• L. Bottura, M.C.L. Buzio, N. Catalan-Lasheras, L. Deniau, M. DiCastro, S.D. Fartoukh, M. Giovannozzi, P. Hagen, J.-P. Koutchouk, M. Lamont, J. Miles, RV. Remondino, N.J. Sammut, S. Sanfilippo, F. Schmidt, D. Sernelius, R.J. Steinhagen, M. Strzelczyk, E. Todesco, R. Tomás, W. Venturini Delsolaro, L. Walckiers, J. Wenninger, R. Wolf, P. Xydi
  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

• E.H.M. Wildner, F. Cerutti, A. Ferrari, A. Mereghetti, E. Todesco
  CERN, Geneva
• F. Broggi
  INFN/LASA, Segrate (MI)

Recent studies show that the energy deposition for the LHC phase one luminosity upgrade, aiming at a peak luminosity 2.5 10³⁴ cm^-2s^-1, can be handled by appropriate shielding. The phase II upgrade aims at a further increase of a factor 4, possibly using Nb3Sn quadrupoles. This paper describes how the main features of the triplet layout, such as quadrupole lengths, gaps between magnets, and aperture, affect the energy deposition in the insertion. We show the dependence of the triplet lay-out on the energy deposition patterns in the insertion magnets. An additional variable which is taken into account is the choice of conductor, i.e. solutions with Nb-Ti and Nb3Sn are compared. Nb3Sn technology gives possibilities for increasing the magnet apertures and space for new shielding solutions. Our studies give a first indication on the possibility of managing energy deposition for the phase II upgrade.