| Paper | Title | Page |
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| TUYAA01 | High Currents Effects in DAΦNE | 82 |
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| DAΦNE, the Italian lepton collider, operates routinely with high intensity electron and positron colliding beams. The high current multi-bunch beams are stored in two independent rings, each of them 97 m long, and are distributed in 100 ’ 110 contiguous buckets out of the 120 available, spaced by only 2.7 ns. Since its construction, DAΦNE has been operated in different configurations which, overall, allowed to store current up to 1.4 A and 2.45 A in the positron and in the electron beam respectively. Still today DAΦNE holds the record for the highest electron beam current ever stored in particle factories and modern synchrotron radiation sources. The DAΦNE experience in terms of beam dynamics optimization aimed at achieving the high intensity beams is presented, with special emphasis on the e-cloud related issues, which represent the dominant effect limiting the positron beam current. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYAA01 | |
| About • | paper received ※ 24 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | |
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| TUYBA02 | Beam-beam Effects at High Energy e+e− Colliders | 106 |
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Funding: Russian Science Foundation, project N14-50-00080. One of the main requirements for future e+e− colliders is high luminosity. If the energy per beam does not exceed 200 GeV, the optimal choice will be a circular collider with "crab waist" collision scheme. Here, to achieve maximum luminosity, the beams should have a very high density at the IP. For this reason, radiation in the field of a counter bunch (BS - beamstrahlung) becomes an appreciable factor affecting the dynamics of particles. In particular, in the simulation for FCC-ee, new phenomena were discovered: 3D flip-flop and coherent X-Z instability. The first is directly related to BS. The second can manifest itself at low energy (where BS is negligible), but at high energies BS substantially changes the picture. In the example of FCC-ee, we will consider the features of beam-beam interaction at high-energy crab waist colliders, and optimization of parameters for high luminosity. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYBA02 | |
| About • | paper received ※ 19 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | |
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| TUYBA03 | Beam-beam Blowup in the Presence of x-y Coupling Sources for FCC-ee | 112 |
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| FCC-ee, the lepton version of the Future Circular Collider (FCC), is a 100 Km future machine under study to be built at CERN. It acquires two experiments with a highest beam energy of 182.5 GeV. FCC-ee aims to operate at four different energies, with different luminosities to fulfill physics requirements. Beam-beam effects at such a high energy/luminosity machine are very challenging and require a deep understanding, especially in the presence of x-y coupling sources. Beam-beam effects include the beamstrahlung process, which limits the beam lifetime at high energies, as well as dynamic effects at the Interaction point (IP) which include changes in the beta functions and emittances. In this report, we will define the beam-beam effects and their behaviours in the FCC-ee highest energy lattice after introducing x-y coupling in the ring. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYBA03 | |
| About • | paper received ※ 11 October 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | |
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| TUYBA04 | Some Issues on Beam-beam Interaction at CEPC | 116 |
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Funding: Project 11775238 supported by NSFC In this paper, the beam-beam study in CEPC CDR is briefly introduced. Some issues related with beam-beam interaction will be emphasized. The bunch lengthening due to impedance and beamstrahlung is simulated in a more self-consistent method. It is found that there exist very narrow stable working point space at W-mode during the CDR design study. We’ll show wider tune scan result. It is found that there exist some disagreement between dynamic aperture and beam lifetime. We try to define the so-called diffusion rate map to explain the cause. Some initial result for different lattice solution is shown. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-eeFACT2018-TUYBA04 | |
| About • | paper received ※ 26 September 2018 paper accepted ※ 19 February 2019 issue date ※ 21 April 2019 | |
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TUYBA05 |
Analytical Estimation of the Beam-beam Limited Dynamic Apertures and Liftimes | |
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| In this paper, we will discuss analytical estimation of the beam beam limited dynamic aperture and lifetimes, which are very important for modern electron positron designs and operations, such as CEPC and FCCee, super Tau Charm factories, Super KEK B and BEPC-II, etc. This dicussion is in complementary to the beam beam limit discussion from the beam beam heating induced diffussion effect. The combination of the two effects from beam-beam interaction, i.e. nonlinear beam beam induced dynamic aperture limitation effect and the heating induced diffusion effect, makes the discussion of beam beam effect complete. | ||
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TUPBB07 |
Experience with the Large Angle Beamstrahlung Monitor (LABM) at SuperKEKB | |
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| The LABM is a set of four telescopes pointed to the SuperKEKB Interaction Point (IP). It measures large angle beamstrahlung in the visible range, providing both polarization and spectral information. The experience with the LABM during both Phase I and Phase II is reviewed. It is shown that large angle beamstrahlung has been observed, and beam parameters are preliminarly extracted from the measured yields. The measurements during beam-beam controlled oscillations are also discussed. | ||
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