Plate Nº 41 · recorded October 2, 2026
PhysicsReported finding
Protons Surf Laser-Made Waves to a Record 132 MeV
Osaka researchers accelerated protons to a record 132 MeV using graphene targets, long laser pulses, and an AI that spots rare proton signals with 99.2% precision.
By Priya Raman3 min read624 words
In brief
- University of Osaka researchers accelerated protons to 132 MeV, nearly half the speed of light, using a long-pulse laser and nanometer-thick graphene targets.
- Simulations indicate a propagating electrostatic wave in the plasma carried protons forward and boosted their energy for several picoseconds.
- A convolutional neural network achieved 99.2% precision in identifying rare high-energy proton signals among millions of detector images.
A team at the University of Osaka has accelerated protons to 132 MeV — nearly half the speed of light — by making them ride a moving electric field, an approach the researchers describe as proton "surfing." The result, published in Progress in Theoretical and Experimental Physics, sets an energy record for this class of laser-driven ion acceleration.
Laser-driven ion acceleration is attractive because it could offer a compact alternative to conventional particle accelerators, which span kilometers of steel and magnets. But the standard approach has a built-in weakness. The ultrathin films that boost ion energy are fragile, and the faint prepulse that arrives just before a laser's main high-intensity pulse can damage or destroy them before the real work begins.
The Osaka group sidestepped this problem by changing two things at once: the target material and the length of the laser pulse.
Why graphene matters
Graphene, a sheet of carbon just one atom thick, combines extreme thinness with unusual mechanical durability. That combination proved decisive. The nanometer-thick graphene targets withstood the laser's prepulse and stayed intact until the main pulse arrived, something more conventional foil targets often fail to do.
The team paired those graphene sheets with a relatively long laser pulse. Simulations showed that once the main pulse struck, it launched a propagating electrostatic wave — a traveling electric field — through the plasma, the cloud of electrically charged gas that forms when the laser hits the target. Energetic protons caught this wave and gained energy from it for several picoseconds, the extended ride that pushed them to record energies.
"By using ultrathin graphene layers and a relatively long laser pulse, we are able to accelerate protons for an extended period and reach a record energy of 132 MeV," says lead author Takumi Minami. "Our results show that long-duration acceleration can push proton energies beyond those typically achieved with shorter laser pulses."
Finding needles in millions of images
Producing high-energy protons is only half the battle. These particles are rare, and the signals they leave in detectors are faint and easy to confuse with background noise. Manually combing through the data would be impractical.
"The challenge is not only to produce these rare high-energy protons, but also to reliably identify them," says senior author Yasuhiro Kuramitsu. "We need to search millions of detector images for signals left by individual ions and distinguish the highest-energy protons from background noise."
To do this, the researchers trained a convolutional neural network — a type of artificial intelligence specialized in image recognition — to sift through the detector images. The network achieved 99.2% precision in one high-energy measurement and confirmed the presence of proton signals at 132 MeV.
Preliminary but promising
Some caution is warranted. The energy-boosting mechanism of the moving electrostatic wave comes from simulations, not direct measurement, and the results rest on rare events identified statistically rather than on a dense, reproducible beam. Whether the approach scales to higher energies or higher proton counts remains an open question.
Still, the study points to two parallel gains. Long-pulse laser acceleration extends the time protons can spend gaining energy, and AI-based detection makes rare high-energy events tractable to find. The team is now developing real-time online ion detectors.
The researchers suggest that combining these technologies could eventually let laser experiments analyze their own results and tune themselves mid-run — a step toward autonomous laser systems and new experimental possibilities for future research in plasma physics and accelerator development.
The paper is Takumi Minami et al., "Proton Surfing Acceleration via Propagating Electrostatic Waves Induced by Intense Laser Irradiation on Large-Area Suspended Graphene," Progress in Theoretical and Experimental Physics (2026), DOI: 10.1093/ptep/ptag130.
via Phys.org Physics (Source)
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Senior reporter covering industry trends and analytics at SciBeat.
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