The regular lattice of the large Hadron collider (LHC) will make use of more than 1600 main magnets and about 7600 corrector magnets, all superconducting and working in pressurized superfluid helium bath. This complex magnet system will fill more than 20 km of the LHC underground tunnel. In this paper an overview of the cold test program and quality assurance plan to qualify all LHC superconducting magnets will be presented. The quench training performance of more than 1100 LHC main dipoles and about 300 main quadrupoles, cold tested to date, will be reviewed. From these results an estimate of the number of quenches that will be required to start operation of the whole machine at nominal energy will be discussed. The energy level at which the machine could be operated at the early phase of the commissioning without being disturbed by training quenches will be addressed. The LHC magnet program required the development of many new tools and techniques for the testing of superconducting magnet coils, magnet protection systems, cryogenics, and instrumentation. This paper will also present a summary of this development work and the results achieved.

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Review of Quench Performance of LHC Main Superconducting Magnets

During the hardware commissioning in 2008 more than 30 training quenches were performed in the main dipole circuits in sectors 4-5, 5-6, and 7-8. An overview of these quenches will be given, and the quench levels will be compared to the training observed in SM-18. Quench propagation to adjacent dipoles will be discussed, and an estimate will be given of the total number of training quenches required to reach 6, 6.5, and 7 TeV in all eight sectors. INTRODUCTION During the hardware commissioning in 2008 more than 30 training quenches were performed in the main dipole circuits in sectors 4-5, 5-6, and 7-8. Each sector contains 154 dipoles (MB) assembled by three different companies, Alstom (ALS), Ansaldo (ANS), and Noell (NOE), see Table 1. Note that the numbers for sector 3-4 denote the original distribution which will alter due to the repair work after the incident. Table 1: Distribution of the dipole magnets per sector for each of the three cold mass assemblers

http://cds.cern.ch/record/1172379/files/AV_1_01.pdf

Training the dipoles

This note presents the final assessment of the static heat loads in the LHC arc cryostats, using different experimental methods during the first commissioning period in 2007. This assessment further develops and completes previous estimates made during the commissioning of sector 7-8 [1]. The estimate of the helium inventory, a prerequisite for the heat load calculation, is also presented. Heat loads to the cold mass are evaluated from the internal energy balance during natural as well as powered warm-ups of the helium baths in different subsector. The helium inventory is calculated from the internal energy balance during powered warm-ups and matched with previous assessments. Furthermore, heat loads to the thermal shield are estimated from the non-isothermal cooling of the supercritical helium in line E. The comparison of measured heat loads with previous estimates and with budgeted values is then presented, while their correlation with some important parameters like insulation vacuum pressure and some heat interception temperatures is proposed and discussed.

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Static heat loads in the lhc arc cryostats: final assessment

/pdf/study-of-atlas-sensitivity-to-the-single-top-s-channel-3vhkqb4zj3.pdf

Study of ATLAS sensitivity to the single top s-channel production

http://inspirehep.net/record/1088005/files/CERN-THESIS-2010-252.pdf

Study of ATLAS sensitivity to the single top s-channel production Dissertacao submetida para a obtencao do Grau de Mestre em F´õsica Nuclear e de Part´õculas

The main superconducting dipoles for the LHC are being stored outdoors for periods from a few weeks to several years after conditioning with dry nitrogen gas. Such a storage before installation in the 27 km circumference tunnel may affect not only the mechanical and cryogenic functionality of the cryodipoles but also their quench and field performance. A dedicated task force was established to study all aspects of long term behavior of the stored cryodipoles, with particular emphasis on electrical and vacuum integrity, quench training behavior, magnetic field quality, performance of the thermal insulation, mechanical stability of magnet shape and of the interface between cold mass and cryostat, degradation of materials and welds. In particular, one specifically selected cryodipole stored outdoors for more than one year, was re-tested at cold. In addition, various tests have been carried out on the cryodipole assembly and on the most critical subcomponents to study aspects such as the hygrothermal behavior of the supporting system and the possible oxidation of the Multi Layer Insulation reflective films. This paper summarizes the main investigations carried out and their results

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G.A. Izquierdo

Papers

Long Term Stability of the LHC Superconducting Cryodipoles After Outdoor Storage