MOVIR —  MC1 & MC2 Presentations   (11-May-20   09:00—16:00)
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MOVIR01 The Future Circular Collider Study 6
  • F. Zimmermann, M. Benedikt
    CERN, Meyrin, Switzerland
  • A.-S. Muellerpresenter
    KIT, Eggenstein-Leopoldshafen, Germany
  Funding: This work was supported, in part, by the European Commission under the HORIZON2020 Research and Innovation Programme, grant agreement 951754 (FCCIS).
At the end of 2018, a large worldwide collaboration, with contributors from more than 350 institutes completed the conceptual design of the Future Circular Collider (FCC), a ~100 km accelerator infrastructure linked to the existing CERN complex, that would open up the way to the post-LHC era in particle physics. We present an overview of the two main accelerator options considered in the design study, namely the lepton collider (FCC-ee), serving as highest-luminosity Higgs and electroweak factory, and the 100-TeV energy-frontier hadron collider (FCC-hh), along with the ongoing technological R&D efforts and the planned next steps. A recently approved EU co-funded project, the FCC Innovation Study (FCCIS), will refine the design of the lepton collider and prepare the actual implementation of the FCC, in collaboration with European and global partners, and with the local authorities.
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DOI • reference for this paper ※  
About • paper received ※ 09 June 2020       paper accepted ※ 04 September 2020       issue date ※ 12 October 2020  
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Designs of Electon Ion Colliders  
  • F.J. Willeke
    BNL, Upton, New York, USA
  Updates on the designs of the electron ion collider - eRHIC and JLEIC versions - will be presented in this talk.  
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Highlights from SuperKEKB Beam Commissioning  
  • K. Shibata
    KEK, Ibaraki, Japan
  SuperKEKB is an ambitious new collider presently being commissioned. In 2019 the vertical IP beta function will be squeezed towards the design value of ~300 micron. Achieving the target value of the specific luminosity is one of the challenges. Another concern is the detector background, e.g. due to beam-beam tails or due to top-up injection. An international collaboration participates in the SuperKEKB beam commissioning. SuperKEKB is an important demonstrator for proposed future high-energy circular colliders like CEPC and FCC-ee.  
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Exploration of Positron Beams for New Frontier Research  
  • F. Lin, Y.S. Derbenev, J.M. Grames, J. Guo, V.S. Morozov, E.J-M. Voutier, Y. Zhang
    JLab, Newport News, Virginia, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, and Office of Nuclear Physics under Contracts DE-AC05-06OR23177.
The comparison of electron and positron collisions with ions or fix targets has been used at HERA*, ** to explore the nuclear structure and investigate predictions of the Stantard Model. High luminosity and/or a high polarization positron beams are today considered at Jefferson Lab for physics experiments***. The understanding of different physics processes requires both unpolarized and polarized positron beams to unveil the internal structure of nuclei. In this paper, we report on integration schemes of positron beams at the CEBAF and for the proposed JLEIC. We explore possible injection schemes that provide the desired bunch charge and injection bunch pattern for both unpolarized and polarized positrons. For the JLEIC, we also estimate the collider performance in terms of luminosity and polarization.
* A. Airapetian et al, JHEP 07 (2012) 032.
** P. Abramowicz et al. Eur. Phys. J. C 70 (2010) 945.
*** J. Grames, E. Voutier et al. Jefferson Lab LOI12-18-004 (2018); arXiv:1906.09419 (2019).
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First Demonstration of Electron Cooling in a Collider  
  • A.V. Fedotov, M. Blaskiewicz, K.A. Drees, W. Fischer, X. Gu, D. Kayran, J. Kewisch, C. Liu, A. Marusic, K. Mernick, M.G. Minty, V. Ptitsyn, G. Robert-Demolaize, V. Schoefer, S. Seletskiy, P. Thieberger, H. Zhao
    BNL, Upton, New York, USA
  Funding: Work supported by the U.S. Department of Energy.
High-energy electron cooling is being considered for several accelerator physics projects worldwide, including various designs of an Electron Ion Collider. Since accelerating dc electron beams above few MeV is technologically challenging, rf-acceleration of electron bunches becomes more practical for high-energy applications. A world’s first electron cooling of ion beams employing such rf-accelerated electron bunches was recently demonstrated at BNL using the Low Energy RHIC electron Cooler (LEReC). Many challenges associated with such an approach were successfully overcome. The cooling task becomes even more challenging when one attempts to cool ion beams in collisions, requiring careful optimization between the electron cooling process and the ion beam lifetime due to various effects, including the beam-beam interactions. In this paper, we discuss first successful application of electron cooling for colliding ion beams in RHIC, as well as requirements and challenges of electron cooling in a collider.
