IPAC2017 - List of Authors (Papaphilippou, Y.)

Paper	Title	Page
MOPAB110	Comparison of Transverse Emittance Measurements in the LHC	377
	M. Hostettler, R. Alemany-Fernández, F. Alessio, M. Ferro-Luzzi, K. Fuchsberger, G. Iadarola, R. Matev, S. Papadopoulou, Y. Papaphilippou, G. Papotti, G. Trad CERN, Geneva, Switzerland F. Antoniou The University of Liverpool, Liverpool, United Kingdom G.R. Coombs University of Glasgow, Glasgow, United Kingdom T.B. Hadavizadeh Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Transverse emittance measurement in a collider is of crucial importance for understanding beam dynamics observations and evaluating the machine performance. Devices measuring the beam emittance face the challenge of dealing with considerable systematic errors that can compromise the quality of the measurement. Having different instruments or techniques that provide beam size estimations in order to compare the outcome and give an unbiased value of the emittance is very important in a collider. The comparison of the different results is as well very useful to identify possible problems in a given equipment which could remain unnoticed if such device is the only source of emittance reconstruction. In the LHC several of these instruments and techniques are available; wire scanners, synchrotron light monitors, emittance reconstruction from transverse convolved beam sizes extracted from luminosity scans at the LHC collision points and from beam-gas imaging in the vertex detector of the LHCb experiment. Those systems are briefly presented in this paper together with the comparison of the emittances reconstructed by each of them during physics production over the 2016 LHC run.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB110
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MOPVA029	Conceptual Design of a Pre-Booster Ring for the FCC e⁺e⁻ Injector	917
	O. Etisken, A.K. Çiftçi Ankara University, Faculty of Sciences, Ankara, Turkey Y. Papaphilippou CERN, Geneva, Switzerland
	The FCC-ee injector complex needs to produce and to transport a high-intensity e⁺/e⁻ beam at a fast repetition rate of about 0.1 Hz for topping up the collider at its collision energy. A basic parameter set exists for all the collider energies, assuming a 10 GeV linac operating with a large number of bunches being accumulated in the existing SPS, which serves as pre-accelerator and damping ring before the bunches are transferred to the high-energy booster. The purpose of this study is to provide the conceptual design of an alternative accelerator ring, replacing the SPS in the present scheme. This ring will have injection energy of around 5 GeV and extraction energy of around 20 GeV. Apart from establishing the basic parameters of the ring, the study work will include the optics design and layout, single particle linear and non-linear dynamics optimization, including magnetic and alignment error tolerances. The study will also contain some basic estimation of collective effects and address the issue of synchrotron radiation handling.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA029
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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.
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TUPVA005	Impact of the Crossing Angle on Luminosity Asymmetries at the LHC in 2016 Proton Physics Operation	2035
SUSPSIK001	use link to see paper's listing under its alternate paper code
	M. Hostettler LHEP, Bern, Switzerland F. Antoniou, I. Efthymiopoulos, K. Fuchsberger, G. Iadarola, N. Karastathis, M. Lamont, Y. Papaphilippou, G. Papotti, J. Wenninger CERN, Geneva, Switzerland
	During 2016 proton physics operation at the CERN Large Hadron Collider (LHC), an asymmetry of up to 10% was observed between the luminosities measured by the ATLAS and CMS experiments. As the same bunch pairs collide in both experiments, a difference in luminosities must be of either geometric or instrumental origin. This paper quantifies the impact of the crossing angle on this asymmetry. As the beams cross in different planes in the two experiments, non-round beams are expected to yield an asymmetry due to the crossing angle. Results from crossing angle measurements at both experiments are also shown and the impact on the luminosities is evaluated.
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TUPVA009	Multiparametric Response of the LHC Dynamic Aperture in Presence of Beam-Beam Effects	2051
	D. Pellegrini, F. Antoniou, S.D. Fartoukh, G. Iadarola, Y. Papaphilippou CERN, Geneva, Switzerland
	We performed extended simulations of LHC dynamic aperture (DA) in the presence of beam-beam effects in the weak-strong approximation, evaluating the contributions of parameters such as: tunes, optics, bunch intensity, crossing angle, emittance, chromaticity and current in the Landau octupoles. Here we present a summary of these studies, giving an overview of the amplitude of the LHC operational space and pointing out the remaining margins for mitigation of instabilities. These studies supported the actions deployed during the 2016 run of the LHC, which aimed at maximising its performances. Examples of such actions are the switch to lower emittance beams, the reduction of crossing angle and tune trims. More recently, DA scans have been used to help the definition of the operational scenarios for the 2017 run. Additional room for improvements, for instance by deploying crossing angle levelling, will be explained.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA009
