Keyword: luminosity
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MOYPLM3 Progress with the High Luminosity LHC Project at CERN cavity, operation, quadrupole, collider 17

• L. Rossi, O.S. Brüning
CERN, Geneva, Switzerland

The High Luminosity LHC (HL-LHC) project aims at upgrading the LHC by increasing the peak luminosity by a factor five, to allow to collect 3000 fb-1 for ATLAS and CMS experiments, each, which is ten times more than what is foreseen in the LHC. The upgrade is based on multiple factors. One factor is doubling the beam current, also thanks to the injector upgrade (LIU) project, and another one is operation in levelling mode. The most critical upgrade is the deploying of a stronger inner quadrupole triplet in the low-beta insertions with more than twice-larger aperture w.r.t. present LHC triplet, thanks to the use of Nb3Sn superconductor, a world first for accelerators, with almost 12 T peak field in the coils. The novel concept of ATS optics allows to utilise the increased aperture efficiently by generating β* values 3 to 4 times below the nominal values of the LHC. We will make use of compact crab cavities for hadrons (also a novelty in accelerators) to allow almost head-on collisions despite the larger crossing angle. We are developing new collimator insertions in the dispersion suppressor region to handle the losses in the cold part of the machine (the beam halo stores 30 MJ) thanks to the use of a few 11 T dipoles based on Nb3Sn technology. We also aim at reducing drastically the impedance contribution of collimators by utilizing new materials and coating techniques. Many other technologies are developed for HL-LHC like new SC links of 100 kA: HL-LHC is critical as a technology turning point for HEP colliders as it is for Physics reach. The technologies developed for HL-LHC, namely (but not only) the high field superconducting magnets, are critical for the post-LHC hadron collider, like a High Energy LHC or the 100 km Future Circular Collider
Slides MOYPLM3 [21.679 MB]
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOYPLM3
About • paper received ※ 19 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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MOZZPLS1 eRHIC Design Overview electron, hadron, proton, storage-ring 45

• C. Montag, G. Bassi, J. Beebe-Wang, J.S. Berg, M. Blaskiewicz, A. Blednykh, J.M. Brennan, S.J. Brooks, K.A. Brown, K.A. Drees, A.V. Fedotov, W. Fischer, D.M. Gassner, W. Guo, A. Hershcovitch, C. Hetzel, D. Holmes, H. Huang, W.A. Jackson, J. Kewisch, Y. Li, C. Liu, H. Lovelace III, Y. Luo, F. Méot, M.G. Minty, R.B. Palmer, B. Parker, S. Peggs, V. Ptitsyn, V.H. Ranjbar, G. Robert-Demolaize, S. Seletskiy, V.V. Smaluk, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, S. Verdú-Andrés, W.-T. Weng, F.J. Willeke, H. Witte, Q. Wu, W. Xu, A. Zaltsman, W. Zhang
BNL, Upton, Long Island, New York, USA
• E. Gianfelice-Wendt
Fermilab, Batavia, Illinois, USA
• Y. Hao
FRIB, East Lansing, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The Electron-Ion Collider (EIC) is being envisioned as the next facility to be constructed by the DOE Nuclear Physics program. Brookhaven National Laboratory is proposing eRHIC, a facility based on the existing RHIC complex as a cost effective realization of the EIC project with a peak luminosity of 1034 cm-2 sec-1. An electron storage ring with an energy range from 5 to 18 GeV will be added in the existing RHIC tunnel. A spin-transparent rapid-cycling synchrotron (RCS) will serve as a full-energy polarized electron injector. Recent design improvements include reduction of the IR magnet strengths to avoid the necessity for Nb3Sn magnets, and a novel hadron injection scheme to maximize the integrated luminosity. We will provide an overview of this proposed project and present the current design status.

Slides MOZZPLS1 [5.428 MB]
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOZZPLS1
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPGW031 Analysis and Correction for the Effect of Multipoles with Skewed Errors on IP Beam Dynamics in SuperKEKB coupling, MMI, betatron, optics 159

• K. Hirosawa
Sokendai, Ibaraki, Japan
• Y. Funakoshi, H. Koiso, A. Morita, K. Ohmi, Y. Ohnishi, H. Sugimoto, D. Zhou
KEK, Ibaraki, Japan

The beam dynamics at the interaction point (IP) in the accelerators which has the nano-beam scheme like as SuperKEKB is extremely sensitive for skewed error of final focusing magnets (QCS). As proceeding the beta squeezing in the interaction region (IR), the effect of optics aberrations at IP is enhanced. In the SuperKEKB Phase-2 commissioning, there was the problem come from skewed quadrupole fields in IR. The dominant skew parameters ‘‘R" for this problem is very hard to see directly by using beam position monitors, thus it was corrected by scanning R parameters. In the next commissioning Phase-3 which is just before the operation with the Belle II experiment, it is planned that the IP beta squeezing is going forward to design parameters which is smaller than it achieved in Phase-2 by the factor of 4 (for horizontal beta) and 10 (for vertical beta). Hence the effect of skew error will be considerable larger and it is estimated that skew sextupoles will emerge as a serious cause for the aberration from the orbit. This report is the study of analysis and correction results for the effect of QCS skewed errors in the SuperKEKB commissioning.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW031
About • paper received ※ 19 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPGW068 Crosstalk of Beam-Beam Effect and Longitudinal Impedance at CEPC impedance, simulation, collider, factory 247

• Y. Zhang, N. Wang, C.H. Yu
IHEP, Beijing, People’s Republic of China
• C.T. Lin
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

Funding: Project 11775238 supported by NSFC
In conventional e+e storage ring colliders, we only use lengthend bunch length in beam-beam simulation instead of considering impedance directly. It is no problem since the longitudinal dynamics is not sensitive to beam-beam interaction. But it is different since the bunch will also be lengthend during beam-beam interaction by beamstrahlung effect. It is very natural and more self-consistent to consider the longitudinal impedance in the beam-beam simulation. The simulation shows that the working point region of stable collision is slightly shifted by the longitudinal impedance. It is found that the vertical coherent oscillation may decreases the beam-beam limit with impedance at some working point.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW068
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPGW069 Recent Beam Performance Achievements with the Pb-Ion Beam in the SPS for LHC Physics Runs injection, target, optics, flattop 250

• H. Bartosik, R. Alemany-Fernández, T. Argyropoulos, T. Bohl, H. Damerau, V. Kain, G. Papotti, G. Rumolo, A. Saá Hernández, E.N. Shaposhnikova
CERN, Meyrin, Switzerland

