IPAC2017 - List of Authors (Zimmermann, F.)

Paper	Title	Page
MOZA1	Electron Cloud Effects at the LHC and LHC Injectors	30
	G. Rumolo, H. Bartosik, E. Belli, P. Dijkstal, G. Iadarola, K.S.B. Li, L. Mether, A. Romano, M. Schenk, F. Zimmermann CERN, Geneva, Switzerland E. Belli University of Rome La Sapienza, Rome, Italy P. Dijkstal TU Darmstadt, Darmstadt, Germany M. Schenk EPFL, Lausanne, Switzerland
	Electron cloud effects are one of the main limitations of the performance of the LHC and its injectors. Enormous progress has been done in the simulation of the electron cloud build-up and of the effects on beam stability while mitigation measures have been identified and implemented (scrubbing, low secondary electron yield coatings, etc.). The above has allowed reaching nominal beam parameters in the LHC during Run 2. A review of the studies and results obtained and the strategy and expected performance for the High Luminosity operation of the LHC will be presented.
	Slides MOZA1 [12.855 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOZA1
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TUOCB1	Progress in the Design of Beam Optics for FCC-ee Collider Ring*	1281
	K. Oide, K. Ohmi KEK, Ibaraki, Japan M. Benedikt, H. Burkhardt, B.J. Holzer, A. Milanese, J. Wenninger, F. Zimmermann CERN, Geneva, Switzerland A.P. Blondel, M. Koratzinos DPNC, Genève, Switzerland A.V. Bogomyagkov, E.B. Levichev, D.N. Shatilov BINP SB RAS, Novosibirsk, Russia M. Boscolo INFN/LNF, Frascati (Roma), Italy
	The beam optics for the FCC-ee collider has been updated: (a) the layout is adjusted to a new footprint of FCC-hh, (b) the design around the interaction point is refined considering a number of machine-detecor interface issues, (c) the arc lattice is refined taking realistic magnet designs into account, (d) the β^* and betatron tunes are re-optimized according to recent results of the beam-beam simulations, and more. These changes make the collider design more realistic without performance degradation.
	Slides TUOCB1 [4.891 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUOCB1
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TUPAB014	Preliminary Design of FCC-ee Pre-Injector Complex	1337
SUSPSIK006	use link to see paper's listing under its alternate paper code
	S. Ogur, Y. Papaphilippou, F. Zimmermann CERN, Geneva, Switzerland A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia K. Furukawa, N. Iida, F. Miyahara, K. Oide KEK, Ibaraki, Japan
	The design of a 100 km circular e⁺e⁻ collider with extremely high luminosity is an important component of the global Future Circular Collider (FCC) study hosted by CERN. FCC-ee is being designed to serve as Z, W, H and top factory, covering beam energies from 45.6 to 175 GeV. For the injectors, the Z-operation is the most challenging mode, due to the high total charge and low equilibrium emittance in the collider at this energy. Thus, fulfilling the Z-mode will also meet the demands for all other modes of FCC-ee. This goal can be achieved by using a 6 GeV NC linac with an S-band RF frequency of 2.856 GHz and a repetition rate of 100 Hz. This linac will accelerate two bunches per RF pulse, each with a charge of 6.5 nC. Positrons will be generated by sending 4.46 GeV e^- onto a hybrid target so that the e⁺ created can still be accelerated to 1.54 GeV in the remaining part of the same linac. The emittance of the e⁺ beam will then shrink to the nm level in a 1.54 GeV damping ring. After damping, the e⁺ will be reinjected into the linac and accelerated to 6 GeV. The e^- and e⁺ will then be accelerated alternately to 45.6 GeV in the booster, before they are injected into the collider.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB014
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TUPAB110	Possible Limits of Plasma Linear Colliders	1576
	F. Zimmermann CERN, Geneva, Switzerland
	Plasma linear colliders have been proposed as next or next-next generation energy-frontier machines for high-energy physics. I investigate possible fundamental limits on energy and luminosity of such type of colliders, considering acceleration, multiple scattering off plasma ions, intrabeam scattering, bremsstrahlung, and betatron radiation. The question of energy efficiency will also be addressed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB110
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TUPVA011	Comparing Behaviour of Simulated Proton Synchrotron Radiation in the Arcs of the LHC with Measurements	2059
	G. Guillermo Cantón, M. Ady, R. Kersevan, F. Zimmermann CERN, Geneva, Switzerland M. Angelucci, R. Cimino, E. La Francesca INFN/LNF, Frascati (Roma), Italy D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Funding: EuCARD2 CONACyT In previous work it was shown that at high proton-beam energies, synchrotron radiation is an important source of beam-screen heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can contribute to electron cloud formation. We have used the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we studied the effect of the sawtooth chamber. In this paper specific results of the Synrad3D simulations are compared with simulations in Synrad+, developed at CERN; and later on compared with experimental data for actual LHC vacuum-chamber samples.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA011
