Keyword: luminosity
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MOXGB1 Report on SuperKEKB Phase 2 Commissioning MMI, detector, optics, emittance 1
 
  • Y. Ohnishi
    KEK, Ibaraki, Japan
  
  The SuperKEKB electron-positron collider is being commissioned at KEK in three phases. The first phase was successfully completed in 2016, focusing on vacuum scrubbing and single beam studies without final focus optics. The second phase will start in March 2018 and until mid of July 2018. It will be dedicated to achieving the target specific luminosity larger than 4x1031 cm-2s-1/mA2, using the novel "nano-beam" collision scheme. Final focus optics will be installed, as well as the Belle-II detector, but without the vertex detector. The second phase of commissioning will also serve to assess and learn to control backgrounds induced by beam losses near the interaction region, expected to be larger than at KEKB in the past, as a result of the much smaller beams. This will be important before installing the vertex detector for the final phase of commissioning, due to start at the beginning of 2019, when high luminosity needed for data taking with the Belle-II detector should be achieved. The speaker will present the recent progress and performance of SuperKEKB that is enabled by these upgrades.  
slides icon Slides MOXGB1 [28.594 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOXGB1  
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MOPMF011 Beam-Beam Issues With Two Interaction Points in eRHIC proton, electron, detector, simulation 102
 
  • Y. Luo, M. Blaskiewicz, A. He, C. Montag, V. Ptitsyn
    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.
In this article, we study the beam-beam interaction related issues with two interaction points in the current eRHIC ring-ring design. We carried out strong-strong beam-beam simulation in a 2-d bunch intensity scan. We observed coherent beam-beam instability and emittance blowup with 2 collisions per turn at lower bunch intensities than the case with only 1 collision per turn. To deliver collisions to the two experiments simultaneously, we proposed a new bunch filling pattern to avoid 2 collisions per turn for any electron or proton bunch. We proved that the parasitic beam-beam effect with the new bunch filling pattern is negligible. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF011  
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MOPMF012 Study of Crabbed Collision in eRHIC With a Combination of Strong-Strong and Weak-Strong Simulations simulation, electron, proton, cavity 105
 
  • 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
  • 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 present design of the future electron-ion collider eRHIC at the Brookhaven National Laboratory, a crossing angle of 22~mrad between the electron and proton orbits at the interaction region is adopted. To compensate the geometric luminosity loss, a local compensation scheme with two sets of crab cavities for each beam is considered. In this article, we first carry out strong-strong beam-beam simulation to study possible coherent beam-beam instability. Under the assumption of no coherent beam-beam motion, we then carry out a weak-strong beam-beam simulation to determine the long-term stability of the proton beam with the equilibrium electron beam sizes extracted from the strong-strong beam-beam simulation. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF012  
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MOPMF022 Luminosity Reduction Caused by the Full-Detuning LLRF Scheme on the HL-LHC Crab Cavities cavity, simulation, proton, LLRF 129
 
  • E. Yamakawa, R. Apsimon, A.C. Dexter
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • P. Baudrenghien, R. Calaga, F.J. Galindo Guarch
    CERN, Geneva, Switzerland
  
  The High-Luminosity LHC (HL-LHC) crab cavities (CCs) will be installed on both sides of IP1 (ATLAS) and IP5 (CMS) to compensate for the geometric luminosity reduction due to the crossing angle. To cope with the increased beam current (0.55 A DC for LHC, 1.1 A for HL-LHC), the operation of the LLRF system has been changed: rather than fully compensating the transient beam loading, we allow the phase to vary along the turn (100 ps peak-peak with 1.1 A DC). This has been implemented at LHC since July 2017. The CCs have high loaded Q (5e5) and the available RF power is insufficient to follow the bunch phase modulation. The crabbing voltage is not modulated, causing a phase error w.r.t. the individual bunch centroids, leading to transverse kicks of the centroids and an asymmetric crabbing of the bunch cores. We present an analytical model for the resulting luminosity reduction and validate with particle tracking simulations. Due to the symmetry of the bunch filling patterns for the counter-rotating beams, the peak luminosity is reduced by only 2% for nominal HL-LHC parameters at IPs 1 and 5, which is within tolerable limits.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF022  
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MOPMF039 First Xenon-Xenon Collisions in the LHC experiment, proton, injection, emittance 180
 
  • M. Schaumann, R. Alemany-Fernández, P. Baudrenghien, T. Bohl, C. Bracco, R. Bruce, N. Fuster-Martínez, M.A. Jebramcik, J.M. Jowett, T. Mertens, D. Mirarchi, S. Redaelli, B. Salvachua, M. Solfaroli, H. Timko, J. Wenninger
    CERN, Geneva, Switzerland
  
  In 2017, the CERN accelerator complex once again demonstrated its flexibility by producing beams of a new ion species, xenon, that were successfully injected into LHC. On 12 October, collisions of fully stripped xenon nuclei were recorded for the first time in the LHC at a centre-of-mass energy per colliding nucleon pair of 5.44 TeV. Physics data taking started 9.5 h after the first injection of xenon beams and lasted a total of 6 h. The integrated luminosity delivered to the four LHC experiments was sufficient that new physics results can be expected soon. We provide a general overview of this Xe-Xe pilot run before focussing on beam data at injection energy and at flat-top.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF039  
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MOPMF040 Crossing Angle Anti-Leveling at the LHC in 2017 operation, proton, simulation, experiment 184
 
  • N. Karastathis, K. Fuchsberger, M. Hostettler, Y. Papaphilippou, D. Pellegrini
    CERN, Geneva, Switzerland
  
  In 2017, LHC incorporated in operation an anti-leveling procedure of adapting in steps the crossing angle of the colliding beams to increase the integrated luminosity. In this paper, we present the Dynamic Aperture simulations that were employed to identify the operational margins, and therefore define the leveling steps. The results are complemented by observations from nominal operation and projections for the 2018 operation. Additional anti-leveling techniques, investigated in dedicated machine studies are also discussed  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF040  
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MOPMF041 Refining the HL-LHC Operational Settings with Inputs From Dynamic Aperture Simulations: A Progress Report octupole, operation, dynamic-aperture, experiment 188
 
  • N. Karastathis, R. De Maria, S.D. Fartoukh, Y. Papaphilippou, D. Pellegrini
    CERN, Geneva, Switzerland
  
  Recent Dynamic Aperture (DA) simulations aimed at providing guidance for the latest updates of the operational scenario for the High Luminosity upgrade of the LHC. The impact of the increased chromaticity and octupole current has been assessed considering the latest updates of the optics. Additional means to improve the lifetime, such as tune optimization, have been identified and deployed. We also briefly discuss the impact of delivering high luminosity to the LHCb experiment.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF041  
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MOPMF042 Crab Cavity Failures Combined with a Loss of the Beam-Beam Kick in the High Luminosity LHC cavity, beam-losses, dumping, collimation 192
 
  • B. Lindstrom, H. Burkhardt, V.K.B. Olsen, A. Santamaría García, K.N. Sjobak, M. Valette, D. Wollmann
    CERN, Geneva, Switzerland
  
