon collider ring with the center of mass energy of 6 TeV is presented. The ring circumference is about 6.3 km, and the beta functions at collision point are 1 cm in both planes. The ring linear optics, the non-linear chromaticity correction scheme in the Interaction Region (IR), and the additional non-linear field orthogonal knobs are described in detail. The IR magnet specifications are based on the maximum pole tip field of 20 T in dipoles and 15 T in quadrupoles. The results of the beam dynamics optimization for maximum dynamic aperture are presented.

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TUPTY082

Scanning Synchronization of Colliding Bunches for MEIC Project

cavity, ion, controls, electron

2229

Y.S. Derbenev, V.P. Popov
JLab, Newport News, Virginia, USA
Y.D. Chernousov
ICKC, Novosibirsk, Russia
G.M. Kazakevich
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contracts No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
Synchronization of colliding beams is one of the major issues of an electron-ion collider (EIC) design because of sensitivity of ion revolution frequency to beam energy. A conventional solution for this trouble is insertion of bent chicanes in the arcs space. In our report we consider a method to provide space coincidence of encountering bunches in the crab-crossing orbits Interaction Region (IR) while repetition rates of two beams do not coincide. The method utilizes pair of fast kickers realizing a bypass for the electron bunches as the way to equalize positions of the colliding bunches at the Interaction Point (IP). A dipole-mode warm or SRF cavities fed by the magnetron transmitters are used as fast kickers, allowing a broad-band phase and amplitude control. The proposed scanning synchronization method implies stabilization of luminosity at a maximum via a feedback loop. This synchronization method is evaluated as perspective for the Medium Energy Electron-Ion collider (MEIC) project of JLab with its very high bunch repetition rate.

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TUPTY084

Update on the MEIC Electron Collider Ring Design

electron, dipole, quadrupole, optics

2236

F. Lin, Y.S. Derbenev, L. Harwood, A. Hutton, V.S. Morozov, F.C. Pilat, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Cai, Y. Nosochkov, M.K. Sullivan, M.-H. Wang, U. Wienands
SLAC, Menlo Park, California, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work also supported by the U.S. DOE Contract No. DE-AC02-76SF00515.
The electron collider ring of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab is designed to accumulate and store a high-current polarized electron beam for collisions with an ion beam. We consider a design of the electron collider ring based on reusing PEP-II components, such as magnets, power supplies, vacuum system, etc. This has the potential to significantly reduce the cost and engineering effort needed to bring the project to fruition. This paper reports on an electron ring optics design considering the balance of PEP-II hardware parameters (such as dipole sagitta, magnet field strengths and acceptable synchrotron radiation power) and electron beam quality in terms of equilibrium emittances.

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TUPWI029

Baseline Scheme for Polarization Preservation and Control in the MEIC Ion Complex

polarization, ion, controls, solenoid

2301

V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The scheme for preservation and control of the ion polarization in the Medium-energy Electron-Ion Collider (MEIC) has been under active development in recent years. The figure-8 configuration of the ion rings provides a unique capability to control the polarization of any ion species including deuterons by means of "weak" solenoids rotating the particle spins by small angles. Insertion of "weak" solenoids into the magnetic lattices of the booster and collider rings solves the problem of polarization preservation during acceleration of the ion beam. Universal 3D spin rotators designed on the basis of "weak" solenoids allow one to obtain any polarization orientation at an interaction point of MEIC. This paper presents the baseline scheme for polarization preservation and control in the MEIC ion complex.

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TUPWI030

Numerical Calculation of the Ion Polarization in MEIC

polarization, controls, solenoid, proton

2304

V.S. Morozov, Y.S. Derbenev, F. Lin, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Filatov
MIPT, Dolgoprudniy, Moscow Region, Russia
A.M. Kondratenko, M.A. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
Ion polarization in the Medium-energy Electron-Ion Collider (MEIC) is controlled by means of universal 3D spin rotators designed on the basis of “weak” solenoids. We use numerical calculations to demonstrate that the 3D rotators have negligible effect on the orbital properties of the ring. We present calculations of the polarization dynamics along the collider’s orbit for both longitudinal and transverse polarization directions at a beam interaction point. We calculate the degree of depolarization due to the longitudinal and transverse beam emittances in case when the zero-integer spin resonance is compensated.

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TUPWI031

Status of the MEIC Ion Collider Ring Design

ion, electron, dipole, optics

2307

V.S. Morozov, Y.S. Derbenev, L. Harwood, A. Hutton, F. Lin, F.C. Pilat, Y. Zhang
JLab, Newport News, Virginia, USA
Y. Cai, Y. Nosochkov, M.K. Sullivan, M.-H. Wang, U. Wienands
SLAC, Menlo Park, California, USA
J. Gerity, T.L. Mann, P.M. McIntyre, N. Pogue, A. Sattarov
Texas A&M University, College Station, Texas, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Work supported in part by the US DOE Contract No. DE-AC02-76SF00515.
We present an update on the design of the ion collider ring of the Medium-energy Electron-Ion Collider (MEIC) proposed by Jefferson Lab. The design is based on the use of super-ferric magnets. It provides the necessary momentum range of 8 to 100 GeV/c for protons and ions, matches the electron collider ring design using PEP-II components, fits readily on the JLab site, offers a straightforward path for a future full-energy upgrade by replacing the magnets with higher-field ones in the same tunnel, and is more cost effective than using presently available current-dominated super-conducting magnets. We describe complete ion collider optics including an independently-designed modular detector region.

