| Paper |
Title |
Page |
| WEPD025 |
A Feasibility Study of Superconducting Dipole for the Early Separation Scheme of SLHC
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2461 |
| |
- G. Sterbini, D. Tommasini
CERN, Geneva
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In the framework of the LHC luminosity upgrade an early separation scheme is being studied for the final phase (L~1035 cm-2 s-1 with substantial changes in the IR). In this paper we compare a Nb3Sn and a Nb-Ti cos(θ) design: the aim is to explore the benefits and the limits of a compact solution with respect to the detector's constraints and the energy deposition issues. We propose to put the dipole system (cryostat and magnet) at a location starting at 6.8 m from the IP. The preliminary cross section, the achievable integrated field, the energy deposition on the magnet are presented and discussed.
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| WEPP013 |
Increasing the Integrated Luminosity of SLHC by Levelling via the Crossing Angle
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2554 |
| |
- J.-P. Koutchouk, G. Sterbini
CERN, Geneva
- K. Ohmi
KEK, Ibaraki
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With an increase of luminosity by a factor of 10, the luminosity lifetime in an upgraded LHC would be limited to a few hours. Furthermore, schemes relying on stronger focusing and reduced beam current increase (which are intrisically less dangerous for machine protection) are penalized by a very short lifetime of around 2 hours. We show in this paper that the "early separation" scheme and/or crab cavities scheme lend themselves to a very efficient luminosity leveling scheme. It allows constant luminosity over many hours as well as a significant increase of integrated luminosity above the performance announced so far. This is achieved by adjusting the crossing angle rather than the beam size by means of a bump closed inside the experimental straight section, i.e. operationally simple. The initially large crossing angle reduces the beam-beam tune shift, allowing an increased beam current and higher performance for lower pile-up in the detector and lower energy deposition in the triplet. The impact of the required large Piwinski angle is investigated.
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