Beyond LHC

Taking a closer look at LHC

When the results of the LHC commissioning starts to come in and exploration of the machine limits will start, a Task force should be put in place to develop a coherent plan for an LHC injector chain upgrade and a roadmap for superconducting magnet development and production.

In "Upgrading Superconductivity" some improvements are considered. Here, other aspects are taken into account in a very brief way.

Filling the LHC should be made as fast as possible. The basic period can be reduced, resulting in shorter cycles of the PSB and PS. Moreover the SPS acceleration time can also be shortened. This has to be implemented in the short term, keeping the average thermal load constant for the PS and SPS magnets until they are felt dependable enough.

All possible means to reduce beam loss should be pursued. The proposed project for a new multi-turn ejection from the PS is particularly relevant and deserves a high priority, because it is expected to reduce loss at 14 GeV/c by a factor of ~3 for the high intensity/high flux beam for the CERN Neutrino to Gran-Sasso experiment. Improvements must be implemented to prepare the injectors for delivering the ultimate type of beam to the LHC. The known bottlenecks must be treated by upgrading the equipment, and the suspected ones must be further studied. In the SPS , this includes increasing the peak RF power capability, reducing the impedance of the kickers and searching for other impedance sources. The future programme of consolidation of the SPS magnets, if decided, may provide the opportunity to improve impedance and reduce the electron cloud generation by modifying the vacuum chamber.

Studies in the SPS will help confirming the interest of a new ~50 GeV synchrotron replacing the PS.

In the medium term, the new linear accelerator Linac4 will remove the bottleneck at injection in the PSB. This will make possible the regular delivery of the ultimate beam to the LHC, reduce its filling time and positively contribute to the overall reliability of the injector complex.

We can summarize the necessary changes in the following image

In order to continue to probe the structure of matter, to understand what the smallest constituents of nature are and how they interact, it is necessary to think big and plan for the long term. Possibilities include machines that would dwarf the Large Hadron Collider, and neutrino beams crossing half a continent.

Maybe the new LHC could also be built in the future in Geneve.


A new tunnel of 80–100 km circumference could host a 100 TeV centre-of-mass energy-frontier proton collider (FCC-hh/VHE-LHC), with a circular lepton collider (FCCee/TLEP) as potential intermediate step, and a leptonhadron collider (FCC-he) as additional option. FCC-ee, operating at four different energies for precision physics of the Z, W, and Higgs boson and the top quark, represents a significant push in terms of technology and design parameters.

Pertinent R&D efforts include the RF system, topup injection scheme, optics design for arcs and final focus, effects of beamstrahlung, beam polarization, energy calibration, and power consumption. FCC-hh faces other challenges, such as high-field magnet design, machine protection and effective handling of large synchrotron radiation power in a superconducting machine. All these issues are being addressed by a global FCC collaboration. A parallel design study in China prepares for a similar, but smaller collider, called CepC/SppC.

(*) Taking from M. Benedikt, D. F. Zimmermann, Schulte, J. Wenninger, CERN. (2014) CHALLENGES FOR HIGHEST ENERGY CIRCULAR COLLIDERS. Proceedings of IPAC2014, Dresden, Germany MOXAA01 

See more in The Future Circular Collider






Xabier Cid Vidal, PhD in experimental Particle Physics for Santiago University (USC). Research Fellow in experimental Particle Physics at CERN from January 2013 to Decembre 2015. Currently, he is in USC Particle Physics Department ("Ramon y Cajal", Spanish Postdoctoral Senior Grants).

Ramon Cid Manzano, secondary school Physics Teacher at IES de SAR (Santiago - Spain), and part-time Lecturer (Profesor Asociado) in Faculty of Education at the University of Santiago (Spain). He has a Degree in Physics and in Chemistry, and is PhD for Santiago University (USC).



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 For the bibliography used when writing this Section please go to the References Section

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