In the SPS, which is the last accelerator in the LHC ion injector chain, multiple injections of the Pb-ion beam have to be accumulated. On this injection plateau the beam suffers from considerable degradation such as emittance growth and losses. This paper summarises the achievements on improving the beam parameters and maximising the performance of the Pb-ion beam for the LHC physics run in 2018. The results are discussed in view of the target beam parameters of the LHC injectors upgrade project, which is being deployed during the presently ongoing long shutdown.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW069
About • paper received ※ 12 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019
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MOPGW071 Resistive Wall Effects in the CLIC Beam Delivery System wakefield, collider, vacuum, feedback 258

• D. Arominski, A. Latina, D. Schulte
CERN, Meyrin, Switzerland

Resistive wall wakefields are an important issue to study for future linear colliders. Wakefields in the Beam Delivery System (BDS) might cause severe multi-bunch effects, leading to beam quality and luminosity losses. The resistive wall effects depend on the beam pipe apertures and materials, which are optimised to limit the impact on the beam. This paper presents a study of this problem for the 380 GeV and 3 TeV beam parameters and optics of the Compact Linear Collider’s BDS. First, the optimisation of the beam pipe apertures to limit the impact of resistive wall effect on the beam quality is shown, then the luminosity and its quality are presented. Finally, the proposed design parameters are discussed.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW071
About • paper received ※ 16 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPGW085 Intensity Dependent Effects in the ILC BDS wakefield, collider, simulation, linear-collider 305

• P. Korysko, A. Latina
CERN, Geneva, Switzerland
• P. Burrows
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

The International Linear Collider (ILC) is an electron-positron collider being considered for the post-LHC era. Its Beam Delivery System (BDS) receives the beam from the main linac. This beam is then focused to the nanometer scale after going through collimators, beam diagnostic systems, strong magnets, etc. Effects such as wakefields due to resistive-wall, BPMs and collimators make the system very sensitive to the beam intensity. Understanding these effects is crucial in order to demonstrate that the nominal beam size at the Interaction Point (IP) can be reached in realistic scenarios. In this paper, results of the intensity dependence effects in the ILC BDS, simulated with PLACET, are presented.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW085
About • paper received ※ 23 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPGW094 First Machine Developments Result with HL-LHC Crab Cavities in the SPS cavity, proton, closed-orbit, diagnostics 338

• L.R. Carver, A. Alekou, F. Antoniou, H. Bartosik, T. Bohl, R. Calaga, M. Carlà, T.E. Levens, G. Papotti
CERN, Meyrin, Switzerland
• A. Alekou, R.B. Appleby, R.B. Appleby
UMAN, Manchester, United Kingdom
• G. Burt
Cockcroft Institute, Warrington, Cheshire, United Kingdom
• G. Burt, J.A. Mitchell
Lancaster University, Lancaster, United Kingdom
• C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Crab cavities are a critical component within the High Luminosity upgrade project for the Large Hadron Collider (HL-LHC). It is foreseen to use crab cavities in order to compensate the geometric luminosity reduction factor (reduction of the luminous region at the Interaction Point [IP]) due to the beam crossing angle (required for minimizing the impact of the long range beam-beam effects on the single particle beam dynamics) and increase the number of collisions per bunch crossing. In 2018 the first beam tests of crab cavities with protons were performed in the Super Proton Synchrotron (SPS) at CERN. Two vertical superconducting cavities of the Double Quarter Wave (DQW) type were fabricated and installed in the SPS to verify some key components of the cavity design and operation. This paper will present some of the first results relating to the proton beam dynamics in the presence of crab cavities.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW094
About • paper received ※ 25 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPGW095 Beam Dynamics Simulations with Crab Cavities in the SPS Machine multipole, cavity, simulation, optics 342

• A. Alekou, A. Alekou, H. Bartosik, H. Bartosik, M. Carlà, Y. Papaphilippou, Y. Papaphilippou, Y. Papaphilippou
CERN, Meyrin, 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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MOPMP016 Intra-Bunch Energy Spread Minimisation for CLIC Operation at a Centre-of-Mass Energy of 350 GeV linac, collider, emittance, linear-collider 458

• N. Blaskovic Kraljevic, D. Arominski, D. Schulte
CERN, Meyrin, Switzerland

The first stage of the electron-positron Compact Linear Collider (CLIC) is designed with a centre-of-mass energy of 380 GeV. A dedicated threshold scan in the vicinity of 350 GeV is envisioned with a total integrated luminosity of 100 fb-1. This scan calls for a very small intra-bunch energy spread in order to achieve an excellent collision energy resolution. This paper presents an optimised assignment of RF accelerating gradients and phases in the CLIC main linac for operation at 350 GeV, which minimises the energy spread at the end of the main linac whilst preserving a small emittance growth. Variation of the bunch length and charge is studied in order to further reduce the energy spread; the effect on both the peak and total luminosity is discussed.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP016
About • paper received ※ 13 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPMP019 High Luminosity LHC Optics and Layout HLLHCV1.4 optics, operation, experiment, cavity 468

• R. De Maria, R. Bruce, D. Gamba, M. Giovannozzi, F. Plassard
CERN, Geneva, Switzerland

The goal of the High Luminosity Project is the upgrade of the LHC to deliver an integrated luminosity of at least 250 \rm fb-1 per year in each of the two high-luminosity, general-purpose detectors ATLAS and CMS. This article presents the latest layout design and the corresponding optics features, which comprise optimisation of the orbit corrector and crab cavity systems, and new estimates of the performance reach thanks to the new concept of fully remote alignment. In addition, the new optics version incorporates improvements required by beam instrumentation, dump system, and collimation system, as well as low-beta solutions for the LHCb experiment.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP019
About • paper received ※ 17 April 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPMP022 K-Modulation in Future High Energy Colliders quadrupole, collider, optics, power-supply 476

• M. Hofer, F.S. Carlier, R. Tomás
CERN, Geneva, Switzerland

K-Modulation of the quadrupoles closest to the interaction point (IP) has been an indispensable tool to accurately measure the beta-function in the interaction point (β*) in the Large Hadron Collider (LHC) at CERN. K-Modulation may become even more important to control the lower β* and reach the design luminosities in the High-Luminosity LHC (HL-LHC) and the Future Circular Collider (FCC). K-Modulation results also provide important input for the luminosity calibration and help in the identification and correction of errors in the machines. This paper presents a method for determining β* using K-Modulation adapted to the characteristic layout of both colliders. Using the latest models for the HL-LHC and the FCC-hh, estimated uncertainties on the measurements are presented. The results are compared to the accuracy of an alternative modulation scheme using a different powering scheme.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP022
About • paper received ※ 06 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019
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MOPMP024 Prospects for Future Asymmetric Collisions in the LHC proton, experiment, operation, hadron 484

