Friday 21 March 2025
The latest upgrade to the ALICE experiment at CERN’s Large Hadron Collider (LHC) has resulted in a major boost to its tracking capabilities, allowing scientists to study the properties of subatomic particles with unprecedented precision.
The Inner Tracking System 2 (ITS2) is a crucial component of the ALICE detector, responsible for reconstructing particle trajectories and identifying their types. The previous iteration, ITS1, was already an impressive feat of engineering, but its successor has taken things to the next level.
One of the key improvements is the closer positioning of the innermost layer to the interaction point, allowing scientists to track particles with even greater accuracy. This, in turn, enables them to study weak decays and non-prompt cascades in unprecedented detail.
But it’s not just about precision – the ITS2 has also seen a significant reduction in noise levels. Fake hits, which can occur when the detector mistakenly registers a particle signal, are now less than 10^-6 per event per pixel. This is thanks to the implementation of advanced auto-recovery systems and strict noise criteria.
Another major innovation is the use of binary readout MAPS (Monolithic Active Pixel Sensors) in the inner barrel. These sensors can detect particles with far greater accuracy than their analogue counterparts, thanks to their ability to process signals in real-time.
The results are already starting to pay off. Scientists have used the ITS2 to study the properties of strange baryons, such as the Ξ- particle, which is a type of hadron made up of three quarks. By tracking its decay products, researchers can gain insights into the fundamental forces that govern the behavior of these particles.
The ITS2 has also enabled scientists to identify particles with unprecedented precision. By analyzing the time over threshold information from ALPIDE chips, researchers have been able to reconstruct particle tracks and identify their types using nothing more than data from MAPS sensors.
As the LHC continues to push the boundaries of human knowledge, the ITS2 is poised to play a key role in uncovering its secrets. With its advanced tracking capabilities and reduced noise levels, it’s an essential tool for scientists seeking to understand the fundamental nature of matter and energy. And as the experiment continues to produce new and exciting results, one thing is clear: the future of particle physics has never looked brighter.
Cite this article: “ALICE Experiment Upgrades Tracking Capabilities at CERNs Large Hadron Collider”, The Science Archive, 2025.
Large Hadron Collider, Alice Experiment, Inner Tracking System 2, Particle Tracking, Precision, Noise Reduction, Binary Readout Maps, Monolithic Active Pixel Sensors, Strange Baryons, Ξ- Particle, Hadron Physics.
Reference: A. Isakov, “ALICE ITS2: overview and performance” (2025).