IPAC2019 - List of Authors (Papaphilippou, Y.)

Paper	Title	Page
MOPGW095	Beam Dynamics Simulations with Crab Cavities in the SPS Machine	342
	A. Alekou, A. Alekou, H. Bartosik, H. Bartosik, M. Carlà, Y. Papaphilippou, Y. Papaphilippou, Y. Papaphilippou CERN, Geneva, Switzerland A. Alekou, A. Alekou, R.B. Appleby, R.B. Appleby UMAN, Manchester, United Kingdom R.B. Appleby Cockcroft Institute, Warrington, Cheshire, United Kingdom
	The LHC Upgrade, called High Luminosity LHC, aims to increase the integrated luminosity by a factor of 10. To achieve this, the project relies on a number of key innovative technologies, including the use of superconducting Crab Cavities with ultra-precise phase control for beam rotation. A set of prototype Crab Cavities has been recently installed in the second largest machine of CERN, the Super Proton Synchrotron (SPS), that operated as a test-bed from May to November of 2018. The tight LHC constraints call for axially non-symmetric cavity designs that introduce high order multipole components. Furthermore, the Crab Cavities in the presence of SPS non-linearities can affect the long term stability of the beam. This paper presents how the SPS dynamic aperture is affected for different cavity, machine and beam configurations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW095
About •	paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP002	Linac and Damping Ring Designs for the FCC-ee	420
	S. Ogur, 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, K. Oide KEK, Ibaraki, Japan E.V. Ozcan Bogazici University, Bebek / Istanbul, Turkey S.M. Polozov MEPhI, Moscow, Russia L. Rinolfi ESI, Archamps, France F. Yaman IZTECH, Izmir, Turkey
	We report the design of the pre-injector chain for the Future Circular e⁺ e⁻ Collider (FCC-ee) system. The electron beam from a low-emittance RF gun is accelerated by an S-band linac up to 6 GeV. A damping ring at 1.54 GeV is required for emittance cooling of the positron beam. The intermediate energy step from the exit of the S-band linac at 6 GeV to the 20 GeV injection energy of the top-up booster can be provided by the modified Super Proton Synchrotron (SPS), serving as a pre-booster ring (PBR). An alternative option to reach 20 GeV energy would be to extend the S-band linac with a C- or X-band linac. An overall cost optimisation will determine the choice of the final configuration. Beam loss and emittance dilution in the linac due to space charge effects, wakefields, and misalignment of accelerator components can be mitigated by RF phasing and orbit steering. Start-to-end simulations examine the beam transport through the linac up to either 6 GeV or 20 GeV. The results indicate large design margins. Simulations of the beam dynamics in the damping ring (DR) demonstrate a sufficiently large momentum acceptance. Effects of intrabeam scattering and electron cloud instability in the DR are also studied.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP002
About •	paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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MOPMP003	Positron Source for FCC-ee	424
	I. Chaikovska, R. Chehab, A. Faus-Golfe, Y. Han LAL, Orsay, France A. Apyan ANSL, Yerevan, Armenia Y. Enomoto, K. Furukawa, T. Kamitani, F. Miyahara, M. Satoh, Y. Seimiya, T. Suwada KEK, Ibaraki, Japan P.V. Martyshkin BINP SB RAS, Novosibirsk, Russia S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, P. Sievers, F. Zimmermann CERN, Meyrin, Switzerland
	The FCC-ee is a high-luminosity, high-precision circular collider to be constructed in a new 100 km tunnel in the Geneva area. The physics case is well established and the FCC-ee operation is foreseen at 91 GeV (Z-pole), 160 GeV (W pair production threshold), 240 GeV (Higgs resonance) and 365 GeV (t-tbar threshold). Due to the large 6D production emittance and important thermal load in the production target, the positron injector, in particular the positron source, is one of the key elements of the FCC-ee, requiring special attention. To ensure high reliability of the positron source, conventional and hybrid targets are currently under study. The final choice of the positron target will be made based on the estimated performances. In this framework, we present a preliminary design of the FCC-ee positron source, with detailed simulation studies of positron production, capture and primary acceleration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP003
