AIDA-THESIS-2014-003 AIDA - CERN Document Server AIDA Advanced European Infrastructures for Detectors

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  • AIDA-THESIS-2014-003

    AIDAAdvanced European Infrastructures for Detectors at Accelerators

    Academic Dissertation

    Design study of a low-energy extensionof the H8 beam-line at the CERN Super

    Proton Synchrotron

    Turner, M (TuGraz)

    01 May 2014

    The research leading to these results has received funding from the European Commissionunder the FP7 Research Infrastructures project AIDA, grant agreement no. 262025.

    This work is part of AIDA Work Package 8: Improvement and equipment of irradiationand test beam lines.

    The electronic version of this AIDA Publication is available via the AIDA web site or on the CERN Document Server at the following URL:

    AIDA-THESIS-2014-003

    http://cern.ch/aidahttp://cds.cern.ch/search?p=AIDA-THESIS-2014-003

  • Marlene Turner, BSc

    Design study of a low-energyextension of the H8 beam-line at theCERN Super Proton Synchrotron

    MASTER THESIS

    For obtaining the academic degreeDiplom-Ingenieur

    Master Programme of Technical Physics

    Graz University of Technology

    Supervisor:

    Dr. Ilias Efthymiopoulos

    CERN

    Assoc.Prof. Dipl.-Phys. Dr.rer.nat. Wolfgang Sprengel

    Institute of Materials Physics

    Graz, May 2014

    The work was supported by the AIDA, EC/FP7 Grant Agreement 262025

  • Acknowledgement:

    I would like to express my special appreciation and thanks to CERN andmy supervisor Ilias Efthymiopoulos for giving me the possibility to writemy Master Thesis at CERN in Geneva, Switzerland. Furthermore, I wantto thank him for encouraging my research and for allowing me to grow as aresearch scientist. His advice on both research as well as on my career havebeen exceptional. The work was supported by the AIDA, EC/FP7 GrantAgreement 262025.

    Even though I have not had the opportunity to work directly with LauGatignon (CERN), the impact of his help and advice on my own study isobvious throughout this thesis.

    Moreover, I have to thank my supervisor at the TU Graz Prof. WolfgangSprengel. Without his assistance and dedicated involvement, this thesiswould have never been possible. I would like to thank for his support andunderstanding.

    Getting through university required more than academic support, and Ihave many people to thank for listening to and, at times, having to tolerateme over the past five years. I cannot begin to express my gratitude and appre-ciation for their friendship. Lisa Marx and Barbara Geier, have been unwaver-ing in their personal and professional support during the time I spent at theUniversity. For many memorable evenings out and in, I must thank everyoneabove as well as Manuel Zingl, Gernot Kraberger, Patrick Falk, Martin Kup-per, Paul Christian, Georg Urstoger, Christian Rothel, Christian Neubauer,Oliver Hiden, Katharina Pirsch, Yisel Martinez Palenzuela and Harald Fitzek.

    Most importantly, none of this could have happened without my family.My mother and father, who offered their permanent encouragement. It wouldbe an understatement to say that, as a family, we have experienced some upsand downs in the past five years. Every time I needed some support they gaveit to me and I am forever grateful. This thesis stands as a testimony to yourunconditional love and encouragement.

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  • CONTENTS CONTENTS

    Contents

    1 Introduction 71.1 The CERN Accelerator Complex . . . . . . . . . . . . . . . . . 71.2 Goal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

    2 Beam Design Principles 102.1 Particle Production . . . . . . . . . . . . . . . . . . . . . . . . . 102.2 Beam Preparation and Transport . . . . . . . . . . . . . . . . . 13

    2.2.1 Main elements of the beam-line . . . . . . . . . . . . . . 132.3 Particle Selection . . . . . . . . . . . . . . . . . . . . . . . . . . 152.4 Very Low Energy Beam Designs . . . . . . . . . . . . . . . . . 162.5 Layout 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192.6 Layout 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202.7 Low-Energy Tertiary Beams . . . . . . . . . . . . . . . . . . . . 202.8 Beam Simulation Codes . . . . . . . . . . . . . . . . . . . . . . 21

    3 Beam Performance 243.1 Beam Optics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

    3.1.1 Muon Beam . . . . . . . . . . . . . . . . . . . . . . . . . 243.1.2 Pion Beam . . . . . . . . . . . . . . . . . . . . . . . . . 253.1.3 Electron Beam . . . . . . . . . . . . . . . . . . . . . . . 263.1.4 Acceptance of the Beam-lines . . . . . . . . . . . . . . . 263.1.5 Simulation Tests . . . . . . . . . . . . . . . . . . . . . . 29

    3.2 Particle Production and Target Study . . . . . . . . . . . . . . 303.2.1 Target Study for the Pion and Muon Beam . . . . . . . 313.2.2 Target Study for the Electron Beam . . . . . . . . . . . 323.2.3 Particle Background . . . . . . . . . . . . . . . . . . . . 33

