We present the response time measurements of a Cs2Te photocathode illuminated with two 100 fs duration, variable time separation laser pulses at 266 nm wavelength. The response time was confirmed in dispersive region downstream of a 12-cell standing wave S-band acceleration structure using a well-known RF zero-crossing technique. At the same time it was also measured by changing mechanical path-length difference between two micro-bunches. Both methods agree that Cs2Te photocathode time response is of the order of 250 fs and thereby it is possible to generate and control a THz sequence of relativistic electron bunches by a conventional S-band RF gun. This result further opens a possibility to construct wide-range tunable THz FEL.
@article{arxiv.1507.03302,
title = {Femtosecond response time measurements of a Cs2Te photocathode},
author = {A. Aryshev and M. Shevelev and Y. Honda and N. Terunuma and J. Urakawa},
journal= {arXiv preprint arXiv:1507.03302},
year = {2017}
}