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TUPWI033

Matching into the Helical Bunch Coalescing Channel for a High Luminosity Muon Collider

emittance, acceleration, simulation, luminosity

2315

A.V. Sy, Y.S. Derbenev, V.S. Morozov
JLab, Newport News, Virginia, USA
C.M. Ankenbrandt, R.P. Johnson
Muons, Inc, Illinois, USA
D.V. Neuffer, K. Yonehara, C.Y. Yoshikawa
Fermilab, Batavia, Illinois, USA

Funding: This work was supported in part by U.S. DOE STTR Grant DE-SC0007634. This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
For high luminosity in a muon collider, muon bunches that have been cooled in the six-dimensional helical cooling channel (HCC) must be merged into a single bunch and further cooled in preparation for acceleration and transport to the collider ring. The helical bunch coalescing channel has been previously simulated [*, **] and provides the most natural match from helical upstream and downstream subsystems. This work focuses on the matching from the exit of the multiple bunch HCC into the start of the helical bunch coalescing channel. The simulated helical matching section simultaneously matches the helical spatial period λ in addition to providing the necessary acceleration for efficient bunch coalescing. Previous studies assumed that the acceleration of muon bunches from p=209.15 MeV/c to 286.816 MeV/c and matching of λ from 0.5 m to 1.0 m could be accomplished with zero particle losses and zero emittance growth in the individual bunches. This study demonstrates nonzero values for both particle loss and emittance growth, and provides considerations for reducing these adverse effects to best preserve high luminosity.
*C. Yoshikawa, et al., “Bunch Coalescing in a Helical Channel,” MAP-doc-4302-v2.
**C. Yoshikawa, et al., “Bunch Coalescing in a Helical Channel,” IPAC12 TUPPD013, New Orleans, Louisiana, USA.

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TUPWI034

Capture, Acceleration and Bunching RF Systems for the MEIC Booster and Storage Rings

ion, cavity, electron, bunching

2318

S. Wang, J. Guo, F. Lin, V.S. Morozov, R.A. Rimmer, H. Wang, Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The MEIC, proposed by Jefferson Lab, consists of a series of accelerators. The electron collider ring accepts electrons from CEBAF at energies from 3 to 12 GeV. Protons and ions are delivered to a booster and captured in a long bunch before ramping and transfer to the ion collider ring. The ion collider ring accelerates a small number of long ion bunches to colliding energy before they are re-bunched into a high frequency train of very short bunches for colliding. Two sets of low frequency RF systems are needed for the long ion bunch energy ramping in the booster and ion collider ring. Another two sets of high frequency RF cavities are needed for re-bunching in the ion collider ring and compensating synchrotron radiation energy loss in the electron collider ring. The requirements from energy ramping, ion beam bunching, electron beam energy compensation, collective effects, beam loading and feedback capability, RF power capability, etc. are presented. The preliminary designs of these RF systems are presented. Concepts for the baseline cavity and RF station configurations are described, as well as some options that may allow more flexible injection and acceleration schemes.

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TUPWI035

MEIC Proton Beam Formation with a Low Energy Linac

booster, ion, linac, proton

2322

Y. Zhang
JLab, Newport News, Virginia, USA

The MIEC proton and ion beams are generated, accumulated, accelerated and cooled in a new green-field ion injector complex designed specifically to support its high luminosity goal. This injector consists of sources, a linac and a small booster ring. In this paper we explore feasibility of a short ion linac that injects low energy protons and ions into the booster ring.

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TUPWI038

A High Energy e-p/A Collider Based on CepC-SppC

proton, electron, luminosity, ion

2329

Y. Zhang
JLab, Newport News, Virginia, USA
Y.M. Peng
IHEP, Beijing, People's Republic of China

Construction of CepC and SppC, the proposed future energy frontier circular e⁺e⁻ and pp colliders in China, provides an opportunity to realize e-p or e-A collisions in a CM energy range up to 4.1 TeV. This paper presents a preliminary conceptual design of this e-p/A collider. The design parameters and anticipated luminosities will be given. We also discuss staging approaches to realize this collider with a low cost and at an earlier time.

