<title>Detection of 1-100 keV x rays from high-intensity 500-fs laser-produced plasmas using charge-coupled devices</title>

Abstract

We describe a compact, vacuum compatible, large format, charge-coupled device (CCD) camera for scientific imaging and detection of 1 - 100 keV x-rays in experiments at the Lawrence Livermore National Laboratory JANUS-1 ps laser. A standard, front-illuminated, multi-pin phase device with 250 k electron full well capacity, low dark current (10 pA/cm<SUP>2</SUP> at 20 degree(s)C) and low read noise (5 electrons rms) is cooled to -35 degree(s)C to give the camera excellent 15-bit dynamic range and signal-to-noise response. The intensity and x-ray energy linear response have been determined for optical and x-ray (&lt; 65 keV) photons and are found to be in excellent agreement. Departure from linearity has been measured to be less than 0.7%. The inherent linearity and energy dispersive characteristics of CCD cameras are well suited for hard x-ray photon counting techniques in scientific applications. X-rays absorbed within the depletion and field-free regions can be distinguished by studying the pulse height spectrum. Results are presented for the detection of 1 - 100 keV Bremsstrahlung continuum, K-shell and L-shell fluorescence spectra emitted from high intensity (10<SUP>18</SUP> W cm<SUP>-2</SUP>), 500 fs laser-produced plasmas.