About •	paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP029	Analysis on Bunch-by-Bunch Beam Losses at 6.5 TeV in the Large Hadron Collider	500
SUSPFO105	use link to see paper's listing under its alternate paper code
	K. Paraschou, G. Iadarola, N. Karastathis, S. Kostoglou, Y. Papaphilippou, L. Sabato CERN, Geneva, Switzerland S. Kostoglou National Technical University of Athens, Zografou, Greece K. Paraschou AUTH, Thessaloniki, Greece
	In 2018, a large fraction of the physics data taking at the Large Hadron Collider has been performed with a beam energy of 6.5 TeV, the nominal bunch spacing of 25 ns and beta functions at the high luminosity interaction points of 30 cm. In order to maximize the integrated luminosity, the crossing angles are gradually reduced as the beam intensity reduces due to luminosity burn-off. In these conditions the beam lifetime is visibly affected by collective effects and in particular by beam-beam interaction and electron cloud effects. By analyzing the beam losses at a bunch-by-bunch level, it is possible to disentangle the contributions from different effects and to assess the impact on the losses of changes applied to the machine configuration.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP029
About •	paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP052	Numerical Simulations of the DC Wire Prototypes in LHC for Enhancing the HL-LHC Performances	566
	A. Poyet Université Grenoble Alpes, Grenoble, France S.D. Fartoukh, N. Karastathis, Y. Papaphilippou, K. Skoufaris, G. Sterbini CERN, Geneva, Switzerland
	For the last 15 years, the compensation of the Beam-Beam Long-Range (BBLR) interaction in colliders using DC wires has been studied. In 2015, in the frame of the HL-LHC project, it has been shown that a compensation of all the Resonance Driving Terms (RDTs) generated by the BBLR interaction is possible using wires with constraints on their transverse and longitudinal positions. In 2017, an experimental campaign has been launched in the present LHC, with wires installed in sub-optimal positions due to integration constraints. The aim of this paper is therefore to apply the formalism developped for HL-LHC to the LHC case and to compare the experimental results to the numerical tracking studies of the compensation using wires.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP052
About •	paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPMP053	Numerical Optimization of DC Wire Compensation in HL-LHC	570
	K. Skoufaris, S.D. Fartoukh, N. Karastathis, Y. Papaphilippou, D. Pellegrini, A. Poyet, A. Rossi, G. Sterbini CERN, Geneva, Switzerland
	The electromagnetic field generated from a set of DC wires parallel to the beam opens the path to the compensation of the beam-beam long-range (BBLR) interactions for the future operation of large hadron colliders, in particular for the upcoming High Luminosity upgrade of the Large Hadron Collider (HL-LHC). The effectiveness and simplicity of a current carrying wire are critical for overcoming some technical constraints of the machine. In order to better understand the potential of this device for the HL-LHC, various simulation studies are presented. The different observables are the dynamic aperture and the frequency analysis.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP053
About •	paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS097	Updates on Alternative Pre-Booster Ring Design and Wiggler Magnet Considerations of SPS for the FCC e⁺e⁻ Injector	1094
	O. Etisken Ankara University, Faculty of Sciences, Ankara, Turkey F. Antoniou, Y. Papaphilippou, T. Tydecks CERN, Geneva, Switzerland A.K. Çiftçi Izmir University of Economics, Balçova/Izmir, Turkey
	The Future Circular e⁺e⁻ Collider (FCC- e⁺e⁻) injector complex needs to produce and to transport a high-intensity e⁺e⁻ beam at a fast repetition rate for topping up the collider at its collision energy. Two different options are under consideration as pre-accelerator before the bunches are transferred to the high-energy booster: using the existing SPS and designing a completely new ring. The purpose of this paper is to explore the needs and parameters of the existing SPS, to investigate wiggler magnet options for SPS, and provide an updated study of alternative accelerator ring design with injection and extraction energies of 6 and 20 GeV, respectively. In this study, the parameters of both choices are established, including the optics design, layout update and considerations for non-linear dynamics optimization.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS097