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TUPWI039

Modeling Crabbing Dynamics in an Electron-Ion Collider

electron, proton, betatron, ion

2333

A. Castilla, J.R. Delayen, T. Satogata
ODU, Norfolk, Virginia, USA
A. Castilla, J.R. Delayen, V.S. Morozov, T. Satogata
JLab, Newport News, Virginia, USA
A. Castilla
DCI-UG, León, Mexico

Funding: *Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A local crabbing scheme requires π/2 (mod π) horizontal betatron phase advances from an interaction point (IP) to the crab cavities on each side of it. However, realistic phase advances generated by sets of quadrupoles, or Final Focusing Blocks (FFB), between the crab cavities located in the expanded beam regions and the IP differ slightly from π/2. To understand the effect of crabbing on the beam dynamics in this case, a simple model of the optics of the Medium Energy Electron-Ion Collider (MEIC) including local crabbing was developed using linear matrices and then studied numerically over multiple turns (1000 passes) of both electron and proton bunches. The same model was applied to both local and global crabbing schemes to determine the linear-order dynamical effects of the synchro-betatron coupling induced by crabbing.

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TUPWI040

End-to-End Simulation of Bunch Merging for a Muon Collider

solenoid, kicker, emittance, simulation

2336

Y. Bao, G.G. Hanson
UCR, Riverside, California, USA
R.B. Palmer, D. Stratakis
BNL, Upton, Long Island, New York, USA

Muon accelerator beams are commonly produced indirectly through pion decay by interaction of a charged particle beam with a target. Efficient muon capture requires the muons to be first phase-rotated by rf cavities into a train of 21 bunches with much reduced energy spread. Since luminosity is proportional to the square of the number of muons per bunch, it is crucial for a Muon Collider to use relatively few bunches with many muons per bunch. In this paper we will describe a bunch merging scheme that should achieve this goal. We present for the first time a complete end-to-end simulation of a 6D bunch merger for a Muon Collider. The 21 bunches arising from the phase-rotator, after some initial cooling, are merged in longitudinal phase space into 7 bunches, which then go through 7 paths with different lengths and reach at the final collecting ”funnel” at the same time. The final single bunch has a transverse and a longitudinal emittance that matches well with the subsequent 6D rectilinear cooling scheme.

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TUPWI043

Chromatic Effects in Long Periodic Transport Channels

emittance, lattice, linac, linear-collider

2342

V. Litvinenko
Stony Brook University, Stony Brook, USA
Y. Hao, Y.C. Jing
BNL, Upton, Long Island, New York, USA

Long periodic transport channels are frequently used in accelerator complexes and suggested for using in high-energy ERLs for electron-hadron colliders. Without proper chromaticity compensation, such transport channels exhibit high sensitivity to the random orbit errors causing significant emittance growth. Such emittance growth can come from both the correlated and the uncorrelated energy spread. In this paper we present results of our theoretical and numerical studies of such effects and develop a criteria for acceptable chromaticity in such channels

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TUPWI044

Final Muon Emittance Exchange in Vacuum for a Collider

quadrupole, emittance, betatron, focusing

2346

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

Funding: Work supported by NSF Award 0969770
We outline a plan for final muon ionization cooling with quadrupole doublets focusing onto short absorbers followed by emittance exchange in vacuum to achieve the small transverse beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized xyz emittances of (0.071, 0.141, 2.4) mm-rad are exchanged into (0.025, 0.025, 70) mm-rad. Thin electrostatic septa efficiently slice the bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 microseconds, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87%.

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TUPWI045

Consequences of Bounds on Longitudinal Emittance Growth for the Design of Recirculating Linear Accelerators

linac, emittance, quadrupole, dipole

2350

J.S. Berg
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Recirculating linear accelerators (RLAs) are a cost-effective method for the acceleration of muons for a muon collider in energy ranges from a couple GeV to a few 10s of GeV. Muon beams generally have longitudinal emittances that are large for the RF frequency that is used, and it is important to limit the growth of that longitudinal emittance. This has particular consequences for the arc design of the RLAs. I estimate the longitudinal emittance growth in an RLA arising from the RF nonlinearity. Given an emittance growth limitation and other design parameters, one can then compute the maximum momentum compaction in the arcs. I describe how to obtain an approximate arc design satisfying these requirements based on the deisgn in Bogacz (2005)*. Longitudinal dynamics also determine the energy spread in the beam, and this has consequences on the transverse phase advance in the linac. This in turn has consequences for the arc design due to the need to match beta functions. I combine these considerations to discuss design parameters for the acceleration of muons for a collider in an RLA from 5 to 63 GeV.
*Bogacz, S. A. 2005. Low energy stages - 'dogbone' muon RLA. Nucl. Phys. B (Proc. Supp.) 149:309-312.

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TUPWI054

9-D Polarized Proton Transport in the MEIC "Figure-8" Collider Ring - First Steps

dipole, lattice, polarization, quadrupole

2375

F. Méot
BNL, Upton, Long Island, New York, USA
V.S. Morozov
JLab, Newport News, Virginia, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Spin tracking studies in the MEIC figure-8 collider ion ring are presented, based on a preliminary design of the lattice. They provide numerical illustrations of some of the aspects of the figure-8 concept, including spin-rotator based spin control, and lay out the path towards complete spin tracking simulations.

