IPAC2018 - List of Authors (Zimmermann, F.)

Paper	Title	Page
MOPMF001	Bunch Schedules for the FCC-ee Pre-injector	79
	S. Ogur, K. Oide, Y. Papaphilippou, F. Zimmermann CERN, Geneva, Switzerland D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	The latest design of the Future Circular electron-positron Collider (FCC-ee) foresees a luminosity per interaction point above 2.0·10³⁶/cm²/s for operation at the Z pole. The filling from zero current occurs in collision to profit from the bunch lengthening due to beamstrahlung (so-called bootstrapping). At any time when new e^- and e⁺ buckets or bunchlets are injected into the collider, they will collide instantly. For this reason, we may provide the charge in each injected bunch in a way to pre-compensate for anticipated beam loss, and to reach the target luminosity as soon as possible after the first injection. In this way, we optimise the injection schedules for Z-mode so as to reach the peak luminosity in less than 20 minutes by interleaved injection of the two species at some portion of full bucket charge. Filling from zero the injector should allow accumulating 1.7·10¹¹ particles in one collider bucket within at least 10 injections, assuming a total transmission above 80%. In steady-state operation, the injector chain continually produces and accelerates lower bunch charges so as to maintain nearly constant bunch currents and constant peak luminosity.
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MOPMF034	Layout and Performance of the FCC-ee Pre-Injector Chain	169
	S. Ogur, T.K. Charles, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann CERN, Geneva, Switzerland A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia I. Chaikovska, R. Chehab LAL, Orsay, France K. Furukawa, N. Iida, T. Kamitani, F. Miyahara KEK, Ibaraki, Japan E.V. Ozcan Bogazici University, Bebek / Istanbul, Turkey S.M. Polozov MEPhI, Moscow, Russia
	The Future Circular e⁺e⁻ Collider pre-injector chain consists of a 6 GeV S-Band linac, a damping ring at 1.54 GeV and pre-booster ring to reach 20 GeV for injection to the main booster. The electron and positron beams use the same accelerator chain alternatively. The e⁺ beam is generated from a novel low level RF-gun providing 6.5 nC charge at 11 MeV with 0.5 micron geometric emittance. The e⁺ beam is produced by the impact of a 4.46 GeV e^- beam onto a hybrid target, accelerated in the linac up to 1.54 GeV, and injected to the damping ring for emittance cooling. Simulations on the performance of the DR are presented for reaching the required equilibrium emittances at the required damping time. As an alternative option, a 20 GeV linac is considered utilising C-Band cavities and simulations studies have been undertaken regarding the beam transport and transmission efficiency up to that energy.
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MOPMF064	High-Energy LHC Design	269
	F. Zimmermann, D. Amorim, S. A. Antipov, S. Arsenyev, M. Benedikt, R. Bruce, M.P. Crouch, S.D. Fartoukh, M. Giovannozzi, B. Goddard, M. Hofer, R. Kersevan, V. Mertens, Y. Muttoni, J.A. Osborne, V. Parma, V. Raginel, S. Redaelli, T. Risselada, I. Ruehl, B. Salvant, D. Schoerling, E.N. Shaposhnikova, L.J. Tavian, E. Todesco, R. Tomás, D. Tommasini, F. Valchkova-Georgieva, V. Venturi, D. Wollmann CERN, Geneva, Switzerland J.L. Abelleira, E. Cruz Alaniz, P. Martinez Mirave, A. Seryi, L. van Riesen-Haupt JAI, Oxford, United Kingdom A. Apyan ANSL, Yerevan, Armenia J. Barranco García, L. Mether, T. Pieloni, L. Rivkin, C. Tambasco EPFL, Lausanne, Switzerland F. Burkart DESY, Hamburg, Germany Y. Cai, Y.M. Nosochkov SLAC, Menlo Park, California, USA G. Guillermo Cantón CINVESTAV, Mérida, Mexico K. Ohmi, K. Oide, D. Zhou KEK, Ibaraki, Japan
	In the frame of the FCC study we are designing a 27 TeV hadron collider in the LHC tunnel, called the High Energy LHC (HE-LHC).
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MOPMF065	LHC- and FCC-Based Muon Colliders	273
	F. Zimmermann CERN, Geneva, Switzerland
	Funding: Work supported by the European Commission under the HORIZON 2020 project ARIES, grant agreement no. 730871. In recent years, three schemes for producing low-emittance muon beams have been proposed: (1) e⁺e⁻ annihilation above threshold using a positron storage ring with a thin target [M. Boscolo, P. Raimondi et al.], (2) laser/FEL-Compton back-scattering off high-energy proton beams circulating in the LHC or FCC-hh [L. Serafini et al.], (3) the Gamma factory concept, where partially stripped heavy ions collide with a laser pulse to directly generating muons [W. Krasny]. The Gamma factory would also generate copious amounts of positrons which could in turn be used as source for option (1). On the other hand the top-up booster of the FCC-ee design would be an outstanding e⁺ storage ring, at the right beam energy, around 45 GeV. After rapid acceleration the muons, produced in one of the three ways, could be collided in machines like the SPS, LHC or FCC-hh. Possible collider layouts are suggested.
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MOPMF067	Optimized Arc Optics for the HE-LHC	277
	Y.M. Nosochkov, Y. Cai SLAC, Menlo Park, California, USA M.P. Crouch, M. Giovannozzi, M. Hofer, J. Keintzel, T. Risselada, E. Todesco, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland D. Zhou KEK, Ibaraki, Japan L. van Riesen-Haupt JAI, Oxford, United Kingdom
