NRF-iThemba LABS: Where local scientists and global experts meet

The ATLAS Tile-Calorimeter (TileCal)-collaboration gathered for their collaboration meeting at NRF-iThemba LABS from Monday, 29 September until Friday, 3 October 2025. The meeting is hosted at an institution outside of CERN every two years and brings together researchers, engineers, and students to discuss operation, calibrations, performance and critical upgrades in ATLAS Hadronic TileCal detector. The meeting was coordinated under the auspices of the SA-ATLAS pillar of the SA-CERN consortium for which NRF-iThemba LABS is the institutional host.

The ATLAS is the largest general-purpose particle detector at the Large Hadron Collider (LHC) at CERN that is designed to study fundamental questions in particle physics such as the nature of the Higgs-boson and physics beyond the Standard Model including Dark Matter. The detector consists of various sub-detector systems of which the Tile Calorimeter is one. The calorimeter measures the energy of hadrons, jets, and the missing energy in the ATLAS-detector. The TileCal-collaboration has been in existence for 31 years, spanning the research and development phase and the construction phase, as well as the operational phase that was initiated in 2009/10. The current focus of the collaboration is on the operation and calibration of the existing system, and the future upgrade of the Tile Calorimeter.

The process of increasing the intensity of the LHC will commence in 2026 and will result in an increase in the luminosity by a factor of 7,5. This increased luminance will result in greater reaction rates as well as an increased flux of reaction products. The presence of a harsher radiation environment necessitates the need to upgrade the Tile Calorimeter and the associated infrastructure that includes the data-acquisition system. This will be needed to not only withstand the radiation environment, but also to manage the higher trigger rates.

The TileCal collaboration consists of more than 100 active participants that is represented by 21 Institutes of which the SA-ATLAS pillar is one. South Africa will be contributing 50% of the low-voltage power supplies that includes production, manufacturing, and testing, and 24% of the Tile pre-processors needed. Two of the boards needed for the pre-processors will be solely produced in South Africa. The biggest challenge linked to the production of the low-voltage power supplies is the radiation environment that introduces very stringent constraints on the manufacturing process to resist the very harsh radiation environment. On the other end, the pre-processors should be able to handle and transmit the very fast data signals. The bulk of the developmental work will be coordinated by the University of the Witwatersrand under the leadership of Prof Bruce Mellado, Director of the Wits Institute for Collider Particle Physics.

The original proposal for the upgrade of the Tile Calorimeter dates back to 2017 and the installation of the upgraded Tile Calorimeter is expected to start in 2026 during the long-shutdown of the LHC. It is expected that the installation will be completed by 2030 for a planned data-taking period lasting up to 2040.

The challenge is to play both the long and short game as young and emerging scientists are able to contribute to the development of the new technology, whilst also analysing existing data-sets.

“The development of more complex detection systems is set to allow the exploration of phenomenon not yet observed. The future is bright, not only due to the increased luminosity of the LHC, but also through the availability of new data sets,” said Tile Calorimeter Phase-II Upgrade Project Leader, Research Prof. Giulio Usai.

“We are happy with the progress made since our previous meeting and glad to report that there are no major complications,” said Dr Henric Wilkens, Senior Physicist and Tile System Project Leader at CERN.

Added Dr Mukesh Kumar, Deputy Director of Wits Institute for Collider Particle Physics, ATLAS scientist, and Chair of the TileCal Week 2025 outside CERN, “We, as the scientific community in South Africa, are extremely honoured to have hosted and chaired this meeting at NRF-iThemba LABS.”