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WEAB1

Compensating Tune Spread Induced by Space Charge in Bunched Beams

hadron, electron, space-charge, proton

2450

V. Litvinenko
Stony Brook University, Stony Brook, USA
G. Wang
BNL, Upton, Long Island, New York, USA

The effects of space charge play a significant role in modern-day accelerators, frequently constraining the beam parameters attainable in an accelerator or in an accelerator chain. They also can limit the luminosity of hadron colliders operating either at low energies or with sub-TeV high-brightness hadron beams. The latter is applied for strongly cooled proton and ion beams in eRHIC – the proposed future electron-ion collider at Brookhaven National Laboratory. Several schemes were proposed to compensate for space charge effects in a coasting (e.g., continuous) hadron beam, and some have been tested. Using an appropriate transverse profile of the electron beam (or plasma column) for a coasting beam would compensate both the tune shift and the tune spread in the hadron beam. But none of these methods address the issue of compensating space-charge induced tune spread in a bunched hadron beam. In this paper we propose and evaluate a novel idea of using a co-propagating electron bunch with miss-matched longitudinal velocity to compensate the space charge induced tune-shift and tune spread. We present several practical examples of such a system.

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WEBB2

First Considerations on Beam Optics and Lattice Design for the Future Hadron-Hadron Collider FCC-hh

dipole, quadrupole, optics, injection

2466

B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
R. Alemany-Fernández, B.J. Holzer, D. Schulte
CERN, Geneva, Switzerland
A. Chancé, J. Payet
CEA, Gif-sur-Yvette, France

The main emphasis of the Future Circular Collider study is the design of a 100~TeV proton-proton collider in a new tunnel of about 100 km circumference. This paper presents the first optics design of the future hadron collider (FCC-hh). The basic layout follows a quasi-circular geometry ‘‘quasi racetrack'' with 8 arcs and 8 straight sections, four of which designed as interaction points. Assuming 16~T dipole magnets, a first version of the ring geometry and magnet lattice is presented, including the optics of the foreseen high luminosity regions and of the other straight sections dedicated to the installation of injection/extraction lines, beam dump etc., and an arc structure with optimized dipole fill factor to reach the target center-of-mass energy of 100~TeV.

Slides WEBB2 [4.622 MB]

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WEAD3

Quantum Efficiency Improvement of Polarized Electron Source using Strain Compensated Super Lattice Photocathode

electron, laser, gun, polarization

2479

N. Yamamoto, M. Hosaka, A. Mano, T. Miyauchi, Y. Takashima, Y. Takeda
Nagoya University, Nagoya, Japan
X.J. Jin, M. Yamamoto
KEK, Ibaraki, Japan

Polarized electron beam is essential for future electron-positron colliders and electron-ion colliders. Improving the quantum efficiency is an important subject to realize those proposed applications. Recently we have developed the strain compensated superlattice (SL) photocathode. In the strain compensated SLs, the equivalent compressive and tensile strains introduced in the well and barrier SL layers so that strain relaxation is effectively suppressed with increasing the SL layer thickness and high crystal quality can be expected. In this study, we fabricated the GaAs/GaAsP strain compensated SLs with the thickness up to 90-pair SL layers. Up to now, the electron spin polarization of 92 % and the quantum efficiency of 1.6 % were simultaneously achieved from 24-pair sample. In the presentation, we show the effect of the superlattice thickness on the photocathode performances and discuss the photocathode physics.

Slides WEAD3 [3.064 MB]

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WEPWA057

Design Concepts for Muon-Based Accelerators

factory, simulation, target, proton

2633

R.D. Ryne
LBNL, Berkeley, California, USA
Y.I. Alexahin, A.D. Bross, K. E. Gollwitzer, N.V. Mokhov, D.V. Neuffer, M.A. Palmer, K. Yonehara
Fermilab, Batavia, Illinois, USA
J.S. Berg, H.G. Kirk, R.B. Palmer, D. Stratakis
BNL, Upton, Long Island, New York, USA
S.A. Bogacz
JLab, Newport News, Virginia, USA
J.-P. Delahaye
SLAC, Menlo Park, California, USA
T.J. Roberts
Muons, Inc, Illinois, USA
P. Snopok
Illinois Institute of Technology, Chicago, Illinois, USA

Muon-based accelerators have the potential to enable facilities at both the Intensity and the Energy Frontiers. Muon storage rings can serve as high precision neutrino sources, and a muon collider is an ideal technology for a TeV or multi-TeV collider. Progress in muon accelerator designs has advanced steadily in recent years. In regard to 6D muon cooling, detailed and realistic designs now exist that provide more than 5 order-of-magnitude emittance reduction. Furthermore, detector performance studies indicate that with suitable pixelation and timing resolution, backgrounds in the collider detectors can be significantly reduced thus enabling high quality physics results. Thanks to these and other advances in design & simulation of muon systems, technology development, and systems demonstrations, muon storage-ring-based neutrino sources and a muon collider appear more feasible than ever before. A muon collider is now arguably among the most compelling approaches to a multi-TeV lepton collider. This paper summarizes the current status of design concepts for muon-based accelerators for neutrino factories and a muon collider.