	Funding: Work supported by the European Commission under Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and the HORIZON 2020 project EuroCirCol, grant agreement 654305. The High Energy LHC (HE-LHC) proton-proton collider is a proposed replacement of the LHC in the existing 27-km tunnel, with the goal of reaching the centre-of-mass beam energy of 27 TeV. The required higher dipole field can be realized by using 16-T dipoles being developed for the FCC-hh design. A major concern is the dynamic aperture at injection energy due to degraded field quality of the new dipole based on Nb3Sn superconductor, the potentially large energy swing between injection and collision, and the slightly reduced magnet aperture. Another issue is the field in quadrupoles and sextupoles at top energy, for which it may be cost-effective, wherever possible, to stay with Nb-Ti technology. In this study, we explore design options differed by arc lattice, for three choices of injection energy, with the goal of attaining acceptable magnet field and maximum injection dynamic aperture with dipole non-linear field errors.
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MOPMF068	Quantum Excitation due to Classical Beamstrahlung in Circular Colliders	281
	M.A. Valdivia García, D. El Khechen, K. Oide, F. Zimmermann CERN, Geneva, Switzerland
	In the collisions of proposed future circular colliders, like FCC-ee and CEPC, the beamstrahlung regime is classical, i.e. with an "Upsilon parameter" much smaller than 1. In the classical regime, for a constant electromagnetic field a simple relation exists between the average photon energy u and the average squared photon energy u², which is the same as for standard synchrotron radiation in storage rings. This relation breaks down, however, if the electromagnetic field is not constant in time and position, as is the case for a beam-beam collision. We derive an analytical expression for u²/u², considering the case of Gaussian-bunch collisions with crossing angle (and possibly crab waist). We compare our result with the photon energies obtained in beam-beam simulation for FCC-ee at beam energies of 45.6 GeV and 175 GeV, using the two independent codes BBWS and Guineapig. Finally, we re-optimize the FCC-ee parameters of a possible mono-chromatization scheme for direct Higgs production at 125 GeV, derived previously, by applying the refined expression for the rms photon energy.
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MOPMF069	The High Energy LHC Beam-Beam Effects studies	285
	T. Pieloni, J. Barranco García, L. Rivkin, C. Tambasco EPFL, Lausanne, Switzerland D. Amorim, S. A. Antipov, X. Buffat, B. Salvant, F. Zimmermann CERN, Geneva, Switzerland
	Funding: This work is supported by the Swiss State Secretariat for Education, Research and Innovation SERI. We present in this paper the studies of beam-beam effects for the High Energy Large Hadron Collider. We will describe and review the different aspects of beam-beam interactions (i.e. orbit effects, Landau damping, compensation schemes and operational set-up). An operational scenario for the collider will also be given as a result of the study.
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MOPMK001	Optics for RF Acceleration Section for the High Energy Large Hadron Collider	345
	L. van Riesen-Haupt, J.L. Abelleira University of Oxford, Oxford, United Kingdom J.L. Abelleira, E. Cruz Alaniz, P. Martinez Mirave, A. Seryi JAI, Oxford, United Kingdom M. Hofer, F. Zimmermann CERN, Geneva, Switzerland D. Zhou KEK, Ibaraki, Japan
	Funding: Work supported by the Horizon 2020 project EuroCirCol, grant 654305 and by the Science and Technology Facilities Council As part of the FCC study, the design of the High Energy LHC (HE-LHC) is addressed. A proposed layout for the interaction region for the containing the radio frequency (RF) cavities and various beam instrumentation will be discussed. The higher energy requires more RF cavities, which strongly restricts the space available for optics and instrumentation. Another challenge arises because the beam rigidity increases whilst the LHC geometry has to be conserved. To this end, next generation dipoles have to be used in order to achieve sufficient beam to beam separation. A design that provides enough beam stay clear (BSC) in all the magnets will be presented. The design introduces an additional quadrupole on either side of the RF region to be used for phase advance adjustments that can increase the dynamic aperture.
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MOPMK002	Integrated Full HE-LHC Optics and Its Performance	348
	M. Hofer TU Vienna, Wien, Austria M.P. Crouch, J. Keintzel, T. Risselada, R. Tomás, F. Zimmermann CERN, Geneva, Switzerland Y.M. Nosochkov SLAC, Menlo Park, California, USA D. Zhou KEK, Ibaraki, Japan L. van Riesen-Haupt JAI, Oxford, United Kingdom
	One possible future hadron collider design investigated in the framework of the Future Circular Collider (FCC) study is the High-Energy LHC (HE-LHC). Using the 16 T dipoles developed for the FCC-hh the center of mass energy of the LHC is set to increase to 27 TeV. To achieve this set energy goal, a new optics design is required, taking into account the constraint from the LHC tunnel geometry. In this paper, two different lattices for the HE-LHC are presented. Initial considerations take into account the physical aperture at the proposed injection energy as well as the energy reach of these lattices. The dynamic aperture at the injection energies is determined using latest evaluations of the field quality of the main dipoles.
