Author: Nisbet, D.
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MOPMF050 LHC Operational Experience of the 6.5 TeV Proton Run with ATS Optics 216
 
  • M. Pojer, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, A. Calia, G.E. Crockford, S.D. Fartoukh, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, M. Hostettler, W. Höfle, Y. Le Borgne, D. Nisbet, L. Ponce, S. Redaelli, B. Salvachua, M. Solfaroli, R. Suykerbuyk, D.J. Walsh, J. Wenninger, M. Zerlauth
    CERN, Geneva, Switzerland
 
  In May 2017, the CERN Large Hadron Collider (LHC) restarted operations at 6.5 TeV using the Achromatic Telescopic Squeeze (ATS) scheme with a target beta-star of 40 cm in ATLAS and CMS. The number of bunches was progressively increased to a maximum of 2556 with emittances of 2.5 um. In August, several machine parameters had to be re-tuned to mitigate beam loss induced instabilities and maintain a steady increase of the instantaneous luminosity. The use of a novel beam type and filling pattern produced in the injectors, allowed filling the machine with very low emittance beam (1.5 um) achieving an equivalent luminosity with 1868 bunches. In September, the beta-star was further lowered to 30 cm (using, for the first time, the telescopic technique of the ATS) and the bunch intensity pushed to 1.25·1011 protons. In the last 3 months of 2017, the LHC produced more than 500 pb-1 of integrated luminosity per day, delivering to each of the high luminosity experiments 50.6 fb-1, 10% above the 2017 target. A general overview of the operational aspects of the 2017 proton run will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF050  
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MOPMF051 LHC Operational Scenarios During 2017 Run 220
 
  • B. Salvachua, M. Albert, R. Alemany-Fernández, T. Argyropoulos, E. Bravin, H. Burkhardt, G.E. Crockford, JCD. Dumont, S.D. Fartoukh, K. Fuchsberger, R. Giachino, M. Giovannozzi, G.H. Hemelsoet, W. Höfle, J.M. Jowett, Y. Le Borgne, D. Nisbet, M. Pojer, L. Ponce, S. Redaelli, M. Solfaroli, R. Suykerbuyk, D.J. Walsh, J. Wenninger, M. Zerlauth
    CERN, Geneva, Switzerland
 
  During 2017, the Large Hadron Collider LHC delivered luminosity for different physics configuration in addtion to the nominal 6.5 TeV proton-proton run. About 18.5 days were dedicated to commission and to deliver special physics to the experiments. Condifurations with large beta-star of 19 m and 24 m were prepared for luminosity calibration with Van de Meer scans. A proton-proton run at 2.51 TeV took place during the last weeks of November to provide reference data for the heavy ion (Pb-Pb, p-Pb) collisions at the same equivalent nucleon energy . A very short (0.5 days) but effective ion run was scheduled where the LHC saw the first Xe beams collissions and delivered around 3 ub-1 to ATLAS and CMS. The run ended with a low event pile-up run at 6.5TeV. This contribution summarizes the operational aspects and delivered targets for the different configurations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF051  
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WEPAF064 Dependable Implementation of the Beam Interlock Mechanism in CERN Power Converter Controllers 1975
 
  • M. Di Cosmo, Q. King, R. Murillo-Garcia, D. Nisbet, B. Todd
    CERN, Geneva, Switzerland
 
  At CERN a Beam Interlock System (BIS) protects accelerators from accidental and uncontrolled release of beam energy, avoiding machine downtime. Throughout the accelerator complex numerous critical subsystems, including power converters, interact with the BIS indicating their readiness for operation with beam. Power converters play a vital role in establishing operational conditions, and an unmitigated power converter malfunction could lead to damage to the machine. For example a bending magnet converter set at an incorrect current would result in an incorrect field strength, and beam passing through this may impact and damage the machine. A fast and dependable Beam Interlock Mechanism is required between power converters and BIS, verifying that voltage and current levels are within tolerances. This paper describes the design and realisation of the Beam Interlock Mechanism, based on CERN's Function Generator Controller (FGC), the central processing unit power converter control. Particular emphasis is placed on the system architecture required to assure the integrity of the power converter parameters, and the protection of the CERN accelerator complex.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF064  
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