Photoelectric quantum efficiencies and filter window absorption coefficients from 20 eV to 10 KeV

Abstract

Photodiodes with x-ray sensitive photocathodes are commonly used as broadband x-ray detectors in fusion plasma diagnostics. We have measured the photocathode quantum efficiency between 1–500 Å of common photocathode materials including aluminum, copper, nickel, gold, three forms of carbon, chromium, and cesium iodide. We have also studied the effects of the experimental environment and long-term cathode aging on the measured quantum efficiencies. In addition, we have measured the x-ray mass-absorption coefficients of x-ray filter windows of Kimfoil, aluminum, polypropylene, and Formvar in energy regions where data were previously unavailable. Measurements between 1–50 Å were performed at the Los Alamos Scientific Laboratory’s low-energy x-ray calibration facility, while the measurements between 50–500 Å were performed at the National Bureau of Standard’s synchrotron ultraviolet radiation facility.