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MOPMK006	Experimental Interaction Region Optics for the High Energy LHC	360
SUSPF002	use link to see paper's listing under its alternate paper code
	L. van Riesen-Haupt, J.L. Abelleira University of Oxford, Oxford, United Kingdom J.L. Abelleira, E. Cruz Alaniz, A. Seryi JAI, Oxford, United Kingdom M.P. Crouch, F. Zimmermann CERN, Geneva, Switzerland D. Zhou KEK, Ibaraki, Japan
	Funding: Work supported by the Horizon 2020 project EuroCirCol, grant 654305 and by the Science and Technology Facilities Council The High Energy LHC (HE-LHC) is one option for a next generation hadron collider explored in the FCC-hh program. The core concept of the HE-LHC is to install FCC-hh technology magnets in the LHC tunnel. The higher beam rigidity and the increased radiation debris, however, impose severe challenges on the design of the triplet for the low beta insertions. In order to achieve 25 cm β^* optics and survive a lifetime integrated luminosity of 10 ab-1 a new longer triplet was designed that provides sufficient shielding and enough beam stay clear. This triplet has been designed using complimentary radiation studies to optimise the shielding that will also be presented. The optics for the rest of the interaction region had to be adjusted in order to host this more rigid beam and longer triplet whilst leaving enough room for crab cavities. Moreover, the effects non-linear errors in this triplet have on the dynamic aperture will be outlined.
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TUPAF030	Electron Cloud Build Up for LHC Sawtooth Vacuum Chamber	744
SUSPF052	use link to see paper's listing under its alternate paper code
	G. Guillermo Cantón, F. Zimmermann CERN, Geneva, Switzerland G.H.I. Maury Cuna, E. D. Ocampo Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
	At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. For the arcs of LHC a sawtooth pattern had been imprinted on the horizontally outward side of the vacuum chamber in order to locally absorb synchrotron radiation photons without dispersing them all around the chamber. Using the combination of the codes Synrad3D and PyCLOUD we examine the effect of realistic absorption distributions with and without sawtooth on the build up of electron clouds.
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WEYGBD3	The CERN Gamma Factory Initiative: An Ultra-High Intensity Gamma Source	1780
	M.W. Krasny LPNHE, Paris, France R. Alemany-Fernández, H. Bartosik, N. Biancacci, P. Czodrowski, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M.W. Krasny, M. Lamont, D. Manglunki, A.V. Petrenko, M. Schaumann, C. Yin Vallgren, F. Zimmermann CERN, Geneva, Switzerland P.S. Antsifarov Institute of Spectroscopy, Russian Academy of Science, Troitsk, Moscow, Russia A. Apyan ANSL, Yerevan, Armenia E.G. Bessonov LPI, Moscow, Russia J. Bieron, K. Dzierzega, W. Placzek, S. Pustelny Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland D. Budker Johannes Gutenberg University Mainz, Institut für Physik, Mainz, Germany K. Cassou, I. Chaikovska, R. Chehab, K. Dupraz, A. Martens, Z.F. Zomer LAL, Orsay, France F. Castelli Università degli Studi di Milano, Milano, Italy C. Curatolo, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy K. Kroeger FSU Jena, Jena, Germany V. Petrillo Universita' degli Studi di Milano & INFN, Milano, Italy V.P. Shevelko LPI RAS, Moscow, Russia T. Stöhlker HIJ, Jena, Germany G. Weber IOQ, Jena, Germany Y.K. Wu FEL/Duke University, Durham, North Carolina, USA M.S. Zolotorev LBNL, Berkeley, California, USA
	This contribution discusses the possibility of broadening the present CERN research programme making use of a novel concept of light source. The proposed, Partially Stripped Ion beam driven, light source is the backbone of the Gamma Factory (GF) initiative. It could be realized at CERN by using the infrastructure of the already existing accelerators. It could push the intensity limits of the presently operating light-sources by up to 7 orders of magnitude, reaching fluxes of 10¹⁷ photons/s in the interesting gamma-ray energy domain between 1 MeV and 400 MeV. The GF light-source cannot be replaced, in this energy domain, by a FEL source as long as the multi TeV electron beams are not available. Its intensity is beyond the reach of the Inverse Compton Scattering sources. The unprecedented-intensity, energy-tuned gamma beams, together with the gamma-beams-driven secondary beams of polarized leptons, neutrinos, neutrons and radioactive ions are the basic research tools of the proposed Gamma Factory. A broad spectrum of new opportunities, in a vast domain of uncharted fundamental and applied physics territories, could be opened by the Gamma Factory research programme.
	Slides WEYGBD3 [7.531 MB]
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THYGBD1	FCC: Colliders at the Energy Frontier	2908
	M. Benedikt, F. Zimmermann CERN, Geneva, Switzerland
