| Paper | Title | Page |
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| MOPAB032 | Estimates of Collective Effects for the FCC-e+e− Pre-Booster Ring | 148 |
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| The FCC-e+e− injector complex needs to produce and to transport high-intensity e+ and e- beams at a fast repetition rate for topping up the collider at its collision energy. Two different options are under consideration as pre-accelerator before the bunches are transferred to the high-energy booster: either using the existing SPS machine or designing a completely new ring. The purpose of this paper is to present the studies of collective effects with analytical estimates for both the pre-booster ring design options including space charge (SC), longitudinal micro-wave instability (LMI), transverse mode coupling instability (TMCI), ion effects, electron cloud (e-cloud), coherent synchrotron radiation (CSR), and intra-beam scattering (IBS). | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB032 | |
| About • | paper received ※ 17 May 2021 paper accepted ※ 27 May 2021 issue date ※ 15 August 2021 | |
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| MOPAB168 | Nanoplasmonic Accelerators Towards Tens of TeraVolts per Meter Gradients Using Nanomaterials | 574 |
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Funding: University of Colorado Denver Ultra-high gradients which are critical for future advances in high-energy physics, have so far relied on plasma and dielectric accelerating structures. While bulk crystals were predicted to offer unparalleled TV/m gradients that are at least two orders of magnitude higher than gaseous plasmas, crystal-based acceleration has not been realized in practice. We have developed the concept of nanoplasmonic crunch-in surface modes which utilizes the tunability of collective oscillations in nanomaterials to open up unprecedented tens of TV/m gradients. Particle beams interacting with nanomaterials that have vacuum-like core regions, experience minimal disruptive effects such as filamentation and collisions, while the beam-driven crunch-in modes sustain tens of TV/m gradients. Moreover, as the effective apertures for transverse and longitudinal crunch-in wakes are different, the limitation of traditional scaling of structure wakefields to smaller dimensions is significantly relaxed. The SLAC FACET-II experiment of the nano2WA collaboration will utilize ultra-short, high-current electron beams to excite nonlinear plasmonic modes and demonstrate this possibility. * doi:10.1109/ACCESS.2021.3070798 ** doi:10.1142/S0217751X19430097 *** indico.fnal.gov/event/19478/contributions/52561 **** indico.cern.ch/event/867535/contributions/3716404 |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-MOPAB168 | |
| About • | paper received ※ 11 May 2021 paper accepted ※ 08 June 2021 issue date ※ 20 August 2021 | |
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| TUPAB005 | Emittance Estimates for the Future Circular Collider | 1338 |
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| The alignment strategy of the FCC-ee has a large impact on its luminosity. Larger alignment tolerances result in increased coupling and a subsequently higher vertical emittance. At the same time, tighter alignment tolerances around the 100 km ring are a major cost driver. This paper applies analytical emittance estimate methods to the FCC-ee and compares their predictions to data from simulations with different alignment tolerances. These methods can be used to help understand the impact of misalignments of certain magnet groups and to come up with an efficient alignment strategy. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB005 | |
| About • | paper received ※ 16 May 2021 paper accepted ※ 14 June 2021 issue date ※ 26 August 2021 | |
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| TUPAB010 | Impact of Bunch Current on Optics Measurements in SuperKEKB | 1356 |
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| SuperKEKB has recently achieved the world record instantaneous luminosity of 2.8 × 1034 \si{cm-2s-1} and aims at reaching a target luminosity of about 6 × 1035 \si{cm-2s-1}. To accomplish this goal it is planned to increase beam currents up to §I{3.6}{A} and §I{2.6}{A} for the positron and the electron ring, respectively. Increasing the beam currents and, in particular, the number of leptons per bunch, can impact the optics parameters obtained by turn-by-turn measurements, such as the betatron tune or phase advance. Optics measurements performed at various bunch currents can give first indications of possible intensity dependent effects. In this paper, the effect of varying bunch current on optics measurements at SuperKEKB is explored. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB010 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 10 June 2021 issue date ※ 30 August 2021 | |
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| TUPAB027 | Review of Accelerator Limitations and Routes to Ultimate Beams | 1397 |
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Funding: This work was supported in part by the European Commission under the HORIZON 2020 project I.FAST, no. 101004730. Various physical and technology-dependent limits are encountered for key performance parameters of accelerators such as high-gradient acceleration, high-field bending, beam size, beam brightness, beam intensity and luminosity. This paper will review these limits and the associated challenges. Possible figures-of-merit and pathways to ultimate colliders will also be explored. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-TUPAB027 | |
| About • | paper received ※ 16 May 2021 paper accepted ※ 02 August 2021 issue date ※ 23 August 2021 | |
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| WEPAB011 | Update on the Low Emittance Tuning of the e+/e- Future Circular Collider | 2601 |
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| The FCC-ee project studies the design of a future 100 km e+/e circular collider for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 1035 cm-2 s−1. To achieve ultra-low vertical emittance a highly effective emittance tuning scheme is required. In this paper, we describe a comprehensive correction strategy used for the low emittance tuning. The strategy includes Dispersion Free Steering, linear coupling compensation based on Resonant Driving Terms and beta beat correction utilising response matrices. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB011 | |
| About • | paper received ※ 18 May 2021 paper accepted ※ 23 June 2021 issue date ※ 02 September 2021 | |
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| WEPAB029 | Challenges for the Interaction Region Design of the Future Circular Collider FCC-ee | 2668 |
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Funding: This work was partially supported by the EC HORIZON 2020 project FCC-IS, grant agreement n.951754, and by the U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-76SF-00515. The FCC-ee is a proposed future high-energy, high-intensity and high precision lepton collider. Here, we present the latest developments for the FCC-ee interaction regions, which shall ensure optimum conditions for the particle physics experiments. We discuss measures of background reduction and a revised interaction region layout including a low impedance compact beam chamber design. We also discuss the possible impact of the radiation generated in the interaction region including beamstrahlung. |
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| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB029 | |
| About • | paper received ※ 11 May 2021 paper accepted ※ 23 June 2021 issue date ※ 30 August 2021 | |
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| WEPAB225 | Transverse and Longitudinal Single Bunch Instabilities in FCC-ee | 3153 |
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| Improving the accuracy of the impedance model of an accelerator is important for keeping beam instabilities and power loss under control. Here, by means of the PyHEAD- TAIL tracking code, we first review the longitudinal mi- crowave instability threshold for FCC-ee by taking into ac- count the longitudinal impedance model evaluated so far. Moreover, we present the results of beam dynamics simula- tions, including both the longitudinal and transverse wake- fields due to the resistive wall, in order to evaluate the influ- ence of the bunch length on the transverse mode coupling instability. The results of the transverse beam dynamics are also compared with the Vlasov solver DELPHI. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-WEPAB225 | |
| About • | paper received ※ 10 May 2021 paper accepted ※ 01 July 2021 issue date ※ 18 August 2021 | |
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| THPAB233 | Could "Flakes" of Neutral Paramagnetic or Dipolar Molecules Explain Beam Losses in the LHC? | 4254 |
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| "Flakes" of neutral water or oxygen molecules carrying an electric or magnetic dipole moment can be attracted and trapped by the electromagnetic field of the circulating LHC proton beam. The possible presence of such flakes in the vacuum system could explain beam losses and beam instabilities encountered during the 2017 and 2018 LHC runs, and the observed effect of an external magnetic field. | ||
| DOI • | reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2021-THPAB233 | |
| About • | paper received ※ 09 May 2021 paper accepted ※ 12 July 2021 issue date ※ 02 September 2021 | |
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