Luminosity Measurements and Two-Photon Physics with the DELPHI VSAT at LEP

Per M Jonsson

Research output: ThesisDoctoral Thesis (compilation)

Abstract

This thesis describes analysis of data from the DELPHI Very Small Angle Tagger (VSAT) calorimeter at LEP1. The VSAT consists of four Silicon-Tungsten calorimeter modules symmetrically positioned 7.7 meters away from the interaction point. It measures elastically scattered electrons and positrons, Bhabha events, within the polar angular region between 5-12 mrad. Trigger efficiency and reconstruction procedures for the energy and position measurement of VSAT data are described. Off momentum electron background and online luminosity monitoring with the VSAT are also discussed. The extraction of various beamparameters from analysis of the impact point of Bhabha pairs reveal the ability to measure variations in beam angles with a precision of 50 microrad. The relative luminosity measurement of the VSAT with a precision level of 0.1% for the 1993-1994 Z scan is also presented. Through the study of double-tag two-photon events, using the VSAT for measuring the energy of both scattered electrons, the behaviour of the total hadronic two-photon cross section is for the first time investigated up to invariant masses of 35 GeV.
Original languageEnglish
QualificationDoctor
Awarding Institution
  • Particle and nuclear physics
Supervisors/Advisors
  • [unknown], [unknown], Supervisor, External person
Award date1998 Mar 6
Publisher
Publication statusPublished - 1998

Bibliographical note

Defence details

Date: 1998-03-06
Time: 10:15
Place: Lecture hall B, Physics department

External reviewer(s)

Name: Erdmann, Martin
Title: Dr
Affiliation: DESY, Germany

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Subject classification (UKÄ)

  • Subatomic Physics

Free keywords

  • Elementary particle physics
  • kvantfältteori
  • Elementarpartikelfysik
  • quantum field theory
  • Fysicumarkivet A:1998:Jonsson

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