• M.A. Jebramcik, J.M. Jowett
CERN, Geneva, Switzerland

The proton-lead runs of the LHC in 2012, 2013 and 2016 provided luminosity far beyond expectations in a diversity of operating conditions and led to important new results in high-density QCD. This has permitted the scope of the future physics programme to be expanded in a recent review. Besides further high-luminosity p-Pb collisions, lighter nuclei are also under consideration. A short proton-oxygen run, on the model of the 2012 p-Pb run, would be of interest for cosmic-ray physics. Other collision systems like proton-argon or collisions of protons with other noble gases are also discussed. We provide an overview of the operational strategies and potential performance of various asymmetric collision options. Potential performance limits from moving beam-beam encounters at injection and various beam-loss mechanisms are evaluated in the light of our understanding of the LHC to date.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP024
About • paper received ※ 18 April 2019       paper accepted ※ 18 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 betatron, beam-losses, operation, collider 500

• 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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MOPMP031 Operation and Performance of the Cern Large Hadron Collider During Proton Run 2 operation, proton, emittance, injection 504

• R. Steerenberg, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, G.E. Crockford, J.-C. Dumont, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, D. Jacquet, M. Lamont, E. Métral, D. Nisbet, G. Papotti, M. Pojer, L. Ponce, S. Redaelli, B. Salvachua, M. Schaumann, M. Solfaroli, R. Suykerbuyk, G. Trad, J.A. Uythoven, S. Uznanski, D.J. Walsh, J. Wenninger, M. Zerlauth
CERN, Geneva, Switzerland

Run 2 of the CERN Large Hadron Collider (LHC) was successfully completed on 10th December 2018, achieving largely all goals set in terms of luminosity production. Following the first two-year long shutdown and the re-commissioning in 2015 at 6.5 TeV, the beam performance was increased to reach a peak luminosity of more than twice the design value and a colliding beam time ratio of 50%. This was accomplished thanks to the increased beam brightness from the injector chain, the high machine availability and the performance enhancements made in the LHC for which some methods and tools, foreseen for the High Luminosity LHC (HL-LHC) were tested and deployed operationally. This contribution provides an overview of the operational aspects, main limitations and achievements for the proton Run 2.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP031
About • paper received ※ 13 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019
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MOPMP033 LHC Run 2 Optics Commissioning Experience in View of HL-LHC optics, coupling, simulation, experiment 508

• R. Tomás, F.S. Carlier, J. Coello, J. Dilly, S.D. Fartoukh, E. Fol, D. Gamba, A. Garcia-Tabares, M. Giovannozzi, M. Hofer, E.H. Maclean, L. Malina, T. H. B. Persson, P.K. Skowroński, M. Solfaroli, M.L. Spitznagel, A. Wegscheider, J. Wenninger, D.W. Wolf
CERN, Geneva, Switzerland

LHC Run 2 has achieved a beta lower than a factor 2 below design. This has significantly challenged optics measurement and correction techniques in the linear and non-linear regimes, leading to the development of new approaches. Furthermore, experimenting with a large variety of optics has allowed facing the difficulties of future optics and gaining understanding of the machine imperfections. A summary of these aspects is given in view of their implications for the HL-LHC Project.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP033
About • paper received ※ 07 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPMP034 Tuning Studies of the CLIC 380 Gev Final Focus System sextupole, alignment, collider, linear-collider 512

• J. Ögren, A. Latina, D. Schulte, R. Tomás
CERN, Meyrin, Switzerland

We present tuning studies of the Compact Linear Collider final-focus system under static imperfections including transverse misalignments, roll errors and magnetic strength errors. The tuning procedure consists of beam-based alignment for correcting the linear part of the system followed by sextupole pre-alignment and use of multipole tuning knobs. The sextupole pre-alignment is very robust and allows the tuning time to be greatly reduced.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP034
About • paper received ※ 06 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPMP035 Effect of Emittance Constraints on Monochromatization at the Future  Circular e+e Collider emittance, collider, radiation, photon 516

• M.A. Valdivia García, F. Zimmermann
CERN, Meyrin, Switzerland

Direct s-channel Higgs production in e+e− collisions is of interest if the collision energy spread can be comparable to the natural width of the standard model Higgs boson. At the Future Circular e+e Collider (FCC-ee), a monochromatization scheme could be employed in order to reduce the collision energy spread to the target value. This may be achieved by introducing a non-zero horizontal dispersion of opposite sign for the two colliding beams at the interaction point. In this case, the beamstrahlung increases the horizontal emittance in addition to energy spread and bunch length.  The vertical emittance could either be tuned to a certain minimum value, possibly limited by the diagnostics resolution, or it could scale linearly with the horizontal emittance. For the FCC-ee at 62.5 GeV beam energy, we optimize the IP optics and beam parameters, considering these two different assumptions for the vertical emittance. We derive the maximum achievable luminosity as a function of collision energy spread for either case.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP035
About • paper received ※ 16 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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MOPMP039 Developments in the Experimental Interaction Regions of the High Energy LHC dipole, dynamic-aperture, beam-beam-effects, shielding 532

• L. van Riesen-Haupt, J.L. Abelleira
University of Oxford, Oxford, United Kingdom
• J.L. Abelleira, E. Cruz Alaniz
JAI, Oxford, United Kingdom
• J. Barranco García, T. Pieloni, C. Tambasco
EPFL, Lausanne, Switzerland
• M. Hofer, J. Keintzel, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland

Funding: Work supported by the Swiss institute for Accelerator Research and Technology , CHART.
The High Energy LHC (HE-LHC) aims to collide 13.5 TeV protons in two high luminosity experiments and two low luminosity experiments. In the following, the recent updates in the two high luminosity experimental interaction regions (EIR) of the HE-LHC will be illustrated. These EIR aim to focus the beams to a β* of 0.45 m at the interaction point (IP) to achieve a lifetime integrated luminosity of 10 ab-1. On top of the triplet optics designed to achieve this, it will present energy deposition driven separation dipole designs, optics solutions for the matching section and dispersion suppressors as well as studies involving the integration into the lattice options. In particular it will outline geometric considerations, spurious dispersion suppression as well as results from dynamic aperture studies.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP039
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPMP040 US Contributions to the High Luminosity LHC Upgrade - Focusing Quadrupoles and Crab Cavities cavity, quadrupole, HOM, SRF 536

