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Identifier

000427560

Title

Bunch characteristics evolution for lepton and hadron rings under the influence of the Intra-beam scattering effect

Alternative Title

Εξέλιξη χαρακτηριστικών δέσμης σωματιδίων σε επιταχυντικούς δακτυλίους λεπτονίων και αδρονίων υπό την επίδραση του φαινομένου ενδο-δεσμικής σκέδασης

Author

Παπαδοπούλου, Παρθένα-Στεφανία Γ.

Thesis advisor

Τομαράς, Θεόδωρος
Παπαφιλίππου, Ιωάννης

Reviewer

Τσιρώνης, Γεώργιος
Κομίνης, Ιωάννης
Μακρής, Κωνσταντίνος
Παυλίδου, Βασιλική
Τσάμης, Νικόλαος

Abstract

The physical parameter quantifying particle events' production and thereby the performance of a collider is the luminosity. High luminosities are reached by increasing the beam brightness, i.e. the intensity on a specific phase space volume (emittance). In this respect, the luminosity of hadron and lepton rings is limited by a combination of collective effects causing particle losses and emittance growth. In particular, Intra-beam scattering (IBS) impacts beam quality, through emittance growth. Several IBS theoretical models and their approximations exist, all assuming Gaussian beams. This thesis elaborates the optimization of the lattice design for a lepton ring and the study of the bunch characteristics evolution for a hadron ring, under the influence of IBS. Taking into account IBS, based on analytical results and numerical simulations, the optics design optimization is presented for the damping rings (DRs) of the Compact Linear Collider (CLIC). Specifically, aiming to reduce the betatron emittance of the DRs, dipoles whose magnetic field varies longitudinally are used together with high-field SC wigglers. Based on measurements and Monte-Carlo simulations, the interplay between IBS and radiation effects is also studied for the Large Hadron Collider (LHC), in view of understanding the bunch parameters evolution that determine the delivered luminosity. For the LHC bunch profiles which are observed to be non-Gaussian along the LHC energy cycle, appropriate fitting functions are used in order to describe accurately the distributions. In addition, the impact of the non-Gaussian distributions on the estimation of the beam size and thus, of the luminosity is studied. The importance to develop analytical formulas and simulation tools that calculate IBS for any distribution is underlined.

Language

English

Subject

Accelerator physics

Beams

CLIC

Cern

LHC

Δέσμη σωματιδίων

Επιταχυντές

Φυσική επιταχυντών

Issue date