	The international Future Circular Collider study, launched in 2014, is finalizing a multi-volume conceptual design report. The FCC develops high-energy circular collider options based on a new 100 km tunnel. Long-term goal is a 100 TeV proton-proton collider (FCC-hh). The study also includes a high-luminosity electron-positron collider (FCC-ee), and it also examines lepton-hadron scenarios (FCC-he). Civil engineering and technical infrastructure studies were carried out. Global programs advance the development of high-field superconducting magnet technology based on Nb3Sn, the optimization of a suitable large superconducting RF system, and schemes for synchrotron radiation handling. In addition, the FCC study includes the design of the HE-LHC, housed in the LHC tunnel, and based on the same high-field magnet technology as the FCC-hh. The FCC study further includes an elaboration of the physics cases, including for heavy-ion collisions, and detector concepts, as well as staging and implementation scenarios. The FCC collaboration has grown to more than 120 institutes from 30 countries around the world. This invited talk summarizes the study achievements and the final designs.
	Slides THYGBD1 [12.503 MB]
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THPAF037	Bunch Compression and Turnaround Loops Design in the FCC-ee Injector Complex	3044
	T.K. Charles, F. Zimmermann CERN, Geneva, Switzerland M.J. Boland CLS, Saskatoon, Saskatchewan, Canada K. Oide KEK, Ibaraki, Japan
	The Future Circular e⁺e⁻ Collider (FCC-ee) requires two 180-degree turnaround loops to transport the positron beam from the damping ring to the lower energy section of the linac. In addition bunch compression is required to reduce the RMS bunch length from 5 mm to 0.5 mm, prior to injection into the linac. A dogleg bunch compressor comprised of two triple bend achromat (TBAs) can achieve this compression. Sextupole magnets are incorporated into the bunch compressor design for chromaticity correction as well as optimisation of the second-order longitudinal dispersion, T₅₆₆, and to linearize the longitudinal phase space distribution. In this paper we present the design of the transport line and the bunch compressor. Measures to limit emittance growth due to coherent synchrotron radiation (CSR) are also discussed, because despite the relatively long bunch length, the large degree of bending required introduces cause for consideration of CSR.
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THPAF089	Mode Coupling Theory in Collisions With a Large Crossing Angle	3197
	N. Kuroo UTTAC, Tsukuba, Ibaraki, Japan K. Hirosawa, K. Ohmi, D. Zhou KEK, Ibaraki, Japan K. Oide, F. Zimmermann CERN, Geneva, Switzerland
	We discuss a novel coherent beam-beam instability in collisions with a large crossing angle. The instability appears in the correlated head-tail motion of the two colliding beams. Cross wake force is introduced to represent the head-tail correlation between colliding beams. The cross wake force is localized at the collision point. Mode coupling theory based on the cross wake force is developed. Collision scheme with a large crossing angle is being very popular in design of electron positron collider. In SuperKEKB project, a collision with a large crossing angle is performed to boost the luminosity ~ 10³⁶ cm^-2s⁻¹. Future circular collider, FCC is also designed with a large crossing angle. Strong-strong simulations have shown a strong coherent head-tail instability, which can limit the performance of proposed future colliders. The mode coupling theory using the cross wake force explains the instability. The instability may affect all colliders designs based on the crab waist scheme.
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THPMF015	Lifetime and Beam Losses Studies of Partially Strip Ions in the SPS (129Xe³⁹⁺)	4070
	S. Hirlaender, R. Alemany-Fernández, H. Bartosik, N. Biancacci, T. Bohl, S. Cettour Cave, K. Cornelis, B. Goddard, V. Kain, M.W. Krasny, M. Lamont, D. Manglunki, G. Papotti, M. Schaumann, F. Zimmermann CERN, Geneva, Switzerland K. Kroeger FSU Jena, Jena, Germany V.P. Shevelko LPI RAS, Moscow, Russia T. Stöhlker, G. Weber IOQ, Jena, Germany
	The CERN multipurpose Gamma Factory proposal relies on using Partially Stripped Ion (PSI) beams, instead of electron beams, as the drivers of its light source. If such beams could be successfully stored in the LHC ring, fluxes of the order of 10¹⁷ photons/s, in the gamma-ray energy domain between 1 MeV and 400 MeV could be achieved. This energy domain is out of reach for the FEL-based light sources as long as the multi TeV electron beams are not available. The CERN Gamma Factory proposal has the potential of increasing by 7 orders of magnitude the intensity limits of the present Inverse Compton Scattering sources. In 2017 the CERN accelerator complex demonstrated its flexibility by producing a new, xenon, ion beam. The Gamma Factory study group, based on this achievement, requested special studies. Its aim was to inject and to accelerate, in the SPS, partially stripped xenon ions Xe³⁹⁺ measure their life time, and determine the relative strength of the processes responsible for the PSI beam losses. This study, the results of which are presented in this contribution, was an initial step in view of the the future studies programmed for 2018 with lead PSI beams.
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Paper

