TU Darmstadt / ULB / TUbiblio

Creation and Storage of Long and Flat Bunches in the LHC

Damerau, Heiko (2005)
Creation and Storage of Long and Flat Bunches in the LHC.
Technische Universität Darmstadt
Ph.D. Thesis, Primary publication

Abstract

To maximize the luminosity of the Large Hadron Collider (LHC), the collision of particle bunches with a uniform longitudinal particle density is considered for a future upgrade. The benefits of such bunches and their generation by means of special longitudinal beam manipulations are presented in this report. Three possible options are analyzed with respect to their potential luminosity gain at the beam-beam limit: short rectangular bunches held by radio frequency (RF) harmonics using multiples of the nominal RF frequency of 400.8 MHz, long and flat bunches held by multiples of 40.08 MHz, and so-called superbunches, confined by barrier buckets. The comparison of the three different approaches shows that flat bunches, with an intermediate bunch length of the order of several meters, are capable of producing a comparable luminosity to superbunches, while avoiding most of their inherent disadvantages. Possible schemes to create the bunches with uniform line density are studied and a longitudinal manipulation to combine a batch of ordinary bunches into a long and flat bunch is proposed. These RF gymnastics are based on well-proven techniques such as batch compression and bunch pair merging. Their advantages and disadvantages, including optimization with respect to degradation of the longitudinal particle density, are discussed in detail. Special attention is paid to the investigation of collective effects due to the large line charge density and the influence of the beam on the RF installation is also studied.

Item Type: Ph.D. Thesis
Erschienen: 2005
Creators: Damerau, Heiko
Type of entry: Primary publication
Title: Creation and Storage of Long and Flat Bunches in the LHC
Language: English
Referees: Wille, Prof. Dr. Klaus
Advisors: Weiland, Prof. Dr. Thomas
Date: 13 October 2005
Place of Publication: Darmstadt
Publisher: Technische Universität
Refereed: 1 September 2005
URL / URN: urn:nbn:de:tuda-tuprints-6129
Abstract:

To maximize the luminosity of the Large Hadron Collider (LHC), the collision of particle bunches with a uniform longitudinal particle density is considered for a future upgrade. The benefits of such bunches and their generation by means of special longitudinal beam manipulations are presented in this report. Three possible options are analyzed with respect to their potential luminosity gain at the beam-beam limit: short rectangular bunches held by radio frequency (RF) harmonics using multiples of the nominal RF frequency of 400.8 MHz, long and flat bunches held by multiples of 40.08 MHz, and so-called superbunches, confined by barrier buckets. The comparison of the three different approaches shows that flat bunches, with an intermediate bunch length of the order of several meters, are capable of producing a comparable luminosity to superbunches, while avoiding most of their inherent disadvantages. Possible schemes to create the bunches with uniform line density are studied and a longitudinal manipulation to combine a batch of ordinary bunches into a long and flat bunch is proposed. These RF gymnastics are based on well-proven techniques such as batch compression and bunch pair merging. Their advantages and disadvantages, including optimization with respect to degradation of the longitudinal particle density, are discussed in detail. Special attention is paid to the investigation of collective effects due to the large line charge density and the influence of the beam on the RF installation is also studied.

Alternative Abstract:
Alternative abstract Language

Die Kollision von Teilchenpaketen (Bunchen) mit gleichförmiger longitudinaler Ladungsverteilung wird als Ausbaumöglichkeit zur Maximierung der Luminosität des Large Hadron Colliders (LHC) angesehen. Die Vorteile solcher speziellen Teilchenbunche und ihre Erzeugung durch dedizierte longitudinale Strahlmanipulationen werden in dieser Dissertation untersucht. Drei mögliche Optionen werden unter Berücksichtigung der potentiellen Luminositäts-Erhöhung an der Strahl-Strahl-Stabilitätsgrenze analysiert: kurze, rechteckförmige Bunche, die von einem Multiharmonischen-Hochfrequenz-System (HF) mit Vielfachen der nominalen HF-Frequenz von 400.8 MHz gehalten werden, lange und flache Bunche, die mit HF-Systemen auf Vielfachen von 40.08 MHz gespeichert werden, und sogenannte Superbunche, die von Barrier-Buckets zusammengehalten werden. Der Vergleich der drei verschiedenen Varianten zeigt, dass bei der Kollision von flachen Bunchen mit einer intermediären Bunchlänge in der Größenordnung mehrerer Meter eine den Superbunchen nahezu gleichwertige Luminositätsausbeute erreicht werden kann. Gleichzeitig können jedoch einige inhärente Nachteile von Superbunchen vermieden werden. Mögliche Schemata zur Generierung von Bunchen mit gleichförmiger longitudinaler Ladungsdichte werden untersucht, und Strahlmanipulationen werden vorgeschlagen, um eine Kette von Bunchen zu einem langen und flachen Bunch zu vereinigen. Diese sogenannte Hochfrequenz-Gymnastik basiert auf hinlänglich erprobten Manipulationstechniken wie Batch-Kompression und Bunchpaar-Merging. Ihre Vor- und Nachteile, einschließlich der Optimierung unter Berücksichtigung der longitudinalen Teilchendichte, werden detailliert dargestellt und untersucht. Besondere Aufmerksamkeit wird der Berücksichtigung kollektiver Effekte auf Grund der hohen longitudinalen Ladungsdichte gewidmet, und die direkte Rückwirkung des Strahls auf die HF-Systeme wird analysiert.

German
Uncontrolled Keywords: Teilchenpaket, Batch-Kompression, Bunch-Vereinigung, Hochfrequenz-Gymnastik, longitudinale Manipulation, Strahl-Strahl Wechselwirkung, longitudinale Teilchendichte
Alternative keywords:
Alternative keywordsLanguage
bunch, batch compression, bunch merging, bunch pair merging, radiofrequency gymnastics, longitudinal manipulation, beam-beam interaction, longitudinal particle densityEnglish
Divisions: 18 Department of Electrical Engineering and Information Technology
Date Deposited: 17 Oct 2008 09:22
Last Modified: 26 Aug 2018 21:25
PPN:
Referees: Wille, Prof. Dr. Klaus
Refereed / Verteidigung / mdl. Prüfung: 1 September 2005
Alternative keywords:
Alternative keywordsLanguage
bunch, batch compression, bunch merging, bunch pair merging, radiofrequency gymnastics, longitudinal manipulation, beam-beam interaction, longitudinal particle densityEnglish
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