• G. Apollinari, G. Ambrosio, R.H. Carcagno, SF. Feher, L. Ristori
Fermilab, Batavia, Illinois, USA

In the early 2000’s, the US High Energy Physics community contributing to the Large Hadron Collider (LHC) launched the LHC Accelerator R&D Program) (LARP), a long-vision focused R&D program, intended to bring the Nb3Sn and other technologies to a maturity level that would allow applications in HEP machines. Around 2015, the technologies developed by LARP were mature enough to allow the spin-off of a major upgrade project to the LHC complex, the High Luminosity LHC (HL-LHC). This paper will focus on the US contribution to HL-LHC, namely the large-aperture low-beta focusing Nb3Sn quadrupoles and the Radio Frequency Dipole (RFD) Crab Cavities, located in close proximity to the ATLAS and CMS experiments. This contribution, called the HL-LHC Accelerator Upgrade Project (HL-LHC AUP), focuses on production of these quadrupoles and cavities by sharing the work among a consortium of US Laboratories (FNAL, LBNL, BNL and SLAC) and Universities and in close connection with the CERN-led HL-LHC Collaboration. The collaboration achieved commonality of specifications and uniformity of performance. Final development of design, construction and first results from the prototypes are described to indi-cate the status of these critical components for HL-LHC.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP040
About • paper received ※ 30 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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MOPMP044 Improving the Luminosity for Beam Energy Scan II at RHIC cavity, operation, electron, space-charge 540

• C. Liu, M. Blaskiewicz, K.A. Drees, A.V. Fedotov, W. Fischer, C.J. Gardner, H. Huang, D. Kayran, Y. Luo, G.J. Marr, A. Marusic, K. Mernick, M.G. Minty, C. Montag, I. Pinayev, S. Polizzo, V.H. Ranjbar, D. Raparia, G. Robert-Demolaize, T. Roser, J. Sandberg, V. Schoefer, T.C. Shrey, S. Tepikian, P. Thieberger, A. Zaltsman, K. Zeno, I.Y. Zhang, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The QCD (Quantum Chromodynamics) phase diagram has many uncharted territories, particularly the nature of the transformation from Quark-Gluon plasma (QGP) to the state of Hadronic gas. The Beam Energy Scan I (BES-I) at the Relativistic Heavy Ion Collider (RHIC) was completed but measurements had large statistical errors. To improve the statistical error and expand the search for first-order phase transition and location of the critical point, Beam Energy Scan II will commence in 2019 with a goal of improving the luminosity by a factor of 3-4. The beam lifetime at low energies was and will be limited by some physical effects of which the most significant are intrabeam scattering, space charge, beam-beam, persistent current effects. This article will review these potential limiting factors and introduce the countermeasures which will be in place to improve BES-II luminosity.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP044
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPMP049 6 T Cable-in-conduit Dipole to Double the Ion Energy for JLEIC dipole, electron, collider, injection 556

• P.M. McIntyre, J. Breitschopf, J. Gerity
Texas A&M University, College Station, USA
• J. Breitschopf, D.C.V. Chavez, J.N. Kellams, A. Sattarov
ATC, College Station, Texas, USA

The proposed electron-ion collider JLEIC would make high-luminosity collisions of polarized ions and polarized electrons with electron energy up to 12 GeV and ion energy up to 40 GeV/u. Both the luminosity and the collision energy could be increased by doubling the dipole field in the ion ring from 3 T to 6 T, and the enhanced performance would access the full range of parameters for the physics objectives of the project. The Texas A&M group has developed the large-aperture 3 T dipoles for the baseline project, based upon a novel superconducting cable-in-conduit. (CIC). A closely similar 6 T design is being developed, utilizing a 2-layer CIC. Details of the magnet design and development of the 2-layer CIC will be presented.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP049
About • paper received ※ 19 May 2019       paper accepted ※ 23 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 experiment, simulation, optics, resonance 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 operation, collider, hadron, simulation 570

• K. Skoufaris, S.D. Fartoukh, N. Karastathis, Y. Papaphilippou, D. Pellegrini, A. Poyet, A. Rossi, G. Sterbini
CERN, Meyrin, 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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MOPRB031 Progress of Conceptual Study for the Accelerators of a 2-7GeV Super Tau Charm Facility at China collider, factory, electron, operation 643

• Q. Luo, W. Li, D.R. Xu
USTC/NSRL, Hefei, Anhui, People’s Republic of China
• W.W. Gao, J.Q. Lan
Fujian University of Technology, Fuzhou, People’s Republic of China

Funding: Supported by National Natural Science Foundation of China U1832169 and the Double Fist-Class University Project Foundation of USTC.
This paper shows the progress of the conceptual study for the accelerators of a super tau charm facility in China. Since the BEPCII will finish its historical mission in 5~10 years and its upgrade plan will only achieve a small luminosity enhancement of 3~5 times, a new next generation tau-charm collider will play an irreplaceable role in future high energy physics study. The luminosity of this successor is about 5×1034cm−2s−1 pilot and 1×1035cm−2s−1 nominal, with the electron beam longitudinally polarized at the IP. The general scheme of the accelerators and the beam pa-rameters are shown. Several key technologies such as beam polarization and beam emittance diagnostics are also discussed.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB031
About • paper received ※ 14 May 2019       paper accepted ※ 17 May 2019       issue date ※ 21 June 2019
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MOPRB032 Interaction Section Lattice Design for a STCF Project sextupole, betatron, interaction-region, quadrupole 646

• W.W. Gao, J.Q. Lan
Fujian University of Technology, Fuzhou, People’s Republic of China
• Q. Luo
USTC/NSRL, Hefei, Anhui, People’s Republic of China

The Super Tau-Charm Factory (STCF) planning in China is characterized with high luminosity, wide energy range and high longitudinal polarized electron beam. In order to achieve high luminosity, this project will adopt the recently proposed collision scheme based on Large Piwinski angle and Crab Waist. In this paper, a preliminary lattice design of interaction region meeting the above collision scheme is described.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB032
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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• J. Guo, R.A. Rimmer, H. Wang, S. Wang
JLab, Newport News, Virginia, USA
• J.D. Fox
Stanford University, Stanford, California, USA
• T. Mastoridis
CalPoly, San Luis Obispo, California, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177, with additional support from U.S. DOE Award Number DE-SC-0019287
The Jefferson Lab Electron-Ion Collider (JLEIC) is an asymmetric high luminosity ring-ring collider proposed as the next major R&D facility for the nuclear physics community. Both of JLEIC’s electron and ion collider rings have high beam current with gaps serving the pur-poses of beam abort, ion clearing, etc. Such a time-varying beam loading in the RF cavities would generate modulation in cavity RF phase/voltage, causing cyclic shift of collision point and potential luminosity loss. We studied a few approaches to mitigate the RF phase modu-lation and IP shift, such as correcting the RF phase/voltage modulation with traditional LLRF feed-back, one-turn feedback (OTFB), or RF feedforward (FF); optimizing the bunch fill pattern to limit the RF phase/voltage modulation to a small fraction of the bunch trains in the collider ring; or matching the RF phase modulation in the two rings. The preliminary re-sults are discussed in this paper.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB080
About • paper received ※ 23 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019
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MOPRB081 Electron Beam’s Closed Orbit in the Crab Crossing Scheme of Future Electron-Ion Colliders electron, closed-orbit, cavity, simulation 762

