Nonlinear response of the photocathode of an x-ray streak camera to UV light

摘要

We have found that a potassium-iodide photocathode of an x-ray streak camera responds to UV light at (lambda)=308 nm. The photocathode surface work function, 6.5 eV, is larger than the 4 eV energy of the UV photon, hence the source of the response is interesting. We will present results on the response of a transmission type potassium-iodide photocathode to the UV light from a (lambda)308 nm, subpicosecond XeCl laser and from a (lambda)=326 nm HeCd laser. We will test for the nonlinearity of the yield to measure of the number of photons that are needed to be absorbed before a signal is recorded. We will present data on the effect of the UV irradiance on the yield, as well as on the temporal width of the recorded signal. We will give an explanation of the observation and its effect on the dynamic-range response of the streak-camera. We will show that the response is linear with the incident irradiance, up to an incident irradiance of 10(sup 8) W/cm(sup 2) and we will explain the observation.