Caliste 64, an Innovative CdTe Hard X-Ray Micro-Camera

Abstract

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A prototype 64 pixel miniature camera has been designed and tested for the Simbol-X hard X-ray observatory to be flown on the joint CNES-ASI space mission in 2014. This device is called Caliste 64. It is a high performance spectro-imager with event time-tagging capability, able to detect photons between 2 keV and 250 keV. Caliste 64 is the assembly of a 1 or 2 mm thick CdTe detector mounted on top of a readout module. CdTe detectors equipped with Aluminum Schottky barrier contacts are used because of their very low dark current and excellent spectroscopic performance. Front-end electronics is a stack of four IDeF-X V1.1 ASICs, arranged perpendicular to the detection plane, to read out each pixel independently. The whole camera fits in a 10<formula formulatype="inline"><tex>$\,\times\,$</tex></formula>10<formula formulatype="inline"> <tex>$\,\times\,$</tex></formula>20 <formula formulatype="inline"><tex>${\rm mm}^{3}$</tex></formula> volume and is juxtaposable on its four sides. This allows the device to be used as an elementary unit in a larger array of Caliste 64 cameras. Noise performance resulted in an ENC better than 60 electrons rms in average. The first prototype camera is tested at <formula formulatype="inline"> <tex>$-10^{\circ}{\rm C}$</tex></formula> with a bias of <formula formulatype="inline"> <tex>$-400~{\rm V}$</tex></formula>. The spectrum summed across the 64 pixels results in a resolution of 697 eV FWHM at 13.9 keV and 808 eV FWHM at 59.54 keV. </para>