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TUPVA010	Multiparametric Response of the HL-LHC Dynamic Aperture in Presence of Beam-Beam Effects	2055
	D. Pellegrini, S.D. Fartoukh, N. Karastathis, Y. Papaphilippou CERN, Geneva, Switzerland
	We performed extended simulations of HL-LHC dynamic aperture in the presence of beam-beam effects in the weak- strong approximation, evaluating the contributions of param- eters such as: bunch intensity, crossing angle, chromaticity, current in the Landau octupoles and multipole errors. From the beam dynamics point of view, the main differ- ence between the LHC (until 2017) and the HL-LHC is the deployment of the achromatic telescopic squeezing (ATS) optics, allowing not only for a smaller '' reach, but also modifying the phase advances between the lattice correctors (sextupoles, octupoles) and the main IPs, and increasing the peak ' functions in the arcs. These correctors become therefore more efficient for the chromatic correction, but also a mitigation of the beam-beam long range interactions using the Landau octupoles is enabled, resulting in a possible reduction of the normalised crossing angle. The limits have been investigated in a tracking simulation campaign aimed at exploring the operational space for the HL-LHC and two possible options for luminosity levelling.
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TUPVA034	SPS Studies in Preparation for the Crab Cavity Experiment	2133
	A. Alekou, A. Alekou, F. Antoniou, F. Antoniou, G. Arduini, G. Arduini, H. Bartosik, H. Bartosik, R. Calaga, R. Calaga, Y. Papaphilippou, Y. Papaphilippou, Y. Papaphilippou CERN, Geneva, Switzerland A. Alekou, R.B. Appleby, R.B. Appleby UMAN, Manchester, United Kingdom R.B. Appleby, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	A local Crab Cavity (CC) scheme will recover head-on collisions at the Interaction Points (IPs) of the High Luminosity LHC (HL-LHC), which aims to increase the LHC luminosity by a factor of 3-10. The first time that CC will ever be tested with proton beams will be in 2018 in the SPS machine. The available dedicated Machine Development (MD) time after the installation of the cavities will be limited and therefore good preparation is essential in order to ensure that the MDs are as efficient as possible. This paper presents the simulations and experimental studies performed in preparation for the future MDs and discusses the next steps.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA034
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TUPVA044	Modelling and Measurements of Bunch Profiles at the LHC	2167
	S. Papadopoulou, F. Antoniou, T. Argyropoulos, M. Hostettler, Y. Papaphilippou CERN, Geneva, Switzerland M. Fitterer Fermilab, Batavia, Illinois, USA
	The bunch profiles in the LHC are often observed to be non-Gaussian, both at Flat Bottom (FB) and Flat Top (FT) energies. Especially at FT, an evolution of the tail population in time is observed. In this respect, the Monte-Carlo Software for IBS and Radiation effects (SIRE) is used to track different types of beam distributions. The impact of the distribution shape on the evolution of bunch characteristics is studied. The results are compared with observations from the LHC Run 2 data.
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TUPVA115	Progress with Long-Range Beam-Beam Compensation Studies for High Luminosity LHC	2358
	A. Rossi, O. Aberle, J. Albertone, A. Bertarelli, C.B. Boccard, F. Carra, G. Cattenoz, Y. Delaup, S.D. Fartoukh, G. Gobbi, J. Lendaro, Y. Papaphilippou, D. Perini, S. Redaelli, H. Schmickler, C. Zanoni CERN, Geneva, Switzerland A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov BINP SB RAS, Novosibirsk, Russia M. Fitterer, A.S. Patapenka, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA
	Long-range beam-beam (LRBB) interactions can be a source of emittance growth and beam losses in the LHC during physics and will become even more relevant with the smaller '* and higher bunch intensities foreseen for the High Luminosity LHC upgrade (HL-LHC), in particular if operated without crab cavities. Both beam losses and emittance growth could be mitigated by compensat-ing the non-linear LRBB kick with a correctly placed current carrying wire. Such a compensation scheme is currently being studied in the LHC through a demonstration test using current-bearing wires embedded into col-limator jaws, installed either side of the high luminosity interaction regions. For HL-LHC two options are considered, a current-bearing wire as for the demonstrator, or electron lenses, as the ideal distance between the particle beam and compensating current may be too small to allow the use of solid materials. This paper reports on the ongoing activities for both options, covering the progress of the wire-in-jaw collimators, the foreseen LRBB experiments at the LHC, and first considerations for the design of the electron lenses to ultimately replace material wires for HL-LHC.