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WEPIK001	Advanced Beam Dump for FCC-ee	2906
	A. Apyan ANSL, Yerevan, Armenia B. Goddard, F. Zimmermann CERN, Geneva, Switzerland K. Oide KEK, Ibaraki, Japan
	A modified beam dump for the future electron positron circular collider FCC-ee is discussed. The extraction line with a dilution kicker system distributes bunches at different transverse locations on the face of the beam dump. For a standard absorber the maximum energy deposition of all bunches occurs at the same longitudinal position inside the beam dump. This region experiences an enormous temperature rise compared with the surrounding parts of the beam dump. We propose a novel type of beam dump which spreads out the deposited energy over its whole volume quasi-uniformly, thereby reducing the maximum temperature rise. Results of Monte-Carlo simulations for a multi-material mosaic beam dump and for absorbers with distorted shapes are shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK001
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WEPIK015	Optimized Monochromatization for Direct Higgs Production in Future Circular e⁺e⁻ Colliders	2950
	F. Zimmermann CERN, Geneva, Switzerland M.A. Valdivia García DCI-UG, León, Mexico
	Funding: This work was supported in part by the European Commission under the HORIZON2020 Integrating Activity project ARIES, grant agreement 730871, and by the Mexican CONACyT ‘‘BEAM'' Programme. Direct s-channel Higgs production in e⁺e⁻ collisions is of interest if the centre-of-mass energy spread can be reduced to be comparable to the width of the standard model Higgs boson. A monochromatization scheme could be employed in order to achieve the desired reduction, by introducing a non-zero horizontal dispersion of opposite sign for the two colliding beams at the interaction point. In high-energy high-luminosity circular colliders, beamstrahlung may increase the energy spread and bunch length. The horizontal emittance blow up due to beamstrahlung, a new effect not present in past monochromatization proposals, may degrade the performance, especially the luminosity. We study, for the FCC-ee at 62.5 GeV beam energy, how we can optimize the IP optics parameters (betax, Dx) along with the number of particles per bunch so as to obtain maximum luminosity at a desired target value of the collision energy spread.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK015
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WEPIK034	Progress in the FCC-ee Interaction Region Magnet Design	3003
	M. Koratzinos, A.P. Blondel DPNC, Genève, Switzerland M. Benedikt, F. Zimmermann CERN, Geneva, Switzerland E.R. Bielert University of Illinois at Urbana-Champaign, Illinois, USA A.V. Bogomyagkov, S.V. Sinyatkin, P. Vobly BINP SB RAS, Novosibirsk, Russia M. Boscolo INFN/LNF, Frascati (Roma), Italy M. Dam NBI, København, Denmark K. Oide KEK, Ibaraki, Japan
	The design of the region close to the interaction point of the FCC-ee experiments is especially challenging. The beams collide at an angle (±15mrad) in a region where the detector solenoid magnetic field is large. Moreover, the very low vertical β^* of the machine necessitates that the final focusing quadrupoles are also inside this high field region. The beams should be screened from the effect of the detector solenoid field, and the emittance blow-up due to vertical dispersion in the interaction region should be minimized while leaving enough space for detector components. Crosstalk between the two final focus quadrupoles, only about 6 cm apart at the tip, should also be minimized. We present an update on the subject.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK034
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THPAB021	Wake Field and Head-Tail Instability in Beam-Beam Collision with a Large Crossing Angle	3738
	K. Ohmi, D. Zhou KEK, Ibaraki, Japan N. Kuroo UTTAC, Tsukuba, Ibaraki, Japan K. Oide, F. Zimmermann CERN, Geneva, Switzerland
	Head-tail type of coherent beam-beam instability has been seen in a strong-strong beam-beam simulation for collision with a large Piwinski angle σ_zθ/σ_x>>1, where θ is a half crossing angle. Beta x* is key parameter for the instability. The instability is not serious for SuperKEKB, but can be seen in phase II commissioning stage. It has a large impact for design of FCC-ee. We introduce wake field due to the beam-beam collision. The wake field gives turn-by-turn correlation of head-tail mode. Head-tail instability caused by the wake field explains that seen in the strong-strong beam-beam simulation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB021
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Paper

