X-ray Instruments

1. Development of precision hard X-ray multilayer optics with sub-arcminute performance X-ray Instruments Science Goals Columbia Astrophysics LaboratoryJim Chonko, Chuck Hailey, Jason Koglin, Mike Sileo, Marcela Stern, David Windt, Haitao Yu Caltech Space Radiation LaboratoryHubert Chen, Fiona Harrison Danish Space Research InstituteFinn Christensen, Carsten Jensen Lawrence Livermore National LaboratoryBill Craig, Todd Decker, Kurt Gunderson • Non-focusing Detectors: • Previous instruments for hard X-rays: coded aperture (e.g. GRATIS) and collimated. • Detector background determines the minimum detectable X-ray flux. • Detector area @Collecting area • Imaging and spectroscopy of 44Ti emissions in young Supernova remnants • Sensitive observations of obscured Active Galactic Nuclei (AGN) • Spectroscopic observations of accreting high-magnetic field pulsars • Mapping the Galactic Center NASA/CXC/SAO/Rutgers J.Hughes NASA/CXC/SAO H. Marshall et al. • Focusing Telescopes: • Soft X-ray telescopes (e.g., ASCA, Chandra) focus via total external reflection. • aCritµ 1/EnergyÞ very small incidence angles are required for hard X-rays. • Detector area << Collecting area • Improved imaging capability F. R. Harnden (CfA) Correspondence: koglin@astro.columbia.edu, http://astro.columbia.edu/~koglin This work is supported in part by several NASA grants. NASA/CXC/SAO GRANAT Þ A new generation of hard X-ray telescopes using focusing optics are required to dramatically improve the sensitivity and angular resolution at energies above 10 keV Multilayer Coatings Thermally Formed Glass • Enhanced reflectivity from multiple interfaces of two materials with large optical contrast (e.g. W/Si). Optics Assembly Approach • Broad-band energy response by using a range layer thicknesses. • Glass microsheets (originally developed for the flat panel industry) are positioned on a Quartz mandrel in a commercially available oven. • As the oven is headed, the glass slowly assumes the large scale figure of the mandrel • The process is terminated just before it touches the mandrel by decreasing the oven temperature. • Near net shaped optic substrates are produced without perturbing the excellent initial X-ray properties of the glass micro-sheet (~3.5 Åroughness), even without the aid of highly polished and very expensive mandrels. • The formed shells are cut to the appropriate size – this also removes the curled edges • Graphite spacers are epoxied onto a mandrel and machined to the correct radius and angle. • Coated glass substrates are epoxied to the spacers. • After epoxy cure, the next layer of spacers is epoxied to the previous layer of glass. • These spacers are machined and another layer of glass is epoxied to the spacers. • In a similar way, subsequent layers are added to the optic. Prototype Development Assembly Metrology • Several prototypes were built in two-bounce configurations with various size and thickness of AF45 and D263 glass – segments were cut to either 5 or 10 cm long and ~5 cm arclength (~35°). • Sample LVDT measurements are shown for each type of glass • The results of X-ray pencil beam scans are also shown for each prototype with the Half Power Diameter (HPD) indicated. • The individual performance results for the 34 segments in the 10 cm x 300 mm prototype are histogramed – this length and type of substrate has been adopted for HEFT. • The 200 mm thick glass meet the Con-X HXT angular resolution requirement – in addition, these substrates are light enough to meet the severe weight restriction of this mission. • The performance of our thermally formed substrates is largely limited by axial bows that are introduced in the forming process – in this way, shorter segments yield improved performance. The Spacers are machined very flat and uniform. The ~1.5 mm peak to valley spacer roughness is typically on a millimeter length scale, much shorter than the scale at which the glass can be deformed. The conformance of the glass directly on top of these spacers is superb (24" figure). Much of this can be attributed to the intrinsic figure of the substrate (~60") and not to errors in the assembly process, which is estimated to be only 8". 10 cm long, 200 mm thick substrates 10 cm long, 300 mm thick substrates 5 cm long, 300 mm thick substrates Metrology Techniques A two-bounce prototype optic with three full layers was built & characterized with three separate metrology techniques – LVDT surface metrology, & X-ray pencil beam scans, full illumination with UV – all yielded consistent results.