• Y. Hao, V. Ptitsyn
BNL, Upton, Long Island, New York, USA
• J. Qiang
LBNL, Berkeley, California, USA

In crab-crossing collision geometry the closed orbit of the electron beam will be altered by the beam-beam interaction and the tilted head and tail of the ion beam. We will present the linear model to determine the closed orbit and compare with the simulation. Also, the relation of the closed orbit and the synchro-betatron resonance will be presented.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB081
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPRB082 Scaling Properties of the Synchro-Beta Resonance in Crab Crossing Scheme of Future Electron Ion Collider resonance, electron, simulation, cavity 766

• Y. Hao, Y. Luo, V. Ptitsyn
BNL, Upton, Long Island, New York, USA
• J. Qiang
LBNL, Berkeley, California, USA

The synchro - beta resonance due to the beam-beam interaction was predicted by the strong-strong simulation in the future electron-ion collider designs. In this paper, we study the scaling properties of the degradation rate of this unwanted resonance. These studies motivated the possible countermeasures of the luminosity degradation associated with the resonance.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB082
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPRB091 Combined Strong-Strong and Weak-Strong Beam-Beam Simulations for Crabbed Collision in eRHIC electron, proton, simulation, cavity 788

• Y. Luo, G. Bassi, M. Blaskiewicz, W. Fischer, Y. Hao, C. Montag, V. Ptitsyn, V.V. Smaluk, F.J. Willeke
BNL, Upton, Long Island, New York, USA
• K. Ohmi
KEK, Ibaraki, Japan
• J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In the eRHIC, to compensate the geometric luminosity loss, local crab cavities on both sides of the interaction points are to adopted. The previous strong-strong beam-beam simulations showed that the luminosity degradation depends on the crab cavity frequency, proton synchrotron tune, proton bunch length and so on. In this article, we apply a combined strong-strong and weak-strong beam-beam simulation to investigate the incoherent and coherent beam motions with crabbed collison, and to calculate more realistic beam emittance growth rates and luminosity degradation rate.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB091
About • paper received ※ 14 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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MOPTS099 The Development Programme of Cathodes and Electron Guns for the Hollow Electron Lenses of the High Luminosity LHC Project cathode, electron, gun, proton 1102

• D. Perini, G. Gobbi
CERN, Geneva, Switzerland
• D.J. Crawford, J. Ruan, G. Stancari, L.R. Valerio
Fermilab, Batavia, Illinois, USA
• J. Feng, Z. Li, W. Shao, K. Zhang
BVERI, Beijing, People’s Republic of China
• W. Liu, J. Wang, Y. Wang, Y. Yang
Beijing University of Technology, Beijing, People’s Republic of China

Funding: Research supported by the HL-LHC project
The High Luminosity LHC project (HL-LHC) foresees the construction and installation of important new equipment to increase the performance of the LHC machine. The Hollow Electron Lens (HEL) is a promising system to control the beam halo. It improves the beam collimation system of the HL-LHC and mitigates possible equipment damage in case of failure scenarios from halo losses. The halo can store up to 30 MJ energy. The specifications for this new device are quite demanding. The source, an electron gun with an annular shaped cathode, has to deliver a current up to 5 A. This is five times higher than the current in the existing electron lenses in Fermi and Brookhaven national laboratories. This note describes the programme carried out to design and test high-perveance guns equipped with two types of high-performance scandate cathodes. The size of the final gun is now considerably smaller than the one of the first prototype, allowing a reduction of diameter and cost of the superconducting magnet system used to steer the electron beam. The tests carried out at FNAL, BVERI and BJUT demonstrated that the developed cathodes fulfil the specifications and can supply a 5 A fully Space Charge Limited (SCL) current.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPTS099
About • paper received ※ 17 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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TUPRB112 JLEIC: A High Luminosity Polarized Electron-Ion Collider at Jefferson Lab electron, collider, proton, emittance 1916

• Y. Zhang
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The recent National Academies of Science Review concluded the science questions that could be answered by an electron-ion collider are significant to advancing our understanding of the atomic nuclei that make up all visible matter in the universe. To meet this science need, a high luminosity polarized electron-ion collider (JLEIC) was envisioned at Jefferson Lab, based on the existing CEBAF recirculated SRF electron linac. Over the past 16 years, Jefferson Lab has been actively engaged in the design study and accelerator R&D for JLEIC, a comprehensive Pre-Conceptual Design Report has been completed recently. The JLEIC baseline design has also been continuously optimized including extending the CM energy to 100 GeV. In this paper, we present a summary of the JLEIC baseline design and also briefly discuss the accelerator R&D.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB112
About • paper received ※ 07 June 2019       paper accepted ※ 07 June 2019       issue date ※ 21 June 2019
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WEYPLM1 Status of Circular Electron-Positron Collider and Super Proton-Proton Collider collider, injection, booster, cavity 2244

• C.H. Yu, S. Bai, X. Cui, J. Gao, H. Geng, D.J. Gong, D. Ji, Y.D. Liu, C. Meng, Q. Qin, J.Y. Tang, D. Wang, N. Wang, Y. Wang, Y. Wei, J.Y. Zhai, Y. Zhang, H.J. Zheng, Y.S. Zhu
IHEP, Beijing, People’s Republic of China

