Replacing Millions of Components with Light
Researchers at ETH Zurich and EPFL have unveiled PLATON, a particle detection prototype that swaps millions of individual detector components for light-field camera technology. By reconstructing 3D particle paths within unsegmented scintillators, the system offers a scalable, cost-effective alternative for high-energy physics experiments, from neutrino detection to advanced medical imaging.
The Bottleneck of Traditional Tracking
High-energy physics has long been constrained by the physical complexity of its instruments. Traditional experiments, such as the T2K neutrino-oscillation experiment in Japan, rely on highly segmented detectors. These systems require millions of individual scintillator cubes and thousands of optical fibers to trace particle trajectories. While effective, the architecture creates significant manufacturing and financial bottlenecks as researchers attempt to scale experiments to larger volumes.
The PLATON project, funded by the Swiss National Science Foundation and detailed in Nature Communications, proposes a radical departure from this complexity. Rather than subdividing detector material, the team utilizes a single, large, unsegmented block of scintillator. The system reconstructs particle paths by capturing scintillation light using plenoptic—or light-field—camera technology.
Capturing Photons with SPAD Precision
PLATON functions by recording not only light intensity but also the specific direction from which individual photons arrive. This is achieved by placing a micro-lens array (MLA), designed by Raytrix GmbH, between the main lens and the sensor.
At the heart of the system is the SwissSPAD2, a single-photon avalanche diode (SPAD) array sensor developed by the EPFL team. This sensor enables gated photon detection, allowing researchers to record light only within specific time windows. Such precision is vital for filtering out background noise, a necessity when isolating the faint signals produced by weakly interacting particles like neutrinos.
From Lab Tests to Cubic-Meter Scaling
Laboratory testing with a strontium-90 electron source confirmed that the prototype’s reconstruction capabilities align with detailed simulations. Remarkably, the system successfully reconstructed particle positions even with limited photon counts—down to five detected photons.
Simulations suggest that a 10x10x10 cm³ unsegmented detector could achieve spatial resolution below 1 millimeter. When modeled at a larger scale of one cubic meter, the system is expected to perform on par with state-of-the-art plastic scintillator detectors. The team, led by Professor Davide Sgalaberna and Professor Edoardo Charbon, is now working on an upgraded sensor version to provide sub-nanosecond timing for individual photons, further increasing tracking accuracy.
Clinical Potential in PET Scanning
The implications of this work extend well beyond fundamental physics. The ETH Zurich team has identified significant potential for the technology in medical diagnostics and has already filed three patents regarding the use of PLATON in positron emission tomography (PET) scanners.
By applying neural network-based image processing to light-field data, the technology could sharpen the precision of radioactive tracer tracking within the human body. This trajectory follows a historical pattern in particle physics, where experimental instrumentation—such as the World Wide Web at CERN or advancements in proton therapy—eventually drives innovation in clinical and commercial sectors.
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