Extended Data Fig. 3: Transverse beam size.
From: Ultrafast visualization of an electric field under the Lorentz transformation
a, An image of the fluorescence generated by injecting a relativistic electron bunch into a scintillator. This fluorescence is proportional to the density profile of the electron bunch. The transverse electron beam profile shows axial symmetry around the z-axis. b, A horizontal lineout of the electron density profile obtained across the black dashed line in a. Black circles are the data points; this profile is fitted with a Gaussian function (red curve), and the beam size (diameter) is estimated as 3.5 mm (FWHM).