Title

Page

Bunch Schedules for the FCC-ee Pre-injector

79

S. Ogur, K. Oide, Y. Papaphilippou, F. Zimmermann
CERN, Geneva, Switzerland
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

The latest design of the Future Circular electron-positron Collider (FCC-ee) foresees a luminosity per interaction point above 2.0·10³⁶/cm²/s for operation at the Z pole. The filling from zero current occurs in collision to profit from the bunch lengthening due to beamstrahlung (so-called bootstrapping). At any time when new e^- and e⁺ buckets or bunchlets are injected into the collider, they will collide instantly. For this reason, we may provide the charge in each injected bunch in a way to pre-compensate for anticipated beam loss, and to reach the target luminosity as soon as possible after the first injection. In this way, we optimise the injection schedules for Z-mode so as to reach the peak luminosity in less than 20 minutes by interleaved injection of the two species at some portion of full bucket charge. Filling from zero the injector should allow accumulating 1.7·10¹¹ particles in one collider bucket within at least 10 injections, assuming a total transmission above 80%. In steady-state operation, the injector chain continually produces and accelerates lower bunch charges so as to maintain nearly constant bunch currents and constant peak luminosity.

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MOPMF034

Layout and Performance of the FCC-ee Pre-Injector Chain

169

S. Ogur, T.K. Charles, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann
CERN, Geneva, Switzerland
A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia
I. Chaikovska, R. Chehab
LAL, Orsay, France
K. Furukawa, N. Iida, T. Kamitani, F. Miyahara
KEK, Ibaraki, Japan
E.V. Ozcan
Bogazici University, Bebek / Istanbul, Turkey
S.M. Polozov
MEPhI, Moscow, Russia

The Future Circular e⁺e⁻ Collider pre-injector chain consists of a 6 GeV S-Band linac, a damping ring at 1.54 GeV and pre-booster ring to reach 20 GeV for injection to the main booster. The electron and positron beams use the same accelerator chain alternatively. The e⁺ beam is generated from a novel low level RF-gun providing 6.5 nC charge at 11 MeV with 0.5 micron geometric emittance. The e⁺ beam is produced by the impact of a 4.46 GeV e^- beam onto a hybrid target, accelerated in the linac up to 1.54 GeV, and injected to the damping ring for emittance cooling. Simulations on the performance of the DR are presented for reaching the required equilibrium emittances at the required damping time. As an alternative option, a 20 GeV linac is considered utilising C-Band cavities and simulations studies have been undertaken regarding the beam transport and transmission efficiency up to that energy.

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MOPMF064

High-Energy LHC Design

269

F. Zimmermann, D. Amorim, S. A. Antipov, S. Arsenyev, M. Benedikt, R. Bruce, M.P. Crouch, S.D. Fartoukh, M. Giovannozzi, B. Goddard, M. Hofer, R. Kersevan, V. Mertens, Y. Muttoni, J.A. Osborne, V. Parma, V. Raginel, S. Redaelli, T. Risselada, I. Ruehl, B. Salvant, D. Schoerling, E.N. Shaposhnikova, L.J. Tavian, E. Todesco, R. Tomás, D. Tommasini, F. Valchkova-Georgieva, V. Venturi, D. Wollmann
CERN, Geneva, Switzerland
J.L. Abelleira, E. Cruz Alaniz, P. Martinez Mirave, A. Seryi, L. van Riesen-Haupt
JAI, Oxford, United Kingdom
A. Apyan
ANSL, Yerevan, Armenia
J. Barranco García, L. Mether, T. Pieloni, L. Rivkin, C. Tambasco
EPFL, Lausanne, Switzerland
F. Burkart
DESY, Hamburg, Germany
Y. Cai, Y.M. Nosochkov
SLAC, Menlo Park, California, USA
G. Guillermo Cantón
CINVESTAV, Mérida, Mexico
K. Ohmi, K. Oide, D. Zhou
KEK, Ibaraki, Japan

In the frame of the FCC study we are designing a 27 TeV hadron collider in the LHC tunnel, called the High Energy LHC (HE-LHC).

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MOPMF065

LHC- and FCC-Based Muon Colliders

273

F. Zimmermann
CERN, Geneva, Switzerland

Funding: Work supported by the European Commission under the HORIZON 2020 project ARIES, grant agreement no. 730871.
In recent years, three schemes for producing low-emittance muon beams have been proposed: (1) e⁺e⁻ annihilation above threshold using a positron storage ring with a thin target [M. Boscolo, P. Raimondi et al.], (2) laser/FEL-Compton back-scattering off high-energy proton beams circulating in the LHC or FCC-hh [L. Serafini et al.], (3) the Gamma factory concept, where partially stripped heavy ions collide with a laser pulse to directly generating muons [W. Krasny]. The Gamma factory would also generate copious amounts of positrons which could in turn be used as source for option (1). On the other hand the top-up booster of the FCC-ee design would be an outstanding e⁺ storage ring, at the right beam energy, around 45 GeV. After rapid acceleration the muons, produced in one of the three ways, could be collided in machines like the SPS, LHC or FCC-hh. Possible collider layouts are suggested.