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WEOAB2	Correction of Beta-Beating Due to Beam-Beam for the LHC and Its Impact on Dynamic Aperture	2512
	L.E. Medina Medrano, J. Barranco García, X. Buffat, Y. Papaphilippou, T. Pieloni, R. Tomás CERN, Geneva, Switzerland J. Barranco García, T. Pieloni EPFL, Lausanne, Switzerland L.E. Medina Medrano UGTO, Leon, Mexico
	Funding: This work is supported by the European Circular Energy-Frontier Collider Study, H2020 programme under grant agreement no. 654305, by the Swiss State Secretariat for Education, Research and Innovation SERI, and by the Beam project (CONACYT, Mexico). Minimization of the beta-beating at the two main interaction points of the LHC arising from the head-on and long-range beam-beam interactions can be performed by adjusting the strength of quadrupole or sextupole correctors. This compensation scheme is applied to the current LHC optics where the results show a significant reduction of the peak and RMS beta-beating; and the impact on the dynamic aperture is computed. A proposal for a similar strategy to be adopted in the High Luminosity LHC is also discussed.
	Slides WEOAB2 [6.292 MB]
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WEPIK031	Challenges and Status of the Rapid Cycling Top-Up Booster for FCC-ee	2996
	B. Härer, S. Aumon, B.J. Holzer, Y. Papaphilippou, T. Tydecks CERN, Geneva, Switzerland K. Oide KEK, Ibaraki, Japan
	FCC-ee is a 100 km e⁺ e⁻ collider, which is being designed within the Future Circular Collider Study (FCC) for precision studies and rare decay observations in the range of 90 to 350 GeV center-of- mass energy. The beam lifetime will be limited to less than one hour, because of radiative Bhaba scattering and beamstrahlung. In order to keep the luminosity on the high level of 10³⁵ cm^-2s^-1 continuous top-up injection is required. Therefore, besides the collider, that will operate at constant energy, a fast cycling booster synchrotron will be installed in the tunnel. The injection energy to the booster synchrotron will be around 6-20 GeV. Such a small energy together with the large bending radius not only creates an ultra-small beam emittance, but also requires very low magnetic fields close to the limit of technical feasibility. This paper will focus on the challenges and requirements for the top-up booster design arising from low magnetic fields and collective instabilities and present the status of the lattice design.
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WEPIK068	Non-Linear Beam Dynamics Studies of the CLIC Damping Wiggler Prototype	3087
	J. Gethmann, A. Bernhard, E. Blomley, E. Huttel, A.-S. Müller, A.I. Papash, M. Schedler KIT, Karlsruhe, Germany Y. Papaphilippou, P. Zisopoulos CERN, Geneva, Switzerland K. Zolotarev BINP SB RAS, Novosibirsk, Russia
	Funding: Julian Gethmann acknowledges the support by the DFG-funded Doctoral School Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology First beam dynamics studies of a damping wiggler prototype for the CLIC damping rings have been carried out at the KIT storage ring. Effects of the 2.9 T superconducting wiggler on the electron beam in the 2.5 GeV standard operation mode have been measured and compared with theoretical predictions. Higher order multipole components were investigated using local orbit bump measurements. Based on these findings the simulation models for the storage ring optic have been adjusted. The refined optics model has been applied to the 1.3 GeV, low-operation case. This case will be used to experimentally benchmark beam dynamics simulations involving strong wiggler fields and dominant collective effects. We present these measurements, comparisons and the findings of the simulations with the updated low-mode optics model.
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THPAB044	Development of Computational Tools for Noise Studies in the LHC	3807
SUSPSIK067	use link to see paper's listing under its alternate paper code
	S. Kostoglou, N. Karastathis, Y. Papaphilippou, D. Pellegrini, P. Zisopoulos CERN, Geneva, Switzerland P. Zisopoulos Uppsala University, Uppsala, Sweden
	Noise can have a significant impact on the beam dynamics in the LHC, enhancing diffusion processes and leading to emittance blowup. In order to study the details of such effects with computer simulations, a new set of tools is being developed. In particular, a demonstrator GPU-based particle tracker has been built profiting from the technology provided by the NVRTC Cuda library. Its performances for short term beam dynamic simulations in presence of many macro particles are highly promising. In addition, the Numerical Analysis of Fundamental Frequencies (NAFF) algorithm has been thoroughly inspected. Several alternatives to its fundamental steps have been investigated in a modern C++ implementation. The method was also used to produce Frequency Maps and benchmark these tools with other simulations.
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Paper

