| Paper | Title | Page |
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| MOPCH124 | Energy Deposition in Adjacent LHC Superconducting Magnets from Beam Loss at LHC Transfer Line Collimators | 336 |
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| Injection intensities for the LHC are over an order of magnitude above the damage threshold. The collimation system in the two transfer lines is designed to dilute the beam sufficiently to avoid damage in case of accidental beam loss or mis-steered beam. To maximise the protection for the LHC most of the collimators are located in the last 300 m upstream of the injection point where the transfer lines approach the LHC machine. To study the issue of possible quenches following beam loss at the collimators the entire collimation section in one of the lines, TI 8, together with the adjacent part of the LHC has been modeled in FLUKA. The simulated energy deposition in the LHC for worst-case accidental losses as well as for losses expected during a normal filling is presented. The operational implications are discussed. | ||
| TUPLS014 | Optics Flexibility and Dispersion Matching at Injection into the LHC | 1517 |
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| The LHC requires very precise matching of transfer line and LHC optics to minimise emittance blow-up and tail repopulation at injection. The recent addition of a comprehensive transfer line collimation system to improve the protection against beam loss has created additional matching constraints and consumed a significant part of the flexibility contained in the initial optics design of the transfer lines. Optical errors, different injection configurations and possible future optics changes require however to preserve a certain tuning range. Here we present methods of tuning optics parameters at the injection point by using orbit correctors in the main ring, with the emphasis on dispersion matching. The benefit of alternative measures to enhance the flexibility is briefly discussed. | ||
| TUPLS126 | Interaction of the CERN Large Hadron Collider (LHC) Beam with Carbon Collimators | 1798 |
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The LHC will operate at 7 TeV with a luminosity of 1034 cm-2s-1. Each beam will have 2808 bunches, with nominal intensity per bunch of 1.1x1011 protons. The energy stored in each beam of 362 MJ. In a previous paper the mechanisms causing equipment damage in case of a failure of the machine protection system was discussed, assuming that the entire beam is deflected into a copper target. Another failure scenario is the deflection of beam into carbon material. Carbon collimators and beam absorbers are installed in many locations around the LHC to diffuse or absorb beam losses. Since their jaws are close to the beam, it is very likely that they are hit first when the beam is accidentally deflected. Here we present the results of two-dimensional hydrodynamic simulations of the heating of a solid carbon cylinder irradiated by the LHC beam with nominal parameters, carried out using the BIG-2 computer code* while the energy loss of the 7 TeV protons in carbon is calculated using the well known FLUKA code**. Our calculations suggest that the LHC beam may penetrate up to 10 m in solid carbon, resulting in a substantial damage of collimators and beam absorbers.
*V. E. Fortov et al. Nucl. Sci. Eng. 123 (1996) 169. **A. Fasso et al. The physics models of FLUKA: status and recent development, CHEP 2003, La Jolla, California, 2003. |
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| WEPLS081 | Modifications to the SPS LSS6 Septa for LHC and the SPS Septa Diluters | 2565 |
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| The Large Hadron Collider required the modification of the existing extraction channel in the long straight section (LSS) 6 of the CERN Super Proton Synchrotron (SPS), including the suppression of the electrostatic wire septa. The newly set up fast extraction will be used to transfer protons at 450 GeV/c as well as ions via the 2.9 km long transfer line TI 2 to Ring 1 of the LHC. The girder of the existing SPS DC septa was modified to accommodate a new septum protection element. Changes were also applied to the septum diluter in the fast extraction channel in SPS LSS4, leading to the other LHC ring and the CNGS facility. The requirements and the layout of the new LSS6 extraction channel will be described including a discussion of the design and performance of the installed septum diluters. | ||
| TUODFI01 | The Final Collimation System for the LHC | 986 |
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| The LHC collimation system has been re-designed over the last three years in order to address the unprecedented challenges that are faced with the 360 MJ beams at 7 TeV. The layout of the LHC has now been fixed and a final approach for collimation and cleaning has been adopted. In total 132 collimator locations have been reserved in the two LHC rings and can be installed in a phased approach. Ninety collimators of five different types will be available for initial beam operation. The system has been fully optimized for avoiding quenches of super-conducting magnets during beam losses and for sufficient survival of beamline components against radioactive dose. The phased approach for LHC collimation is described, the various collimators and their functionalities are explained, and the expected system performance is summarized. | ||
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