  Crab cavities are an essential component of the High Luminosity LHC (HL-LHC) project. In case of a failure they can create large transverse kicks on the beam within tens of microseconds and, therefore, require a fast extraction of the circulating beam. In this paper, the effects of different crab cavity failures in combination with the missing beam-beam kick following the dump of only one LHC beam are presented and consequences for the interlocking strategy of crab cavities are discussed.
Work supported by the High Luminosity LHC project. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF042  
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MOPMF043 Tuning of CLIC-Final Focus System 3 TeV Baseline Design Under Static and Dynamic Imperfections ISOL, collider, linear-collider, simulation 196
 
  • E. Marín, A. Latina, J. Pfingstner, D. Schulte, R. Tomás
    CERN, Geneva, Switzerland
  • J. Pfingstner
    University of Oslo, Oslo, Norway
  
  In this paper we present the tuning study of the Compact Linear Collider - Final Focus System (CLIC-FFS) 3~TeV baseline design under static and dynamic imperfections for the first time. The motion of the FFS magnets due to ground motion and the impact of active and passive mechanisms envisaged to stabilize both e- and e+ systems are described. It is found that the Pre-isolator required for stabilization of the Final Doublet drives the performance of the collider at the final stages of the tuning process. The obtained tuning performance depending on the stabilization techniques are discussed in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF043  
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MOPMF050 LHC Operational Experience of the 6.5 TeV Proton Run with ATS Optics operation, optics, emittance, proton 216
 
  • M. Pojer, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, A. Calia, G.E. Crockford, S.D. Fartoukh, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, M. Hostettler, W. Höfle, Y. Le Borgne, D. Nisbet, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli, R. Suykerbuyk, D.J. Walsh, J. Wenninger, M. Zerlauth
    CERN, Geneva, Switzerland
  
  In May 2017, the CERN Large Hadron Collider (LHC) restarted operations at 6.5 TeV using the Achromatic Telescopic Squeeze (ATS) scheme with a target beta-star of 40 cm in ATLAS and CMS. The number of bunches was progressively increased to a maximum of 2556 with emittances of 2.5 um. In August, several machine parameters had to be re-tuned to mitigate beam loss induced instabilities and maintain a steady increase of the instantaneous luminosity. The use of a novel beam type and filling pattern produced in the injectors, allowed filling the machine with very low emittance beam (1.5 um) achieving an equivalent luminosity with 1868 bunches. In September, the beta-star was further lowered to 30 cm (using, for the first time, the telescopic technique of the ATS) and the bunch intensity pushed to 1.25·1011 protons. In the last 3 months of 2017, the LHC produced more than 500 pb-1 of integrated luminosity per day, delivering to each of the high luminosity experiments 50.6 fb-1, 10% above the 2017 target. A general overview of the operational aspects of the 2017 proton run will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF050  
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MOPMF051 LHC Operational Scenarios During 2017 Run proton, experiment, optics, hadron 220
 
  • B. Salvachua, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, H. Burkhardt, G.E. Crockford, JCD. Dumont, S.D. Fartoukh, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, J.M. Jowett, Y. Le Borgne, D. Nisbet, M. Pojer, L. Ponce, S. Redaelli, M. Solfaroli, R. Suykerbuyk, D.J. Walsh, J. Wenninger, M. Zerlauth
    CERN, Geneva, Switzerland
  
  During 2017, the Large Hadron Collider LHC delivered luminosity for different physics configuration in addtion to the nominal 6.5 TeV proton-proton run. About 18.5 days were dedicated to commission and to deliver special physics to the experiments. Condifurations with large beta-star of 19 m and 24 m were prepared for luminosity calibration with Van de Meer scans. A proton-proton run at 2.51 TeV took place during the last weeks of November to provide reference data for the heavy ion (Pb-Pb, p-Pb) collisions at the same equivalent nucleon energy . A very short (0.5 days) but effective ion run was scheduled where the LHC saw the first Xe beams collissions and delivered around 3 ub-1 to ATLAS and CMS. The run ended with a low event pile-up run at 6.5TeV. This contribution summarizes the operational aspects and delivered targets for the different configurations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF051  
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MOPMF052 Monitoring and Modeling of the LHC Luminosity Evolution in 2017 emittance, experiment, operation, monitoring 224
 
  • N. Karastathis, F. Antoniou, I. Efthymiopoulos, M. Hostettler, G. Iadarola, S. Papadopoulou, Y. Papaphilippou, D. Pellegrini, B. Salvachua
    CERN, Geneva, Switzerland
  
  In 2017, the Large Hadron Collider (LHC) restarted operation at 6.5 TeV, after an extended end-of-the-year stop, scheduled to deliver 45/fb to the two general-purpose experiments. Continuous monitoring of the key beam parameters and machine configurations that impact the delivered luminosity was introduced, providing fast feedback to operations for further optimisation. The numerical model based on simulations and use of selected machine parameters to estimate the machine luminosity was further developed. The luminosity evolution and comparisons to the model predictions is presented in this paper. The impact of the dynamic variation of the crossing angle, which was incorporated into nominal LHC operation, is also discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF052  
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MOPMF064 High-Energy LHC Design impedance, optics, injection, proton 269
 
  • F. Zimmermann, D. Amorim, S. A. Antipov, S. Arsenyev, M. Benedikt, R. Bruce, M.P. Crouch, S.D. Fartoukh, M. Giovannozzi, B. Goddard, M. Hofer, R. Kersevan, V. Mertens, Y. Muttoni, J.A. Osborne, V. Parma, V. Raginel, S. Redaelli, T. Risselada, I. Ruehl, B. Salvant, D. Schoerling, E.N. Shaposhnikova, L.J. Tavian, E. Todesco, R. Tomás, D. Tommasini, F. Valchkova-Georgieva, V. Venturi, D. Wollmann
    CERN, Geneva, Switzerland
  • J.L. Abelleira, E. Cruz Alaniz, P. Martinez Mirave, A. Seryi, L. van Riesen-Haupt
    JAI, Oxford, United Kingdom
  • A. Apyan
    ANSL, Yerevan, Armenia
  • J. Barranco García, L. Mether, T. Pieloni, L. Rivkin, C. Tambasco
    EPFL, Lausanne, Switzerland
  • F. Burkart
    DESY, Hamburg, Germany
  • Y. Cai, Y.M. Nosochkov
    SLAC, Menlo Park, California, USA
  • G. Guillermo Cantón
    CINVESTAV, Mérida, Mexico
  • K. Ohmi, K. Oide, D. Zhou
    KEK, Ibaraki, Japan
  
  In the frame of the FCC study we are designing a 27 TeV hadron collider in the LHC tunnel, called the High Energy LHC (HE-LHC).  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF064  
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MOPMF072 On the Feasibility of a Pulsed 14 TeV C.M.E. Muon Collider in the LHC Tunnel collider, proton, acceleration, SRF 296
 
  • V.D. Shiltsev, D.V. Neuffer
    Fermilab, Batavia, Illinois, USA
  
  We will consider technical feasibility, key machine parameters and major challenges of the recently proposed 14 TeV c.m.e. muon-muon collider in the LHC tunnel.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF072  
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MOPMF088 Preparation Activity for the Siddharta-2 Run at DAΦNE experiment, controls, feedback, quadrupole 334
 