Title

Page

Comparison of Transverse Emittance Measurements in the LHC

377

M. Hostettler, R. Alemany-Fernández, F. Alessio, M. Ferro-Luzzi, K. Fuchsberger, G. Iadarola, R. Matev, S. Papadopoulou, Y. Papaphilippou, G. Papotti, G. Trad
CERN, Geneva, Switzerland
F. Antoniou
The University of Liverpool, Liverpool, United Kingdom
G.R. Coombs
University of Glasgow, Glasgow, United Kingdom
T.B. Hadavizadeh
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Transverse emittance measurement in a collider is of crucial importance for understanding beam dynamics observations and evaluating the machine performance. Devices measuring the beam emittance face the challenge of dealing with considerable systematic errors that can compromise the quality of the measurement. Having different instruments or techniques that provide beam size estimations in order to compare the outcome and give an unbiased value of the emittance is very important in a collider. The comparison of the different results is as well very useful to identify possible problems in a given equipment which could remain unnoticed if such device is the only source of emittance reconstruction. In the LHC several of these instruments and techniques are available; wire scanners, synchrotron light monitors, emittance reconstruction from transverse convolved beam sizes extracted from luminosity scans at the LHC collision points and from beam-gas imaging in the vertex detector of the LHCb experiment. Those systems are briefly presented in this paper together with the comparison of the emittances reconstructed by each of them during physics production over the 2016 LHC run.