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WEPJE010

Particle Production of a Graphite Target System for the Intensity Frontier

target, proton, emittance, factory

2692

X.P. Ding
UCLA, Los Angeles, California, USA
H.G. Kirk
BNL, Upton, Long Island, New York, USA
K.T. McDonald
PU, Princeton, New Jersey, USA

A solid graphite target system is considered for an intense muon and/or neutrino source in support of physics at the intensity frontier. We previously optimized the geometric parameters of the beam and target to maximize particle production at low energies by incoming protons with kinetic energy of 6.75 GeV and an rms geometric emittance of 5 mm-mrad using the MARS15(2014) code. In this study, we ran MARS15 with ROOT-based geometry and also considered a mercury-jet target as an upgrade operation. The optimization was extended to focused proton beams with transverse emittances from 5 to 50 mm-mrad, showing that the particle production decreases slowly with increasing emittance. We also studied the beam dump configuration to suppress the rate of undesirable higher-energy secondary particles in the beam.

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WEPMN003

The Magnetic Measurement for Low Magnetic Field Stability of Dipole Magnet for CEPC

collimation, positron, dipole, electron

2917

Z. Zhang, F.S. Chen, H. Geng, B. Yin
IHEP, Beijing, People's Republic of China

The CEPC (China Electron-Positron Collider) project is in the pre-research stage. When the beam energy of booster is 120 GeV, the magnetic field of deflection magnet is 640 G. In order to save funds for scientific research, we are ready to select the injection energy for 6 GeV, this corresponds to a magnetic field about 32 G. In such a low magnetic field, the effects of earth's magnetic field and ambient temperature variations cannot be ignored. In this paper, first written the collection procedures for magnetic field value and ambient temperature values by Labview software, then used a one-dimensional probe to measure the background magnetic field for three directions (Bx, By, Bz) and the value of the ambient temperature values, the time of data collection for each direction are more than 24 hours (every minute collecting a set of values). Finally, plus the different currents (3A, 6A.. 15A) to the dipole magnet, the time of measured and the data collected by over 24 hours. Based on the results of the analysis of large amounts of data, summarized and analyzed the effect of Earth's magnetic field and ambient temperature for dipole magnet in a low magnetic field.

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WEPHA003

Measurement of NEG Coating Performance Variation in the LHC after the First Long Shutdown

vacuum, simulation, injection, hadron

3100

V. Bencini, V. Baglin, G. Bregliozzi, P. Chiggiato, R. Kersevan, C. Yin Vallgren
CERN, Geneva, Switzerland

During the Long Shutdown 1 (LS1) of the Large Hadron Collider, 90% of the Non-Evaporable Getter (NEG) coated beam pipes in the Long Straight Sections (LSS) were vented to undertake the planned upgrade and consolidation programmes. After each intervention, an additional bake-out and NEG activation were performed to reach the vacuum requirements. An analysis of the coating performance variation after the additional activation cycle has been carried out by using ultimate pressure and pressure build-up measurements. In addition, laboratory measurements have been carried out to mimic the LHC coated beam pipe behaviour. The experimental data have been compared with calculation obtained by Molflow+.

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WEPTY041

DESIGN CONCEPT AND PARAMETERS OF A 15 T Nb3Sn DIPOLE DEMONSTRATOR FOR A 100 TEV HADRON COLLIDER

dipole, hadron, controls, magnet-design

3365

A.V. Zlobin, N. Andreev, E.Z. Barzi, V.V. Kashikhin, 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
Hadron Colliders (HC) are the most powerful discovery tools in modern high energy physics. A 100 TeV HC in a ~100 km tunnel with a nominal operation field of ~15 T is being considered for the post-LHC era. The choice of a 15 T nominal field requires using the Nb3Sn technology. Practical demonstration of this field level in an accelerator-quality magnet and substantial reduction of magnet costs are key conditions for the realization of such a machine. FNAL has started the development of a 15 T Nb3Sn dipole demonstrator for a 100 TeV HC. As a first step in this direction, the existing 11 T dipole magnet, developed for LHC upgrades, will be modified by adding two layers to achieve the nominal field of 15 T in a 60 mm aperture. As the next step, to increase the field margin the innermost 2-layer coil will be replaced with an optimized coil using the conductor grading approach. This paper describes the design concept and parameters of the 15 T Nb3Sn dipole demonstrators. Magnetic, mechanical and quench protection issues are discussed.