  • C. Milardi, D. Alesini, S. Bini, O.R. Blanco-García, M. Boscolo, B. Buonomo, S. Cantarella, S. Caschera, A. D'Uffizi, A. De Santis, G.O. Delle Monache, D.G.C. Di Giulio, G. Di Pirro, A. Drago, L.G. Foggetta, A. Gallo, R. Gargana, A. Ghigo, S. Guiducci, S. Incremona, F. Iungo, C. Ligi, M. Maestri, A. Michelotti, L. Pellegrino, R. Ricci, U. Rotundo, L. Sabbatini, C. Sanelli, G. Sensolini, A. Stecchi, A. Stella, A. Vannozzi, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • G. Castorina
    INFN-Roma1, Rome, Italy
  • J. Chavanne, G. Le Bec, P. Raimondi
    ESRF, Grenoble, France
  
  DAΦNE, the Frascati lepton collider working at the c.m. energy of the F resonance, continues to be a very suitable infrastructure to realize experiments aimed at studying elementary particles and nuclear physics. The motivations of this long lasting interest are related to the DAΦNE ability of increasing its performances in terms of luminosity thanks to the innovative Crab-Waist collision scheme. In this framework, a new run for the SIDDHARTA-2 experiment has been planned in the year 2019. The detector presently installed in the interaction region, KLOE-2, will be removed and a new low-beta session, equipped with new permanent magnets quadrupoles, will be installed. Diagnostics tools will be improved especially the ones used to keep under control the beam-beam interaction. The horizontal feedback in the positron ring will be potentiated in order to achieve a higher positron current. The design and development work done in view of the SIDDHARTA-2 run is presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF088  
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MOPMF089 DAΦNE Luminosity Monitor detector, experiment, scattering, injection 338
 
  • A. De Santis, C. Bisegni, O.R. Blanco-García, O. Coiro, A. Michelotti, C. Milardi, A. Stecchi
    INFN/LNF, Frascati (Roma), Italy
  
  This work presents a new method to measure the DAΦNE collider instantaneous luminosity. The method is based on the identification of Bhabha scattering events at low polar angle (∼10 degree) around the beam axis by using two small crystal calorimeters shared with the KLOE-2 experiment. A new experimental setup has been designed and realized in order to implement the fast luminosity monitor, also in view of the DAΦNE future physics runs. Besides total instantaneous luminosity the new diagnostic measures also Bunch-by-Bunch (BBB) luminosity. This peculiarity allows to investigate the beam-beam interaction for the Crab- Waist collisions at DAΦNE and luminosity dependence on the bunch train structure.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF089  
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MOPMK003 Energy Deposition Studies and Luminosity Evolution for the Alternative FCC-hh Triplet optics, quadrupole, radiation, dipole 352
 
  • J.L. Abelleira, E. Cruz Alaniz, A. Seryi, L. van Riesen-Haupt
    JAI, Oxford, United Kingdom
  • J.L. Abelleira, E. Cruz Alaniz, L. van Riesen-Haupt
    University of Oxford, Oxford, United Kingdom
  
  Funding: Work supported by EuroCircol, EU's Horizon 2020 grant No 654305 & STFC grant to the John Adams Institute
The international Future Circular Collider (FCC) study comprises the development of a new scientific structure in a tunnel of 100 km. This will allow the installation of a proton collider with a centre of mass energy of 100 TeV, called FCC-hh. An alternative design of the final focus triplet for the FCC-hh has been developed in parallel to the alternative one, and adapted to the constraint of a free length (L*) of 40 m. We discuss in this paper the energy deposition issues as well as the luminosity evolution for two different optics choices: round and flat beams. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK003  
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MOPMK005 HE-LHC Final Focus: Flat Beam Parameters and Energy Deposition Studies optics, cavity, quadrupole, dipole 356
 
  • J.L. Abelleira, E. Cruz Alaniz, A. Seryi, L. van Riesen-Haupt
    JAI, Oxford, United Kingdom
  • J.L. Abelleira, E. Cruz Alaniz, L. van Riesen-Haupt
    University of Oxford, Oxford, United Kingdom
  
  Funding: Work supported by EuroCircol, EU's Horizon 2020 grant No 654305 & STFC grant to the John Adams Institute
The High Energy LHC (HE-LHC) project is studying the feasibility of a new proton-proton collider with a beam energy of 13.5 TeV. The nominal optics features a β* of 0.25 m and crab-cavities. Here we present a flat-beam optics that can be used with a non-zero crossing angle, in the absence of crab cavities. This is followed by energy deposition studies for the superconducting quadrupoles and dipole separators. The total dose in these magnets coming from the collision debris is evaluated. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK005  
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MOPMK007 An Optimised Triplet for the Final Focus of the FCC-HH with a 40m Final Drift optics, quadrupole, collider, injection 364
 
  • L. van Riesen-Haupt, J.L. Abelleira
    University of Oxford, Oxford, United Kingdom
  • J.L. Abelleira, E. Cruz Alaniz, A. Seryi
    JAI, Oxford, United Kingdom
  
  Funding: Work supported by the Horizon 2020 project EuroCirCol, grant 654305 and by the Science and Technology Facilities Council
The sizes of the beta functions in the final focus triplet of a synchrotron collider have a great impact on the chromaticity and dynamic aperture of the machine. These beta functions are proportional to the square of the length of the final drift so it is desirable to keep it as short as possible whilst leaving enough room for the experiment. In the latest design of the FCC-hh this drift was reduced from 45 m to 40 m. In the following an alternative final focus for this new design will be presented. The effects this change has on the interaction region will examined and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK007  
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MOPMK010 Study Progress of the Coupling Resonance of the Crab Crossing Scheme in Electron-Ion Collider electron, synchrotron, simulation, cavity 368
 
  • Y. Hao
    FRIB, East Lansing, USA
  • Y. Luo, V. Ptitsyn
    BNL, Upton, Long Island, New York, USA
  • 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.
Crab crossing scheme is essential collision scheme to achieve high luminosity for the future electron-ion collider (EIC). The bunch length effect of the ion beam cannot be ignored even when cooling is present compared with the wavelength of the crab cavity, therefore, the nonlinear dependence of the crabbing kick may present a challenge to the beam dynamics of the ion beam, hence an impact to the luminosity lifetime. In this paper, we present the result of numerical beam dynamics studies of the crab crossing scheme. The result indicates that there is a special coupling resonance in the nonlinear relation of the crab crossing scheme of the EIC, which dominates the luminosity degradation. And we will discuss the possible remedies for such resonance. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK010  
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MOPMK016 Calculations of Beam-Beam Effect and Luminosity for Crab Dynamics Simulations in JLEIC simulation, collider, electron, beam-beam-effects 386
 
