CERN Accelerating science

 HiLumi-LHC moves on to construction phase
by Agnes Szeberenyi and Alessia Barachetti (CERN)

October 2015 was a turning point for the High Luminosity LHC (HL-LHC) project, marking the end of the European-funded HiLumi LHC Design Study activities, and the transition to the main hardware prototyping and industrialization phase, which is also reflected in the redesigned logo that was recently presented. The green light was given between 26 and 30 October 2015, when more than 230 experts from all over the world gathered at CERN to attend the 5th Joint HiLumi/LARP Annual Meeting.

During five days of intense plenary meetings and working sessions, a first version of the Technical Design Report was approved and released. The document, following the Preliminary Design Report issued in 2014, describes in detail how the LHC upgrade programme will be carried out. During the meeting, the seventeen Work Packages that over these four years worked to address the technological and technical challenges related to the upgrade also presented the main outcomes of their work.

5th Joint HiLumi LHC-LARP Annual Meeting. Image credits: CERN

The accelerator physics and performance team reported on the parameter sets and machine optics that would allow HiLumi LHC to reach the very ambitious performance target of an integrated luminosity of 250 fb-1 per year. The study of the beam-beam effects confirmed the feasibility of the nominal scenario based on the baseline b* levelling mechanism, providing sufficient operational margin for operation with the new ATS (Achromatic Telescopic Scheme) at the nominal levelling luminosity of 5×1034 cm-2s-1, with possibility to reach up to 50% more. The magnet design activity launched the hardware fabrication of short models of the Nb3Sn quadrupoles’ triplet (QXF), separation dipole, two-in-one large aperture quadrupole and 11 T dipole for Dispersion Suppressor collimators. Single short coils in the mirror configuration have already been successfully tested for the triplet. The first model of the QXF triplet containing two CERN and two LARP coils was assembled in the US in summer 2015 and is being tested this fall, while a short model of the 11 T dipole fabricated at CERN reached 12T. To protect the magnets from the higher beam currents, the collimation team was focusing on the design and verification of the new generation of collimators. The team presented a complete technical solution for the collimation in and around the insertions in HL-LHC, providing improved flexibility against optics changes. The crab cavities activity finalized and launched the manufacturing of the crab cavity interfaces, including the helium vessels and the cryo-module assembly. All cavity parts stamped in the US will be assembled and surface processed in the US in addition to electron-beam welding and testing. Last but not least, as part of their efforts to develop a superconducting transmission line, the cold powering activity hit a world record current of 20kA at 24K in a 40m long MgB2 electrical transmission line. The team has finalised the development and launched the procurement of the first MgB2 PIT round wires. This is an important achievement that will enable the start of a large cabling activity in industry, as required for the production of prototype Cold Powering System for the HL-LHC.

In the recently released open access HiLumi LHC book “The High Luminosity Large Hadron Collider. The New Machine for Illuminating the Mysteries of the Universe”, you can find out more about the High Luminosity LHC project, its technology and design as well as the challenges ahead.