Bibliographic Metadata

Beam emittance preservation and tuning in the FCC-ee lepton collider / Andreas Doblhammer
Additional Titles
Strahlemittanzkontrolle für den FCC-ee Lepton Kollisionsbeschleuniger
AuthorDoblhammer, Andreas
CensorBenedikt, Michael ; Holzer, Bernhard
PublishedWien, 2018
Description78 Blätter : Diagramme
Institutional NoteTechnische Universität Wien, Diplomarbeit, 2018
Zusammenfassung in deutscher Sprache
Abweichender Titel nach Übersetzung der Verfasserin/des Verfassers
Document typeThesis (Diplom)
Keywords (DE)Lepton Kollisionsbeschleuniger / Beschleunigerdesign / Emittanz / Synchrotronstrahlung
Keywords (EN)Lepton collider / lattice design / emittance / synchrotron radiation
URNurn:nbn:at:at-ubtuw:1-112062 Persistent Identifier (URN)
 The work is publicly available
Beam emittance preservation and tuning in the FCC-ee lepton collider [6.37 mb]
Abstract (English)

Following the recommendations of the European Strategy Group for High Energy Physics, CERN launched the Future Circular Collider Study (FCC) to investigate the feasibility of large-scale circular colliders for future high energy physics research. In the electron-positron collider of the study, FCC-ee, large synchrotron radiation losses cause the beam to have large local deviations from the design energy. These energy deviations cause orbit osets and create the so-called sawtooth eect, which causes particles to pass the magnets of the accelerator o-centre. This in turn causes perturbing magnetic elds via the feed-down eect. In order to correct the sawtooth eect and therefore the feed-down eect, the dipole magnets in the machine can be adjusted to the local beam energy in a process called dipole tapering. In the course of this thesis, dierent dipole magnet tapering scenarios are compared in terms of their eectiveness, feasibility and cost. Furthermore, this thesis focuses on tuning the horizontal beam emittance using wigglers. A small value of the beam emittance corresponds to a small beam cross-section, resulting in an increased likelihood of particle collisions and thus a higher luminosity. However, a number of perturbations can cause the beam emittance to deviate from its design value. In order to restore the design emittance, wigglers are implemented in the accelerator lattice. Dierent wiggler designs will be presented for both decreasing and increasing the value of the horizontal beam emittance. It will be shown, that an emittance decrease and increase by a factor of 10 % with an acceptable increase in synchrotron radiation is possible. The last section of this thesis focuses on chromaticity correction in FCC- ee and its inuence on the beam emittance. Chromaticity correction schemes with varying numbers of sextupole families are implemented into the FCC-ee lattice. Sextupole strengths are optimized using a downhill simplex algorithm in order to reduce chromaticities up to the fourthorder. Finally, emittance calculations after the application of each correction scheme show, that chromaticity correction schemes can have a signicant inuence on the beam emittance, which should be considered in the design of these correction schemes.

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