  • H. Huang, V.S. Morozov, A.V. Sy
    JLab, Newport News, Virgina, USA
  
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contracts DE-AC05-06OR23177 and DE-AC02-06CH11357.
Crab crossing is an integral part of the Jefferson Lab Electron-Ion Collider (JLEIC) design to achieve high luminosity while meeting the detection and physics pro-gram requirements. The crab crossing scheme provides a head-on beam-beam collision for beams with a nonzero crossing angle. Simulations of crabbing dynamics currently do not include beam-beam effects. We describe a framework for accurate simulation of beam-beam effects on crabbing dynamics by applying a numerical calculation of the Bassetti-Erskine analytic solution to symplectic particle tracking codes. The numerical calculation is benchmarked against the analytic solution by calculating the luminosity reduction for several colliding beam scenarios. Benchmarking results show good agreement be-tween the numerical calculation and analytic solution, paving the way for implementation of the beam-beam kick to Elegant tracking simulations. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK016  
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MOPMK017 Transient Beam Loading Due to the Bunch Train Gap and Its Compensation Experiments at BEPC-II and ALS cavity, experiment, feedback, beam-loading 390
 
  • H. Wang, R.A. Rimmer, S. Wang
    JLab, Newport News, Virginia, USA
  • J.P. Dai, Q. Qin, J. Xing, J.H. Yue, Y. Zhang
    IHEP, Beijing, People's Republic of China
  • D. Teytelman
    Dimtel, San Jose, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Non-uniform bunch fill patterns in storage rings, driven by the need to provide gaps for beam aborting and ion clearing cause a large beam loading change in the RF cavities. The induced turn-periodic transient in the cavity voltage modulates longitudinal beam properties along the train, such as synchronous position and bunch length. In the EIC design, due to the asymmetric bunch train structure between the electron and the ion beam, such modulation results in shifting collision point and leads to reduced luminosity. We have carried out the beam based experiments at BEPC-II and ALS using bunch-by-bunch diagnostic capabilities of the coupled-bunch feedback systems to study this transient effect. A modulated bunch filling pattern with higher charge density around the gap has been demonstrated to be effective in partially compensating this transient modulation. Details of the experimental setups and the data analysis will be presented to this conference. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK017  
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MOPML009 New High Luminosity LHC Baseline and Performance at Ultimate Energy operation, optics, emittance, cavity 408
 
  • L.E. Medina Medrano
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
  • A. Apollonio, G. Arduini, O.S. Brüning, M. Giovannozzi, L.E. Medina Medrano, S. Papadopoulou, Y. Papaphilippou, S. Redaelli, R. Tomás
    CERN, Geneva, Switzerland
  
  Funding: Research supported by the HL-LHC project and the Beam project (CONACYT, Mexico).
The LHC machine is envisioned to operate eventually at an ultimate beam energy of 7.5 TeV at the end of LHC Run 4, i.e. after commissioning of the HL-LHC systems, a stage falling into the High Luminosity LHC (HL-LHC) era. In this paper we review the latest baseline parameters and performance, and study the potential reach of the HL-LHC with pushed optics at the ultimate beam energy. Results in terms of integrated luminosity and effective pile-up density of both the nominal (5.0×1034 cm-2 s−1) and ultimate (7.5×1034 cm-2 s−1) levelling operations are discussed 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML009  
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MOPML010 Challenges and Status of Tuning Simulations for CLIC Traditional Beam Delivery System linear-collider, collider, simulation, lattice 412
 
  • R.M. Bodenstein, P. Burrows
    JAI, Oxford, United Kingdom
  • E. Marín
    CERN, Geneva, Switzerland
  
  The beam delivery system (BDS) for the 3 TeV version of the Compact Linear Collider (CLIC) has two main design types. One type is referred to as the local scheme, as it is approximately one kilometer shorter and corrects the chromaticity in both planes. The other type is referred to as the traditional scheme, and separates the chromaticity correction of each plane into different areas. The expectation early in the studies was that the traditional scheme would be easier to tune. This work will address the problems experienced in tuning simulations for the traditional BDS and describe the current state of these simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML010  
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MOPML013 Progress on Preliminary Conceptual Study of HIEPA, a Super Tau-Charm Factory in China collider, positron, factory, electron 422
 
  • Q. Luo, D.R. Xu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: Work supported by National Natural Science Foundation of China 11375178 and the Fundamental Research Funds for the Central Universities, Grant No WK2310000046.
As the most successful tau-charm factory of the world, BEPC II will celebrate its 10th birthday this year and will finish its historical mission in the next decade. Because of its very important role in high energy phys-ics study, BEPC II will certainly need a successor, a new tau-charm collider. This paper discusses the feasi-bility of a greenfield next generation tau-charm collid-er named HIEPA. The luminosity of this successor is about 5×1034 cm−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 parameters are shown. Several key technologies such as beam polarization and beam emittance diag-nostics are also discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML013  
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TUXGBD2 Colliding Heavy Ions in the LHC heavy-ion, experiment, operation, proton 584
 
  • J.M. Jowett
    CERN, Geneva, Switzerland
  
  The Large Hadron Collider at CERN not only collides protons but also heavier nuclei. So far Pb+Pb, Xe-Xe and p+Pb collisions, at multiple energies, have been provided for what was initially conceived as a distinct physics program on the collective behavior of QCD matter at extreme energy density and temperature. However unexpected phenomena observed in p+Pb and p+p collisions at equivalent energies have blurred the distinction. Intense, low-emittance, ion beams are provided by a dedicated source and injector chain setup. When Pb beams collide, new luminosity limits arise from photon-photon and photonuclear interactions but effective mitigations have allowed luminosities over 3 times design. Asymmetric p+Pb collisions introduce new features and beam-dynamical phenomena into operation of the LHC but have also achieved luminosity far beyond expectations. With experimental requirements for multiple changes in energy and data-taking configurations during very short heavy-ion runs, high operational efficiency and reliability are vital. This invited talk discusses performance, future prospects, and technical challenges for the LHC heavy ion program, including injector performance.  
slides icon Slides TUXGBD2 [5.317 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBD2  
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TUXGBD3 Ideas and Concepts for Future Electron Ion Colliders electron, collider, polarization, detector 590
 
  • F.C. Pilat
    ORNL, Oak Ridge, Tennessee, USA
  
  Different versions of future electron-ion colliders have been proposed by Brookhaven National Laboratory (BNL) and Thomas Jefferson National Laboratory (JLAB), one based on colliding protons in a ring with electrons from an Energy Recovery Linac (ERL), the other two based on ring-ring colliders. To attain the luminosity goal strong hadron cooling is required, as could be provided with several proposed new cooling schemes. Polarization of both colliding beams is essential. This invited talk will compare the various designs and highlight some of the novel ideas and concepts.  
slides icon Slides TUXGBD3 [76.608 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUXGBD3  
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TUYGBD2 A Review of DAΦNE Performances During the KLOE-2 Run detector, operation, vacuum, collider 624
 
  • C. Milardi, D. Alesini, S. Bini, O.R. Blanco-García, M. Boscolo, B. Buonomo, S. Cantarella, S. Caschera, A. D'Uffizi, A. De Santis, G.O. Delle Monache, D.G.C. Di Giulio, G. Di Pirro, A. Drago, L.G. Foggetta, A. Gallo, R. Gargana, A. Ghigo, S. Guiducci, C. Ligi, M. Maestri, A. Michelotti, L. Pellegrino, R. Ricci, U. Rotundo, A. Stecchi, A. Stella, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  
  DAΦNE, the Frascati electron-positron accelerator complex, has almost completed the last and more chanlleging period of operation for the KLOE-2 detector. In this context the performances of the collider, based on the Crab-Waist collision scheme, are reviewed and the limiting factors discussed.  
slides icon Slides TUYGBD2 [9.928 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBD2  
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TUYGBD3 eRHIC Design Status electron, hadron, storage-ring, proton 628
 
