Overview
- The ATLAS Collaboration used newly introduced oxygen beams collided with LHC proton beams to recreate high-energy cosmic-ray interactions with Earth's atmosphere in a controlled experiment.
- The experiment captured millions of high-resolution images with a 100-million-pixel ATLAS camera that records collisions at up to 40 million frames per second to measure particle counts, energies, and angles.
- The Physical Review Letters paper, published Monday, 14 September 2026, presents the first laboratory measurements of these particle cascades—often called 'cosmic rainstorms'—and shows clear differences from widely used simulation predictions.
- Co-authors say the data demonstrate that standard air-shower models 'are actually very inaccurate,' which will force model recalibration and change how observatories infer the energy and origin of cosmic rays.
- Before this test physicists relied on computer simulations that gave divergent results; these new empirical measurements supply a direct benchmark for improving cosmic-ray interpretation and guiding follow-up experiments and telescope analyses.