The facility is compact (just 8 m x 14 m). Thanks to an innovative optical design based on an asymmetrical-cut crystal associated with a paraboloidal grazing incidence mirror, it can produce an expanded X-ray beam (170 mm x 60 mm) with low divergence (about 2 arcsec measured for the 4.51 keV beamline) at the two monochromatic energies of 4.51 keV and 1.49 keV. This allows us to calibrate each SPO MM's Effective Area and Point Spread Function precisely.
The first beamline, at 4.51 keV photon energy, is already operational, as the commissioning was completed in Q1-2023. The second beamline, at 1.49 keV energy, is being developed. It presents some more challenging aspects from both the design and implementation points of view. The monochromator stage is based on two Quartz (100); two ADP asymmetric-cut crystals (101) will provide the horizontal expansion of the beam. The X-ray source needs to be very brilliant (5 x 1011 - 1012 ph/s/sterad) due to the large fraction of photons rejected by the crystals.
This paper describes the ongoing activities. It will present the results of the 4.51 keV X-ray beamline optimization and the tests performed on a coated MM. It will also describe the progress in implementing the 1.49 keV components and discuss the comparison with other X-ray testing facilities.
To overcome these limitations, we started in 2012 to design a facility aimed at generating a broad (170 x 60 mm2), uniform and low-divergent (1.5 arcsec HEW) X-ray beam within a small lab (∼ 9 x 18 m2), to characterize the ATHENA MM. BEaTriX (the Beam Expander Testing X-ray facility) makes use of an X-ray microfocus source, a paraboloidal mirror, a crystal monochromation system, and an asymmetrically-cut diffracting crystal for the beam expansion. These optical components, in addition to a modular low-vacuum level (10-3 mbar), enable to match the ATHENA SPO acceptance requirements.
The realization of this facility at INAF-OAB in Merate (Italy) is now on going. Once completed, BEaTriX can be used to test the Silicon Pore Optics modules of the ATHENA X-ray observatory, as well as other optics, like the ones of the Arcus mission. In this paper we report the advancement status of the facility.
In this paper we present the tests performed so far, giving a first assessment on the deterministic process definition. In particular, we report on the results achieved on flat samples of D263 and Eagle glass, focusing on the removal function characterization, the micro-roughness evolution and the plate shape variation.
Future high energy astrophysics missions will require high performance novel X-ray optics to explore the Universe beyond the limits of the currently operating Chandra and Newton observatories. Innovative optics technologies are therefore being developed and matured by the European Space Agency (ESA) in collaboration with research institutions and industry, enabling leading-edge future science missions.
Silicon Pore Optics (SPO) [1 to 21] and Slumped Glass Optics (SGO) [22 to 29] are lightweight high performance X-ray optics technologies being developed in Europe, driven by applications in observatory class high energy astrophysics missions, aiming at angular resolutions of 5” and providing effective areas of one or more square meters at a few keV.
This paper reports on the development activities led by ESA, and the status of the SPO and SGO technologies, including progress on high performance multilayer reflective coatings [30 to 35]. In addition, the progress with the X-ray test facilities and associated beam-lines is discussed [36].
Silicon Pore Optics is an enabling technology for future L- and M-class astrophysics X-ray missions, which require high angular resolution (~5 arc seconds) and large effective area (1 to 2 m2 at a few keV). The technology exploits the high-quality of super-polished 300 mm silicon wafers and the associated industrial mass production processes, which are readily available in the semiconductor industry. The plan-parallel wafers have a surface roughness better than 0.1 nm rms and are diced, structured, wedged, coated, bent and stacked to form modular Silicon Pore Optics, which can be grouped into a larger optic. The modules are assembled from silicon alone, with all the mechanical advantages, and form an intrinsically stiff pore structure.
The optics design was initially based on long (25 to 50 m) focal length X-ray telescopes, which could achieve several arc second angular resolution by curving the silicon mirror in only one direction (conical approximation).
Recently shorter focal length missions (10 to 20 m) have been discussed, for which we started to develop Silicon Pore Optics having a secondary curvature in the mirror, allowing the production of Wolter-I type optics, which are on axis aberration-free.
In this paper we will present the new manufacturing process, the results achieved and the lessons learned.
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