  • V. Ptitsyn, 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, Y. Hao, A. Hershcovitch, H. Huang, W.A. Jackson, J. Kewisch, C. Liu, H. Lovelace III, Y. Luo, F. Méot, M.G. Minty, C. Montag, R.B. Palmer, B. Parker, S. Peggs, V.H. Ranjbar, G. Robert-Demolaize, S. Seletskiy, V.V. Smaluk, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, 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
  
  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 eRHIC aims at a luminosity around 1034cm-2sec-1, using strong cooling of the hadron beam. Since the required cooling techniques are not yet readily available, an initial version with a peak luminosity of 3*1033cm-2sec-1 is being developed that can later be outfitted with strong hadron cooling. We will report on the current design status and the envisioned path towards 1034cm-2sec-1 luminosity. 		 
slides icon Slides TUYGBD3 [11.790 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBD3  
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TUPAF045 Studies for Future Fixed-Target Experiments at the LHC in the Framework of the CERN Physics Beyond Colliders Study target, experiment, collider, proton 798
 
  • S. Redaelli, M. Ferro-Luzzi
    CERN, Geneva, Switzerland
  • C. Hadjidakis
    IN2P3-CNRS, Orsay, France
  
  A study on prospects for Physics Beyond Colliders at CERN was launched in September 2016 to assess the capabilities of the existing accelerators complex. Among several other working groups, this initiative triggered the creation of a working group with the scope of studying a few specific proposals to perform fixed-target physics experiments at the Large Hadron Collider (LHC). This includes for example physics experiments with solid or gaseous internal targets, polarized gas targets, and experiments using bent-crystals for halo splitting from beam core for internal targets. The focus of the working group's activities is on the technical feasibility and on implications to the LHC ring. In this paper, the current status of the studies is presented and future plans are discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF045  
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WEYGBE4 Low-Impedance Collimators for HL-LHC impedance, octupole, operation, collimation 1794
 
  • S. A. Antipov, N. Biancacci, R. Bruce, A. Mereghetti, D. Mirarchi, E. Métral, S. Redaelli, B. Salvant
    CERN, Geneva, Switzerland
  • D. Amorim
    Université Grenoble Alpes, Grenoble, France
  
  The High-Luminosity upgrade of the Large Hadron Collider (HL-LHC) will double its beam intensity for the needs of High Energy Physics frontier. This increase requires a reduction of the machine's impedance to ensure the coherent stability of the beams until they are put in collision. A major part of the impedance is the resistive wall contribution of the collimators. To reduce this contribution several coating options have been proposed. We have studied numerically the effect of the novel coatings on the beam stability. The results show that a decrease of up to 30% of the machine impedance and a reduction of up to 120 A in the stabilizing octupole current threshold can be achieved by coating the secondary collimators with Molybdenum. Half of that improvement can be obtained by coating the jaws of a subset of four collimators identified as the highest contributors to machine impedance. The installation of this subset of low-impedance collimators is planned for the Long Shutdown 2 in 2019-2020.  
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DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBE4  
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WEPAF034 A Supersonic Gas Jet-Based Beam Profile Monitor Using Fluorescence for HL-LHC electron, photon, gun, hadron 1891
 
  • H.D. Zhang, A.S. Alexandrova, R. Schnuerer, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M. Ady, E. Barrios Diaz, N. Chritin, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
    CERN, Geneva, Switzerland
  • A.S. Alexandrova, A. Salehilashkajani, R. Schnuerer, C.P. Welsch, H.D. Zhang
    The University of Liverpool, Liverpool, United Kingdom
  • P. Forck, S. Udrea
    GSI, Darmstadt, Germany
  • P. Smakulski
    WRUT, Wroclaw, Poland
  
  Funding: The HL-LHC project, the Helmholtz Association under contract VH-NG-328, the EU's 7th Framework Programme under grant agreement no 215080 and the STFC Cockcroft core grant No. ST/G008248/1.
The High-Luminosity Large Hadron Collider (HL-LHC) project aims to increase the machine luminosity by a factor of 10 as compared to the LHC's design value. To achieve this goal, a special type of electron lens is being developed. It uses a hollow electron beam which co-propagates with the hadron beam to act on any halo particles without perturbing the core of the beam. The overlapping of both beams should be carefully monitored. This contribution presents the design principle and detailed characteristics of a new supersonic gas jet-based beam profile monitor. In contrast to earlier monitors, it relies on fluorescence light emitted by the gas molecules in the jet following interaction with the primary hadron beams. A dedicated prototype has been designed and built at the Cockcroft Institute and is being commissioned. Details about monitor integration, achievable resolution and dynamic range will be given. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF034  
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WEPAF069 Evaluation of Frequency Scanning Interferometer Performances for Surveying, Alignment and Monitoring of Physics Instrumentation alignment, laser, target, cavity 1990
 
  • J. Gayde, S.W. Kamugasa
    CERN, Geneva, Switzerland
  
  During the last three years, the performance of Frequency Scanning Interferometry, accurate to a few micrometres, has been evaluated at CERN in the frame of the PACMAN project. Improvements have been studied and tested to make it better suited for typical alignment and survey conditions in accelerators and experiments. The results of these developments and tests, coupled with the multi-channel capability of the system, and its compactness which eases its integration in the area to be surveyed, offer a wide scope of possible applications for in-situ large scale metrology for physics equipment and facility elements. Furthermore, the fact that the system electronics can be placed far away from the position to be measured, allows the system to be used in confined and hazardous spaces. This paper briefly describes the system and its improvements. It gives the precision obtained for distance measurements and for the 3D point reconstruction based on FSI observations in the case of CLIC component fiducialisation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF069  
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WEPAF082 A Systematic Analysis of the Prompt Dose Distribution at the Large Hadron Collider operation, radiation, experiment, proton 2036
 
  • O. Stein, K. Bilko, M. Brugger, S. Danzeca, D. Di Francesca, R. Garcia Alia, Y. Kadi, G. Li Vecchi, C. Martinella
    CERN, Geneva, Switzerland
  
  During the operation of the Large Hadron Collider (LHC) the continuous particle losses create a mixed particle radiation field in the LHC tunnel and the adjacent caverns. Exposed electronics and accelerator components show dose dependent accelerated aging effects. In order to achieve an optimal lifetime associated to radiation damage, the position of the equipment is chosen in dependency of the amplitude of the radiation fields. Based on the continuous analysis of the data from more than 3900 ionisation chamber beam loss monitors the evolution of the radiation levels is monitored during the accelerator operation. Normalising the radiation fields with either the integrated luminosity or the integrated intensities allows extrapolating the radiation levels of future accelerator operation. In this paper, the general radiation levels in the arcs and the insertion regions at the LHC and their evolution will be presented. The changes in the prompt dose distribution along the LHC between the operation in 2016 and 2017 will be discussed. The impact of different accelerator settings on the local dose distribution will be addressed as well.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF082  
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WEPAL037 Simulation Study on Luminosity Feedback for Horizontal Beam Stabilization at Superkekb feedback, simulation, ground-motion, monitoring 2250
 
