A Simplified Structural Model for the Analysis of Shape Deformations of the LHC Superconducting Dipole Cold Mass

In superconducting magnets for particle accelerators the mechanical accuracy along the length of the Cold Mass is one of the crucial parameters to guarantee the field quality needed by beam dynamics. This issue is made even more challenging in the twin-aperture LHC superconducting dipole where tolerances in the 0.3-1 mm range shall be obtained over a length of 15 m, for a Cold Mass of about 30 tonnes which, to minimize thermal losses, is supported in three points only. To reach this goal a number of geometrical checks and analyses are carried out at all stages of magnet assembly, handling, installation and operation. In this paper we present the structural model of the dipole based on which the checks and the analysis are performed, the nature of the geometrical imperfections identified and the temporary or permanent shape modifications predicted

Control of the Dipole Cold Mass Geometry at CERN to Optimize LHC Performance

The detailed shape of the 15 m long superconducting LHC dipole cold mass is of high importance as it determines three key parameters: the beam aperture, nominally of the order of 10 beam standard deviations; the connectivity of the beam- and technical lines between magnets; the transverse position of non-linear correctors mounted on the dipole ends. An offset of the latter produces unwanted beam dynamics perturbations. The tolerances are in the order of mm over the length of the magnet. The natural flexibility of the dipole and its mechanical structure allow deformations during handling and transportation which exceed the tolerances. This paper presents the observed deformations of the geometry during handling and various operations at CERN, deformations which are interpreted thanks to a simple mechanical model. These observations have led to a strategy of dipole geometry control at CERN, based on adjustment of the position of its central support (the dipole is supported at three positions, horizontally and vertically) to recover individually or statistically their original shape as manufactured. The implementation of this strategy is discussed, with the goal of finding a compromise between conflicting requirements: quality of the dipole geometry, available resources for corrective actions and magnet installation strategy whereby the geometry tolerances depend on the final magnet position in the machine

Automatic beam steering in the CERN PS complex

The recombination, transfer and injection of the four beams from the PS Booster to the PS Main Ring, have a high level of intri-cacy and are a subject of permanent concern for the operation of the PS Injector Complex. These tasks were thus selected as a test bench for the implementation of a prototype of an auto-matic beam steering system. The core of the system is based on a generic trajectory optimizer, robust enough to cope with imper-fect observations. The algorithmic engine is connected to pick-up monitors and corrector magnets and its decision can be val-idated by the operator through a graphics user interface. Auto-matic beam steering can only be ef®cient if the beam optics is fully con®rmed by experimental observations, a conditionwhich forces the systematic elimination of errors both in hardware and software. I

Automated Beam Optics Correction for Emittance Preservation

The operation of ever more complex high energy particle accelerators requires a powerful and user friendly architecture of application programs for machine physics. Among the possible applications, those concerning beam optics have been selected and it is shown that all the first order corrections, whether they are related to linear or non-linear fields, can be treated within a unified system. Examples of application are given for various types of beam steering in the PS comple

LHC Luminosity Upgrade: Protecting Insertion Region Magnets from Collision Debris

The Large Hadron Collider built at CERN now enters a starting-up phase where the present design luminosity up to 1034 cm-2 s-1 will be reached after the running in phase. A possible upgrading of the machine to luminosity up to 10^35 cm^-2 s^-1 requires a 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. Here we will describe design proposals for the phase I upgrade lay-out, i.e. luminosity up to 2.5 10^34 cm^-2 s^-1

Optimization of Neutrino Rates from the EURISOL Beta-Beam Accelerator Complex

The beta beam concept for the production of intense (anti-)neutrino beams is now well established. A baseline design has recently been published for a beta-beam facility at CERN. It has the virtue of respecting the known limitations of the CERN PS and SPS synchrotrons, but falls short of delivering the requested annual rate of neutrinos. We report on a first analysis to increase the rate using the baseline ions of 6He and 18 Ne. A powerful method to understand the functional dependence of the many parameters that influence the figure of merit for a given facility is available with modern analytical calculation software. The method requires that a symbolic analytical description is produced of the full accelerator chain. Such a description has been made using Mathematica for the proposed beta beam facility at CERN. The direct access from Mathematica to an ORACLE database for reading basic design parameters and re-injecting derived parameters for completion of the parameter list is both convenient and efficient

The information system for LHC parameters and layouts

The construction of the Large Hadron Collider, LHC, at CERN implies both the handling of a huge amount of information and the control of the coherence of this information. The LHC machine parameters have to be maintained coherent as the design evolves from the conceptual stage to the actual, installed, machine and have to be made available to all concerned. Design data is provided in many different formats from the machine builders, drawings, technical documents, meeting notes, lattice simulation input files, etc. The World Wide Web is being used to make the information accessible both at CERN and at the external collaborating laboratories. In this paper we describe the implementation of an Oracle database as the central common repository for machine parameters and of information for the automatic generation of CAD layout drawings and WWW pages. This system is integrated in a larger context, the EDMS system for the LHC project, which encompasses both the accelerator and the experiments

Parametric Study of Energy Deposition in the LHC Inner Triplet for the Phase 1 Upgrade

To be able to make a global parametric analysis and to have some basic understanding of the influence of critical parameters, scaling laws may be of help. For the design of the LHC insertion regions triplets, among the critical parameters the energy deposited in the superconducting triplet plays a fundamental role in avoiding magnet quench, too heavy load on the cryogenic system, and degradation of the materials due to radiation. The influence on energy deposition of the lay-out key parameters, such as the magnet apertures, the magnet lengths and positions, has been studied for beta* = 0.25