About •	paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPTS098	A Primary Electron Beam Facility at CERN	1098
	Y. Papaphilippou, R. Corsini, Y. Dutheil, L.R. Evans, B. Goddard, A. Grudiev, A. Latina, S. Stapnes CERN, Geneva, Switzerland T.P.Å. Åkesson Lund University, Department of Physics, Lund, Sweden
	This paper describes the concept of a primary electron beam facility at CERN, to be used for dark gauge force and light dark matter searches. The electron beam is produced in three stages: A Linac accelerates electrons from a photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally, the accelerated beam is slowly extracted to an experiment, possibly followed by a fast dump of the remaining electrons to another beamline. The beam parameters are optimized using the requirements of the Light Dark Matter eXperiment, LDMX, as benchmark.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS098
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEYYPLM3	First Results of the Compensation of the Beam-Beam Effect with DC Wires in the LHC	2262
	G. Sterbini, D. Amorim, H. Bartosik, A. Bertarelli, R. Bruce, X. Buffat, F. Carra, L.R. Carver, G. Cattenoz, E. Effinger, S.D. Fartoukh, N. Fuster-Martínez, M. Gąsior, M. Gonzalez-Berges, A.A. Gorzawski, G.H. Hemelsoet, M. Hostettler, G. Iadarola, O.R. Jones, N. Karastathis, S. Kostoglou, I. Lamas Garcia, T.E. Levens, L.E. Medina Medrano, D. Mirarchi, J. Olexa, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, M. Pojer, L. Ponce, A. Poyet, S. Redaelli, A. Rossi, B. Salvachua, H. Schmickler, F. Schmidt, K. Skoufaris, M. Solfaroli, R. Tomás, G. Trad, D. Valuch, C. Xu, C. Zamantzas, P. Zisopoulos CERN, Geneva, Switzerland D. Amorim Grenoble-INP Phelma, Grenoble, France M. Fitterer, A. Valishev Fermilab, Batavia, Illinois, USA D. Kaltchev TRIUMF, Vancouver, Canada S. Kostoglou National Technical University of Athens, Zografou, Greece A.E. Levichev BINP SB RAS, Novosibirsk, Russia A. Poyet Université Grenoble Alpes, Grenoble, France
	The compensation of the long-range beam-beam interactions using DC wires is presently under study as an option for enhancing the machine performance in the frame of the High-Luminosity LHC project (HL-LHC). The original idea dates back more than 15 years. After the installation of four wire prototypes in the LHC in 2018, a successful experimental campaign was performed during the last months. The experimental setup and the main results are reported in this paper.
	Slides WEYYPLM3 [6.371 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM3
About •	paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPMP041	Damping Bunch Oscillations Due to Off-Axis Injection	2422
	F. Zimmermann, O. Etisken, N. Mounet, A. Oeftiger, S. Ogur, Y. Papaphilippou, B. Salvant CERN, Geneva, Switzerland K. Oide KEK, Ibaraki, Japan
	Funding: This work was supported by the European Commission under the HORIZON 2020 project ARIES, grant agreement no. 730871. In the FCC-ee pre-injector complex, a slightly modified SPS can serve as pre-booster. The baseline design foresees injecting the low-emittance electron and positron bunches off-axis into the SPS, and deploying strong wigglers to greatly enhance the radiation damping at the injection energy. We here compare the damping of large injection oscillations by means of radiation damping with the effect of other possible damping mechanisms such as a fast bunch-by-bunch feedback system and/or head-tail damping via nonzero chromaticity. As a by-product, we investigate the transverse beam stability.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP041
About •	paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEPTS041	Coupling and Space Charge Studies at the CERN PSB	3192
	F. Asvesta NTUA, Athens, Greece F. Antoniou, H. Bartosik, G.P. Di Giovanni, Y. Papaphilippou CERN, Meyrin, Switzerland
