The LHC enters a long technical shutdown: at LIP, science continues
"Over the coming years, LIP teams will analyse the data already collected and prepare for the high-luminosity phase of the LHC."
The Large Hadron Collider (LHC), the world’s most powerful particle accelerator, ended its latest data-taking period on 29 June before entering Long Shutdown 3, known as LS3. This shutdown marks one of the most ambitious interventions in CERN’s accelerator complex since the construction of the LHC itself.
Over the next few years, there will be no particle beams circulating in the LHC. But that does not mean science will stop. On the contrary, an intense phase of maintenance, consolidation and detector upgrades is now beginning, paving the way for the high-luminosity phase of the LHC, the HL-LHC.
Since its first beams in September 2008, the LHC has transformed particle physics. Its best-known milestone came on 4 July 2012, when the ATLAS and CMS collaborations announced the discovery of the Higgs boson. Since then, LHC data have made it possible to test the Standard Model with great precision and to search for signs of as-yet unknown phenomena.
LIP in the next phase of ATLAS and CMS
As Portugal’s reference institution in experimental particle physics, LIP has taken part in CERN’s scientific programme for decades. In the ATLAS and CMS experiments, this participation now continues with the preparation of the detectors for the high-luminosity phase of the LHC.
In the ATLAS experiment, the Portuguese team will contribute to the upgrade of two key detector systems: the High Granularity Timing Detector (HGTD) and the TileCal hadronic calorimeter. The work will be carried out at LIP, in Lisbon and Coimbra, with strong involvement from Portuguese industry.
“In TileCal, Portugal is responsible for producing the new high-voltage distribution system, which will be relocated outside the detector, reducing exposure to radiation. In the HGTD, the team will develop electronics for the detector control system and filters for the high-voltage distribution. The work includes the development, connectorisation and installation of more than one thousand small-diameter high-voltage cables, the production of thousands of electronic boards and the corresponding quality control tests,” explains Patrícia Conde, coordinator of the ATLAS group at LIP.
In the CMS experiment, the LIP group is involved in several central components of the detector upgrade, including the Precision Proton Spectrometer (PPS), the precision timing detectors of the Barrel Timing Layer (BTL), and the electronics of the electromagnetic calorimeter, ECAL.
“The LIP CMS group is leading the development of the new Precision Proton Spectrometer, which has demonstrated, for the first time, the feasibility of operating a proton spectrometer close to the beam under high-luminosity conditions. The team is involved in the PPS upgrade, in particular in the precision timing detectors, and is also responsible for the design and construction of the readout system for the new Barrel Timing Layer, including a high-performance ASIC for time measurement. In collaboration with Portuguese industry, LIP has also developed a radiation-hard ASIC for the front-end electronics of ECAL and participates in studies for the integration of its modules,” explains Michele Gallinaro, coordinator of the CMS group at LIP.
More luminosity, more data, new challenges
These contributions address the main challenge of the next phase of the LHC. When it returns to operation, the HL-LHC is expected to increase the accelerator’s luminosity by up to ten times compared with its original design. This will make it possible to collect far more data and study the Higgs boson with unprecedented precision.
At the same time, the experiments will have to cope with much more demanding environments, facing dozens or even hundreds of proton collisions at the same time.
The gradual restart of the accelerator complex is scheduled from 2028, paving the way for the HL-LHC to enter operation in 2030. The next stage will bring more data, more demanding detectors and new questions about the fundamental structure of the Universe.
Images: CERN