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MOVIR06 Preliminary Sirius Commissioning Results 11
  • L. Liu, M.B. Alves, F.C. Arroyo, J.F. Citadini, R.H.A. Farias, J.G.R.S. Franco, R. Junqueira Leão, S.R. Marques, R.T. Neuenschwander, A.C.S. Oliveira, X.R. Resende, A.R.D. Rodrigues, C. Rodrigues, F. Rodrigues, R.M. Seraphim, F.H. de Sá
    LNLS, Campinas, Brazil
  Sirius is a 4th generation 3 GeV low emittance electron storage ring that is in final commissioning phase at the Brazilian Centre for Research in Energy and Materials (CNPEM) campus in Campinas, Brazil. Presently (April 2020) we have accumulated 15 mA of current, limited by vacuum, using a nonlinear kicker for injection. In this paper we report on the Sirius main commissioning results and main subsystems issues during installation and commissioning.  
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DOI • reference for this paper ※  
About • paper received ※ 01 June 2020       paper accepted ※ 11 June 2020       issue date ※ 01 September 2020  
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Review of Attosecond Free Electron Lasers  
  • S. Li
    SLAC, Menlo Park, California, USA
  Attosecond free electrons are now becoming a reality. A review of the advances, different methods and schemes will be presented. Needs from users and progress in various FEL facilities world-wide are discussed. Requirements for futher progress in schemes and technology are reviewed.  
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First Experimental Demonstration of the Mechanism of Steady-state Microbunching  
  • C.-X. Tang, X.J. Deng, W.-H. Huang, L.X. Yan
    TUB, Beijing, People’s Republic of China
  • A. Chao
    SLAC, Menlo Park, California, USA
  • J. Feikes, J. Li, A.N. Matveenko, Y. Petenev, M. Ries
    HZB, Berlin, Germany
  • A. Hoehl, R. Klein
    PTB, Berlin, Germany
  The concept of steady-state microbunching (SSMB) in electron storage rings implies a longitudinal bunch structure given by an optical or ultraviolet wavelength rather than a conventional radio frequency wavelength, typically six or more orders of magnitude smaller. The strong coherent radiation from the steady-state microbunches will support a facility with high-power, high-repetition-rate or continuous-wave, narrow-band, and short-wavelength radiation, which can provide unprecedented new possibilities for accelerator photon science and industry applications. It has been proved that the electron beam energy modulation induced by an externally applied 1064 nm laser in an undulator can yield microbunching and coherent radiation one turn later at exactly the same place where the modulation was applied. The results confirm that the phase of an electron beam relative to a laser in a storage ring can be locked turn-by-turn in a sub-laser-wavelength precision, therefore making SSMB possible. This validation represents the first key advance in the development of an SSMB high-power light source.
Phys. Rev. Lett. 105, 154801 (2010)
The SSMB collaboration: [FLS2018-THP2WB02]
X. Deng, et al. First Experimental Demonstration of the Mechanism of Steady-state Microbunching, under review.
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First results of the Hard X-Ray Self-Seeding Commissioning at the European XFEL  
  • S. Liu, W. Decking, L. Fröhlich, N. Golubeva, M.W. Guetg, R. Kammering, V. Kocharyan, E. Negodin, E. Saldin, T. Wohlenberg
    DESY, Hamburg, Germany
  • S. Abeghyan, G. Geloni, J. Grünert, S.K. Karabekyan, A. Koch, N.G. Kujala, D. La Civita, A. Rodriguez-Fernandez, L. Samoylova, S. Serkez, R.A. Shayduk, H. Sinn, V. Sleziona, T. Tanikawa, S. Tomin, M. Vannoni, M. Yakopov
    EuXFEL, Schenefeld, Germany
  • J.W.J. Anton, S.P. Kearney, D. Shu
    ANL, Lemont, Illinois, USA
  • V.D. Blank, S. Terentiev
    TISNCM, Troitsk, Russia
  • P. Rauer
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  At the Euorpean XFEL, a Hard X-Ray Self-Seeding (HXRSS) setup with two chicanes was installed in one of the two Hard X-Ray beamlines (SASE2). With the help of the two-stage scheme, HXRSS at the European XFEL will benefit from an increased signal-to-noise ratio, which can be used to cope, for the first time, with high-repetition rate X-ray pulses within a bunch train. This also allows for unprecedented output characteristics*. Commissioning of this setup has been started in Sept. 2019. In this paper, we will present the first commissioning results and our future plans.