	In the nominal optics of the CERN PS-Booster (PSB), the fourth order coupling resonance is excited by space charge (Montague resonance) due to the same integer tune values. This resonance can be avoided by changing the tunes to different integers. A new PSB optics is presented and emittance measurements crossing the coupling resonance for the nominal and the new optics are shown.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS041
About •	paper received ※ 17 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPTS046	Monitoring and Modelling of the LHC Emittance and Luminosity Evolution in 2018	3212
	S. Papadopoulou, F. Antoniou, I. Efthymiopoulos, M. Hostettler, G. Iadarola, N. Karastathis, S. Kostoglou, Y. Papaphilippou, G. Trad CERN, Meyrin, Switzerland
	Operating at 6.5 TeV, the LHC surpassed the expectations and delivered an average of 66 fb−1 integrated luminosity to the two high luminosity experiments ATLAS and CMS by the end of 2018. In order to provide a continuous feedback to the machine coordination for further optimizing the performance, an automated tool for monitoring the main beam parameters and machine configurations, has been devised and extensively used. New features like the coupling between the two planes and effects of noise, were added to the numerical model used since 2016 to calculate the machine luminosity. Estimates, based both on simulations and on observed beam parameters, were reported fill-by-fill as well as in overall trends during the year. Highlights of the observations including the observed additional emittance blow up (on top of IBS, SR and elastic scattering) as well as additional losses (on top of the expected proton burn off) are presented for the 2018 data. Finally, cumulated integrated luminosity projections from the model for the entire 2018 data based on different degradation mechanisms are compared also with respect to the achieved luminosity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS046
About •	paper received ※ 17 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPTS047	Space Charge Driven Resonances in the CERN PS	3216
	F. Asvesta NTUA, Athens, Greece H. Bartosik, A. Huschauer, Y. Papaphilippou CERN, Meyrin, Switzerland
	In the CERN Proton Synchrotron space charge driven resonances are excited around the operational working point due to the periodicity of the optics functions. In this paper, the resonances are studied using analytical methods, i.e. the evaluation of the resonance driving terms connected to the space charge potential of Gaussian distributions. Furthermore, the resonances are characterized in measurements and simulations for various beams. The beams considered are different in terms of brightness, in order to study the dependence of the resonance strength on the space charge force.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS047
About •	paper received ※ 17 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THPRB071	Beam-Based Measurements on Two ±12.5 kV Inductive Adders, together with Striplines, for CLIC Damping Ring Extraction Kickers	3970
	J. Holma, M.J. Barnes, M. Carlà, N. Catalán Lasheras, Y. Papaphilippou CERN, Meyrin, Switzerland U. Iriso, Z. Martí, F. Pérez, M. Pont ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	The CLIC study is investigating the technical feasibil-ity of an electron-positron linear collider with high lumi-nosity and a nominal centre-of-mass energy of 3 TeV. Pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. The DR kicker systems, each of which consists of a set of striplines and two inductive adders, must provide ex-tremely stable field pulses. The DR extraction kicker system is the most demanding: specifications require a field uniformity within ±0.01% and pulses up to 900 ns flattop duration, at ±12.5 kV and 309 A, with ripple and droop of not more than ±0.02 % (±2.5 V), with respect to a reference waveform. Two prototype inductive adders have been designed and built at CERN, and have been tested with prototype striplines installed in the storage ring of the ALBA Synchrotron Light Source, in Spain. The stability of the kicker system, including the modulators, has been evaluated from the beam-based measure-ments and is reported in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB071
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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Paper