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MOPMF067

Optimized Arc Optics for the HE-LHC

277

Y.M. Nosochkov, Y. Cai
SLAC, Menlo Park, California, USA
M.P. Crouch, M. Giovannozzi, M. Hofer, J. Keintzel, T. Risselada, E. Todesco, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
D. Zhou
KEK, Ibaraki, Japan
L. van Riesen-Haupt
JAI, Oxford, United Kingdom

Funding: Work supported by the European Commission under Capacities 7th Framework Programme project EuCARD-2, grant agreement 312453, and the HORIZON 2020 project EuroCirCol, grant agreement 654305.
The High Energy LHC (HE-LHC) proton-proton collider is a proposed replacement of the LHC in the existing 27-km tunnel, with the goal of reaching the centre-of-mass beam energy of 27 TeV. The required higher dipole field can be realized by using 16-T dipoles being developed for the FCC-hh design. A major concern is the dynamic aperture at injection energy due to degraded field quality of the new dipole based on Nb3Sn superconductor, the potentially large energy swing between injection and collision, and the slightly reduced magnet aperture. Another issue is the field in quadrupoles and sextupoles at top energy, for which it may be cost-effective, wherever possible, to stay with Nb-Ti technology. In this study, we explore design options differed by arc lattice, for three choices of injection energy, with the goal of attaining acceptable magnet field and maximum injection dynamic aperture with dipole non-linear field errors.

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MOPMF068

Quantum Excitation due to Classical Beamstrahlung in Circular Colliders

281

M.A. Valdivia García, D. El Khechen, K. Oide, F. Zimmermann
CERN, Geneva, Switzerland

In the collisions of proposed future circular colliders, like FCC-ee and CEPC, the beamstrahlung regime is classical, i.e. with an "Upsilon parameter" much smaller than 1. In the classical regime, for a constant electromagnetic field a simple relation exists between the average photon energy u and the average squared photon energy u², which is the same as for standard synchrotron radiation in storage rings. This relation breaks down, however, if the electromagnetic field is not constant in time and position, as is the case for a beam-beam collision. We derive an analytical expression for u²/u², considering the case of Gaussian-bunch collisions with crossing angle (and possibly crab waist). We compare our result with the photon energies obtained in beam-beam simulation for FCC-ee at beam energies of 45.6 GeV and 175 GeV, using the two independent codes BBWS and Guineapig. Finally, we re-optimize the FCC-ee parameters of a possible mono-chromatization scheme for direct Higgs production at 125 GeV, derived previously, by applying the refined expression for the rms photon energy.

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MOPMF069

The High Energy LHC Beam-Beam Effects studies

285

T. Pieloni, J. Barranco García, L. Rivkin, C. Tambasco
EPFL, Lausanne, Switzerland
D. Amorim, S. A. Antipov, X. Buffat, B. Salvant, F. Zimmermann
CERN, Geneva, Switzerland

Funding: This work is supported by the Swiss State Secretariat for Education, Research and Innovation SERI.
We present in this paper the studies of beam-beam effects for the High Energy Large Hadron Collider. We will describe and review the different aspects of beam-beam interactions (i.e. orbit effects, Landau damping, compensation schemes and operational set-up). An operational scenario for the collider will also be given as a result of the study.

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MOPMK001

Optics for RF Acceleration Section for the High Energy Large Hadron Collider

345

L. van Riesen-Haupt, J.L. Abelleira
University of Oxford, Oxford, United Kingdom
J.L. Abelleira, E. Cruz Alaniz, P. Martinez Mirave, A. Seryi
JAI, Oxford, United Kingdom
M. Hofer, F. Zimmermann
CERN, Geneva, Switzerland
D. Zhou
KEK, Ibaraki, Japan

Funding: Work supported by the Horizon 2020 project EuroCirCol, grant 654305 and by the Science and Technology Facilities Council
As part of the FCC study, the design of the High Energy LHC (HE-LHC) is addressed. A proposed layout for the interaction region for the containing the radio frequency (RF) cavities and various beam instrumentation will be discussed. The higher energy requires more RF cavities, which strongly restricts the space available for optics and instrumentation. Another challenge arises because the beam rigidity increases whilst the LHC geometry has to be conserved. To this end, next generation dipoles have to be used in order to achieve sufficient beam to beam separation. A design that provides enough beam stay clear (BSC) in all the magnets will be presented. The design introduces an additional quadrupole on either side of the RF region to be used for phase advance adjustments that can increase the dynamic aperture.

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MOPMK002

Integrated Full HE-LHC Optics and Its Performance

348

M. Hofer
TU Vienna, Wien, Austria
M.P. Crouch, J. Keintzel, T. Risselada, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
Y.M. Nosochkov
SLAC, Menlo Park, California, USA
D. Zhou
KEK, Ibaraki, Japan
L. van Riesen-Haupt
JAI, Oxford, United Kingdom

One possible future hadron collider design investigated in the framework of the Future Circular Collider (FCC) study is the High-Energy LHC (HE-LHC). Using the 16 T dipoles developed for the FCC-hh the center of mass energy of the LHC is set to increase to 27 TeV. To achieve this set energy goal, a new optics design is required, taking into account the constraint from the LHC tunnel geometry. In this paper, two different lattices for the HE-LHC are presented. Initial considerations take into account the physical aperture at the proposed injection energy as well as the energy reach of these lattices. The dynamic aperture at the injection energies is determined using latest evaluations of the field quality of the main dipoles.

