A University of Liverpool physicist has received the Faraday Cup Award for his leadership in developing pioneering beam-monitoring technology for CERN’s Large Hadron Collider (LHC).
Professor Carsten Welsch, Head of Accelerator Science at the University and leader of the QUASAR Group, received the award for his work on the Beam Gas Curtain (BGC) monitor – an innovative diagnostic instrument developed through a long-standing collaboration between the University of Liverpool, CERN in Switzerland and the GSI Helmholtz Centre for Heavy Ion Research in Germany.
The Faraday Cup Award, presented at the International Beam Instrumentation Conference (IBIC 2026) in Whistler, Canada, celebrates outstanding innovation in particle beam diagnostics and instrumentation, recognising developments that have demonstrated and published performance.
Professor Welsch initiated research into gas-jet-based beam diagnostics around two decades ago and has led the development of the technology ever since.
Professor Welsch said: “I am delighted to receive this award after more than 20 years of research, and it is wonderful that it was awarded to the entire collaboration. Without the close and fruitful collaboration between our group at the Cockcroft Institute, CERN and GSI, and the commitment of generations of PhD students and postdoctoral researchers, this project would never have come so far.”
Measuring beams without disturbing them
Understanding the precise properties of particle beams is essential for the safe and effective operation of accelerators such as the LHC. However, conventional measurement techniques can become increasingly challenging when working with beams of exceptionally high intensity and energy.
The BGC monitor addresses this challenge by using a precisely shaped, extremely thin curtain of supersonic gas that crosses the particle beam. The interaction generates a faint light signal that enables researchers to measure the beam’s profile and quality without significantly disturbing it.
Over more than two decades, the technology has progressed from an early research concept to an operational instrument at the LHC. A BGC monitor installed at CERN has now been approved for continuous operation, providing high-precision measurements of proton and heavy-ion beams and supporting preparations for the High-Luminosity LHC.
The project has drawn on complementary expertise across the three partner organisations. Researchers at Liverpool led the development of the original concept, system design and associated measurement and analysis techniques. CERN provided expertise in implementing the technology within the demanding LHC environment, while GSI contributed specialist knowledge in beam instrumentation, imaging and simulation.
The technology also has potential applications beyond fundamental physics. Gas-curtain techniques have already been applied to the measurement of proton beams used in cancer therapy, while similar non-invasive diagnostics could play an important role in future accelerator facilities, where increasingly powerful beams require precise measurements with minimal disruption.
The BGC project was supported by the Science and Technology Facilities Council (STFC) and CERN.