Title

Page

Beam Dynamics Simulations with Crab Cavities in the SPS Machine

342

A. Alekou, A. Alekou, H. Bartosik, H. Bartosik, M. Carlà, Y. Papaphilippou, Y. Papaphilippou, Y. Papaphilippou
CERN, Geneva, Switzerland
A. Alekou, A. Alekou, R.B. Appleby, R.B. Appleby
UMAN, Manchester, United Kingdom
R.B. Appleby
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The LHC Upgrade, called High Luminosity LHC, aims to increase the integrated luminosity by a factor of 10. To achieve this, the project relies on a number of key innovative technologies, including the use of superconducting Crab Cavities with ultra-precise phase control for beam rotation. A set of prototype Crab Cavities has been recently installed in the second largest machine of CERN, the Super Proton Synchrotron (SPS), that operated as a test-bed from May to November of 2018. The tight LHC constraints call for axially non-symmetric cavity designs that introduce high order multipole components. Furthermore, the Crab Cavities in the presence of SPS non-linearities can affect the long term stability of the beam. This paper presents how the SPS dynamic aperture is affected for different cavity, machine and beam configurations.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW095

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paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP002

Linac and Damping Ring Designs for the FCC-ee

420

S. Ogur, 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, K. Oide
KEK, Ibaraki, Japan
E.V. Ozcan
Bogazici University, Bebek / Istanbul, Turkey
S.M. Polozov
MEPhI, Moscow, Russia
L. Rinolfi
ESI, Archamps, France
F. Yaman
IZTECH, Izmir, Turkey

We report the design of the pre-injector chain for the Future Circular e⁺ e⁻ Collider (FCC-ee) system. The electron beam from a low-emittance RF gun is accelerated by an S-band linac up to 6 GeV. A damping ring at 1.54 GeV is required for emittance cooling of the positron beam. The intermediate energy step from the exit of the S-band linac at 6 GeV to the 20 GeV injection energy of the top-up booster can be provided by the modified Super Proton Synchrotron (SPS), serving as a pre-booster ring (PBR). An alternative option to reach 20 GeV energy would be to extend the S-band linac with a C- or X-band linac. An overall cost optimisation will determine the choice of the final configuration. Beam loss and emittance dilution in the linac due to space charge effects, wakefields, and misalignment of accelerator components can be mitigated by RF phasing and orbit steering. Start-to-end simulations examine the beam transport through the linac up to either 6 GeV or 20 GeV. The results indicate large design margins. Simulations of the beam dynamics in the damping ring (DR) demonstrate a sufficiently large momentum acceptance. Effects of intrabeam scattering and electron cloud instability in the DR are also studied.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP002

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paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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MOPMP003

Positron Source for FCC-ee

424

I. Chaikovska, R. Chehab, A. Faus-Golfe, Y. Han
LAL, Orsay, France
A. Apyan
ANSL, Yerevan, Armenia
Y. Enomoto, K. Furukawa, T. Kamitani, F. Miyahara, M. Satoh, Y. Seimiya, T. Suwada
KEK, Ibaraki, Japan
P.V. Martyshkin
BINP SB RAS, Novosibirsk, Russia
S. Ogur, K. Oide, Y. Papaphilippou, L. Rinolfi, P. Sievers, F. Zimmermann
CERN, Meyrin, Switzerland

The FCC-ee is a high-luminosity, high-precision circular collider to be constructed in a new 100 km tunnel in the Geneva area. The physics case is well established and the FCC-ee operation is foreseen at 91 GeV (Z-pole), 160 GeV (W pair production threshold), 240 GeV (Higgs resonance) and 365 GeV (t-tbar threshold). Due to the large 6D production emittance and important thermal load in the production target, the positron injector, in particular the positron source, is one of the key elements of the FCC-ee, requiring special attention. To ensure high reliability of the positron source, conventional and hybrid targets are currently under study. The final choice of the positron target will be made based on the estimated performances. In this framework, we present a preliminary design of the FCC-ee positron source, with detailed simulation studies of positron production, capture and primary acceleration.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP003

