CERN, Geneva
Beam commissioning of the LHC started with injection tests in August 2008, and a circulating beam was obtained in little over 3 days in September 2008. Unfortunately a powering incident in one the eight LHC sectors set an abrupt end to the beam commissioning in 2008. This talk will review the LHC beam commissioning achievements. It will describe the repair the LHC sector affected by the incident and present the measures that have been taken to avoid similar incidents in the future. The commissioning steps foreseen for the 2009 run and towards LHC design performance will be outlined.
CERN, Geneva
The start-up of the LHC has provided the first field test for the concept, functionality and accuracy of FiDeL, the Field Description for the LHC. FiDeL is primarily a parametric model of the transfer function of the main field integrals generated by the series of magnets in the LHC powering circuits, from main optical elements to high-order harmonic correctors, both superconducting and normal-conducting magnets. In addition, the same framework is used to predict harmonic errors of both static and dynamic nature, and forecast appropriate corrections. In this paper we give a description of the level of detail achieved in the model and the rationale adopted for the LHC start-up. Beam-based measurements have been used for an assessment of the first-shot accuracy in the prediction of the current setting for the main arc magnets*.
*The work reported has been performed by the authors and the FiDeL Team
CERN, Geneva
The LHC injection tests and first turn beam commissioning took place in late summer 2008, after detailed and thorough preparation. The beam commissioning of the downstream sections of the SPS-to-LHC transfer lines and the LHC injection systems is described. The details of the aperture measurements in the injection regions are presented together with the performance of the injection related equipment. The measured injection stability is compared to the expectations. The operational issues encountered are discussed.
CERN, Geneva
BNL, Upton, Long Island, New York
KEK, Ibaraki
For several years optics measurement and correction algorithms have been developed for the LHC. During 2008 these algorithms have been directly tested in the SPS and RHIC. The experimental results proving the readiness of the applications are presented.
CERN, Geneva
Following a series of injection tests, the first attempts to pass beam around both directions of the LHC were successful and led rapidly to circulating beam in the counter clockwise direction (beam 2) and many turns of beam 1. Unfortunately the beam commissioning was curtailed by the incident in sector 34. However, measurements performed during this first commissioning period should that the magnet model of the machine had delivered optics close to nominal, and also very good performance of beam instrumentation and supporting software. Details of the machine set-up and the commissioning procedures are detailed. The measurements performed and the key results from this period are described.
CERN, Geneva
IN2P3 IPNL, Villeurbanne
INFN/LNL, Legnaro (PD)
Istituto Nazionale di Fisica Nucleare, Milano
The CNGS facility (CERN Neutrinos to Gran Sasso) aims at directly detecting muon-neutrino to tau-neutrino oscillations. An intense muon-neutrino beam (1017 muon-neutrino per day) is generated at CERN and directed over 732 km towards the Gran Sasso National Laboratory, LNGS, in Italy, where two large and complex detectors, OPERA and ICARUS, are located. After a brief overview of the facility, the major events since its commissioning in 2006 will be discussed. Emphasis will be given on the design challenges and operation constraints coupled to such a high-intensity facility summarizing the acquired experience. Highlights of the 2008 operations, which was the first complete year of physics in CNGS with 1.78·1019 protons delivered on target, will be presented.
CERN, Geneva
The Multi-Turn Extraction, a new type of extraction based on beam trapping inside stable islands in the horizontal phase space, has been commissioned during the 2008 run of the CERN Proton Synchrotron. Both single- and multi-bunch beams with a total intensity up to 1.4×1013 protons have been extracted with efficiencies up to 98%. Furthermore, injection tests in the CERN Super Proton Synchrotron were performed, with the beam then accelerated and extracted to produce neutrinos for the CERN Neutrino to Gran Sasso experiments. The results of the extensive measurement campaign are presented and discussed in details.
CERN, Geneva
Initial commissioning of the LHC beam dump system with beam took place in August and September 2008. The preparation, setting-up and the tests performed are described together with results of the extractions of beam into the dump lines. Analysis of the first detailed aperture measurements of extraction channels and kicker performance derived from dilution sweep shapes are presented. The performance of the other equipment subsystems is summarised, in particular that of the dedicated dump system beam instrumentation.
