ELECTRO-OPTIC SPECTRAL DECODING FOR SINGLE-SHOT CHARACTERISATION OF THE COHERENT TRANSITION RADIATION PULSES AT FLASH

We report preliminary single-shot electro-optic spectral decoding (EOSD) measurements of coherent transition radiation (CTR) pulses, generated by the electron bunches of the free-electron laser (FLASH) at DESY, Hamburg. The THz radiation is transported through a 20 m long beam-line from the accelerator tunnel to an experimental station outside. The measurements are performed in vacuum with a 0.5 mm ZnTe crystal in crossed-polarizer and near crossed-polarizer detection schemes. Pulses with complex structure and sharp peaks have been detected. The different components have full width at half maximum in the range 400-900 fs