Author: Solfaroli Camillocci, M.
Paper Title Page
MOPPC004 Experiments on the Margin of Beam Induced Quenches for LHC Superconducting Quadrupole Magnet in the LHC 124
  • C. Bracco, W. Bartmann, M. Bednarek, B. Goddard, E.B. Holzer, A. Nordt, M. Sapinski, R. Schmidt, M. Solfaroli Camillocci, M. Zerlauth, E.N. del Busto
    CERN, Geneva, Switzerland
  Protection of LHC equipment relies on a complex system of collimators to capture injected or circulating beam in case of LHC injection kicker magnet failures. However, for specific failures of the injection kicker, the beam can graze the injection protection collimators and induce quenches of downstream superconducting magnets. This occurred twice during 2011 operation and can also not be excluded during further operation. Tests were performed during Machine Development periods of the LHC to assess the quench margin of the quadrupole located just downstream of the last injection protection collimator in point 8. In addition to the existing Quench Protection System, a special monitoring instrumentation was installed at this magnet to detect any resistance increase below the quench limit. The correlation between the magnet and Beam Loss Monitor signals was analysed for different beam intensities and magnet current. The results of the experiments are presented in this paper.  
THPPD028 Studies on the LHC Superconducting Circuits and Routine Qualification of Their Functionalities 3563
  • M. Pojer, G. D'Angelo, R. Mompo, R. Schmidt, M. Solfaroli Camillocci
    CERN, Geneva, Switzerland
  The Large Hadron Collider (LHC) is systematically undergoing periods of maintenance stop (either 4-5 days stops or longer Christmas breaks), after which some of the superconducting circuits (or the totality of them) have to be re-commissioned to check the correct functionality of all powering and protection systems. Detailed procedures have been developed during the past few years and they have been optimized to increase powering tests efficiency, thus reducing beam downtime. The approach to the routine qualification of the LHC powering systems is described in this paper. During 2011 technical stops, some particular studies on the superconducting circuits were performed, to assess the quality of the superconducting splices of individually powered magnets and to study the quench propagation in the main magnet bus-bars. The methodology of these tests and some results are also presented.  
THPPD029 Machine Availability at the Large Hadron Collider 3566
  • M. Pojer, R. Schmidt, M. Solfaroli Camillocci, S. Wagner
    CERN, Geneva, Switzerland
  One of the most important parameters for a particle accelerator is its uptime, the period of time when it is functioning and available for use. In its second year of operation, the Large Hadron Collider (LHC) has experienced very high machine availability, which is one of the ingredients of its brilliant performance. Some of the strategies followed to increase MTBF are described in the paper. The approach of periodic maintenance stops, often questioned, is also discussed. Some considerations on the ideal length of a physics fill are also drawn.  
THPPD031 Measurement of the Residual Resistivity Ratio of the Bus Bars Copper Stabilizer of the 13 kA Circuits of the LHC 3572
  • A. Apollonio, S.D. Claudet, M. Koratzinos, R. Schmidt, A.P. Siemko, M. Solfaroli Camillocci, J. Steckert, H. Thiesen, A.P. Verweij
    CERN, Geneva, Switzerland
  After the incident of September 2008, the operational beam energy of the LHC has been set to 3.5 TeV, since not all joints of the superconducting busbars between magnets have the required quality for 7 TeV operation. This choice is based on simulations to determine the safe current in the main dipole and quadrupole magnets, reproducing the thermal behavior of a quenched superconducting joint by taking into account all relevant factors that affect a possible thermal runaway. One important parameter of the simulation is the RRR (Residual Resistivity Ratio) of the copper stabilizer of the busbar connecting superconducting magnets. A dedicated campaign to measure this quantity for the main 13kA circuits of the LHC on all sectors was performed during the Christmas stop in December 2010 and January 2011. The measurement method as well as the data analysis and results are presented in this paper.  
THPPP009 Automated Execution and Tracking of the LHC Commissioning Tests 3743
  • K. Fuchsberger, V. Baggiolini, M. Galetzka, R. Gorbonosov, M. Pojer, M. Solfaroli Camillocci, M. Zerlauth
    CERN, Geneva, Switzerland
  To ensure the correct operation and prevent system failures, which can lead to equipment damage in the worst case, all critical systems in the Large Hadron Collider (LHC), have to be tested thoroughly during dedicated commissioning phases after each intervention. In view of the around 7,000 individual tests to be performed each year after a Christmas stop, a lot of effort was already put into the automation of these tests at the beginning of LHC hardware commissioning in 2005, to assure the dependable execution and analysis of these tests. To further increase the productivity during the commissioning campaigns and to enforce amore consistent workflow, the development of a dedicated testing framework was launched. This new framework is designed to schedule and track the automated tests for all systems of the LHC and will also be extendable, e.g., to beam commissioning tests. This is achieved by re-using different, already existing execution frameworks. In this paper, we outline the motivation for this new framework and the related improvements in the commissioning process. Further, we sketch its design and present first experience from the re-commissioning campaign in early 2012.  
THPPP018 Operation of the LHC at High Luminosity and High Stored Energy 3767
  • J. Wenninger, R. Alemany-Fernandez, G. Arduini, R.W. Assmann, B.J. Holzer, E.B. Holzer, V. Kain, M. Lamont, A. Macpherson, G. Papotti, M. Pojer, L. Ponce, S. Redaelli, M. Solfaroli Camillocci, J.A. Uythoven, W. Venturini Delsolaro
    CERN, Geneva, Switzerland
  In 2011 the operation of the Large Hadron Collider LHC entered its first year of high luminosity production at a beam energy of 3.5 TeV. In the first months of 2011 the number of bunches was progressively increased to 1380, followed by a reduction of the transverse emittance, an increase of the bunch population and a reduction of the betatron function at the collision points. The performance improvements steps that were accumulated in 2011 eventually brought the peak luminosity to 3.6·1033 cm-2s−1. The integrated luminosity delivered to each of the high luminosity experiments amounted to 5.6 fb-1, a factor of 5 above the initial target defined in 2010. The operational experience with high intensity and high luminosity at the LHC will be presented here, together with the issues that had to be tackled on the road to high intensity and luminosity.