01 Circular and Linear Colliders
A02 Lepton Colliders
Paper Title Page
MOXGB1 Report on SuperKEKB Phase 2 Commissioning 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 [28.598 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOXGB1  
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MOPMF001 Bunch Schedules for the FCC-ee Pre-injector 79
 
  • S. Ogur, K. Oide, Y. Papaphilippou, F. Zimmermann
    CERN, Geneva, Switzerland
  • D.N. Shatilov
    BINP SB RAS, Novosibirsk, Russia
 
  The latest design of the Future Circular electron-positron Collider (FCC-ee) foresees a luminosity per interaction point above 2.0·1036/cm2/s for operation at the Z pole. The filling from zero current occurs in collision to profit from the bunch lengthening due to beamstrahlung (so-called bootstrapping). At any time when new e- and e+ buckets or bunchlets are injected into the collider, they will collide instantly. For this reason, we may provide the charge in each injected bunch in a way to pre-compensate for anticipated beam loss, and to reach the target luminosity as soon as possible after the first injection. In this way, we optimise the injection schedules for Z-mode so as to reach the peak luminosity in less than 20 minutes by interleaved injection of the two species at some portion of full bucket charge. Filling from zero the injector should allow accumulating 1.7·1011 particles in one collider bucket within at least 10 injections, assuming a total transmission above 80%. In steady-state operation, the injector chain continually produces and accelerates lower bunch charges so as to maintain nearly constant bunch currents and constant peak luminosity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF001  
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MOPMF034 Layout and Performance of the FCC-ee Pre-Injector Chain 169
 
  • S. Ogur, T.K. Charles, K. Oide, Y. Papaphilippou, L. Rinolfi, F. Zimmermann
    CERN, Geneva, Switzerland
  • A.M. Barnyakov, A.E. Levichev, P.V. Martyshkin, D.A. Nikiforov
    BINP SB RAS, Novosibirsk, Russia
  • I. Chaikovska, R. Chehab
    LAL, Orsay, France
  • K. Furukawa, N. Iida, T. Kamitani, F. Miyahara
    KEK, Ibaraki, Japan
  • E.V. Ozcan
    Bogazici University, Bebek / Istanbul, Turkey
  • S.M. Polozov
    MEPhI, Moscow, Russia
 
  The Future Circular e+e Collider pre-injector chain consists of a 6 GeV S-Band linac, a damping ring at 1.54 GeV and pre-booster ring to reach 20 GeV for injection to the main booster. The electron and positron beams use the same accelerator chain alternatively. The e+ beam is generated from a novel low level RF-gun providing 6.5 nC charge at 11 MeV with 0.5 micron geometric emittance. The e+ beam is produced by the impact of a 4.46 GeV e- beam onto a hybrid target, accelerated in the linac up to 1.54 GeV, and injected to the damping ring for emittance cooling. Simulations on the performance of the DR are presented for reaching the required equilibrium emittances at the required damping time. As an alternative option, a 20 GeV linac is considered utilising C-Band cavities and simulations studies have been undertaken regarding the beam transport and transmission efficiency up to that energy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF034  
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MOPMF057 FCC-ee Dynamic Aperture Studies and Frequency Map Analysis 244
 
  • T. Tydecks, S. Aumon, T.K. Charles, B. Härer, B.J. Holzer, K. Oide, Y. Papaphilippou, J. Wenninger
    CERN, Geneva, Switzerland
 
  The FCC-ee Lepton Collider will provide e+e collisions in the beam energy range of 45.6 GeV to 182.5 GeV. FCC-ee will be a precision measurement tool for Z, W, H and t physics with expected luminosities of 2.07× 1036 cm-2 s-1 at the Z-pole and 1.3 × 1034 cm-2 s-1 at the tt- threshold. In order to achieve the foreseen luminosities, a vertical β* of 1 mm to 2 mm is mandatory. Dynamic aperture and frequency map analysis for the 97.75 km machine with such a squeezed accelerator optics are studied. Furthermore, effects of machine misalignments on dynamic and momentum aperture are presented and estimations for the required tolerances are given  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF057  
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MOPMF073 Rejuvenation of 7-Gev SuperKEKB Injector Linac 300
 
  • K. Furukawa, M. Akemoto, D.A. Arakawa, Y. Arakida, H. Ego, A. Enomoto, Y. Enomoto, T. Higo, H. Honma, N. Iida, M. Ikeda, H. Kaji, K. Kakihara, T. Kamitani, H. Katagiri, M. Kawamura, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, H. Nakajima, K. Nakao, T. Natsui, M. Nishida, Y. Ogawa, Y. Ohnishi, S. Ohsawa, F. Qiu, I. Satake, M. Satoh, Y. Seimiya, A. Shirakawa, H. Sugimura, T. Suwada, T. Takenaka, M. Tanaka, N. Toge, Y. Yano, K. Yokoyama, M. Yoshida, R. Zhang, X. Zhou
    KEK, Ibaraki, Japan
 