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MOPVA029

Conceptual Design of a Pre-Booster Ring for the FCC e⁺e⁻ Injector

917

O. Etisken, A.K. Çiftçi
Ankara University, Faculty of Sciences, Ankara, Turkey
Y. Papaphilippou
CERN, Geneva, Switzerland

The FCC-ee injector complex needs to produce and to transport a high-intensity e⁺/e⁻ beam at a fast repetition rate of about 0.1 Hz for topping up the collider at its collision energy. A basic parameter set exists for all the collider energies, assuming a 10 GeV linac operating with a large number of bunches being accumulated in the existing SPS, which serves as pre-accelerator and damping ring before the bunches are transferred to the high-energy booster. The purpose of this study is to provide the conceptual design of an alternative accelerator ring, replacing the SPS in the present scheme. This ring will have injection energy of around 5 GeV and extraction energy of around 20 GeV. Apart from establishing the basic parameters of the ring, the study work will include the optics design and layout, single particle linear and non-linear dynamics optimization, including magnetic and alignment error tolerances. The study will also contain some basic estimation of collective effects and address the issue of synchrotron radiation handling.

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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.

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TUPVA005

Impact of the Crossing Angle on Luminosity Asymmetries at the LHC in 2016 Proton Physics Operation

2035

SUSPSIK001

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M. Hostettler
LHEP, Bern, Switzerland
F. Antoniou, I. Efthymiopoulos, K. Fuchsberger, G. Iadarola, N. Karastathis, M. Lamont, Y. Papaphilippou, G. Papotti, J. Wenninger
CERN, Geneva, Switzerland

During 2016 proton physics operation at the CERN Large Hadron Collider (LHC), an asymmetry of up to 10% was observed between the luminosities measured by the ATLAS and CMS experiments. As the same bunch pairs collide in both experiments, a difference in luminosities must be of either geometric or instrumental origin. This paper quantifies the impact of the crossing angle on this asymmetry. As the beams cross in different planes in the two experiments, non-round beams are expected to yield an asymmetry due to the crossing angle. Results from crossing angle measurements at both experiments are also shown and the impact on the luminosities is evaluated.

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TUPVA009

Multiparametric Response of the LHC Dynamic Aperture in Presence of Beam-Beam Effects

2051

D. Pellegrini, F. Antoniou, S.D. Fartoukh, G. Iadarola, Y. Papaphilippou
CERN, Geneva, Switzerland

We performed extended simulations of LHC dynamic aperture (DA) in the presence of beam-beam effects in the weak-strong approximation, evaluating the contributions of parameters such as: tunes, optics, bunch intensity, crossing angle, emittance, chromaticity and current in the Landau octupoles. Here we present a summary of these studies, giving an overview of the amplitude of the LHC operational space and pointing out the remaining margins for mitigation of instabilities. These studies supported the actions deployed during the 2016 run of the LHC, which aimed at maximising its performances. Examples of such actions are the switch to lower emittance beams, the reduction of crossing angle and tune trims. More recently, DA scans have been used to help the definition of the operational scenarios for the 2017 run. Additional room for improvements, for instance by deploying crossing angle levelling, will be explained.

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TUPVA010

Multiparametric Response of the HL-LHC Dynamic Aperture in Presence of Beam-Beam Effects

2055

D. Pellegrini, S.D. Fartoukh, N. Karastathis, Y. Papaphilippou
CERN, Geneva, Switzerland

We performed extended simulations of HL-LHC dynamic aperture in the presence of beam-beam effects in the weak- strong approximation, evaluating the contributions of param- eters such as: bunch intensity, crossing angle, chromaticity, current in the Landau octupoles and multipole errors. From the beam dynamics point of view, the main differ- ence between the LHC (until 2017) and the HL-LHC is the deployment of the achromatic telescopic squeezing (ATS) optics, allowing not only for a smaller '' reach, but also modifying the phase advances between the lattice correctors (sextupoles, octupoles) and the main IPs, and increasing the peak ' functions in the arcs. These correctors become therefore more efficient for the chromatic correction, but also a mitigation of the beam-beam long range interactions using the Landau octupoles is enabled, resulting in a possible reduction of the normalised crossing angle. The limits have been investigated in a tracking simulation campaign aimed at exploring the operational space for the HL-LHC and two possible options for luminosity levelling.