*S. Liu et al., Phys. Rev. Accel. Beams 22, 060704 (2019).
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Experiments with Coherent Pulses at FERMI  
  • L. Giannessi, E. Allaria, F. Bencivenga, G. De Ninno, C. Masciovecchio, G. Penco
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  Starting from 2019 FERMI has started the full user operations with more than 50% of the machine time dedicated to user’s experiments. Proposals are now received through two calls occurring every year in December and June. Thanks to an optimization of the beamtime allocation the oversubscription has been kept of the order of 1 to 3.5 despite the increase of received proposals. We report here about the latest results from the FERMI FELs focusing on those experiments that exploits the unique capabilities of FERMI of producing fully coherent pulses.  
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Applying Machine Learning to Stabilize the Source Size in the ALS Storage Ring  
  • S.C. Leemann, W.E. Byrne, D.P. Cuneo, M.P. Ehrlichman, T. Hellert, A. Hexemer, Y. Lu, M. Marcus, C.N. Melton, H. Nishimura, G. Penn, F. Sannibale, D.A. Shapiro, C. Sun, D. Ushizima, M. Venturini, E.J. Wallén
    LBNL, Berkeley, USA
  Funding: This research is funded by the US Department of Energy (BES & ASCR Programs) and supported by the Director of the Office of Science of the US Department of Energy under Contract No. DEAC02-05CH11231.
In state-of-the-art synchrotron light sources the overall source stability is presently limited by the achievable level of electron beam size stability. This source size stability is presently on the few-percent level, which is still 1–2 orders of magnitude larger than already demonstrated stability of source position/angle (slow/fast orbit feedbacks) and current (top-off injection). Until now source size stabilization has been achieved through corrections based on a combination of static predetermined physics models and lengthy calibration measurements (feed-forward tables), periodically repeated to counteract drift in the accelerator and instrumentation. We now demonstrate for the first time* how application of machine learning allows for a physics- and model-independent stabilization of source size relying only on previously existing instrumentation in ALS. Such feed-forward correction based on neural networks that can be continuously online-retrained achieves source size stability as low as 0.2 microns rms (0.4%) which results in overall source stability approaching the sub-percent noise floor of the most sensitive experiments.
*Phys. Rev. Lett. 123, 194801 (2019)
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Alternating the Helicity of X-Ray Photons from an Undulator at Unprecedented Speed  
  • K. Holldack, F. Armborst, J. Bahrdt, W. Frentrup, P. Goslawski, N. Pontius, M. Ries, A. Schälicke, M. Scheer, Ch. Schüssler-Langeheine
    HZB, Berlin, Germany
  X-ray circular dichroism (XMCD), one of the main tools of modern X-ray physics for studying magnetism, benefits enormously from the capability of a fast alterable helicity of circularly polarized X-ray photons. Here we present a novel method, which allows boosting the alternating frequency between right- and left-handed photons to the MHz regime, more than three orders of magnitude faster than present state-of-the-art technologies. The method is based on a twin elliptical undulator installed in a low emittance electron storage ring being operated in a novel mode. Here, the electron optics is tuned close to a resonance where the electron bunches are spatially separated in so-called transverse resonance island buckets (TRIBs). Propagating through the magnetic structures of the twin undulator, electrons from different islands emit photons of the same wavelength but of opposite helicity. Radiation from these two helicity components can be alternated as fast as 2 ns, given by the radio frequency of the accelerator cavity. In the present proof-of-principle experiment at BESSY II we demonstrate a XMCD measurement at the L2,3 absorption edges of a Ni sample with an 800 ns helicity flip.  
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Present Status of Siam Photon Source  
  • P. Sudmuang, S. Boonsuya, T. Chanwattana, Ch. Dhammatong, P. Klysubun, A. Kwankasem, C.P. Preecha, T. Pulampong, V. Sooksrimuang, P. Sunwong, N. Suradet
    SLRI, Nakhon Ratchasima, Thailand
  The 1.2 GeV Siam Photon Source (SPS) has been delivering synchrotron radiation for both academic and industrial community in Thailand. Improvement of the SPS has been significantly archived in the past few years. The booster synchrotron and transfer-line have been successfully upgraded to 1.2 GeV in 2018, which is required for full energy injection. To accommodate more users from ASEAN countries, an additional insertion device namely a 3.5 T superconducting multipole wiggler has been installed and operated in 2018. Coupling correction scheme has been improved after modification of sextupole magnets with additional skew quadrupole coils. Longitudinal instability is also investigated by using streak camera.  
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