    3.3 Muon Beam Optimization . . . . . . . . . . . . . . . . . . . . . 343.3.1 Optimization of the Muon Selection Process . . . . . . . 34

    3.4 Pion Beam Optimization . . . . . . . . . . . . . . . . . . . . . . 403.4.1 / ratios . . . . . . . . . . . . . . . . . . . . . . . . . 43

    3.5 Electron Beam Optimization . . . . . . . . . . . . . . . . . . . 45

    4 Beam to Experiment 504.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

    5 Summary 51

    Appendix 53Appendix I - Simulated Beam Rates . . . . . . . . . . . . . . . . . . 53Appendix II - Magnet Settings and Positions of the Elements . . . . 56

    4

  • CONTENTS CONTENTS

    Abstract

    Design study of a new low-energy beam in the H8 beam-line of CERN SPS toprovide 1 to 9 GeV/c electrons, pion and muons. Two layout configurationsare considered. Layout 1 brings the beam back to the central line after theparticle selection. In layout 2 the beam at the experiment is off-axis. Studiesof particle rates with optimized magnet settings and optics studies for beamtransmission and focusing to experiment were performed. Fluka simulationsof all beam-line options were made to estimate the spot-sizes, the particlerates and the backgrounds at the experiments. The results showed that thebackground is significantly lower in layout 2.

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  • CONTENTS CONTENTS

    Kurzfassung

    Fur die CERN SPS H8 beam-line wurde eine neue niederenergetischen Teilchen-strahlerweiterung designed und simuliert. Dieser Erweiterung ermoglicht dieBereitstellung von Elektronen, Pionen und Myonen in einem Energiebere-ich von 1 bis 9 GeV/c. Zwei verschiedene Layout-Konfigurationen wurdengetestet. Layout 1 bringt den Strahl nach der Teilchenselektion wieder zuruckauf die die Strahl-Mittellinie, wahrend der Strahl in Layout 2 die Mittelliniezum Experiment hin schrag uberkreuzt. Die Teilchenraten wurden fur ver-schiedene Magnet-Einstellungen gemessen und optimiert. Strahloptik-Studienfur den Strahltransport und die Strahl-fokussierung am Experiment wurdendurchgefuhrt. Fluka Simulationen zu allen Layout-Optionen wurden aus-gefuhrt um den Strahldurchmesser, die Teilchenraten und Hintergrundeventsam Experiment abzuschatzen. Die Ergebnisse zeigten, dass die Hintergrunde-vents fur Layout 2 signifikant geringer sind.

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  • 1 INTRODUCTION

    1 Introduction

    The H8 beam-line of CERN SPS (Super-Proton-Synchrotron) is locatedin the experimental hall north (North Area, EHN1) on the Prevessin site.The same hall hosts several beam-lines (H2, H4, H6, H8) and many dif-ferent experiments. The H8 beam-line presently provides 10-350 GeV/cmuon, pion or electron beams. For testing the prototype MIND andTASD detectors a tertiary beam extension of the beam-line is needed toprovide optimized beams of electrons (e), pions () and muons () inthe low-energy range of 1-9 GeV.

    1.1 The CERN Accelerator Complex

    Figure 1: Layout of the CERN Accelerator Complex. The H8 beam-line islocated in the North Area. [2]

    After extracting the 400 GeV/c primary proton beam from the SPS,bunches of 1013 protons hit the primary target (T4) producing a sec-ondary hadron beam. The H8 secondary beam has an energy range from

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  • 1.2 Goal 1 INTRODUCTION

    20-350 GeV, and can transport electrons, muons and pions to the EHN1experimental hall.

    The particle transport and focusing is controlled with magnetic fields.Quadrupole Magnets are used for focusing and defocussing, while dipolemagnets are used for bending the beam in an angle. A spectrometersystem combined with two collimators is used for momentum selection.For the design, simulation and calculation of the beam-line the programsTransport [3], Turtle [4], HALO [5] and Fluka [6] are used.

    Figure 2: View of the H8 and other beam-lines emerging from the primary(T4) target located at the North Area test beam facility. [7]

    1.2 Goal

    The goal of this Masters thesis is to design a system capable of providinglow-energy muon, pion and electron beams employing the H8 beam-linein an energy range from 1-9 GeV/c by improving the existing very-lowenergy extension used in the past experiments.

    The main tasks include:

    Design of the optics for the very-low energy muon, pion and electronbeam. Decide how many and which magnets should be used fortransportation and selection.

    Minimize the background (unwanted particles from halo and pion-decay) at the experiment. Testing of different design options.

    Maximize the acceptance of the beam-line. Varying of quadrupolemagnet positions and magnet apertures.

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  • 1.2 Goal 1 INTRODUCTION

    Maximize the / ratio at the experiment and optimize the purity ofthe low-energy muon beam. Select low-energy muons as effectivelyas possible whilst rejecting other particles and muons outside theenergy range.

    Optimize the target size and material for pion,muon and electronproducti