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Sammut, N. J.

Paper Title Page
WEPD031 Dependence of the Static and Dynamic Field Quality of the LHC Superconducting Dipole Magnets on the Pre-cycle Ramp Rate 2479
 
  • N. J. Sammut, L. Bottura, G. Deferne, W. Venturini Delsolaro, R. Wolf
    CERN, Geneva
  • N. J. Sammut
    University of Malta, Faculty of Engineering, Msida
  
  The allowed multipoles in the Large Hadron Collider (LHC) superconducting dipole magnets decay whilst on a constant current plateau. It is known that the decay amplitude is largely affected by the powering history of the magnet, and particularly by the pre-cycle flat top current and duration and the pre-injection preparation duration. Recently, it was observed that the decay amplitude is also highly dependent on the pre-cycle ramp rate, which has an indirect effect also on the sample of data taken at constant field along the magnet loadlines. This is an important consideration to be included in the Field Description for the LHC (FiDeL), to cope with the difference between the test procedure followed for series tests and the expected cycles during the machine operation. This paper presents the results of the measurements performed to investigate this phenomenon and describes the method included in FiDeL to represent this dependence.  
WEPD033 A Demonstration Experiment for the Forecast of Magnetic Field and Field Errors in the Large Hadron Collider 2482
 
  • N. J. Sammut, R. Alemany-Fernandez, L. Bottura, G. Deferne, M. Lamont, J. Miles, S. Sanfilippo, M. Strzelczyk, W. Venturini Delsolaro, P. Xydi
    CERN, Geneva
  • N. J. Sammut
    University of Malta, Faculty of Engineering, Msida
  
  In order to reduce the burden on the beam-based feedback, the Large Hadron Collider (LHC) control system is embedded with the Field Description for the LHC (FiDeL) which provides a forecast of the magnetic field and the multipole field errors. FiDeL has recently been extensively tested at CERN to determine main field tracking, multipole forecasting and compensation accuracy. In this paper we describe the rationale behind the tests, the procedures employed to characterize and power the main magnets and their correctors, and finally, we present the results obtained. We also give an indication of the prediction accuracy that the system can deliver during the operation of the LHC and we discuss the implications that these will have on the machine performance.  
WEPP005 Measurements and Effects of the Magnetic Hysteresis on the LHC Crossing Angle and Separation Bumps 2530
 
  • N. J. Sammut, H. Burkhardt, C. Giloux, W. Venturini Delsolaro, S. M. White
    CERN, Geneva
  • N. J. Sammut
    University of Malta, Faculty of Engineering, Msida
  
  The superconducting orbit corrector magnets (MCBC and MCBY) in the Large Hadron Collider (LHC) at CERN will be used to generate parallel separation and crossing angles at the interaction points during the different phases that will bring the LHC beams into collision. However, the field errors generated by the inherent hysteresis in the operation region of the orbit correctors may lead to unwanted orbit perturbations that could have a critical effect on luminosity. This paper presents the results obtained from dedicated cryogenic measurements on the orbit correctors from the simulated results on the impact of the hysteresis on the LHC orbit.  
WEPD033 A Demonstration Experiment for the Forecast of Magnetic Field and Field Errors in the Large Hadron Collider 2482
 
  • N. J. Sammut, R. Alemany-Fernandez, L. Bottura, G. Deferne, M. Lamont, J. Miles, S. Sanfilippo, M. Strzelczyk, W. Venturini Delsolaro, P. Xydi
    CERN, Geneva
  • N. J. Sammut
    University of Malta, Faculty of Engineering, Msida
  
  In order to reduce the burden on the beam-based feedback, the Large Hadron Collider (LHC) control system is embedded with the Field Description for the LHC (FiDeL) which provides a forecast of the magnetic field and the multipole field errors. FiDeL has recently been extensively tested at CERN to determine main field tracking, multipole forecasting and compensation accuracy. In this paper we describe the rationale behind the tests, the procedures employed to characterize and power the main magnets and their correctors, and finally, we present the results obtained. We also give an indication of the prediction accuracy that the system can deliver during the operation of the LHC and we discuss the implications that these will have on the machine performance.  
WEPD034 Main Field Tracking Measurement in the LHC Superconducting Dipole and Quadrupole Magnets 2485
 
  • P. Xydi, R. Alemany-Fernandez, L. Bottura, G. Deferne, M. Lamont, J. Miles, R. Mompo, M. Strzelczyk, W. Venturini Delsolaro
    CERN, Geneva
  • N. J. Sammut
    University of Malta, Faculty of Engineering, Msida
  
  One of the most stringent requirements during the energy ramp of the Large Hadron Collider (LHC) is to have a constant ratio between dipole-quadrupole and dipole-dipole field so as to control the variation of the betatron tune and of the beam orbit throughout the acceleration phase, hence avoiding particle loss. To achieve the nominal performance of the LHC, a maximum variation of ±0.003 tune units can be tolerated. For the commissioning with low intensity beams, acceptable bounds are up to 30 times higher. For the quadrupole-dipole integrated field ratio, the above requirements translate in the tight windows of 6 ppm and 180 ppm, while for dipole differences between sectors the acceptable error is of the order of 10-4. Measurement and control at this level are challenging. For this reason we have launched a dedicated measurement R&D to demonstrate that these ratios can be measured and controlled within the limits for machine operation. In this paper we present the techniques developed to power the magnets during the current ramps, the instrumentation and data acquisition setup used to perform the tracking experiments, the calibration procedure and the data reduction employed.  
WEPP005 Measurements and Effects of the Magnetic Hysteresis on the LHC Crossing Angle and Separation Bumps 2530
 
  • N. J. Sammut, H. Burkhardt, C. Giloux, W. Venturini Delsolaro, S. M. White
    CERN, Geneva
  • N. J. Sammut
    University of Malta, Faculty of Engineering, Msida
  
  The superconducting orbit corrector magnets (MCBC and MCBY) in the Large Hadron Collider (LHC) at CERN will be used to generate parallel separation and crossing angles at the interaction points during the different phases that will bring the LHC beams into collision. However, the field errors generated by the inherent hysteresis in the operation region of the orbit correctors may lead to unwanted orbit perturbations that could have a critical effect on luminosity. This paper presents the results obtained from dedicated cryogenic measurements on the orbit correctors from the simulated results on the impact of the hysteresis on the LHC orbit.