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WEPTY043

Short Pulse Marx Modulator

high-voltage, controls, flattop, network

3370

R.A. Phillips, M.P.J. Gaudreau, M.K. Kempkes, B.E. Simpson
Diversified Technologies, Inc., Bedford, Massachusetts, USA
J.A. Casey
Rockfield Research Inc., Las Vegas, Nevada, USA

Funding: DE-SC0004251
High energy, short-pulse modulators are being re-examined for the Compact Linear Collider (CLIC) and numerous X-Band accelerator designs. At the very high voltages required for these systems, all of the existing designs are based on pulse transformers, which significantly limit their performance and efficiency. There is not a fully optimized, transformer-less modulator design capable of meeting the demanding requirements of very high voltage pulses at short pulse widths. Under a U.S. Department of Energy grant, Diversified Technologies, Inc. (DTI) has completed development of a short pulse, solid-state Marx modulator. The modulator is designed for high efficiency in the 100 kV to 500 kV range, for currents up to 250 A, pulse lengths of 0.2 to 5.0 μs, and risetimes <300 ns. Key objectives of the development effort were modularity and scalability, combined with low cost and ease of manufacture. For short-pulse modulators, this Marx topology provides a means to achieve fast risetimes and flattop control that are not available with hard switch or transformer-coupled topologies.

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WEPTY047

Thermal and Lorentz Force Analysis of Beryllium Windows for the Rectilinear Muon Cooling Channel

cavity, Windows, simulation, emittance

3381

T.H. Luo, D. Li, S.P. Virostek
LBNL, Berkeley, California, USA
D.L. Bowring
Fermilab, Batavia, Illinois, USA
R.B. Palmer, D. Stratakis
BNL, Upton, Long Island, New York, USA

Reduction of the 6-dimensional phase-space of a muon beam by several orders of magnitude is a key requirement for a Muon Collider. Recently, a 12-stage rectilinear ionization cooling channel has been proposed to achieve that goal. The channel consists of a series of low frequency (325 MHz-650 MHz) normal conducting pillbox cavities, which are enclosed within thin beryllium windows (foils) to increase shunt impedance and give a higher field on-axis for a given amount of power. These windows are subject to ohmic heating from RF currents and Lorentz force from the EM field in the cavity, both of which will produce out of plane displacements that can detune the cavity frequency. In this study, using the TEM3P code, we report on a detailed thermal and mechanical analysis for the actual Be windows used on a 325 MHz cavity in a vacuum ionization cooling rectilinear channel for a Muon Collider.

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WEPTY050

Low Powered RF Measurements of Dielectric Materials for use in High Pressure Gas Filled RF Cavities

cavity, simulation, radio-frequency, factory

3387

B.T. Freemire
IIT, Chicago, Illinois, USA
G. Arriaga
Northern Illinois Univerity, Dekalb, Illinois, USA
D.L. Bowring, A.V. Kochemirovskiy, A. Moretti, A.V. Tollestrup, Y. Torun, K. Yonehara
Fermilab, Batavia, Illinois, USA
H.D. Phan
McDaniel College, Westminster, USA
Y. Torun
Illinois Institute of Technology, Chicago, Illlinois, USA

The Helical Cooling Channel scheme envisioned for a Muon Collider or Neutrino Factory requires high pressure gas filled radio frequency cavities to operate in superconducting magnets. One method to shrink the radii of the cavities is to load them with a dielectric material. The dielectric constant, loss tangent, and dielectric strength are important in determining the most suitable material. Low powered RF measurements of the dielectric constant and loss tangent were taken for multiple purities of alumina and magnesium calcium titanate, as well as cordierite, forsterite, and aluminum nitride. Measurements of alumina were consistent with previously reported results. The results were used to design an insert for a high powered RF test that included sending beam through the cavity.

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WEPWI006

Dither Coils for the SuperKEKB Fast Collision Feedback System

vacuum, feedback, coupling, multipole

3500

U. Wienands, S.D. Anderson, S.M. Gierman, M. Kosovsky, C.M. Spencer, M.K. Sullivan
SLAC, Menlo Park, California, USA
Y. Funakoshi, M. Masuzawa, T. Oki
KEK, Ibaraki, Japan

Funding: Work supported in part by US DOE and in part by the US-Japan collaboration agreement.
The collision feedback system for the SuperKEKB electron-positron collider at KEK will employ a dither feedback with a roughly 100 Hz excitation frequency to generate a signal proportional to the offset of the two beams. The excitation will be provided by a local bump across the interaction point (IP) that is generated by a set of eight air-core solid-wire magnet coil assemblies, each of which provides a horizontal and/or vertical deflection of the beam, to be installed around the vacuum system of the SuperKEKB Low Energy Ring. The design of the coils was challenging as large antechambers had to be accommodated and a 0.1% relative field uniformity across a good-field region of ±1 cm was aimed for, while keeping reasonable dimensions of the coils. This led to non-symmetric, non-flat designs of the coils. The paper describes the magnetic design and the method used to calculate the magnetic field of the coils, the mechanical design and the field measurement results. Tracking in the lattice model has indicated acceptable performance.