Circular electron-positron collider (CEPC) is a dedi-cated project proposed by China to research the Higgs boson. The collider ring provides e+ e collision at two interaction points (IP). The luminosity for the Higgs mode at the beam energy of 120GeV is 3*1034 cm-2s-1 at each IP while the synchrotron radiation (SR) power per beam is 30MW. Furthermore, CEPC is compatible with W and Z experiments, for which the beam energies are 80 GeV and 45.5 GeV respectively. The luminosity at the Z mode is higher than 1.7*1035 cm-2s-1 per IP. Top-up operation is available during the data taking of high energy physics. Super Proton-Proton Collider (SPPC) is envisioned to be an extremely powerful machine, with centre mass energy of 75 TeV, a nominal luminosity of 1.0*1035 cm-2s-1 per IP, and an integrated luminosity of 30 ab-1 assuming 2 interaction points and ten years of running. The status of CEPC and SPPC will be introduced in detail in this paper.
Slides WEYPLM1 [11.814 MB]
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYPLM1
About • paper received ※ 14 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEYYPLM1 Status of Early SuperKEKB Phase-3 Commissioning MMI, optics, detector, operation 2255

• A. Morita
KEK, Ibaraki, Japan

SuperKEKB is an asymmetric energy electron-positron collider for B-meson physics experiment. The beam collision with 3mm vertical beta function at the interaction point is confirmed during prior beam commissioning until July 2018. The next beam commissioning with the inner silicon vertex detectors so called "phase-3 commissioning" will start in March 2019. In the early part of next phase-3 commissioning, we plan to try the collision operation with over 1A stored beam current in order to exceed 1 x 1034 cm-2 s-1 luminosity. We will report the preliminary results of the early stage of the SuperKEKB phase-3 commissioning.
Slides WEYYPLM1 [2.570 MB]
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM1
About • paper received ※ 15 May 2019       paper accepted ※ 20 May 2019       issue date ※ 21 June 2019
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WEYYPLM2 The 2018 Heavy-Ion Run of the LHC heavy-ion, optics, experiment, proton 2258

• J.M. Jowett, C. Bahamonde Castro, W. Bartmann, C. Bracco, R. Bruce, J. Coello, J. Dilly, S.D. Fartoukh, E. Fol, N. Fuster-Martínez, A. Garcia-Tabares, M. Hofer, E.B. Holzer, M.A. Jebramcik, J. Keintzel, A. Lechner, E.H. Maclean, L. Malina, T. Medvedeva, A. Mereghetti, T. H. B. Persson, B.Aa. Petersen, S. Redaelli, B. Salvachua, M. Schaumann, C. Schwick, M. Solfaroli, M.L. Spitznagel, H. Timko, R. Tomás, A. Wegscheider, J. Wenninger, D. Wollmann
CERN, Geneva, Switzerland
• D. Mirarchi
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom

The fourth one-month Pb-Pb collision run brought LHC Run 2 to an end in December 2018. Following the tendency to reduce dependence on the configuration of the preceding proton run, a completely new optics cycle with the strongest ever focussing at the ALICE and LHCb experiments was designed and rapidly implemented, demonstrating the maturity of the collider’s operating modes. Beam-loss monitor thresholds were carefully adjusted to provide optimal protection from the multiple loss mechanisms in heavy-ion operation. A switch from a basic bunch-spacing of 100 ns to 75 ns was made as the beam became available from the injector chain. A new record luminosity, 6 times the original design and close to the operating value proposed for HL-LHC, provided validation of the strategy for mitigating quenches due to bound-free pair production (BFPP) at the interaction points of the ATLAS and CMS experiments. Most of the beam parameters of the HL-LHC Pb-Pb upgrade were attained during this run and the integrated luminosity goals for the first 10 years of LHC operation were substantially exceeded.
Slides WEYYPLM2 [10.884 MB]
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEYYPLM2
About • paper received ※ 08 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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WEPGW067 The Study of Beam-Beam Effects on BINP Electron-Positron Colliders electron, injection, positron, detector 2629

• V.M. Borin, G.V. Karpov, O.I. Meshkov, D.N. Shatilov, D.B. Shwartz, M.V. Timoshenko
BINP SB RAS, Novosibirsk, Russia
• V.L. Dorokhov
BINP, Novosibirsk, Russia

The beam-beam effects depending on the beams current and energy were studied at electron-positron colliders VEPP-2000 and VEPP-4M by the set of different diagnostics: the streak camera, optical dissector, BPM. The beam transverse profiles as well as longitudinal motion were acquired from the moment of a first collision of the beams in the interaction point up to the establishment of an equilibrium state. The spectra of the beams oscillation during this process as well as influence of the transverse feedback were studied. The obtained results are compared with a numerical simulations and discussed.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW067
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEPGW084 Measuring Beamsize with the LHC Beam Gas Vertex Detector emittance, detector, proton, injection 2680

• B. Würkner, A. Alexopoulos, C. Barschel, E. Bravin, G. Bregliozzi, N. Chritin, B. Dehning, M. Ferro-Luzzi, M. Giovannozzi, R. Jacobsson, L.K. Jensen, O.R. Jones, V. Kain, R. Kieffer, R. Matev, M.N. Rihl, V. Salustino Guimaraes, R. Veness, S. Vlachos
CERN, Geneva, Switzerland
• A. Bay, F. Blanc, S. Gianì, O. Girard, G.J. Haefeli, P. Hopchev, A. Kuonen, T. Nakada, O. Schneider, M. Tobin, Z. Xu
EPFL, Lausanne, Switzerland
• R. Greim, T. Kirn, S. Schael, M. Wlochal
RWTH, Aachen, Germany

The Beam Gas Vertex detector (BGV) is an innovative beam profile monitor being developed as part of the High Luminosity LHC (HL-LHC) project at CERN. The goal is to continually measure the transverse beam size by reconstructing beam-gas interaction vertices using high precision tracking detectors. To confirm the feasibility of such a device, a demonstrator based on eight modules of scintillating fiber detectors has been constructed, installed in the LHC and operated for the past 3 years. It will be shown that using the BGV the average transverse beam size can be obtained with a statistical accuracy of better than 5µm (for a gaussian beam with a σ of 200µm). This precision is obtained with an integration time of less than one minute. In addition, the BGV measures the size of individual bunches with a statistical accuracy of better than 5% within 5 minutes. The results obtained from all the data gathered over the past 3 years will be presented and compared to measurements from other beam profile monitors. Some ideas for improvements for the final HL-LHC instrument will also be discussed.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW084
About • paper received ※ 10 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019
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WEPGW088 Characterisation of Electro-Optic Pickups for High Bandwidth Diagnostics at the High Luminosity LHC pick-up, simulation, proton, ECR 2690

• A. Arteche, A. Bosco, S.M. Gibson
Royal Holloway, University of London, Surrey, United Kingdom
• S.E. Bashforth, A. Bosco, S.M. Gibson, I.S. Penman
JAI, Egham, Surrey, United Kingdom
• M. Krupa, T. Lefèvre
CERN, Geneva, Switzerland