Title

Page

Electron Cloud Effects at the LHC and LHC Injectors

30

G. Rumolo, H. Bartosik, E. Belli, P. Dijkstal, G. Iadarola, K.S.B. Li, L. Mether, A. Romano, M. Schenk, F. Zimmermann
CERN, Geneva, Switzerland
E. Belli
University of Rome La Sapienza, Rome, Italy
P. Dijkstal
TU Darmstadt, Darmstadt, Germany
M. Schenk
EPFL, Lausanne, Switzerland

Electron cloud effects are one of the main limitations of the performance of the LHC and its injectors. Enormous progress has been done in the simulation of the electron cloud build-up and of the effects on beam stability while mitigation measures have been identified and implemented (scrubbing, low secondary electron yield coatings, etc.). The above has allowed reaching nominal beam parameters in the LHC during Run 2. A review of the studies and results obtained and the strategy and expected performance for the High Luminosity operation of the LHC will be presented.

Slides MOZA1 [12.855 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOZA1

Export •

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TUOCB1

Progress in the Design of Beam Optics for FCC-ee Collider Ring*

1281

K. Oide, K. Ohmi
KEK, Ibaraki, Japan
M. Benedikt, H. Burkhardt, B.J. Holzer, A. Milanese, J. Wenninger, F. Zimmermann
CERN, Geneva, Switzerland
A.P. Blondel, M. Koratzinos
DPNC, Genève, Switzerland
A.V. Bogomyagkov, E.B. Levichev, D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia
M. Boscolo
INFN/LNF, Frascati (Roma), Italy

The beam optics for the FCC-ee collider has been updated: (a) the layout is adjusted to a new footprint of FCC-hh, (b) the design around the interaction point is refined considering a number of machine-detecor interface issues, (c) the arc lattice is refined taking realistic magnet designs into account, (d) the β^* and betatron tunes are re-optimized according to recent results of the beam-beam simulations, and more. These changes make the collider design more realistic without performance degradation.

Slides TUOCB1 [4.891 MB]

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUOCB1

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TUPAB014

Preliminary Design of FCC-ee Pre-Injector Complex

1337

SUSPSIK006

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

S. Ogur, Y. Papaphilippou, F. Zimmermann
CERN, Geneva, Switzerland
A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia
K. Furukawa, N. Iida, F. Miyahara, K. Oide
KEK, Ibaraki, Japan

The design of a 100 km circular e⁺e⁻ collider with extremely high luminosity is an important component of the global Future Circular Collider (FCC) study hosted by CERN. FCC-ee is being designed to serve as Z, W, H and top factory, covering beam energies from 45.6 to 175 GeV. For the injectors, the Z-operation is the most challenging mode, due to the high total charge and low equilibrium emittance in the collider at this energy. Thus, fulfilling the Z-mode will also meet the demands for all other modes of FCC-ee. This goal can be achieved by using a 6 GeV NC linac with an S-band RF frequency of 2.856 GHz and a repetition rate of 100 Hz. This linac will accelerate two bunches per RF pulse, each with a charge of 6.5 nC. Positrons will be generated by sending 4.46 GeV e^- onto a hybrid target so that the e⁺ created can still be accelerated to 1.54 GeV in the remaining part of the same linac. The emittance of the e⁺ beam will then shrink to the nm level in a 1.54 GeV damping ring. After damping, the e⁺ will be reinjected into the linac and accelerated to 6 GeV. The e^- and e⁺ will then be accelerated alternately to 45.6 GeV in the booster, before they are injected into the collider.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB014

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TUPAB110

Possible Limits of Plasma Linear Colliders

1576

F. Zimmermann
CERN, Geneva, Switzerland

Plasma linear colliders have been proposed as next or next-next generation energy-frontier machines for high-energy physics. I investigate possible fundamental limits on energy and luminosity of such type of colliders, considering acceleration, multiple scattering off plasma ions, intrabeam scattering, bremsstrahlung, and betatron radiation. The question of energy efficiency will also be addressed.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB110

Export •

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TUPVA011

Comparing Behaviour of Simulated Proton Synchrotron Radiation in the Arcs of the LHC with Measurements