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WEPWI022

RF System Requirements for a Medium-Energy Electron-Ion Collider (MEIC) at JLab

ion, electron, booster, SRF

3536

R.A. Rimmer, J. Guo, J. Henry, H. Wang, S. Wang
JLab, Newport News, Virginia, USA
Y.L. Huang
IMP/CAS, Lanzhou, People's Republic of China

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
JLab is studying options for a medium energy electron-ion collider that could fit on the JLab site and use CEBAF as a full-energy electron injector. A new ion source, linac and booster would be required, together with collider storage rings for the ions and electrons. In order to achieve the maximum luminosity these will be high current storage rings with many bunches. We present the high level RF system requirements for the storage rings, ion booster ring and high-energy ion beam cooling system, and describe the technology options under consideration to meet them. We also present options for staging that might reduce the initial capital cost while providing a smooth upgrade path to a higher final energy. The technologies under consideration may also be useful for other proposed storage ring colliders or ultimate light sources.

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WEPWI053

HTS/lTS Hybrid High Field Superconducting Magnet Designs for the Proposed 100 TeV Proton Colliders

dipole, proton, superconductivity, magnet-design

3609

R.C. Gupta, M. Anerella, A.K. Ghosh, W. Sampson, J. Schmalzle
BNL, Upton, Long Island, New York, USA
J. Kolonko, D. Larson, R.M. Scanlan, R.J. Weggel, E. Willen
Particle Beam Lasers, Inc., Northridge, California, USA
C.M. Rey
e2P, Knoxville, USA

Funding: Work supported by Brookhaven Science Associates, LLC under contract Number DE-SC0012704, with the U.S. Department of Energy and STTR contract DOE Grant Number DE-SC0011348.
Proposed proton-proton colliders with a center-of-mass energy up to 100 TeV in a tunnel of desired size require the dipole magnets to be of very high field–20 teslas in some proposals. This field is beyond the limit of present conventional Low Temperature Superconductors (LTS) and requires using High Temperature Superconductors (HTS). The preliminary magnetic design presented in this paper is an HTS/LTS hybrid design with high strength HTS tape used in higher field regions and less expensive LTS in lower field regions, with a goal of optimizing the performance while reducing the cost. A major concern in the magnets built with the HTS tape is the large field errors associated with the conductor magnetization. The strategy presented here aims to reduce those errors considerably. This paper also presents a proof-of-principle design and program to experimentally evaluate that concept.

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WEPWI056

A Number of Upgrades on RHIC Power Supply System

power-supply, controls, operation, superconducting-magnet

3618

C. Mi, D. Bruno, A. Di Lieto, J. Drozd, G. Heppner, T. Nolan, F. Orsatti, T. Samms, J. Sandberg, C. Schultheiss, R. Zapasek
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
This year marks the 15th run for the Relativistic Heavy Ion Collider (RHIC). Operation of a reliable superconducting magnet power supply system is a key factor of accelerator’s performance. Over the past 15 of years, the RHIC power supply system has been made many improvements to increase the machine availability and reduce failures. During these past 15 years of operating RHIC a lot of problems have been solved or addressed. In this paper some of the essential upgrades/improvements are discussed.

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THXB2

Crab Cavities: Past, Present, and Future of a Challenging Device

cavity, luminosity, HOM, operation

3643

Q. Wu
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with LARP and the U.S. Department of Energy and EU FP7 HiLumi LHC - Grant Agreement 284404
In two-ring facilities operating with a crossing angle collision scheme, the luminosity can be limited due to incomplete overlap of the colliding bunches. Crab cavities are introduced to restore head-on collisions by providing destined opposite deflection to the head and tail of the bunch. Luminosity increase has been demonstrated at KEKB with global crab crossing, and the Large Hardron Collider (LHC) at CERN is currently designing local crab crossing for the Hi-Lumi upgrade. Future colliders may investigate both approaches. This paper reviews the challenges in the technology and implementation of crab cavities, discusses experience in past colliders, ongoing R&D and proposed implementations for future facilities such as HL-LHC, CLIC, ILC, and eRHIC/MEIC.

Slides THXB2 [4.307 MB]

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THPF089

Beam Transfer to the FCC-hh Collider from a 3.3 TeV Booster in the LHC Tunnel

injection, kicker, septum, optics

3901

W. Bartmann, M.J. Barnes, M.A. Fraser, B. Goddard, W. Herr, J. Holma, V. Kain, T. Kramer, M. Meddahi, A. Milanese, R. Ostojić, L.S. Stoel, J.A. Uythoven, F.M. Velotti
CERN, Geneva, Switzerland

Transfer of the high brightness 3.3 TeV proton beams from the High Energy Booster (HEB) to the 100 TeV centre-of-mass proton collider in a new tunnel of 80–100 km circumference will be a major challenge. The extremely high stored beam energy means that machine protection considerations will constrain the functional design of the transfer, for instance in the amount of beam transferred, the kicker rise and fall times and hence the collider filling pattern. In addition the transfer lines may need dedicated insertions for passive protection devices. The requirements and constraints are described, and a first concept for the 3.3 TeV beam transfer between the machines is outlined. The resulting implications on the parameters and design of the various kicker systems are explored, in the context of the available technology. The general features of the transfer lines between the machines are described, with the expected constraints on the collider layout and insertion lengths.