Funding: Work supported by UK STFC grants ST/N001583/1, JAI at Royal Holloway University of London and CERN.
A high bandwidth electro-optical beam position monitor is under development for the High Luminosity LHC. A series of measurements of the electro-optic signals were previously obtained by an EO-BPM prototype installed in the SPS. This paper focuses on an advanced design that would further improve the sensitivity of the pick-up by optimising the shape of the metallic electrode mounted onto the crystal. The proposed upgraded electro-optic pickups significantly increase the image field profile of the passing bunch inside a lithium niobate crystal embedded within the pickup. This work is based on parametric studies, performed using CST particle studio, investigating various electro-optic (electrode and crystal) configurations. We present the expected performance of the different designs, alongside with their evaluation on a test bench, highlighting the most relevant choice for a prototype pick-up to be installed on LHC

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW088
About • paper received ※ 22 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019
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WEPGW092 Nanosecond-Latency Sub-Micron Resolution Stripline Beam Position Monitor Signal Processor for CLIC feedback, detector, extraction, kicker 2705

• R.L. Ramjiawan, D.R. Bett, P. Burrows, G.B. Christian, C. Perry
JAI, Oxford, United Kingdom

A high-resolution, low-latency stripline beam position monitor (BPM) signal processor has been developed for use in an intra-train feedback system for the Compact Linear Collider (CLIC). The processor was designed to have extremely low latency of order nanoseconds and a target position resolution of order 1 micron. The processor consists of a pair of diodes to form the difference and sum of a pair of stripline BPM inputs with microstrip filters to reduce out-of-band noise. The assembled prototype was optimized for use with the electron beam in the extraction line of the Accelerator Test Facility at the High Energy Accelerator Research Organization (KEK) in Japan but the underlying design is readily scaleable to a higher frequency response relevant for CLIC. A latency of 3 ns was measured in a testbench setup. We report the results of performance tests with beam in which the position resolution was measured to be c. 325 nm.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW092
About • paper received ※ 15 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEPRB077 Simulation and Measurements of HOM Filter of the LARP Prototype RF-Dipole Crabbing Cavity Using an RF Test Box HOM, cavity, dipole, damping 2999

• S.U. De Silva, J.R. Delayen
ODU, Norfolk, Virginia, USA
• Z. Li
SLAC, Menlo Park, California, USA

The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB077
About • paper received ※ 20 May 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019
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WEPRB093 Design of a Proof-of-principle Crabbing Cavity for the Jefferson Lab Electron-ion Collider cavity, electron, HOM, collider 3027

• H. Park, S.U. De Silva, J.R. Delayen, S.I. Sosa Guitron
ODU, Norfolk, Virginia, USA
• J.R. Delayen, H. Park
JLab, Newport News, Virginia, USA

The Jefferson Lab design for an electron-ion collider (JLEIC) requires crabbing of the electron and ion beams in order to achieve the design luminosity. A number of options for the crabbing cavities have been explored, and the one which has been selected for the proof-of-principle is a 952 MHz, 2-cell rf-dipole (RFD) cavity. This paper summarizes the electromagnetic design of the cavity and its HOM characteristics.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB093
About • paper received ※ 22 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019
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WEPTS046 Monitoring and Modelling of the LHC Emittance and Luminosity Evolution in 2018 emittance, operation, experiment, proton 3212

• S. Papadopoulou, F. Antoniou, I. Efthymiopoulos, M. Hostettler, G. Iadarola, N. Karastathis, S. Kostoglou, Y. Papaphilippou, G. Trad
CERN, Geneva, 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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WEPTS073 Beam-Beam Effect: Crab Dynamics Calculation in JLEIC simulation, collider, electron, cavity 3293

• H. Huang, F. Lin, V.S. Morozov, Y. Roblin, A.V. Sy, Y. Zhang
JLab, Newport News, Virgina, USA
• I. Neththikumara, S. Sosa, B. Terzić
ODU, Norfolk, Virginia, USA

The electron and ion beams of a future Electron Ion Collider (EIC) must collide at an angle for detection, machine and engineering design reasons. To avoid associated luminosity reduction, a local crabbing scheme is used where each beam is crabbed before collision and de-crabbed after collision. The crab crossing scheme then provides a head-on collision for beams with a non-zero crossing angle. We develop a framework for accurate simulation of crabbing dynamics with beam-beam effects by combining symplectic particle tracking codes with a beam-beam model based on the Bassetti-Erskine analytic solution. We present simulation results using our implementation of such a framework where the beam dynamics around the ring is tracked using Elegant and the beam-beam kick is modeled in Python.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS073
About • paper received ※ 16 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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WEPTS082 Luminosity Studies of Asymmetric Crab Crossing in JLEIC ECR, collider, electron, cavity 3311

• E.A. Nissen
JLab, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a non-exclusive, world-wide license to publish or reproduce this manuscript.
The proposed Jefferson Lab Electron Ion Collider (JLE-IC) currently plans to use a crab crossing scheme to max-imize the available luminosity. It had been suggested that space and cost savings, as well as hadron beam quality improvements, could be realized by leaving the ion beam un-crabbed and increasing the crabbing angle of the elec-tron beam. This and variations in-between equal and totally one-sided crabbing are examined for both JLEIC and LHC parameters, with various changes in crabbing angle and frequency studied to maximize luminosity.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS082
About • paper received ※ 14 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019
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THPGW035 Development of Yb-Based Laser System for Crab Crossing Laser-Compton Scattering laser, electron, experiment, scattering 3657

• R. Morita, Y. Koshiba, S. Ota, M. Washio
Waseda University, Tokyo, Japan
• T. Higashiguchi
Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan
• K. Sakaue
The University of Tokyo, The School of Engineering, Tokyo, Japan
• J. Urakawa
KEK, Ibaraki, Japan

Funding: This work was supported by JSPS KAKENHI 18H0123.
We are going to demonstrate the principle of crab crossing in laser-Compton scattering which creates head-on collision in a pseudo manner to enhance the intensity of laser-Compton X-ray. When the electron beam is tilted by half of the collision angle, the scat-tered X-rays becomes the largest. Calculation shows that more than threefold luminosity will be achieved in our system and could be larger luminosity depending on the beam parameters. The intensity of scattered light can be efficiently enhanced by using a collision laser with high intensity, high quality and ultrashort pulse duration. Thus, we have introduced a regenera-tive amplifier using ceramics thin-disk as a collision laser and developed a dedicated laser system. In this conference, we will report on our laser system and results of crab crossing laser-Compton scattering.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW035
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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THPGW057 HL-LHC Full Remote Alignment Study alignment, operation, vacuum, MMI 3716

