Experimental Studies of Strong-field Quantum Electrodynamics

When a very intense laser collides with a highly energetic electron beam, gamma rays are emitted. Together with the extremely high fields from the laser, they can “break” the quantum vacuum and create matter-antimatter particle pairs, the process taking its energy from light via the famous equation E=mc2. This process of matter creation from light in extreme fields is important as it constitutes a fundamental test of our knowledge of the laws of nature in a largely unexplored territory, and because it is relevant in various research fields (astrophysics, laser-plasma interaction, future linear particle colliders). The E-320 experiment at SLAC aims to reach the so-called “Schwinger critical electric field” where such matter-antimatter creation becomes possible. The last measurements showed that the signal was very low and highlighted the need for better detectors. Those detectors would be used to measure scattered electrons losing their energy during the process, gamma rays and electron-positron pairs. This project will provide a fundamental test of our understanding of the laws of nature in an unexplored territory, and will likely lead to very high-profile experimental results of broad interest.