CERN, Geneva
BNL, Upton, Long Island, New York
KEK, Ibaraki
In 2008 beam successfully circulated in the LHC. Thanks to an excellent functioning of the BPM system and the related software, injection oscillations were recorded for the first 90 turns at all BPMs. The analysis of these data gives the unique opportunity of evaluating the periodic optics and inferring possible error sources.
CERN, Geneva
The 3 km long TI 8 transfer line is used to transfer 450 GeV proton and ion beams from the SPS to LHC collider. As part of a detailed optics investigation program the chromaticity of the transfer line was measured. Kick response data of the transfer line was recorded for various extraction energy offsets in the SPS. The quadrupolar and sextupolar field errors over the whole transfer line dipoles, a systematic error of the main quadrupole strengths and the initial momentum error were estimated by a fit. Using the updated model, the chromaticity of the line was then calculated.
ETH, Zurich
CERN, Geneva
The design and operation of the LHC Machine Protection System (MPS) implicates the trade-off between machine safety and beam availability, defined by MPS reliability in terms of missed emergency beam dumps and false dumps. A generic methodology, including almost 5000 MPS components modeled as individual objects and Monte Carlo simulation, has proved feasible and useful to address that trade-off*. The resulting MPS reliability numbers allow for the comparison of different system configurations with regard to safety and availability. In search of a solution to reduce the simulation time needed for addressing the rare events involved, an analytical description of the model has been developed. Its numerical solution provides an advanced verification of the simulation results and the basis for a rare event approach. The paper introduces the analytical description and the verification of the reliability numbers resulting from the simulations. It specifies to which extent the simulations can be replaced by the analytical model description and where the latter reaches its limits. Furthermore, the meaning of the analytical description as a basis for simulation time reduction is discussed.
*S.Wagner, Balancing Safety and Availability for an Electronic Protection System, ESREL08; S.Wagner, Reliability Analysis of the LHC Machine Protection System: Terminology and Methodology, EPAC08
CERN, Geneva
Fermilab, Batavia
Funding: Work partly supported by Fermilab, operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Through May to September 2008, further beam commissioning of the SPS to LHC transfer lines was performed. For the first time, optics and dispersion measurements were also taken in the last part of the lines, and into the LHC. Extensive trajectory and optics studies were conducted, in parallel with hardware checks. In particular dispersion measurements and their comparison with the beam line model were analysed in detail and led to propose the addition of a “dispersion-free” steering algorithm in the existing trajectory correction program.
CERN, Geneva
A series of LHC injection tests was performed in August and September 2008. The first saw beam injected into sector 23; the second into sectors 78 and 23; the third into sectors 78-67 and sectors 23-34-45. The fourth, into sectors 23-34-45, was performed the evening before the extended injection test on the 10th September which saw both beams brought around the full circumference of the LHC. The tests enabled the testing and debugging of a number of critical control and hardware systems; testing and validation of instrumentation with beam for the first time; deployment, and validation of a number of measurement procedures. Beam based measurements revealed a number of machine configuration issues that were rapidly resolved. The tests were undoubtedly an essential precursor to the successful start of LHC beam commissioning. This paper provides an outline of preparation for the tests, the machine configuration and summarizes the measurements made and individual system performance.
CERN, Geneva
The core task of the commissioning of the LHC technical systems was the individual test of the 1572 superconducting circuits of the collider, the powering tests. The two objectives of these tests were the validation of the different sub-systems making each superconducting circuit as well as the validation of the superconducting elements of the circuits in their final configuration in the tunnel. A wide set of software applications were developed by the team in charge of coordinating the powering activities (Hardware Commissioning Coordination) in order to manage the amount of information required for the preparation, execution and traceability of the tests. In all the cases special care was taken in order to keep the tools consistent with the LHC quality assurance policy, avoid redundancies between applications, ensure integrity and coherence of the test results and optimise their usability within an accelerator operation environment. This paper describes the main characteristics of these tools; it details their positive impact on the completion on time of the LHC Hardware Commissioning Project and presents usage being envisaged during the coming years of operation of the LHC.