CAOSP abstracts, Volume: 48, No.: 3, year: 2018

Abstract: ESA's next large X-ray mission Athena will be equipped with two focal plane cameras, a Wide Field Imager (WFI) and an X-ray Integral Field Unit (X-IFU). The WFI instrument is designed for imaging and spectroscopy over a large field of view, and high count rate observations up to and beyond 1 Crab source intensity. Both cameras share alternately a mirror system based on silicon pore optics with a focal length of 12 m and an unprecedented large effective area. Main scientific requirements for WFI are described here and the corresponding conceptual design to meet them. The instrument employs active pixel sensors of DEPFET type, which are fully depleted, back-illuminated silicon devices of 450 μm thickness. In combination with front-end electronics ASICs tailored to the project, the resulting detectors provide high quantum efficiency over the 0.2 keV to 15 keV range with state-of-the art spectral resolution and extremely fast readout speeds compared to previous generations of Si detectors for X-ray astronomy. The focal plane comprises a Large Detector Array (LDA) with over 1 million pixel of 130 μm × 130 μm size, providing oversampling of the PSF by a factor >2 over the 40 arcmin × 40 arcmin large field of view, complemented by a smaller Fast Detector (FD) optimized for high count rate applications.