TV camera. A= streak tube photocathode, B= streak tube phosphor C= intensifier photocathode, D= channel plate E= intensifier phosphor, F= recording medium

A loss ABSTRACT: A loss of efficiency of P-11 and other ZnS phosphors at current densities below 200 mA/cm is well known for relatively long exciting electron pulses. There is no such direct results for electron pulses of shorter duration. It is necessary to have such data if streak tubes and cameras of the photo-electronic type are to be used for quantitative photometry. The authors in two previous papers have furnished evidence of phosphor efficiencies in streak cameras very considerably below the manufactureers quoted values. In this paper, we submit experimental data on the response of phosphors when used in streak cameras and excited by electron pulses only tens to thousands of picoseconds long. Both the rise and decay characteristics appear to be intensity dependent and the overall sensitivity of the phosphor is found to be low.