EPAC08 - List of Authors (Ferrari, A.)

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Ferrari, A.

Paper	Title	Page
WEPP030	LHC Luminosity Upgrade: Protecting Insertion Region Magnets from Collision Debris	2584
	E. Y. Wildner, F. Cerutti, A. Ferrari, M. Mauri, A. Mereghetti CERN, Geneva
	The Large Hadron Collider built at CERN now enters a starting-up phase where with the present design luminosities up to 10³⁴ cm^-2 s^-1 will be reached after the running in phase. A possible upgrading of the machine to luminosities up to 10³⁵ cm^-2 s^-1 requires a completely new insertion region design, and will be implemented in essentially two phases. The energy from collision debris is deposited in the insertion regions and in particular in the superconducting magnet coils with a possible risk of quench. We describe here how to protect the interaction region magnets against this irradiation to keep the energy deposition below critical values estimated for safe operation. The constraint is to keep the absorber size as small as possible to leave most of the magnet aperture available for the beam. This can be done by choosing a suitable material and design minimizing the load on the cryogenic system. We will describe a proposal of a design for the phase I upgrade lay-out (i.e., luminosities up to 2.5 10³⁴ cm^-2 s^-1).
WEPP031	Energy Deposited in the High Luminosity Inner Triplets of the LHC by Collision Debris	2587
	E. Y. Wildner, F. Cerutti, A. Ferrari, C. Hoa, J.-P. Koutchouk CERN, Geneva F. Broggi INFN/LASA, Segrate (MI) N. V. Mokhov Fermilab, Batavia, Illinois
	The 14 TeV center of mass proton-proton collisions in the LHC produce not only interesting events for physics but also debris ending up in the accelerator equipment, in particular in the superconducting magnet coils. Evaluations of the deposited heat, that has to be transferred to the cryogenic system, have been made to guarantee that the energy deposition in the superconducting magnets does not exceed limits for magnet quenching and the capacity of the cryogenic system. The models of the LHC baseline are detailed and include description of, for energy deposition, essential elements like beam-pipes and corrector magnets. The evaluations made using the Monte-Carlo code FLUKA are compared to previous studies using MARS. For the comparison and consolidation of the calculations, a dedicated study of a simplified model has been made, showing satisfactory agreement.
WEPP071	Preliminary Exploratory Study of Different Phase II Collimators	2683
	L. Lari, R. W. Assmann, A. Bertarelli, C. Bracco, M. Brugger, F. Cerutti, A. Dallocchio, A. Ferrari, M. Mauri, S. Roesler, L. Sarchiapone, V. Vlachoudis CERN, Geneva J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith SLAC, Menlo Park, California L. Lari EPFL, Lausanne
	The LHC collimation system is installed and commissioned in different phases, following the natural evolution of the LHC performance. To improve cleaning efficiency towards the end of the low beta squeeze at 7TeV, and in stable physics conditions, it is foreseen to complement the 30 highly robust Phase I secondary collimators with low impedance Phase II collimators. At this stage, their design is not yet finalized. Possible options include metallic collimators, graphite jaws with a movable metallic foil, or collimators with metallic rotating jaws. As part of the evaluation of the different designs, the FLUKA Monte Carlo code is extensively used for calculating energy deposition and studying material damage and activation. This report outlines the simulation approach and defines the critical quantities involved.
WEPP072	Evaluation of Beam Losses and Energy Deposition for A Possible Phase II Design for LHC Collimation	2686
	L. Lari, R. W. Assmann, C. Bracco, M. Brugger, F. Cerutti, A. Ferrari, M. Mauri, S. Redaelli, L. Sarchiapone, V. Vlachoudis, Th. Weiler CERN, Geneva J. E. Doyle, L. Keller, S. A. Lundgren, T. W. Markiewicz, J. C. Smith SLAC, Menlo Park, California L. Lari EPFL, Lausanne
	The LHC beams are designed to have high stability and to be stored for many hours. The nominal beam intensity lifetime is expected to be of the order of 20h. The Phase II collimation system has to be able to handle particle losses in stable physics conditions at 7 TeV in order to avoid beam aborts and to allow correction of parameters and restoration to nominal conditions. Monte Carlo simulations are needed in order to evaluate the behavior of metallic high-Z collimators during operation scenarios using a realistic distribution of losses, which is a mix of the three limiting halo cases. Moreover, the consequences in the IR7 insertion of the worst (case) abnormal beam loss are evaluated. The case refers to a spontaneous trigger of the horizontal extraction kicker at top energy, when Phase II collimators are used. These studies are an important input for engineering design of the collimation Phase II system and for the evaluation of their effect on adjacent components. The goal is to build collimators that can survive the expected conditions during LHC stable physics runs, in order to avoid quenches of the SC magnets and to protect other LHC equipments.