• A. Herty, R. De Maria, P. Fessia, D. Gamba, M. Giovannozzi, J. Hansen, I. Lamas Garcia, H. Mainaud Durand, S. Redaelli
CERN, Meyrin, Switzerland

Funding: Research supported by the HL-LHC project.
This study explores the benefits of extending the monitoring and remote alignment concept, proposed in the HL-LHC baseline, to additional components of the matching sections of the HL-LHC. The objective was to evaluate the benefits in terms of equipment performance and new opportunities for system simplification. In collaboration with the HL-LHC Working Group on Alignment, critical input parameters such as ground motion, manufacturing, assembly, and alignment tolerances, have been quantified. Solutions for the selected, manually aligned compo-nents have been investigated with the particular focus on vacuum design, mechanical design and the new alignment concept compatible with reliability and maintainability requirements. In this context, collimators and masks are key elements to be included in the extended alignment system. Their supporting systems will integrate the concept of on-line monitoring sensors and an actuator based, remote alignment platform. The full remote alignment of components will provide a positive impact to the machine operation reducing the need of human intervention in the tunnel and providing enhanced flexibility to perform the required alignment adjustment as part of an operational tool for the HL-LHC.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW057
About • paper received ※ 09 May 2019       paper accepted ※ 18 May 2019       issue date ※ 21 June 2019
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THPRB084 Run 2 Prompt Dose Distribution and Evolution at the Large Hadron Collider and Implications for Future Accelerator Operation operation, radiation, collimation, proton 4013

• O. Stein, K. Bilko, M. Brugger, R. Garcia Alia, F.J. Harden, Y. Kadi, A. Lechner, G. Lerner
CERN, Geneva, Switzerland

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB084
About • paper received ※ 14 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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THPRB116 Effect of Ground Motion Introduced by HL-LHC CE Work on LHC Beam Operation ground-motion, operation, civil-engineering, GUI 4092

• M. Schaumann, D. Gamba, M. Guinchard, L. Scislo, J. Wenninger
CERN, Geneva, Switzerland

Funding: Research supported by the HL-LHC project
The official groundbreaking of the civil engineering (CE) work for the high luminosity upgrade of the LHC started on 15 June 2018 parallel to LHC beam operation. Compactor work and shaft excavation around the two low beta experiments, ATLAS and CMS, were expected to induce vibrations to the accelerator magnets and cause orbit disturbance, beam loss and potentially premature beam dumps. Ground motion sensors were installed on the surface and close to the triplets, where the CE works were expected to have the largest impact on the beams. This paper discusses the observations made on the LHC beams that could be correlated to CE work.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB116
About • paper received ※ 13 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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THPTS036 Quench Detection and Diagnostic Systems for the Superconducting Circuits for the HL-LHC dipole, data-acquisition, radiation, electronics 4183

• R. Denz, D.O. Calcoen, E. De Matteis, V. Froidbise, S. Georgakakis, S. Haas, S. Mundra, T. Podzorny, A.P. Siemko, J. Spasic, J. Steckert
CERN, Geneva, Switzerland
• D. Blasco Serrano

The High Luminosity LHC project (HL-LHC) will incorporate a new generation of superconducting elements such as high field superconducting magnets based on Nb3Sn conductors and MgB2 based high temperature superconducting links for magnet powering. In addition, the HL-LHC will also feature new generations of NbTi based magnets. The proper protection and diagnostics of those elements require the development of a new generation of integrated quench detection and data acquisition systems as well as novel methods for quench detection. The next generation of quench detection systems is to a large extent software defined and serves at the same time as high performance data acquisition system. The contribution will discuss the specific needs of HL-LHC in terms of quench detection and present recent results from tests with prototype magnets. The contribution will show the implementation of new quench detection methods such as current derivative sensors. Measures for increasing the system dependability and easing its maintenance will be explained, as well as the improved supervision architecture using Ethernet based field-bus systems for fast data transmission.
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS036
About • paper received ※ 07 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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• D. Wollmann, C. Cangialosi, C. Cangialosi, F. Cerutti, G. D’Angelo, S. Danzeca, R. Denz, M. Favre, R. Garcia Alia, D. Hagedorn, A. Infantino, G. Kirby, L. Kistrup, T. Koettig, J. Lendaro, B. Lindstrom, A. Monteuuis, F. Rodriguez-Mateos, A.P. Siemko, K. Stachon, A. Tsinganis, M. Valette, A.P. Verweij, A. Will
CERN, Meyrin, Switzerland
• A. Bernhard, A.-S. Müller
KIT, Karlsruhe, Germany

Funding: Work supported by the HL-LHC Project.
The powering layout of the new HL-LHC Nb3Sn triplet circuits is the use of cryogenic bypass diodes, where the diodes are located inside an extension to the magnet cryostat, operated in superfluid helium and exposed to radiation. Therefore, the radiation hardness of different type of bypass diodes has been tested at low temperatures in CERN’s CHARM irradiation facility during the operational year 2018. The forward characteristics, the turn on voltage and the reverse blocking voltage of each diode were measured weekly at 4.2 K and 77 K, respectively, as a function of the accumulated radiation dose. The diodes were submitted to a dose close to 12 kGy and a 1 MeV equivalent neutron fluence of 2.2x1014,n/cm2. After the end of the irradiation campaign the annealing behaviour of the diodes was tested by increasing the temperature slowly to 300 K. This paper describes the experimental setup, the measurement procedure and discusses the results of the measurements.

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS067
About • paper received ※ 15 May 2019       paper accepted ※ 22 May 2019       issue date ※ 21 June 2019
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THPTS100 Measurements of Decay and Snapback in Nb3Sn Accelerator Magnets at Fermilab dipole, injection, quadrupole, sextupole 4342

• G. Velev, G. Ambrosio, G. Chlachidze, J. DiMarco, S. Stoynev, T. Strauss
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
In recent years, Fermilab has been executing an inten-sive R&D program on Nb3Sn accelerator magnets. This program has included dipole and quadrupole models and demonstrators for various programs and projects, including the HL-LHC accelerator upgrade project. A systematic study of the field decay and snapback during the injection portion of a simulated accelerator cycle was executed at the Fermilab Magnet Test Facility. This paper summarizes the recent measurements of the MQXFS1 short quadrupole model and discusses the results of some previously measured Nb3Sn magnets at CERN

DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS100
About • paper received ※ 15 May 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019
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