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TUPVA034

SPS Studies in Preparation for the Crab Cavity Experiment

2133

A. Alekou, A. Alekou, F. Antoniou, F. Antoniou, G. Arduini, G. Arduini, H. Bartosik, H. Bartosik, R. Calaga, R. Calaga, Y. Papaphilippou, Y. Papaphilippou, Y. Papaphilippou
CERN, Geneva, Switzerland
A. Alekou, R.B. Appleby, R.B. Appleby
UMAN, Manchester, United Kingdom
R.B. Appleby, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

A local Crab Cavity (CC) scheme will recover head-on collisions at the Interaction Points (IPs) of the High Luminosity LHC (HL-LHC), which aims to increase the LHC luminosity by a factor of 3-10. The first time that CC will ever be tested with proton beams will be in 2018 in the SPS machine. The available dedicated Machine Development (MD) time after the installation of the cavities will be limited and therefore good preparation is essential in order to ensure that the MDs are as efficient as possible. This paper presents the simulations and experimental studies performed in preparation for the future MDs and discusses the next steps.

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TUPVA044

Modelling and Measurements of Bunch Profiles at the LHC

2167

S. Papadopoulou, F. Antoniou, T. Argyropoulos, M. Hostettler, Y. Papaphilippou
CERN, Geneva, Switzerland
M. Fitterer
Fermilab, Batavia, Illinois, USA

The bunch profiles in the LHC are often observed to be non-Gaussian, both at Flat Bottom (FB) and Flat Top (FT) energies. Especially at FT, an evolution of the tail population in time is observed. In this respect, the Monte-Carlo Software for IBS and Radiation effects (SIRE) is used to track different types of beam distributions. The impact of the distribution shape on the evolution of bunch characteristics is studied. The results are compared with observations from the LHC Run 2 data.

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TUPVA115

Progress with Long-Range Beam-Beam Compensation Studies for High Luminosity LHC

2358

A. Rossi, O. Aberle, J. Albertone, A. Bertarelli, C.B. Boccard, F. Carra, G. Cattenoz, Y. Delaup, S.D. Fartoukh, G. Gobbi, J. Lendaro, Y. Papaphilippou, D. Perini, S. Redaelli, H. Schmickler, C. Zanoni
CERN, Geneva, Switzerland
A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
BINP SB RAS, Novosibirsk, Russia
M. Fitterer, A.S. Patapenka, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA

Long-range beam-beam (LRBB) interactions can be a source of emittance growth and beam losses in the LHC during physics and will become even more relevant with the smaller '* and higher bunch intensities foreseen for the High Luminosity LHC upgrade (HL-LHC), in particular if operated without crab cavities. Both beam losses and emittance growth could be mitigated by compensat-ing the non-linear LRBB kick with a correctly placed current carrying wire. Such a compensation scheme is currently being studied in the LHC through a demonstration test using current-bearing wires embedded into col-limator jaws, installed either side of the high luminosity interaction regions. For HL-LHC two options are considered, a current-bearing wire as for the demonstrator, or electron lenses, as the ideal distance between the particle beam and compensating current may be too small to allow the use of solid materials. This paper reports on the ongoing activities for both options, covering the progress of the wire-in-jaw collimators, the foreseen LRBB experiments at the LHC, and first considerations for the design of the electron lenses to ultimately replace material wires for HL-LHC.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA115

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WEOAB2

Correction of Beta-Beating Due to Beam-Beam for the LHC and Its Impact on Dynamic Aperture

2512

L.E. Medina Medrano, J. Barranco García, X. Buffat, Y. Papaphilippou, T. Pieloni, R. Tomás
CERN, Geneva, Switzerland
J. Barranco García, T. Pieloni
EPFL, Lausanne, Switzerland
L.E. Medina Medrano
UGTO, Leon, Mexico

Funding: This work is supported by the European Circular Energy-Frontier Collider Study, H2020 programme under grant agreement no. 654305, by the Swiss State Secretariat for Education, Research and Innovation SERI, and by the Beam project (CONACYT, Mexico).
Minimization of the beta-beating at the two main interaction points of the LHC arising from the head-on and long-range beam-beam interactions can be performed by adjusting the strength of quadrupole or sextupole correctors. This compensation scheme is applied to the current LHC optics where the results show a significant reduction of the peak and RMS beta-beating; and the impact on the dynamic aperture is computed. A proposal for a similar strategy to be adopted in the High Luminosity LHC is also discussed.