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MOPMK006

Experimental Interaction Region Optics for the High Energy LHC

360

SUSPF002

use link to see paper's listing under its alternate paper code

L. van Riesen-Haupt, J.L. Abelleira
University of Oxford, Oxford, United Kingdom
J.L. Abelleira, E. Cruz Alaniz, A. Seryi
JAI, Oxford, United Kingdom
M.P. Crouch, F. Zimmermann
CERN, Geneva, Switzerland
D. Zhou
KEK, Ibaraki, Japan

Funding: Work supported by the Horizon 2020 project EuroCirCol, grant 654305 and by the Science and Technology Facilities Council
The High Energy LHC (HE-LHC) is one option for a next generation hadron collider explored in the FCC-hh program. The core concept of the HE-LHC is to install FCC-hh technology magnets in the LHC tunnel. The higher beam rigidity and the increased radiation debris, however, impose severe challenges on the design of the triplet for the low beta insertions. In order to achieve 25 cm β^* optics and survive a lifetime integrated luminosity of 10 ab-1 a new longer triplet was designed that provides sufficient shielding and enough beam stay clear. This triplet has been designed using complimentary radiation studies to optimise the shielding that will also be presented. The optics for the rest of the interaction region had to be adjusted in order to host this more rigid beam and longer triplet whilst leaving enough room for crab cavities. Moreover, the effects non-linear errors in this triplet have on the dynamic aperture will be outlined.

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TUPAF030

Electron Cloud Build Up for LHC Sawtooth Vacuum Chamber

744

SUSPF052

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G. Guillermo Cantón, F. Zimmermann
CERN, Geneva, Switzerland
G.H.I. Maury Cuna, E. D. Ocampo
Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico

At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. For the arcs of LHC a sawtooth pattern had been imprinted on the horizontally outward side of the vacuum chamber in order to locally absorb synchrotron radiation photons without dispersing them all around the chamber. Using the combination of the codes Synrad3D and PyCLOUD we examine the effect of realistic absorption distributions with and without sawtooth on the build up of electron clouds.

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WEYGBD3

The CERN Gamma Factory Initiative: An Ultra-High Intensity Gamma Source

1780

M.W. Krasny
LPNHE, Paris, France
R. Alemany-Fernández, H. Bartosik, N. Biancacci, P. Czodrowski, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M.W. Krasny, M. Lamont, D. Manglunki, A.V. Petrenko, M. Schaumann, C. Yin Vallgren, F. Zimmermann
CERN, Geneva, Switzerland
P.S. Antsifarov
Institute of Spectroscopy, Russian Academy of Science, Troitsk, Moscow, Russia
A. Apyan
ANSL, Yerevan, Armenia
E.G. Bessonov
LPI, Moscow, Russia
J. Bieron, K. Dzierzega, W. Placzek, S. Pustelny
Marian Smoluchowski Institute of Physics, Jagiellonian University, Kraków, Poland
D. Budker
Johannes Gutenberg University Mainz, Institut für Physik, Mainz, Germany
K. Cassou, I. Chaikovska, R. Chehab, K. Dupraz, A. Martens, Z.F. Zomer
LAL, Orsay, France
F. Castelli
Università degli Studi di Milano, Milano, Italy
C. Curatolo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
K. Kroeger
FSU Jena, Jena, Germany
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy
V.P. Shevelko
LPI RAS, Moscow, Russia
T. Stöhlker
HIJ, Jena, Germany
G. Weber
IOQ, Jena, Germany
Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA
M.S. Zolotorev
LBNL, Berkeley, California, USA

This contribution discusses the possibility of broadening the present CERN research programme making use of a novel concept of light source. The proposed, Partially Stripped Ion beam driven, light source is the backbone of the Gamma Factory (GF) initiative. It could be realized at CERN by using the infrastructure of the already existing accelerators. It could push the intensity limits of the presently operating light-sources by up to 7 orders of magnitude, reaching fluxes of 10¹⁷ photons/s in the interesting gamma-ray energy domain between 1 MeV and 400 MeV. The GF light-source cannot be replaced, in this energy domain, by a FEL source as long as the multi TeV electron beams are not available. Its intensity is beyond the reach of the Inverse Compton Scattering sources. The unprecedented-intensity, energy-tuned gamma beams, together with the gamma-beams-driven secondary beams of polarized leptons, neutrinos, neutrons and radioactive ions are the basic research tools of the proposed Gamma Factory. A broad spectrum of new opportunities, in a vast domain of uncharted fundamental and applied physics territories, could be opened by the Gamma Factory research programme.

