CCD imaging from 20 eV to 8 keV

Abstract

Pulsed x‐ray diagnostics operating in the kilovolt and sub‐kilovolt regimes are required in the study of x‐ray laser schemes. Sensitivity and dynamic range measurements are presented for position‐sensitive detector systems, designed and optimized for these spectral regions. Both systems employ cooled, multi‐pinned phase CCD’s for image capture. For photon energies from 20 eV to 1 keV (where direct detection with front illuminated devices is inadequate), a phosphor transducer is used, coupled to the CCD via a fiber optic faceplate with 6 μm diameter channels. From 800 eV to 8 keV, direct detection of electron‐hole pairs generated in the depletion region of the CCD is employed. The systems have been tested with single‐shot sensitivity using a 10 Hz, 2J/7⋅5 ns injection seeded Nd:YAG laser operated at 2ω, using Bragg crystal and flat field grazing incidence spectrometers to monitor the resonance emission from aluminium and carbon targets irradiated at ∼1012 W cm−2. At 182 Å, the sensitivity and dynamic range are enhanced with respect to that for a standard photographic detector, by factors of 8 and 300 respectively. An absolute calibration of the 700 eV–8 keV detector system performed at 1.6 keV, has been shown to agree with a calculation of sensitivity based on photo‐absorption data. For this system, the enhancement in sensitivity and dynamic range over direct exposure x‐ray film is 175 and 43 respectively.