Image plates as x-ray detectors in plasma physics experiments

Abstract

The performance of image plates based on the photostimulable phosphor $\mathrm{BaF}(\mathrm{Br,l}\mathrm{):}{\mathrm{Eu}}^{\text{2+}}$ has been investigated and compared with x-ray film. Evaluation of detective quantum efficiency (DQE), sensitivity, dynamic range, and linearity was carried out for several types of commercially available image plate, using the Excalibur soft x-ray calibration facility at AWE. Image plate response was found to be linear over a dynamic range of 5 orders of magnitude. One type of image plate was found to have a number of advantages for soft x-ray detection, with a measured sensitivity 1 order of magnitude greater than that of Kodak Industrex CX and DEF-5 x-ray film. The DQE of this plate was found to be superior to that of film at low [less than ${10}^3\hspace{0.5em}\mathrm{photons}\text{/(50\hspace{0.5em}μ}\mathrm{m}{)}^2$ ] and high fluxes [greater than ${10}^4\hspace{0.5em}\mathrm{photons}\text{/(50\hspace{0.5em}μ}\mathrm{m}{)}^2$ ]. The spatial resolution of image plates, scanned with several models of commercial image plate readers, has been evaluated using a USAF resolution test target. The highest spatial resolution measured is $\text{35\hspace{0.5em}μ}\mathrm{m}$ . Though this is significantly lower than the resolution possible with film, it is sufficient for many applications. Image plates were fielded in a refractive x-ray lens imaging diagnostic on the 1 TW Helen laser and these results are discussed.