  • C.G. Pang, P. Bambade
    LAL, Orsay, France
  • Y. Funakoshi, S. Uehara
    KEK, Ibaraki, Japan
  
  The SuperKEKB e+ e- collider uses highly focused ultra-low emittance bunches colliding every 4 ns to reach a very high luminosity of 8× 1035 cm-2s-1. It is quite essential to have an orbit feedback system at the Interaction Point (IP) to maintain the optimum overlap between the colliding beams in the presence of ground motion disturbances. For the horizontal motion, a luminosity monitoring system, based on measuring the rate of the Bhabha process at vanishing scattering angle, is developed as input signal to the feedback system. The relative precision needed for this monitor is studied in detail, for the different successive stages of luminosity operation, based on a full simulation of this system, including the detector, DAQ, lock-in amplifier, and feedback control.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL037  
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WEPAL038 First Tests of Superkekb Fast Luminosity Monitors During 2018 Phase-2 Commissioning monitoring, detector, simulation, feedback 2254
 
  • C.G. Pang, P. Bambade, S. Di Carlo, D. Jehanno, V. Kubytskyi, Y. Peinaud, C. Rimbault
    LAL, Orsay, France
  • Y. Funakoshi, S. Uehara
    KEK, Ibaraki, Japan
  
  The SuperKEKB e+e- collider aims to reach a very high luminosity of 8× 1035 cm-2s-1, by using highly focused ultra-low emittance bunches colliding every 4 ns, it is essential to have an orbit feedback system at the Interaction Point (IP) to maintain the optimum overlap between two colliding beams. Luminosity monitoring systems including LumiBelle2 and ZDLM as input to dithering feedback system used to stabilize the horizontal orbit at the IP were developed and will be described, including the detectors, mechanical set-up, DAQ. Preliminary measurements and analysis of background and first stage luminosity monitoring data collected will be reported and compared with simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAL038  
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WEPMF090 Upgrade of the CMS Experimental Beam Vacuum During LS2 vacuum, experiment, detector, operation 2596
 
  • J.S. Sestak, G. Bregliozzi, P. Chiggiato, C. Di Paolo
    CERN, Geneva, Switzerland
  
  Starting from December 2018, the Large Hadron Collider (LHC) is going to interrupt its physic operations for more than two years within the period called second long shutdown (LS2). The Compact Muon Solenoid (CMS) experiment will undergo the biggest upgrade of its experimental beam vacuum system since the first operations in 2008. The new experimental vacuum layout should comply with demanding structural, vacuum, integration and physics requirements. Moreover, the new layout should be compatible with foreseen engineering changes of the detector and the machine during the upgrade phase of High-Luminosity LHC in LS3. This paper gives an overview of the CMS LS2 experimental vacuum sectors upgrades. Both design and production phase of the new vacuum layout is discussed in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF090  
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WEPML026 Large-Aperture High-Field Nb3Sn Dipole Magnets dipole, collider, operation, magnet-design 2738
 
  • A.V. Zlobin, V.V. Kashikhin, I. Novitski
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
Large-aperture high-field dipole magnets based on Nb3Sn superconductor are necessary for various accelerator systems of future hadron and muon colliders. In hadron colliders, they are used needed for beam separation before and after interaction points. In a muon collider, they are considered for both the arc and the interaction regions to provide room for internal absorbers protecting magnets from the muon decay products. These magnets can also be used in test facilities to produce a background magnetic field for testing conductor samples or insert coils. High level of magnetic field and large aperture size lead to large Lorentz forces and mechanical strains and stresses which can damage brittle Nb3Sn coils. This paper describes conceptual designs of 120-mm aperture dipoles with magnetic fields up to 15 T based on cos-theta coils. Stress management technique and magnet parameters are also presented and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML026  
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WEPML027 Conceptual Design of a 17 T Nb3Sn Accelerator Dipole Magnet dipole, magnet-design, collider, quadrupole 2742
 
  • A.V. Zlobin, J.R. Carmichael, V.V. Kashikhin, I. Novitski
    Fermilab, Batavia, Illinois, USA
  
  Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
Nb3Sn dipole magnets with a nominal field of 16 T and sufficient operation margins are being considered for the LHC energy upgrade or a future Very High Energy Hadron Collider. Magnet design studies are being performed in the framework of the US Magnet Development Program to explore the limits of the Nb3Sn accelerator magnet technology and feasibility of such magnets, as well as to optimize the magnet design, performance parameters and cost. This paper describes the conceptual design of a 17 T dipole magnet with 60 mm aperture and 4-layer cos-theta coil being developed at Fermilab. The results of magnetic and mechanical analyses, including the non-linear effects in magnetic field and the possible stress management techniques, are also presented and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML027  
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WEPML058 Observation of Pressure Bursts in the SuperKEKB Positron Ring MMI, positron, electron, operation 2830
 
  • S. Terui, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, Y. Suetsugu
    KEK, Ibaraki, Japan
  
  The SuperKEKB is an electron-positron collider with asymmetric energies in KEK aiming an extremely high luminosity of 8x1035 cm-2 s-1 using a nano-beam scheme. In the Phase 1 commissioning from February to June, 2016, the vacuum system of the main ring worked well as a whole at stored beam currents of approximately 1 A. However, the localized pressure bursts accompanied by beam losses were observed in the positron ring. The beam loss monitors triggered beam aborts, and the phenomena has became an obstacle to the beam commissioning. These pressure bursts were frequently observed from the early stage of the commissioning. Most of the pressure bursts occurred near or inside of aluminum-alloy beam pipes in dipole magnets, which have grooved surface at the top and bottom sides. The various observations indicates that the most probable cause of this phenomenon was the collision between the dusts dropped from the grooves and the circulating positron beam. We report the properties and the probable causes of the pressure bursts, and the possible mitigation methods. Some results of the countermeasures taken prior to the ongoing Phase-2 commissioning will be also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPML058  
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THYGBD1 FCC: Colliders at the Energy Frontier collider, hadron, cavity, injection 2908
 
  • M. Benedikt, F. Zimmermann
    CERN, Geneva, Switzerland
  
  The international Future Circular Collider study, launched in 2014, is finalizing a multi-volume conceptual design report. The FCC develops high-energy circular collider options based on a new 100 km tunnel. Long-term goal is a 100 TeV proton-proton collider (FCC-hh). The study also includes a high-luminosity electron-positron collider (FCC-ee), and it also examines lepton-hadron scenarios (FCC-he). Civil engineering and technical infrastructure studies were carried out. Global programs advance the development of high-field superconducting magnet technology based on Nb3Sn, the optimization of a suitable large superconducting RF system, and schemes for synchrotron radiation handling. In addition, the FCC study includes the design of the HE-LHC, housed in the LHC tunnel, and based on the same high-field magnet technology as the FCC-hh. The FCC study further includes an elaboration of the physics cases, including for heavy-ion collisions, and detector concepts, as well as staging and implementation scenarios. The FCC collaboration has grown to more than 120 institutes from 30 countries around the world. This invited talk summarizes the study achievements and the final designs.  
slides icon Slides THYGBD1 [12.503 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD1  
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THYGBD3 Beam-beam Studies for Super Proton-Proton Collider resonance, closed-orbit, collider, proton 2918
 
