Duration measurement of laser-accelerated electron bunches using single-shot THz time-domain interferometry

Laser-plasma wakefield based electron accelerators are expected to deliver ultrashort electron bunches of unprecedented peak currents. However, their actual pulse duration has never been directly measured in a single-shot experiment. We present measurements of the ultrashort duration of such electron bunches by means of THz time-domain interferometry from coherent transition radiation. Using a ZnTe-based electro-optical setup and a 0.5J, 45fs, 800nm laser beam, we demonstrate that the duration of quasi-monoenergetic electron bunches from laser-wakefield acceleration is 32fs (FWHM) at a best fit and below 38fs at a 90% confidence level.