2059

G. Guillermo Cantón, M. Ady, R. Kersevan, F. Zimmermann
CERN, Geneva, Switzerland
M. Angelucci, R. Cimino, E. La Francesca
INFN/LNF, Frascati (Roma), Italy
D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Funding: EuCARD2 CONACyT
In previous work it was shown that at high proton-beam energies, synchrotron radiation is an important source of beam-screen heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can contribute to electron cloud formation. We have used the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we studied the effect of the sawtooth chamber. In this paper specific results of the Synrad3D simulations are compared with simulations in Synrad+, developed at CERN; and later on compared with experimental data for actual LHC vacuum-chamber samples.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA011

Export •

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WEPIK001

Advanced Beam Dump for FCC-ee

2906

A. Apyan
ANSL, Yerevan, Armenia
B. Goddard, F. Zimmermann
CERN, Geneva, Switzerland
K. Oide
KEK, Ibaraki, Japan

A modified beam dump for the future electron positron circular collider FCC-ee is discussed. The extraction line with a dilution kicker system distributes bunches at different transverse locations on the face of the beam dump. For a standard absorber the maximum energy deposition of all bunches occurs at the same longitudinal position inside the beam dump. This region experiences an enormous temperature rise compared with the surrounding parts of the beam dump. We propose a novel type of beam dump which spreads out the deposited energy over its whole volume quasi-uniformly, thereby reducing the maximum temperature rise. Results of Monte-Carlo simulations for a multi-material mosaic beam dump and for absorbers with distorted shapes are shown.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK001

Export •

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WEPIK015

Optimized Monochromatization for Direct Higgs Production in Future Circular e⁺e⁻ Colliders

2950

F. Zimmermann
CERN, Geneva, Switzerland
M.A. Valdivia García
DCI-UG, León, Mexico

Funding: This work was supported in part by the European Commission under the HORIZON2020 Integrating Activity project ARIES, grant agreement 730871, and by the Mexican CONACyT ‘‘BEAM'' Programme.
Direct s-channel Higgs production in e⁺e⁻ collisions is of interest if the centre-of-mass energy spread can be reduced to be comparable to the width of the standard model Higgs boson. A monochromatization scheme could be employed in order to achieve the desired reduction, by introducing a non-zero horizontal dispersion of opposite sign for the two colliding beams at the interaction point. In high-energy high-luminosity circular colliders, beamstrahlung may increase the energy spread and bunch length. The horizontal emittance blow up due to beamstrahlung, a new effect not present in past monochromatization proposals, may degrade the performance, especially the luminosity. We study, for the FCC-ee at 62.5 GeV beam energy, how we can optimize the IP optics parameters (betax*, Dx*) along with the number of particles per bunch so as to obtain maximum luminosity at a desired target value of the collision energy spread.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK015

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

WEPIK034

Progress in the FCC-ee Interaction Region Magnet Design

3003

M. Koratzinos, A.P. Blondel
DPNC, Genève, Switzerland
M. Benedikt, F. Zimmermann
CERN, Geneva, Switzerland
E.R. Bielert
University of Illinois at Urbana-Champaign, Illinois, USA
A.V. Bogomyagkov, S.V. Sinyatkin, P. Vobly
BINP SB RAS, Novosibirsk, Russia
M. Boscolo
INFN/LNF, Frascati (Roma), Italy
M. Dam
NBI, København, Denmark
K. Oide
KEK, Ibaraki, Japan

The design of the region close to the interaction point of the FCC-ee experiments is especially challenging. The beams collide at an angle (±15mrad) in a region where the detector solenoid magnetic field is large. Moreover, the very low vertical β^* of the machine necessitates that the final focusing quadrupoles are also inside this high field region. The beams should be screened from the effect of the detector solenoid field, and the emittance blow-up due to vertical dispersion in the interaction region should be minimized while leaving enough space for detector components. Crosstalk between the two final focus quadrupoles, only about 6 cm apart at the tip, should also be minimized. We present an update on the subject.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK034

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THPAB021

Wake Field and Head-Tail Instability in Beam-Beam Collision with a Large Crossing Angle

3738

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

Head-tail type of coherent beam-beam instability has been seen in a strong-strong beam-beam simulation for collision with a large Piwinski angle σ_zθ/σ_x>>1, where θ is a half crossing angle. Beta x* is key parameter for the instability. The instability is not serious for SuperKEKB, but can be seen in phase II commissioning stage. It has a large impact for design of FCC-ee. We introduce wake field due to the beam-beam collision. The wake field gives turn-by-turn correlation of head-tail mode. Head-tail instability caused by the wake field explains that seen in the strong-strong beam-beam simulation.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB021

Export •

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