  • L.J. Wang, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  • K. Ohmi
    KEK, Ibaraki, Japan
  
  In China, a two-stage circular collider project, CEPC-SPPC has been proposed. The first stage, CEPC (Circular Electron Positron Collier, a so-called Higgs factory) is focused on the Higgs physics, and the second stage, SPPC (Super Proton-Proton Collider) will be an energy frontier collider and a discovery machine. Luminosity is a key factor for any particle-physics colliders. With the increasing bunch population, beam-beam interaction is increasingly become the limit factor of luminosity improvement. The finite crossing angle scheme is considered firstly. Meanwhile, long-range interaction is another significant source of luminosity degrade. In this report, firstly, we don't consider long-range interactions and study luminosity degrade with crossing angle and without crossing angle for horizontal crossing and horizontal-vertical crossing. Secondly we discuss luminosity decay with long-range interactions for horizontal crossing and horizontal-vertical crossing. Thirdly, we talk about emittance growth and luminosity degradation using resonance analysis for different scenarios. Finally the resulting beam-beam limit will be concluded for SPPC.  
slides icon Slides THYGBD3 [1.374 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBD3  
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THYGBE4 Early Phase 2 Results of LumiBelle2 for the SuperKEKB Electron Ring background, simulation, electron, photon 2934
 
  • S. Di Carlo, P. Bambade, D. Jehanno, V. Kubytskyi, C.G. Pang, Y. Peinaud, C. Rimbault
    LAL, Orsay, France
  
  We report on the early SuperKEKB Phase 2 operations of the fast luminosity monitor (LumiBelle2 project). Fast luminosity monitoring is required by the dithering feedback system, which is used to stabilize the beam in the presence of horizontal vibrations. In this report, we focus on the operations related to the electron side of LumiBelle2. Diamond sensors are located 30 meters downstream of the IP, just above, beside, and below the electron beam pipe. During early Phase 2, the sensors are used to measure the background, arising from beam-gas scattering. We present the hardware design, the detection algorithm, and the analysis of the background measurements taken up-to-date. The results are then compared with a detailed simulation of the background, in order to well understand the physical processes involved. The simulation is performed using SAD for generation and tracking purposes, while Geant4 is used to calculate the energy deposition in the diamond sensors.  
slides icon Slides THYGBE4 [3.091 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THYGBE4  
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THPAF035 Single-Collimator Tune Shift Measurement of the Three-Stripe Collimator at the LHC impedance, octupole, feedback, hadron 3036
 
  • S. A. Antipov
    University of Chicago, Chicago, Illinois, USA
  • D. Amorim, N. Biancacci, L.R. Carver, G. Mazzacano, A. Mereghetti, E. Métral, S. Redaelli, B. Salvant, D. Valuch
    CERN, Geneva, Switzerland
  
  Several options of low resistivity coating have been proposed for the collimator upgrade of the Large Hadron Collider. In order to study their effect on the beam dynamics a special collimator has been built and installed in the machine. Its jaws are coated with three different materials and can be moved transversely to selectively expose the beam to the chosen coating. We have measured the resistive wall tune shifts of each coating material and compared them with that of a standard Carbon Fibre Composite (CFC) collimator jaw. A resolution of the tune shift of the order of 10-5 has been achieved in the measurement. The results show a significant reduction of the resistive wall tune shift with novel materials. The largest improvement is obtained with a 5 μm Molybdenum coating of a Molybdenum-Graphite jaw. The observed tune shifts show a good agreement with the impedance model and the bench impedance and resistivity measurements. Obtained results can be used to further improve the precision of the impedance model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF035  
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THPAF040 Estimated Impact of Ground Motion on HL-LHC Beam Orbit ground-motion, quadrupole, emittance, closed-orbit 3052
 
  • D. Gamba, R. Corsini, M. Guinchard, M. Schaumann, J. Wenninger
    CERN, Geneva, Switzerland
  
  Funding: Research supported by the HL-LHC project.
The High Luminosity LHC (HL-LHC) will require unprecedented orbit stability at the low beta collision points (IP1 and IP5), and the effect of seismic noise might become a relevant source of luminosity loss. Many studies have been conducted in the past to characterise the actual ground motion in the LHC tunnel, and recently a few geo-phones have been installed to permanently monitor the ground stability at IP1 and IP5. An estimate of the impact of the main machine element vibration on orbit at the IPs and collimators is presented, together with a first look at the data collected by the installed geo-phones. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAF040  
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THPAK070 Coupled Bunch Instability from JLEIC Crab Cavity Higher Order Modes cavity, HOM, impedance, feedback 3392
 
  • S.I. Sosa Guitron, S.U. De Silva, J.R. Delayen, H. Park
    ODU, Norfolk, Virginia, USA
  • R. Li, V.S. Morozov, H. Park
    JLab, Newport News, Virginia, USA
  
  Particle bunches traveling in a ring can excite wakefields inside any radio-frequency element present. These electromagnetic modes can resonate long enough and interact with subsequent passing bunches. A coherent oscillation between bunches can quickly become an instability and needs to be addressed. The Jefferson Lab electron ion collider has a large 50 mrad crossing angle and thus relies on bunch crabbing to achieve high luminosity. Bunch crabbing is done with compact superconducting rf dipole cavities. We study coupled bunch oscillations driven by the higher order modes of multicell RFD crab cavities under study for JLEIC, we calculate the instability growth time assuming a symmetric beam spectrum, identify the HOMs driving the instability and discuss mitigation measures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK070  
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THPAK099 The Influence of Higher Order Multipoles of IR Magnets on Luminosity for SuperKEKB sextupole, multipole, octupole, coupling 3463
 
  • K. Hirosawa, T. Okada
    Sokendai, Ibaraki, Japan
  • N. Kuroo
    UTTAC, Tsukuba, Ibaraki, Japan
  • K. Ohmi, N. Ohuchi, D. Zhou
    KEK, Ibaraki, Japan
  
  SuperKEKB is an electron-positron circular collider upgraded from KEKB. To reach higher luminosity, values of beta are extremely small at Interaction Point. Although magnets in interaction region have a very strong focusing effect, they make a large disturbance to beams. Higher order multipoles and their skew components of magnetic fields of IR magnets are located at a very high beta section with pi/2 phase difference from IP. These multipoles can give critical effect to beam dynamics at interaction point and reduce luminosity on SuperKEKB design. In this study, we calculated beam dynamics for effect of skew components for multipole magnet, and estimated the influence on luminosity by them.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK099  
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THPAK123 Updates on Collective Effects Estimations for JLEIC electron, impedance, cavity, collider 3533
 
