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About sLHC

General

The current LHC configuration is set up to produce proton–proton collisions at a centre-of-mass energy of 14 TeV and a luminosity of up to 1034 cm–2 s–1. The sLHC project (super LHC), however, aims for a tenfold increase in luminosity for 14 TeV proton–proton collisions, achieved through the successive implementation of several new elements and technical improvements that are scheduled for 2013–2018. These include the major replacement of several accelerators in the LHC proton-injector chain, upgrades of the LHC interaction regions and enhancements to the general-purpose experiments ATLAS and CMS. The accelerator part of the sLHC project consists of a set of sub-projects that fall into three categories: sLHC construction projects, sLHC project preparation studies and an sLHC luminosity upgrade network. The construction projects have been approved and the project execution has started. This part of sLHC is also indicated as Phase 1. Phase 1 is to be become operational in 2013-2014. The sLHC project preparation studies are preparing a proposal for approval by the CERN council in 2011-2012 and will, if approved, be transformed in construction projects that should be completed by 2017-2018. The sLHC luminosity network studies the options for further upgrades to be implemented after 2017. The sLHC project is led by a project leader who is assisted by a project office in the CERN accelerator sector.

More details in the Academic Training Lectures...

Linac4 project

The first bottleneck in the present layout occurs with the injection of proton bunches from Linac2 into the Booster. Protons are injected at 50 MeV by a multiturn injection process that inherently dilutes the beam brightness (the current within a given emittance). Much can be gained from using H– particles in the linac followed by injection in the Booster using a charge-exchange technique that removes excess electrons. This method avoids a dilution of beam brightness and directly translates into a luminosity increase in the LHC. Capturing and accelerating the now more brilliant beam requires an energy increase in the linac, thus reducing the beam self-repulsion in the Booster. This justifies the present 50 MeV proton linac (Linac2) being replaced by a new 160 MeV linac (Linac4) operated with H– ions. Secondly to the performance argument, the existing Linac2 is displaying worrying wear symptoms and should be replaced within the next 5 years.

LHC IR Upgrade Phase 1 project

Lowering the b* value in the interaction areas from 0.55 m to 0.25 m gives potentially a direct luminosity increase of a factor two. The limiting parameter at the moment is not the strength of the low-b quadrupoles but their aperture. At such low b* values the maximum size of the beam would be too large for the existing magnets. The new insertion quadrupoles will have a coil aperture of 120 mm, while the existing quadrupoles have a coil aperture of 70 mm.

SPL study

The injector machine for the PS2 will have a top energy of 4 GeV, in order to sufficiently reduce the intensity limiting space charge effects in the PS2. The machine will take the beam from Linac4 at 160 MeV and accelerate it in a superconducting linac up to 4 GeV. The SPL will be constructed in two phases. The first phase, L(ow)P(ower)-SPL (0.19 MW) will be optimized for LHC beams. An optional second phase will be to upgrade the SPL to a high power (3-9 MW) 5 GeV machine (HP-SPL) for a possible future neutrino facility.

PS2 study

The existing PS machine accelerates protons, intended for the LHC, from 1.4 GeV up to 26 GeV for injection into the SPS. The PS machine was commissioned in 1959 and despite the latest campaign of consolidation it has a finite lifetime. Before the end of the next decade the machine will have to be replaced. The PS is a combined function machine of a design typical for the 1950-ies. Over the last 5 decades its performance (intensity, emittance, particle types, etc.) has been upgraded well over the design values and the possibilities for further improvements are coming to an end. It is becoming urgent to design a new machine to replace the PS. In order to overcome the present injection intensity limits in the SPS the PS2 extraction energy will be 50 GeV.

SPS Upgrade study

The SPS experiences several intensity limitations (electron cloud, impedance, space charge at injection, injection aperture). Before a program can be started to ‘cure’ the limitations a thorough understanding of the effects is needed. To this aim an extensive measurement campaign on key SPS parameters is currently carried out.