Demonstration of induced current produced by a transited electron beam in an ultraviolet detector

Abstract An ultraviolet (UV) detector with a transmission photocathode is used to measure ultrashort electron beams with energies ranging from 1.8 to 3.0 keV. Both of the photocathode and collector are formed with planar transmission line structures, which could provide fast response time. The induced current in the collector produced by the transited electron beam is simulated using the Ramo theorem. The full width at half maximum (FWHM) of the pulses induced on the photocathode and collector are measured. While the photocathode is applied with -3.0 kV bias voltage, they are approximately 190 ps and 600 ps, respectively. The time of flight of the electron pulse from the photocathode to the collector is also measured, while the photocathode is applied with different bias voltage.