  KEK injector linac has delivered electrons and positrons for particle physics and photon science experiments for more than 30 years. It was upgraded for the SuperKEKB project, which aims at a 40-fold increase in luminosity over the previous project KEKB, in order to increase our understanding of flavor physics beyond the standard model of elementary particle physics. SuperKEKB energy-asymmetric electron-positron collider with its extremely high luminosity requires a high current, low emittance and low energy spread injection beam from the injector. The electron beam is generated by a new type of RF gun, that provides a much higher beam current to correspond to a large stored beam current and a short lifetime in the ring. The positron source is another major challenge that enhances the positron bunch intensity from 1 to 4 nC by increasing the positron capture efficiency, and the positron beam emittance is reduced from 2000 μm to 10 μm in the vertical plane by introducing a damping ring, followed by the bunch compressor and energy compressor. The summary of the rejuvenation is reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF073  
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MOPMF074 Beam Phase Space Jitter and Effective Emittance for SuperKEKB Injector Linac 304
 
  • Y. Seimiya, N. Iida, T. Kamitani, M. Satoh
    KEK, Ibaraki, Japan
 
  In SuperKEKB linac, stable high charged low emittance beam is necessary. Transported beam to SuperKEKB Main Ring (MR) must be stable to the extent that the beam can be injected inside MR acceptance. SuperKEKB requirement must be satisfied for emittance including beam phase space jitter, called as effective emittance. Large amplitude beam position jitter has been measured at linac end. We evaluated that the effect of the beam position jitter on effective emittance and investigated the source of the beam phase space jitter.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF074  
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MOPMF079 The CEPC lattice design with combined dipole magnet 315
 
  • D. Wang, S. Bai, F.S. Chen, W. Chou, J. Gao, Y.M. Peng, Y. Wang, M. Yang, C.H. Yu, Y. Zhang
    IHEP, Beijing, People's Republic of China
 
  For the lattice of CEPC collider ring, the combined magnet (dipole+sextupole) scheme has been developed to reduce the power consumption of the stand-alone sextu-poles. The power consumption of sextupoles has been decreased by 75% due to 50% reduction of strength. The dynamic aperture for the combined magnet scheme is as good as the original lattice. The magnet design for this kind of combined dipole has been done which provides a good support for this new idea.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF079  
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MOPMF085 Beam-gas Background Characterization in the FCC-ee IR 322
 
  • M. Boscolo, O.R. Blanco-García
    INFN/LNF, Frascati (Roma), Italy
  • H. Burkhardt, R. Kersevan, M. Lueckhof
    CERN, Geneva, Switzerland
  • F. Collamati
    INFN-Roma1, Rome, Italy
 
  The MDISim toolkit is used to evaluate and characterize the beam-gas induced background in the FCC-ee Interaction Region. MDISim allows a full characterization of this beam background source with the locations where the beam-gas scattering occurs as well as the loss points, as a function of different vacuum conditions and composition, for the nominal optics and parameters. Detailed pressure distribution profiles have been obtained running coupled synchrotron radiation and molecular flow montecarlo codes, as an input to the GEANT4 calculations. The particles hitting the pipe in the IR can be tracked in the detectors with a full Geant-4 simulation. Semi-analytic estimates for the expected rates and lifetime are also performed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF085  
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MOPMF086 Proposal of an Experimental Test at DAΦNE for the Low Emittance Muon Beam Production From Positrons on Target 326
 
  • M. Boscolo, M. Antonelli, O.R. Blanco-García, S. Guiducci, A. Stella
    INFN/LNF, Frascati (Roma), Italy
  • F. Collamati
    INFN-Roma1, Rome, Italy
  • R. Li Voti
    Sapienza University of Rome, Rome, Italy
  • S.M. Liuzzo, P. Raimondi
    ESRF, Grenoble, France
 
  We present in this paper the proposal of an experimental test at DAΦNE of the positron-ring-plus-target scheme foreseen in the Low EMittance Muon Accelerator. This test would be a validation of the on-going studies for LEMMA and it would be synergic with other proposals at DAΦNE after the SIDDHARTA run. We discuss the beam dynamics studies for different targets inserted in a proper location through the ring, i.e. where the beam is focused and dispersion-free. Optimization of beam parameters, thickness and material of target and optics of the target insertion are shown as well. The development of the existent diagnostic needed to test the behavior of the circulating beam is described together with the turn-by-turn measurement systems of charge, lifetime and transverse size. Measurements on the temperature and thermo-mechanical stress on the target are also under study.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF086  
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MOPMF088 Preparation Activity for the Siddharta-2 Run at DAΦNE 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 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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MOPMK012 Electron Cloud Studies in FCC-ee 374
 
  • E. Belli
    Sapienza University of Rome, Rome, Italy
  • P. Costa Pinto, G. Rumolo, T.F. Sinkovits, M. Taborelli
    CERN, Geneva, Switzerland
  • M. Migliorati
    INFN-Roma1, Rome, Italy
 
  Electron cloud effects are one of the most critical aspects for the LHC and the future circular colliders. In the frame of the electron-positron collider FCC-ee, an estimation of the electron cloud build up in the machine will be discussed in this paper. A preliminary evaluation of the heat load in the arc components and interaction region magnets will be presented, together with possible mitigation strategies.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK012  
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MOPML013 Progress on Preliminary Conceptual Study of HIEPA, a Super Tau-Charm Factory in China 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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TUYGBD2 A Review of DAΦNE Performances During the KLOE-2 Run 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 [9.932 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBD2  
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