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THPF094

Possible Reuse of the LHC as a 3.3 TeV High Energy Booster for Hadron Injection into the FCC-hh Collider

injection, extraction, dipole, insertion

3919

B. Goddard, W. Bartmann, M. Benedikt, W. Herr, M. Lamont, P. Lebrun, M. Meddahi, A. Milanese, M. Solfaroli Camillocci, L.S. Stoel
CERN, Geneva, Switzerland

One option for the injector into a 100 TeV centre-of-mass energy frontier proton collider (FCC-hh) in a new tunnel of 80–100 km circumference is to reuse a suitably modified LHC as 3.3 TeV High Energy Booster (HEB). The changes that would be required to the existing LHC insertions are described, including the types and numbers of new magnets and circuits. The limitations on the maximum LHC ramp rate and minimum cycle time discussed. The key question of the minimum FCC filling time achievable with technically possible upgrades is examined, together with the issues of decommissioning for the elements which would need to be removed from the machine. The potential performance reach of the modified LHC as 3.3 TeV HEB is quantified, and implications for FCC-hh discussed.

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THPF122

The Status of MICE Step IV

solenoid, emittance, experiment, detector

4000

D. Rajaram
Fermilab, Batavia, Illinois, USA
V.C. Palladino
INFN-Napoli, Napoli, Italy

Funding: SFTC, DOE, NSF, INFN, CHIPP and more
Muon (μ) beams of low emittance provide the basis for the intense, well-characterised neutrino beams of the Neutrino Factory and for lepton-antilepton collisions at energies of up to several TeV at the Muon Collider. The International Muon Ionization Cooling Experiment (MICE) will demonstrate ionization cooling; the technique by which it is proposed to reduce the μ phase-space volume. In a cooling channel, the μ beam traverses a material (the absorber) in which it looses energy, then replaced longitudinally by RF cavities. The net effect is to reduce transverse emittance(transverse cooling). MICE is being constructed in a series of Steps. At Step IV, MICE will study the properties of liquid hydrogen and lithium hydride that affect cooling. A solenoidal spectrometer will measure emittance up and downstream of the absorber vessel, where a focusing coil will focus muons. The construction of Step IV at RAL is well advanced towards scheduled completion early in 2015. Its status will be described together with a summary of the performance of the principal components. Plans for the commissioning and operation and the Step IV measurement programme will be described.

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THPF133

Textured-Powder BI-2212 Ag Wire Technology Development

interface, dipole, hadron, electron

4030

P.M. McIntyre, J.N. Kellams, J.M. Vandergrifft
Texas A&M University, College Station, Texas, USA
K.C. Damborsky
Oxford Instruments, Semiconductor Systems, Carteret, New Jersey, USA
L. Motowidlo
SupraMagnetics, Inc., Plantsville, Connecticut, USA
N. Pogue
PSI, Villigen, Villigen, Switzerland

Progress is reported in developing textured-powder Bi-2212 cores as a new approach to Bi-2212/Ag wire tech-nology. The process builds upon earlier work in which Bi-2212 fine powder can be highly textured in its a-b plane orientation and fabricated into square-cross-section bars. The current work concerns an Enhanced Textured Powder (ETP) process, in which silver nanopowder is homogeneously mixed with the Bi-2212 powder. We report studies of the effect of the addition on the phase dynamics near melt temperature. ETP cores are being prepared for compounding into a billet to fabricate multi-filament wire.

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THPF134

Magnet Design and Synchrotron Damping Considerations for a 100 TeV Hadron Collider

dipole, synchrotron, radiation, luminosity

4034

P.M. McIntyre, S. Assadi, J. Gerity, T.L. Mann, A. Sattarov
Texas A&M University, College Station, Texas, USA
D. Chavez
DCI-UG, León, Mexico
N. Pogue
PSI, Villigen, Villigen, Switzerland
M. Tomsic
Hypertech Research, Inc., Columbus, USA

A conceptual design is presented for a 100 TeV hadron collider based upon a 4.5 T NbTi cable-in-conduit dipole technology. It incorporates a side radiation channel to extract synchrotron radiation from the beam channel so that it does not produce limitations from heating on a beam liner or gas load limits on collider performance. Synchrotron damping can be used to support ‘bottom-up’ stacking to sustain maximum luminosity in the collisions.

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