  • R. Li, K. E. Deitrick, T.J. Michalski
    JLab, Newport News, Virginia, USA
  
  Funding: This work is supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
JLEIC is the high luminosity and high polarization electron-ion collider (EIC) currently under active design at Jefferson Lab. It aims at high luminosity (1033~1034 cm-2s−1) for a wide range of ion species and center-of-mass energies. This luminosity performance relies sensibly on beam stability with high intensity electron and ion beam operation. The impedance budget analysis and the estimations of the single and multibunch instabilities are currently underway. In this paper, we present the update status of estimations for the longitudinal and transverse coherent instabilities, and identify areas or parameter regimes where special attentions for instability mitigations are required. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK123  
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THPAK135 Assessment of Linear and Non-Linear Optics Errors due to Beam-Beam with Multipoles for the High Luminosity LHC optics, quadrupole, hadron, beam-beam-effects 3557
 
  • L.E. Medina Medrano
    Universidad de Guanajuato, División de Ciencias e Ingenierías, León, Mexico
  • J. Barranco García, T. Pieloni
    EPFL, Lausanne, Switzerland
  • X. Buffat, L.E. Medina Medrano, R. Tomás
    CERN, Geneva, Switzerland
  
  Funding: HL-LHC project, European Circular Energy-Frontier Collider Study, H2020 programme (Grant 654305), Swiss State Secretariat for Education, Research and Innovation (SERI), Beam project (CONACYT, Mexico).
Study of the head-on and long-range beam-beam effects in the High Luminosity LHC (HL-LHC) is of interest to evaluate their potential impact on performance (in the form of luminosity imbalance) and machine operation (collimator system), and, depending on their magnitude, correction schemes might be necessary to minimize them. In this work, both the β-beating at zero amplitude and its amplitude-dependence are computed for the current HL-LHC baseline optics and parameters, as well as the amplitude detuning, at the main interaction points and collimators. Correction of the β-beating, tune shift and footprint for the HL-LHC, as originally proposed for the LHC, via compensation of the multipolar terms of the beam-beam force with corrector magnets, is also discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK135  
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THPAK145 Methods to Increase the Dynamic Aperture of the FCC-hh Lattice lattice, dynamic-aperture, quadrupole, interaction-region 3593
 
  • E. Cruz Alaniz, J.L. Abelleira, A. Seryi, L. van Riesen-Haupt
    JAI, Oxford, United Kingdom
  • J.L. Abelleira, L. van Riesen-Haupt
    University of Oxford, Oxford, United Kingdom
  • R. Martin, R. Tomás
    CERN, Geneva, Switzerland
  
  The Future Circular Collider (FCC) design study aims to develop the designs of possible circular colliders in the post LHC era. In particular the FCC-hh will aim to produce proton-proton collisions at a center of mass energy of 100 TeV. Initial tracking studies for the FCC-hh lattice at collision energy including field errors on the final focus triplet showed a very low dynamic aperture, most likely affected by the large beta functions and integrated length of the quadrupoles. Using non-linear correctors, the dynamic aperture was increased to acceptable levels; however, the difficulty to have an accurate magnetic model of the magnets required for this correction motivates the development of alternative methods. This work explores the possibility to increase the dynamic aperture by optimizing the phase advance between the main interaction regions. The description of this method along with its impact on the dynamic aperture will be given on this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAK145  
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THPAL067 Room Temperature Measurements of Higher Order Modes for the SPS Prototype RF-Dipole Crabbing Cavity HOM, cavity, dipole, simulation 3805
 
  • S.U. De Silva, J.R. Delayen, H. Park
    ODU, Norfolk, Virginia, USA
  • P. Berrutti
    Fermilab, Batavia, Illinois, USA
  • N.A. Huque, H. Park
    JLab, Newport News, Virginia, USA
  
  LHC High Luminosity Upgrade will be developing two local crabbing systems to increase the luminosity of the colliding bunches at the ATLAS and CMS experiments. One of the crabbing systems uses the rf-dipole cavity design that will be crabbing the beam in the horizontal plane. The fully integrated crabbing cavity has two higher order mode couplers in damping those excited modes. Currently two sets of HOM couplers have been fabricated at Jefferson Lab for prototyping and testing with the LARP crabbing cavities. This paper presents the measurements of the higher order modes with the prototype HOM couplers carried out at room temperature.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPAL067  
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THPMK146 Enhancement of Laser-Compton X-ray by Crab Crossing laser, electron, photon, scattering 4645
 
  • Y. Koshiba, R. Morita, S. Ota, M. Washio
    Waseda University, Tokyo, Japan
  • T. Higashiguchi
    Center for Optical Research and Education, Utsunomiya University, Utsunomiya, Japan
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
  
  Funding: This work is supported by JSPS Research Fellowships for Young Scientists (17J04371).
We are going to apply crab crossing of electrons and laser photons for the enhancement of laser-Compton X-ray flux. Crab crossing will enable quasi-head-on collision and increase the luminosity. Therefore, it could be combined with an optical enhancement cavity without the interference of beams and cavity mirrors, leading to the generation of intense X-ray pulses. Calculation show more than fourfold luminosity will be achievable in our system, and could be larger depending on beam parameters. Although crab crossing in laser-Compton scattering has been already proposed*, it has not been demonstrated yet anywhere. This will be the proof-of-principle study of the crab crossing laser-Compton scattering. In this conference, we will report our laser system based on thin-disk technology, and results of crab crossing laser-Compton scattering.
*Variola Alessandro, et al. "Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators." Physical Review Special Topics-Accelerators and Beams 14.3 (2011): 031001. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPMK146  
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THPML074 Image Reconstruction Technique Based on Coded Aperture Imaging for SuperKEKB X-ray Beam Size Monitor detector, optics, synchrotron, electron 4819
 
  • E. Mulyani, J.W. Flanagan
    Sokendai, Ibaraki, Japan
  • J.W. Flanagan, H. Fukuma, H. Ikeda, M. Tobiyama
    KEK, Ibaraki, Japan
  
  The fast reconstruction techniques based on principles originally developed for coded aperture imaging have been investigated for SuperKEKB accelerator. The establishment of this technique will very important for measuring the beam sizes of all 2500 bunches in the SuperKEKB accelerator over thousands of turns, as needed for instability studies and luminosity tuning, due to the vast quantity of data that needs to be processed in a timely manner.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML074  
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FRXGBD1 Reliability and Availability of Particle Accelerators: Concepts, Lessons, Strategy operation, collider, beam-losses, kicker 5014
 
  • A. Apollonio, L. Ponce, O. Rey Orozko, R. Schmidt, A.P. Siemko, B. Todd, J.A. Uythoven, A.P. Verweij, D. Wollmann, M. Zerlauth
    CERN, Geneva, Switzerland
  
  This paper will present the results and latest status of an extensive effort to analyse and improve the reliability and availability of the LHC. After the introduction of basic concepts and definitions, the paper reviews the performance of the LHC in 2015-2017. A direct comparison of the luminosity production years 2016 and 2017 is presented, with a focus on the main differences in the observed failure modes. Based on the lessons learnt in this time window, expectations for the performance during future LHC runs are discussed. In particular, the thought process for the evaluation of the possible full energy exploitation of the LHC is described, considering relevant factors such as the expected availability loss and the risk associated to magnet training.  
slides icon Slides FRXGBD1 [7.090 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-FRXGBD1  
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