| Paper | Title | Page |
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| MOPWA059 | Dynamic Aperture Studies for the FCC-ee | 258 |
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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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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA059 | |
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| MOPJE065 | Contribution of Optical Aberrations to Spot-size Increase with Bunch Intensity at ATF2 | 455 |
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| A primary goal of ATF2 (Accelerator Test Facility) is to demonstrate a low vertical beam size at the interaction point (IP) of about 37 nm. Measurements over the past years indicate that the ATF2 vertical beam size strongly rises with bunch intensity. Several different origins of this increase are considered, e.g. wakefields occurring between the ATF damping ring and the IP, and/or intrabeam scattering (IBS) causing the increase of transverse emittances and energy spread in the damping ring with the increase of the bunch intensity. In this paper we address the second possibility. Past measurements and simulations of the IBS effects in the ATF are used to model the intensity-dependent initial emittances and energy spread at the entrance of the final focus. Particle tracking simulations predict the IP vertical beam size growth expected from the known optical aberrations for initial beam parameters corresponding to varying bunch intensities. Comparing simulation results with emittance measurements at different locations allows us to draw some conclusions about the impact of IBS in the damping ring on the IP spot size, and about possible single-bunch wakefields in the ATF2. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE065 | |
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| MOPJE073 | The Extreme Beams Initiative in EuCARD-2 | 483 |
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| 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. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE073 | |
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| TUPTY006 | Study of Electron Cloud Instabilities in FCC-hh | 2007 |
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| Electron cloud effects are serious issue for LHC and future hadron colliders, FCC-hh. Electron cloud causes coherent instabilities due to collective motion between beam and electrons. Electron cloud also causes incoherent emittance growth due to nonlinear force of beam-cloud electron force. We discuss the fast head-tail instability and the emittance growth in FCC-hh. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY006 | |
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| TUPTY007 | Study of Beam-beam Effects in FCC-he | 2010 |
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| Beam-beam effects of the ring-ring scheme of FCC-he and LHeC are being studied using weak-strong simulations. The beam-beam tune shift of the electron beam is one order larger than that of proton beam. The study of the electron motion under the beam-beam interaction is the main subject. Luminosity and equilibrium beam size and beam lifetime are analysed. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY007 | |
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| TUPTY045 | Interactions between Macroparticles and High-Energy Proton Beams | 2112 |
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| A known threat to the availability of the LHC is the interaction of macroparticles (dust particles) with the LHC proton beam. At the foreseen beam energy of 6.5 TeV during Run 2, quench margins in the superconducting magnets will be 2-3 times lower, and beam losses due such interactions may result in magnet quenches. The study introduce an improved numerical model of such interactions, as well as Monte-Carlo simulations that give the probability that such events will result in a beam-dump during Run 2. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY045 | |
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| TUPTY057 | Scenarios for Circular Gamma-Gamma Higgs Factories | 2156 |
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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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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY057 | |
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| TUPTY058 | Mitigating Performance Limitations of Single Beam-pipe Circular e+e− Colliders | 2160 |
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| 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. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY058 | |
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| TUPTY059 | First Considerations on Beam Optics and Lattice Design for the Future Electron-Positron Collider FCC-ee | 2162 |
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| 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. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY059 | |
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| TUPTY060 | The FCC-ee Study: Progress and Challenges | 2165 |
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| 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. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY060 | |
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| TUPTY061 | Combined Operation and Staging Scenarios for the FCC-ee Lepton Collider | 2169 |
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| 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. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY061 | |
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| TUPTY062 | FCC-hh Hadron Collider - Parameter Scenarios and Staging Options | 2173 |
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| FCC-hh is a proposed future energy-frontier hadron collider, based on dipole magnets with a field around 16 T installed in a new tunnel with a circumference of about 100 km, which would provide proton collisions at a centre-of-mass energy of 100 TeV, as well as heavy-ion collisions at the equivalent energy. The FCC-hh should deliver a high integrated proton-proton luminosity at the level of several 100 fb-1 per year, or more. The challenges for operating FCC-hh with high beam current and at high luminosity include the heat load from synchrotron radiation in a cold environment, the radiation from collision debris around the interaction region, and machine protection. In this paper, starting from the FCC-hh design baseline parameters we explore different approaches for increasing the integrated luminosity, and discuss the impact of key individual parameters, such as the turnaround time. We also present some injector considerations and options for early hadron-collider operation. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY062 | |
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| TUPTY063 | FCC-ee: Energy Calibration | 2177 |
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| FCC-ee aims to improve on electroweak precision measurements, with goals of 100 keV on the Z mass and width, and a fraction of an MeV on the W mass. Compared to LEP, this implies a much improved knowledge of the centre-of-mass energy when operating at the Z peak and WW threshold. This contribution will describe how it is planned to achieve this, by making systematic use of resonant depolarization. A number of difficulties have been identified, due in particular to the long polarization time and amplified ground motion. However the smaller emittance and energy spread of FCC-ee with respect to LEP should help achieve a much improved performance. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY063 | |
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