Slides WEOAB2 [6.292 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOAB2

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WEPIK031

Challenges and Status of the Rapid Cycling Top-Up Booster for FCC-ee

2996

B. Härer, S. Aumon, B.J. Holzer, Y. Papaphilippou, T. Tydecks
CERN, Geneva, Switzerland
K. Oide
KEK, Ibaraki, Japan

FCC-ee is a 100 km e⁺ e⁻ collider, which is being designed within the Future Circular Collider Study (FCC) for precision studies and rare decay observations in the range of 90 to 350 GeV center-of- mass energy. The beam lifetime will be limited to less than one hour, because of radiative Bhaba scattering and beamstrahlung. In order to keep the luminosity on the high level of 10³⁵ cm^-2s^-1 continuous top-up injection is required. Therefore, besides the collider, that will operate at constant energy, a fast cycling booster synchrotron will be installed in the tunnel. The injection energy to the booster synchrotron will be around 6-20 GeV. Such a small energy together with the large bending radius not only creates an ultra-small beam emittance, but also requires very low magnetic fields close to the limit of technical feasibility. This paper will focus on the challenges and requirements for the top-up booster design arising from low magnetic fields and collective instabilities and present the status of the lattice design.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK031

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WEPIK068

Non-Linear Beam Dynamics Studies of the CLIC Damping Wiggler Prototype

3087

J. Gethmann, A. Bernhard, E. Blomley, E. Huttel, A.-S. Müller, A.I. Papash, M. Schedler
KIT, Karlsruhe, Germany
Y. Papaphilippou, P. Zisopoulos
CERN, Geneva, Switzerland
K. Zolotarev
BINP SB RAS, Novosibirsk, Russia

Funding: Julian Gethmann acknowledges the support by the DFG-funded Doctoral School Karlsruhe School of Elementary and Astroparticle Physics: Science and Technology
First beam dynamics studies of a damping wiggler prototype for the CLIC damping rings have been carried out at the KIT storage ring. Effects of the 2.9 T superconducting wiggler on the electron beam in the 2.5 GeV standard operation mode have been measured and compared with theoretical predictions. Higher order multipole components were investigated using local orbit bump measurements. Based on these findings the simulation models for the storage ring optic have been adjusted. The refined optics model has been applied to the 1.3 GeV, low-operation case. This case will be used to experimentally benchmark beam dynamics simulations involving strong wiggler fields and dominant collective effects. We present these measurements, comparisons and the findings of the simulations with the updated low-mode optics model.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK068

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THPAB044

Development of Computational Tools for Noise Studies in the LHC

3807

SUSPSIK067

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S. Kostoglou, N. Karastathis, Y. Papaphilippou, D. Pellegrini, P. Zisopoulos
CERN, Geneva, Switzerland
P. Zisopoulos
Uppsala University, Uppsala, Sweden

Noise can have a significant impact on the beam dynamics in the LHC, enhancing diffusion processes and leading to emittance blowup. In order to study the details of such effects with computer simulations, a new set of tools is being developed. In particular, a demonstrator GPU-based particle tracker has been built profiting from the technology provided by the NVRTC Cuda library. Its performances for short term beam dynamic simulations in presence of many macro particles are highly promising. In addition, the Numerical Analysis of Fundamental Frequencies (NAFF) algorithm has been thoroughly inspected. Several alternatives to its fundamental steps have been investigated in a modern C++ implementation. The method was also used to produce Frequency Maps and benchmark these tools with other simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB044

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