Model Payload
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Figure 3: Prototype XOU X-ray optic – courtesy Cosine Research |
The mirror is the heart of XEUS and its very challenging requirements called for the development of new technology. This exciting development is high-precision pore optics. The new optics is manufactured using highly polished and flat silicon wafers. These wafers are produced as standard items by industry and have a surface finish and figure perfect for X-ray optics. Following pore production, the processed wafers are assembled into stacks using a conical mandrel in an approximation to Wolter I geometry. As each wafer is bent and introduced into the stack it is bonded to the previous wafer. Up to 100 wafers are integrated to form a complete High-Performance Optic (HPO). Pairs of HPOs are then assembled into a tandem pair or X-ray Optical Unit (XOU). Each XOU is then positioned and aligned in a module, which together form an optic with a single X-ray focus.
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Figure 4: Pencil beam measurements of the first prototype XOU showing the very encouraging spatial resolution |
Figure 4 shows the synthesized PSF for the first prototype XOU derived from pencil beam measurements. A local effective HEW of 3.8 arcsec is very encouraging when compared with the requirement of 3.7 arcsec. The result displayed is not definitive because the prototype does not include high-Z coating or tapering to give a conical approximation to a Wolter Type I geometry. However, the signs are very encouraging and indicative that the intrinsic error allocation can be met. Further development and testing is continuing to fully explore the limiting resolution performance of the XOUs.
The model payload consists of:
- Cryogenic Imaging Spectrometer
A TES microcalorimeter array with a FOV of 40" diameter and an energy resolution, ∆E, of 2-6 eV.
- Wide Field Imager
A silicon active pixel sensor with a FOV of 7' diameter ∆E = 150 eV at 6 keV and a limiting sensitivity of 3x10-18 erg cm-2s-1 (0.2-2 keV)
- Hard X-ray Camera
Confocal CdTe and Si strip detectors to extend the energy range to 40 keV with a FOV of 5' x 5'
- High-Time Resolution Spectrometer
A non-imaging spectrometer that provides 10 μs timing at count rates of 2x106 s-1 and ∆E 30-140 eV
- X-ray Polarimeter
An imaging gas pixel detector providing 2% MDP at 3σ confidence for 10 mCrab source in 10 ksec.
To investigate the performance of the instruments please use the XSPEC response and background files available at ftp://ftp.rssd.esa.int/pub/XEUS/RESPONSE/ and ftp://ftp.rssd.esa.int/pub/XEUS/BACKGROUND/
Last Update: 1 September 2019
