2008 JINST 3 S LHC Machine THE CERN LARGE HADRON COLLIDER: ACCELERATOR AND EXPERIMENTS. Lyndon Evans 1 and Philip Bryant (editors) 2

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1 PUBLISHED BY INSTITUTE OF PHYSICS PUBLISHING AND SISSA RECEIVED: January 14, 2007 REVISED: June 3, 2008 ACCEPTED: June 23, 2008 PUBLISHED: August 14, 2008 THE CERN LARGE HADRON COLLIDER: ACCELERATOR AND EXPERIMENTS LHC Machine Lyndon Evans 1 and Philip Bryant (editors) 2 European Organization for Nuclear Research CERN CH-1211, Genève 23, Switzerland lyn.evans@cern.ch ABSTRACT: The Large Hadron Collider (LHC) at CERN near Geneva is the world s newest and most powerful tool for Particle Physics research. It is designed to collide proton beams with a centre-of-mass energy of 14 TeV and an unprecedented luminosity of cm 2 s 1. It can also collide heavy (Pb) ions with an energy of 2.8 TeV per nucleon and a peak luminosity of cm 2 s 1. In this paper, the machine design is described. KEYWORDS: Acceleration cavities and magnets superconducting; Beam-line instrumentation; Hardware and accelerator control systems; Instrumentation for particle accelerators and storage rings high energy. 1 Corresponding author. 2 This report is an abridged version of the LHC Design Report (CERN ). c 2008 IOP Publishing Ltd and SISSA

2 Contents 1 Introduction 1 2 Main machine layout and performance Performance goals Performance limitations Beam-beam limit Mechanical aperture Maximum dipole field and magnet quench limits Energy stored in the circulating beams and in the magnetic fields Heat load Field quality and dynamic aperture Collective beam instabilities Luminosity lifetime Average turnaround time Integrated luminosity Lattice layout Corrector circuits Arc orbit corrector magnets MCB Chromaticity or lattice sextupoles, MS Lattice skew sextupoles, MSS Tune-shift or tuning quadrupoles, MQT Arc skew quadrupole corrector magnets, MQS Landau damping or lattice octupoles, MO Spool-piece corrector magnets High luminosity insertions (IR1 and IR5) Medium luminosity insertion in IR Beam cleaning insertions in IR3 and IR RF insertion in IR Beam abort insertion in IR Medium luminosity insertion in IR Magnets Overview Superconducting cable Main dipole cold mass Dipole cryostat Short straight sections of the arcs Orbit and multipole correctors in the arcs Insertion magnets Dispersion suppressors 31 ii

3 3.9 Matching section quadrupoles Matching section separation dipoles Low-beta triplets Compensator dipoles in ALICE and LHCb experiments 44 4 The RF systems and beam feedback Introduction Main 400 MHz RF Accelerating System (ACS) Staged 200 MHz Capture System (ACN) Transverse damping and feedback system (ADT) Low-level RF 53 5 Vacuum system Overview Beam vacuum requirements Beam vacuum in the arcs and dispersion suppressors Beam screen (figure 5.1) Cold interconnects (figures 5.2 and 5.3) Beam position monitor bodies and supports (figure 5.4) Beam vacuum in the insertions Beam screen Cold interconnections and Cold-Warm Transitions Room temperature beam vacuum in the field free regions Beam vacuum in room temperature magnets Bake-out and NEG activation Insulation vacuum Vacuum controls 63 6 Powering and protection Overview Powering circuits Powering equipment Current leads Electrical feedboxes Superconducting links Bus-bar systems Normal conducting cables Protection equipment Quench heater power supplies Energy extraction systems ka circuits A extraction equipment Cold diodes 75 iii

4 6.4.6 Controllers Supervision of the Quench Protection System (QPS) Operational aspects and reliability Electrical quality assurance Quench detectors Quench Heater Power Supplies (DQHDS) Energy extraction 78 7 Cryogenic system Overview General architecture Temperature levels Cooling scheme Arc and dispersion suppressor cooling loops Matching section cooling loops Inner triplet cooling loops Cryogenic distribution Refrigeration plants k refrigerators k refrigerators Cryogen storage and management 88 8 Beam instrumentation Beam position measurement Beam current transformers Beam loss system Transverse profile measurement Longitudinal profile measurement Luminosity monitors Tune, chromaticity, and betatron coupling General tune measurement system AC dipole High sensitivity tune measurement system Chromaticity measurement Betatron coupling measurement Long-range beam-beam compensation 97 9 Control system Introduction Architecture Overall architecture Network Equipment access 101 iv

5 9.3.1 The VME and PC Front End Computers The PLCs The supported fieldbuses The WorldFIP fieldbus The Profibus fieldbus Servers and operator consoles Machine timing and UTC Central beam and cycle management Timing generation, transmission and reception UTC for LHC time stamping UTC generation, transmission and reception NTP time protocol Data management Offline and online data repositories Electrical circuits Control system configuration Communication and software frameworks FEC software framework Controls Middleware Device access model Messaging model The J2EE framework for machine control The UNICOS framework for industrial controls The UNICOS object model Control room software Software for LHC beam operation Software requirements The software development process Software for LHC Industrial Systems Services for operations Analogue signals transmission Alarms Logging Post mortem Beam dumping System and main parameters Reliability MKD MKB MSD Vacuum system and TDE Post-mortem 123 v

6 Synchronisation Energy tracking Other protection Main equipment subsystems Fast-pulsed extraction magnets MKD Generator Fast-pulsed dilution magnets MKB Extraction septum magnets MSD Beam dump absorber block TDE Activation Beam injection Overview Injection septa Injection kickers Control system Beam instrumentation Injection chain Introduction LHC and SPS requirements Scheme to produce the LHC proton beam in the PS complex Space charge issues in PSB and PS LHC bunch train generation in the PS Initial debunching-rebunching scheme Multiple splitting scheme Overview of hardware changes LHC as an ion collider LHC parameters for lead ions Nominal ion scheme Early ion scheme Orbits and optical configurations for heavy ions Longitudinal dynamics Effects of nuclear interactions on the LHC and its beams Intra-beam scattering Synchrotron radiation from lead ions 150 LHC machine acronyms 153 Bibliography 154 vi