Slides WEYGBD3 [7.531 MB]

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THYGBD1

FCC: Colliders at the Energy Frontier

2908

M. Benedikt, F. Zimmermann
CERN, Geneva, Switzerland

The international Future Circular Collider study, launched in 2014, is finalizing a multi-volume conceptual design report. The FCC develops high-energy circular collider options based on a new 100 km tunnel. Long-term goal is a 100 TeV proton-proton collider (FCC-hh). The study also includes a high-luminosity electron-positron collider (FCC-ee), and it also examines lepton-hadron scenarios (FCC-he). Civil engineering and technical infrastructure studies were carried out. Global programs advance the development of high-field superconducting magnet technology based on Nb3Sn, the optimization of a suitable large superconducting RF system, and schemes for synchrotron radiation handling. In addition, the FCC study includes the design of the HE-LHC, housed in the LHC tunnel, and based on the same high-field magnet technology as the FCC-hh. The FCC study further includes an elaboration of the physics cases, including for heavy-ion collisions, and detector concepts, as well as staging and implementation scenarios. The FCC collaboration has grown to more than 120 institutes from 30 countries around the world. This invited talk summarizes the study achievements and the final designs.

Slides THYGBD1 [12.503 MB]

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THPAF037

Bunch Compression and Turnaround Loops Design in the FCC-ee Injector Complex

3044

T.K. Charles, F. Zimmermann
CERN, Geneva, Switzerland
M.J. Boland
CLS, Saskatoon, Saskatchewan, Canada
K. Oide
KEK, Ibaraki, Japan

The Future Circular e⁺e⁻ Collider (FCC-ee) requires two 180-degree turnaround loops to transport the positron beam from the damping ring to the lower energy section of the linac. In addition bunch compression is required to reduce the RMS bunch length from 5 mm to 0.5 mm, prior to injection into the linac. A dogleg bunch compressor comprised of two triple bend achromat (TBAs) can achieve this compression. Sextupole magnets are incorporated into the bunch compressor design for chromaticity correction as well as optimisation of the second-order longitudinal dispersion, T₅₆₆, and to linearize the longitudinal phase space distribution. In this paper we present the design of the transport line and the bunch compressor. Measures to limit emittance growth due to coherent synchrotron radiation (CSR) are also discussed, because despite the relatively long bunch length, the large degree of bending required introduces cause for consideration of CSR.

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THPAF089

Mode Coupling Theory in Collisions With a Large Crossing Angle

3197

N. Kuroo
UTTAC, Tsukuba, Ibaraki, Japan
K. Hirosawa, K. Ohmi, D. Zhou
KEK, Ibaraki, Japan
K. Oide, F. Zimmermann
CERN, Geneva, Switzerland

We discuss a novel coherent beam-beam instability in collisions with a large crossing angle. The instability appears in the correlated head-tail motion of the two colliding beams. Cross wake force is introduced to represent the head-tail correlation between colliding beams. The cross wake force is localized at the collision point. Mode coupling theory based on the cross wake force is developed. Collision scheme with a large crossing angle is being very popular in design of electron positron collider. In SuperKEKB project, a collision with a large crossing angle is performed to boost the luminosity ~ 10³⁶ cm^-2s⁻¹. Future circular collider, FCC is also designed with a large crossing angle. Strong-strong simulations have shown a strong coherent head-tail instability, which can limit the performance of proposed future colliders. The mode coupling theory using the cross wake force explains the instability. The instability may affect all colliders designs based on the crab waist scheme.

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THPMF015

Lifetime and Beam Losses Studies of Partially Strip Ions in the SPS (129Xe³⁹⁺)

4070

S. Hirlaender, R. Alemany-Fernández, H. Bartosik, N. Biancacci, T. Bohl, S. Cettour Cave, K. Cornelis, B. Goddard, V. Kain, M.W. Krasny, M. Lamont, D. Manglunki, G. Papotti, M. Schaumann, F. Zimmermann
CERN, Geneva, Switzerland
K. Kroeger
FSU Jena, Jena, Germany
V.P. Shevelko
LPI RAS, Moscow, Russia
T. Stöhlker, G. Weber
IOQ, Jena, Germany

The CERN multipurpose Gamma Factory proposal relies on using Partially Stripped Ion (PSI) beams, instead of electron beams, as the drivers of its light source. If such beams could be successfully stored in the LHC ring, fluxes of the order of 10¹⁷ photons/s, in the gamma-ray energy domain between 1 MeV and 400 MeV could be achieved. This energy domain is out of reach for the FEL-based light sources as long as the multi TeV electron beams are not available. The CERN Gamma Factory proposal has the potential of increasing by 7 orders of magnitude the intensity limits of the present Inverse Compton Scattering sources. In 2017 the CERN accelerator complex demonstrated its flexibility by producing a new, xenon, ion beam. The Gamma Factory study group, based on this achievement, requested special studies. Its aim was to inject and to accelerate, in the SPS, partially stripped xenon ions Xe³⁹⁺ measure their life time, and determine the relative strength of the processes responsible for the PSI beam losses. This study, the results of which are presented in this contribution, was an initial step in view of the the future studies programmed for 2018 with lead PSI beams.

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