Nominal Cycle and Options

The LHC is starting operation with beam. The primary goal of CERN and the LHC community is to ensure that the collider is operated efficiently and that it achieves nominal performance in the shortest term. Since several years the community has been discussing the directions for maximizing the physics reach of the LHC by upgrading the experiments, in particular ATLAS and CMS, the LHC machine and the CERN proton injector complex, in a phased approach. The first phase of the LHC interaction region upgrade was approved by Council in December 2007. This phase relies on the mature Nb-Ti superconducting magnet technology with the target of increasing the LHC luminosity to 2 to 3 10^34 cm^-2s^-1, while maximising the use of the existing infrastructure. In this report, we present the goals and the proposed conceptual solutions for the LHC IR Upgrade Phase-I which include the recommendations of the conceptual design review.

IEEE Transactions on Appiled Superconductivity, 2005

The LHC ring will contain 1232 main dipole and 382 main quadrupole double aperture magnets. All main magnets are superconducting and employ Nb-Ti/Cu Rutherford type cables operated at 1.9 K. The dipole production has reached the equivalent of almost three octants of cold masses and nearly four octants of collared coils. The quadrupole production has reached 75 cold masses and over 150 bare magnets. The ramping up of large scale magnet production has posed several challenges which will be discussed, like: the coil size uniformity, coil pre-stress control, cold mass welding technique and the geometrical shape issues. The magnetic measurement results at warm will be presented together with their usage for the quality control in the production. The common features and differences of the three dipole producers will be discussed. The latest version of the production schedule will be presented.

LHC …, 2002

We discuss a possible staged upgrade of the LHC and of its injectors, with a view to increasing the luminosity from the nominal 10** 34 cm**-2s**-1 to 10** 35 cm**-2s**-1 in each of the two high-luminosity experiments. We also consider possible scenarios for an ...

2019

Run 2 of the CERN Large Hadron Collider (LHC) was successfully completed on 10th December 2018, achieving largely all goals set in terms of luminosity production. Following the first two-year long shutdown and the re-commissioning in 2015 at 6.5 TeV, the beam performance was increased to reach a peak luminosity of more than twice the design value and a colliding beam time ratio of 50%. This was accomplished thanks to the increased beam brightness from the injector chain, the high machine availability and the performance enhancements made in the LHC for which some methods and tools, foreseen for the High Luminosity LHC (HL-LHC) were tested and deployed operationally. This contribution provides an overview of the operational aspects, main limitations and achievements for the proton Run 2.

2003

After the commissioning and the first powering of the main circuits in autumn 2001 in its shorter version, the facility was completed to a full cell of LHC in the regular part of an arc and commissioned in July 2002. During this second run, which accumulated more than 4000 hours below 2 K, a very dense experimental program was carried-out to validate the final versions of the technical systems and design choices such as the bus-bar cables running along the magnet cold masses inside the cryostats. The program included the investigation of thermo-hydraulics of quenches, quench propagation, power converter controls and tracking between power converters. The cryogenic process dynamics were studied in length; predictive control techniques were tested and their performance assessed.

During the LHC Run I a very large amount of data has been collected, which can be used to improve the understanding of the behaviour of the accelerator. In this note, a preliminary analysis of the available data is reported, focusing on the stable beams data for p-p runs of the years 2011 and 2012. Not only time-evolution, but also correlation analysis of the key physical quantities such as peak luminosity, beam intensity etc. are reported here. A digression on the behaviour of the integrated luminosity will be made, while more details on this topic will be given in another paper.

2015

The HL-LHC schedule aims at the installation of the main HL-LHC hardware during the Long Shutdown 3 (LS3), together with the final upgrade of the experimental detectors (so-called upgrade Phase-II). However, a few items like the new cryogenic plant for P4, the 11 T dipole for the Dispersion suppressors (DS) collimation in P2 (for ions), the Superconducting (SC) links in P7 and several prototypes for the collimation, beam instrumentation and injection and beam dump systems are already foreseen for the Long Shutdown 2 (LS2). This paper describes the main activities that the project plans to carry out during LS2

2018

The value of the luminosity at which levelling is performed is calculated assuming a visible cross-section of 81 mb (corresponding to the inelastic proton-proton crosssection at a center of mass energy of 14 TeV), and the cross-section for the burn-off is conservatively assumed to be 111 mb (corresponding to the total proton-proton crosssection at a center of mass energy of 14 TeV) [1,2]. For both scenarios the main assumptions for the first version of this note [3] were:

2004

The following paper reviews the main challenges for bringing the LHC operation to nominal performance and summarizes proposals for future upgrade options. Future upgrade options could either facilitate the machine operation at nominal performance or possibly push the machine performance past the original nominal design values.