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paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP029

Analysis on Bunch-by-Bunch Beam Losses at 6.5 TeV in the Large Hadron Collider

500

SUSPFO105

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

K. Paraschou, G. Iadarola, N. Karastathis, S. Kostoglou, Y. Papaphilippou, L. Sabato
CERN, Geneva, Switzerland
S. Kostoglou
National Technical University of Athens, Zografou, Greece
K. Paraschou
AUTH, Thessaloniki, Greece

In 2018, a large fraction of the physics data taking at the Large Hadron Collider has been performed with a beam energy of 6.5 TeV, the nominal bunch spacing of 25 ns and beta functions at the high luminosity interaction points of 30 cm. In order to maximize the integrated luminosity, the crossing angles are gradually reduced as the beam intensity reduces due to luminosity burn-off. In these conditions the beam lifetime is visibly affected by collective effects and in particular by beam-beam interaction and electron cloud effects. By analyzing the beam losses at a bunch-by-bunch level, it is possible to disentangle the contributions from different effects and to assess the impact on the losses of changes applied to the machine configuration.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP029

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paper received ※ 10 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP052

Numerical Simulations of the DC Wire Prototypes in LHC for Enhancing the HL-LHC Performances

566

A. Poyet
Université Grenoble Alpes, Grenoble, France
S.D. Fartoukh, N. Karastathis, Y. Papaphilippou, K. Skoufaris, G. Sterbini
CERN, Geneva, Switzerland

For the last 15 years, the compensation of the Beam-Beam Long-Range (BBLR) interaction in colliders using DC wires has been studied. In 2015, in the frame of the HL-LHC project, it has been shown that a compensation of all the Resonance Driving Terms (RDTs) generated by the BBLR interaction is possible using wires with constraints on their transverse and longitudinal positions. In 2017, an experimental campaign has been launched in the present LHC, with wires installed in sub-optimal positions due to integration constraints. The aim of this paper is therefore to apply the formalism developped for HL-LHC to the LHC case and to compare the experimental results to the numerical tracking studies of the compensation using wires.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP052

About •

paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPMP053

Numerical Optimization of DC Wire Compensation in HL-LHC

570

K. Skoufaris, S.D. Fartoukh, N. Karastathis, Y. Papaphilippou, D. Pellegrini, A. Poyet, A. Rossi, G. Sterbini
CERN, Geneva, Switzerland

The electromagnetic field generated from a set of DC wires parallel to the beam opens the path to the compensation of the beam-beam long-range (BBLR) interactions for the future operation of large hadron colliders, in particular for the upcoming High Luminosity upgrade of the Large Hadron Collider (HL-LHC). The effectiveness and simplicity of a current carrying wire are critical for overcoming some technical constraints of the machine. In order to better understand the potential of this device for the HL-LHC, various simulation studies are presented. The different observables are the dynamic aperture and the frequency analysis.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP053

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paper received ※ 03 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS097

Updates on Alternative Pre-Booster Ring Design and Wiggler Magnet Considerations of SPS for the FCC e⁺e⁻ Injector

1094

O. Etisken
Ankara University, Faculty of Sciences, Ankara, Turkey
F. Antoniou, Y. Papaphilippou, T. Tydecks
CERN, Geneva, Switzerland
A.K. Çiftçi
Izmir University of Economics, Balçova/Izmir, Turkey

The Future Circular e⁺e⁻ Collider (FCC- e⁺e⁻) injector complex needs to produce and to transport a high-intensity e⁺e⁻ beam at a fast repetition rate for topping up the collider at its collision energy. Two different options are under consideration as pre-accelerator before the bunches are transferred to the high-energy booster: using the existing SPS and designing a completely new ring. The purpose of this paper is to explore the needs and parameters of the existing SPS, to investigate wiggler magnet options for SPS, and provide an updated study of alternative accelerator ring design with injection and extraction energies of 6 and 20 GeV, respectively. In this study, the parameters of both choices are established, including the optics design, layout update and considerations for non-linear dynamics optimization.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS097

