Record-setting proton acceleration achieved using ultrathin graphene laser targets

Researchers at the University of Osaka, working with collaborators across institutions in Japan, Taiwan, the UK, and France, have used an ultrathin, large-area suspended graphene target to accelerate protons to 132 MeV, nearly half the speed of light, in a laser-driven ion acceleration experiment.

Laser-driven ion acceleration is being explored as a more compact alternative to conventional radio-frequency particle accelerators, with potential applications ranging from medicine to laboratory astrophysics. Pushing protons to higher energies generally means using thinner targets, but ultrathin targets are easily destroyed by the weak "prepulse" that precedes a laser's main high-intensity pulse. The team addressed this using large-area suspended graphene (LSG) targets just a few nanometers thick (4, 8, and 16 atomic layers), exploiting graphene's unusual combination of extreme thinness and durability to withstand the prepulse and remain intact until the main pulse arrived.