Model of the electronic wake (blue surfaces) generated by an energetic proton (red sphere) traveling in an aluminum crystal (yellow spheres). The resulting change in electronic density is responsible for modification of chemical bonds between the atoms and consequently for a change in their interactions.
Lawrence Livermore National Laboratory researchers have for the first time identified a precise measurement of the amount of radiation damage that will occur in any given material.
"A full understanding of the early stages of the radiation damage process provides knowledge and tools to manipulate them to our advantage," said Alfredo Correa, a Lawrence Fellow from Lawrence Livermore National Laboratory.
Nuclear radiation leads to highly energetic ions that can penetrate large distances within matter, often leading to the accumulation of damage sites as the ions pass through the material.
During this process, the energetic ions eventually slow down as energy is lost by friction with the materials' electrons. Like a speedboat moving through a calm body of water, the passage of fast ions creates a disturbance in the electron density in the shape of a wake.
Correa along with colleagues from Los Alamos National Laboratory, the U.K., and Spain, have directly simulated this quantum friction of the electrons for the very first time.
The team simulated the passage of a fast proton through crystalline aluminum. By accounting for the energy absorbed by the electrons and the magnitude of the impulse given to the aluminum atoms, the team was able to predict the rate when the proton is stopped. This is a precise measure of the amount of radiation damage that will be produced in the material.
The new method opens up the possibility to predict the effect of radiation on a wide range of complex materials. The research not only applies to materials for nuclear applications, but also for materials related to the space industry, and new processing techniques for lasers and highly energetic ions. In biology and medicine, it also may contribute to understanding the effects of radiation on living tissues, both for damage and therapeutic processes.
In a broader sense, the new simulation capability represents the first step toward a unified method for the simultaneous simulation of electron and ion dynamics. The research appears in Physical Review Letters.