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paper received ※ 06 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPTS098

A Primary Electron Beam Facility at CERN

1098

Y. Papaphilippou, R. Corsini, Y. Dutheil, L.R. Evans, B. Goddard, A. Grudiev, A. Latina, S. Stapnes
CERN, Geneva, Switzerland
T.P.Å. Åkesson
Lund University, Department of Physics, Lund, Sweden

This paper describes the concept of a primary electron beam facility at CERN, to be used for dark gauge force and light dark matter searches. The electron beam is produced in three stages: A Linac accelerates electrons from a photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally, the accelerated beam is slowly extracted to an experiment, possibly followed by a fast dump of the remaining electrons to another beamline. The beam parameters are optimized using the requirements of the Light Dark Matter eXperiment, LDMX, as benchmark.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS098

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paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEYYPLM3

First Results of the Compensation of the Beam-Beam Effect with DC Wires in the LHC

2262

G. Sterbini, D. Amorim, H. Bartosik, A. Bertarelli, R. Bruce, X. Buffat, F. Carra, L.R. Carver, G. Cattenoz, E. Effinger, S.D. Fartoukh, N. Fuster-Martínez, M. Gąsior, M. Gonzalez-Berges, A.A. Gorzawski, G.H. Hemelsoet, M. Hostettler, G. Iadarola, O.R. Jones, N. Karastathis, S. Kostoglou, I. Lamas Garcia, T.E. Levens, L.E. Medina Medrano, D. Mirarchi, J. Olexa, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, M. Pojer, L. Ponce, A. Poyet, S. Redaelli, A. Rossi, B. Salvachua, H. Schmickler, F. Schmidt, K. Skoufaris, M. Solfaroli, R. Tomás, G. Trad, D. Valuch, C. Xu, C. Zamantzas, P. Zisopoulos
CERN, Geneva, Switzerland
D. Amorim
Grenoble-INP Phelma, Grenoble, France
M. Fitterer, A. Valishev
Fermilab, Batavia, Illinois, USA
D. Kaltchev
TRIUMF, Vancouver, Canada
S. Kostoglou
National Technical University of Athens, Zografou, Greece
A.E. Levichev
BINP SB RAS, Novosibirsk, Russia
A. Poyet
Université Grenoble Alpes, Grenoble, France

The compensation of the long-range beam-beam interactions using DC wires is presently under study as an option for enhancing the machine performance in the frame of the High-Luminosity LHC project (HL-LHC). The original idea dates back more than 15 years. After the installation of four wire prototypes in the LHC in 2018, a successful experimental campaign was performed during the last months. The experimental setup and the main results are reported in this paper.

Slides WEYYPLM3 [6.371 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM3

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paper received ※ 06 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPMP041

Damping Bunch Oscillations Due to Off-Axis Injection

2422

F. Zimmermann, O. Etisken, N. Mounet, A. Oeftiger, S. Ogur, Y. Papaphilippou, B. Salvant
CERN, Geneva, Switzerland
K. Oide
KEK, Ibaraki, Japan

Funding: This work was supported by the European Commission under the HORIZON 2020 project ARIES, grant agreement no. 730871.
In the FCC-ee pre-injector complex, a slightly modified SPS can serve as pre-booster. The baseline design foresees injecting the low-emittance electron and positron bunches off-axis into the SPS, and deploying strong wigglers to greatly enhance the radiation damping at the injection energy. We here compare the damping of large injection oscillations by means of radiation damping with the effect of other possible damping mechanisms such as a fast bunch-by-bunch feedback system and/or head-tail damping via nonzero chromaticity. As a by-product, we investigate the transverse beam stability.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP041

