The High-Luminosity Large Hadron Collider (HL-LHC) project aims to crank up the performance of the LHC in order to increase the potential for discoveries after 2029. The objective is to increase the integrated luminosity by a factor of 10 beyond the LHC’s design value.
Luminosity is an important indicator of the performance of an accelerator: it is proportional to the number of collisions that occur in a given amount of time. The higher the luminosity, the more data the experiments can gather to allow them to observe rare processes.
The High-Luminosity LHC, which should be operational from the beginning of 2029, will allow physicists to study known mechanisms in greater detail, such as the Higgs boson, and observe rare new phenomena that might reveal themselves. For example, the High-Luminosity LHC will produce at least 15 million Higgs bosons per year, compared to around three million from the LHC in 2017.
The High-Luminosity LHC project was announced as the top priority of the European Strategy for Particle Physics in 2013.
Its development depends on several technological innovations. The first phase of the project began in 2011 and was partly financed by the European Commission’s seventh framework programme (FP7). This first phase brought together many laboratories from CERN’s Member States, as well as from the US, Japan and Russia. The design study came to a close in October 2015 with the publication of a Preliminary Design Report (PDR), marking the start of the construction phase for the project at CERN and in industry. The HL-LHC Technical Design Report (TDR) was published in 2017 – reflecting the design from before the rescoping exercise in 2016 – and its final version in 2020. The civil-engineering work started in April 2018.
The project is led by CERN with the support of an international collaboration of 44 institutions in 20 countries - the vast majority in various European countries among which Italy, Spain, Sweden and the United Kingdom - and including a number of CERN’s non-Member States such as the United States, Japan and Canada.