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paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPTS041

Coupling and Space Charge Studies at the CERN PSB

3192

F. Asvesta
NTUA, Athens, Greece
F. Antoniou, H. Bartosik, G.P. Di Giovanni, Y. Papaphilippou
CERN, Meyrin, Switzerland

In the nominal optics of the CERN PS-Booster (PSB), the fourth order coupling resonance is excited by space charge (Montague resonance) due to the same integer tune values. This resonance can be avoided by changing the tunes to different integers. A new PSB optics is presented and emittance measurements crossing the coupling resonance for the nominal and the new optics are shown.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS041

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paper received ※ 17 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS046

Monitoring and Modelling of the LHC Emittance and Luminosity Evolution in 2018

3212

S. Papadopoulou, F. Antoniou, I. Efthymiopoulos, M. Hostettler, G. Iadarola, N. Karastathis, S. Kostoglou, Y. Papaphilippou, G. Trad
CERN, Meyrin, Switzerland

Operating at 6.5 TeV, the LHC surpassed the expectations and delivered an average of 66 fb−1 integrated luminosity to the two high luminosity experiments ATLAS and CMS by the end of 2018. In order to provide a continuous feedback to the machine coordination for further optimizing the performance, an automated tool for monitoring the main beam parameters and machine configurations, has been devised and extensively used. New features like the coupling between the two planes and effects of noise, were added to the numerical model used since 2016 to calculate the machine luminosity. Estimates, based both on simulations and on observed beam parameters, were reported fill-by-fill as well as in overall trends during the year. Highlights of the observations including the observed additional emittance blow up (on top of IBS, SR and elastic scattering) as well as additional losses (on top of the expected proton burn off) are presented for the 2018 data. Finally, cumulated integrated luminosity projections from the model for the entire 2018 data based on different degradation mechanisms are compared also with respect to the achieved luminosity.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS046

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paper received ※ 17 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS047

Space Charge Driven Resonances in the CERN PS

3216

F. Asvesta
NTUA, Athens, Greece
H. Bartosik, A. Huschauer, Y. Papaphilippou
CERN, Meyrin, Switzerland

In the CERN Proton Synchrotron space charge driven resonances are excited around the operational working point due to the periodicity of the optics functions. In this paper, the resonances are studied using analytical methods, i.e. the evaluation of the resonance driving terms connected to the space charge potential of Gaussian distributions. Furthermore, the resonances are characterized in measurements and simulations for various beams. The beams considered are different in terms of brightness, in order to study the dependence of the resonance strength on the space charge force.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS047

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paper received ※ 17 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPRB071

Beam-Based Measurements on Two ±12.5 kV Inductive Adders, together with Striplines, for CLIC Damping Ring Extraction Kickers

3970

J. Holma, M.J. Barnes, M. Carlà, N. Catalán Lasheras, Y. Papaphilippou
CERN, Meyrin, Switzerland
U. Iriso, Z. Martí, F. Pérez, M. Pont
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

The CLIC study is investigating the technical feasibil-ity of an electron-positron linear collider with high lumi-nosity and a nominal centre-of-mass energy of 3 TeV. Pre-damping rings and damping rings (DRs) will produce ultra-low emittance beam with high bunch charge. The DR kicker systems, each of which consists of a set of striplines and two inductive adders, must provide ex-tremely stable field pulses. The DR extraction kicker system is the most demanding: specifications require a field uniformity within ±0.01% and pulses up to 900 ns flattop duration, at ±12.5 kV and 309 A, with ripple and droop of not more than ±0.02 % (±2.5 V), with respect to a reference waveform. Two prototype inductive adders have been designed and built at CERN, and have been tested with prototype striplines installed in the storage ring of the ALBA Synchrotron Light Source, in Spain. The stability of the kicker system, including the modulators, has been evaluated from the beam-based measure-ments and is reported in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB071

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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